Synthesis of 3-O-propargylated betulinic acid and its 1,2,3-triazoles as potential apoptotic agents

Article abstract of DOI:10.1016/j.ejmech.2013.03.028

Cytotoxic agents from nature are presently the mainstay of anticancer chemotherapy, and the need to reinforce the arsenal of anticancer agents is highly desired. Chemical transformation studies carried out on betulinic acid, through concise 1,2,3-triazole

Full text of DOI:10.1016/j.ejmech.2013.03.028

European Journal of Medicinal Chemistry 63 (2013) 782e792
Contents lists available at SciVerse ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis of 3-O-propargylated betulinic acid and its 1,2,3-triazoles
as potential apoptotic agents
,
,
a
a
Rabiya Majeed a b, Payare L. Sangwan a , Praveen K. Chinthakindi , Imran Khan ,
*
Nisar A. Dangroo a, Niranjan Thota a, Abid Hamid b , Parduman R. Sharma ,
,
b
*
Ajit K. Saxena b, Surrinder Koul a
,
*
a Bioorganic Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road Jammu, Jammu and Kashmir 180001, India
b Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road Jammu, Jammu and Kashmir 180001, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Cytotoxic agents from nature are presently the mainstay of anticancer chemotherapy, and the need to
reinforce the arsenal of anticancer agents is highly desired. Chemical transformation studies carried out
on betulinic acid, through concise 1,2,3-triazole synthesis via click chemistry approach at C-3position in
ring A have been evaluated for their cytotoxic potentiation against nine human cancer cell lines. Most of
the derivatives have shown higher cytotoxic profiles than the parent molecule. Two compounds i.e. 3
{1N(2-cyanophenyl)-1H-1,2,3-triazol-4yl}methyloxy betulinic acid (7) and 3{1N(5-hydroxy-naphth-1yl)-
Received 1 December 2012
Received in revised form
11 March 2013
Accepted 16 March 2013
Available online 26 March 2013
1H-1,2,3-triazol-4yl}methyloxy betulinic acid (13) displayed impressive IC50 values (2.5 and 3.5
mM
Keywords:
Betulinic acid 1,2,3-trizole derivatives
Click chemistry
Cytotoxicity
DNA fragmentation
Apoptosis
respectively) against leukemia cell line HL-60 (5e7-fold higher potency than betulinic acid). As evident
from various biological end points, inhibition of cell migration and colony formation, mitochondrial
membrane disruption followed by DNA fragmentation and apoptosis, is demonstrated.
Ó 2013 Elsevier Masson SAS. All rights reserved.
1. Introduction
in xenograft mouse models for its cytotoxic effect against primary
cancer cells isolated tumor specimens obtained from glioblastoma
Natural products (NPs) and the molecules based on NP scaffolds
being the proven source of therapeutic agents have increasingly
attracted the interests of researchers involved in the area of cancer
therapy. In fact, the majority of anticancer and anti-infectious
agents are of natural origin [1]. Pentacyclic triterpenoid class of
compounds is found pharmacologically active scaffold, and pro-
vides privileged motifs for further modifications and structure ac-
tivity relationship (SAR) analyses [2,3]. To date several reports are
available wherein simple or advanced modifications have been
performed for the desired biological properties [4e7]. Betulinic
acid, a naturally occurring lupane triterpenoid is reported to exhibit
anti-cancer, antibacterial and anti-HIV activities [7,8]. The induc-
tion of cytotoxicity involves modulation of Bcl-2 family, cell cycle
and leukemia [10] and the molecule is currently undergoing clinical
study at national cancer institute (NCI) [11].
In continuation of our interest involving structural modification
of natural products [12,13] for better efficacy, lesser toxicity, betu-
linic acid was chosen for chemical modification targeting position-
3 of ring A, one of the hot spots of the molecule (Fig. 1) in a bid to
arrive at a more potent analog having some possible clinical utility
and application. Triazole compounds in biological system show
binding ability with a variety of enzymes and receptors via diverse
non-covalent interactions and display versatile biological activities
and many of them have been identified as clinical drugs or candi-
dates for the treatment of various types of diseases [14e16]. These
have shown their large development value and wide potential as
therapeutic agents such as anti-infective, anticancer, antiviral, and
anti-hypertensive agents. In the present paper, the preparation of
C3-aryl substituted 1,2,3-triazoles of betulinic acid and their cyto-
toxic profiles is described.
regulatory proteins, regulation of the nuclear factor kappa B (NFkB),
as well as inhibition of aminopeptidase N, and growth factor-
induced angiogenesis [9,10]. The NP has been extensively studied
2. Result and discussion
* Corresponding authors. Tel.: þ91 191 2569021; þ91 191 2569001 to 11x232/
371; fax: þ91 191 2569333.
Betulinic acid (1) is reported as cytotoxic against several human
cancer cell lines with IC50 > 40 baring one or two cell lines where
E-mail addresses: plsangwan@iiim.ac.in (P.L. Sangwan), ahdar@iiim.ac.in
(A. Hamid), skoul@iiim.ac.in (S. Koul).
0223-5234/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2013.03.028

R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
783
N2Cl
NH2
N3
29
HCl/NaNO2
NaOAc
NaN3
30
20
R1
R1
R1
19
17
22
25
26
13
27
1
O
COOH
28
O
N3
OH
AcO
HBr/AcOH
NaN3/DMF
AcO
10
8
3
HO
Scheme 2. Synthesis of substituted aryl azides and acetylated sugar azides.
23
24
Fig. 1. Chemical structure of betulinic acid.
assess their cytotoxic potential using sulforhodamine B (SRB) assay.
In the primary screening of these compounds against cancer cell
lines at 50 mM concentration for 48 h, most of the cell lines were
single digit IC50 value is observed [8,10]. The molecule offers several
hot spots (e.g. C-3, C-20 and C-28) to provide enough space for
chemical modification (Fig. 1). We selected C-3 site as this center is
shown to play a lesser role in anti-cancer activity compared to other
two important sites [8]. One of the goals of cancer chemotherapy is
to explore and develop discovery leads that can selectively induce
apoptosis in cancer cells [17]. The strategy envisaged in the present
study involved the prologue of nitrogen atom to generate mole-
cules bearing heterocyclic moiety. To achieve this, preparation of
1,2,3-triazole derivatives was undertaken and click chemistry
strategy was adopted on the 3-propargyloxy betulinic acid (2)
(prepared as per Scheme 1) and made to react with appropriate
azide (prepared as per Scheme 2). A library of 18 triazoles de-
rivatives bearing structural diversity were thus prepared (Scheme
1) and their chemical identity established by spectral analysis.
The overall chemical yields of the synthesized compounds ranged
from 92 to 98%.
found to be sensitive to betulinic acid and its derivatives with many
of them exhibiting ꢀ90 inhibition against various cancer cell lines
(Table S1). The sensitivity of the cell lines was also tested at 30 mM
and 10 mM concentration. At 10 mM concentration, betulinic acid did
not sensitize any of the cancer cell line. However, many of its de-
rivatives produced concentration dependent growth inhibition ef-
fect on several cancer cell lines. Triazole derivatives 5, 7,13,15,17,18
(HL-60 only) and 19 at lowest concentration (10 mM), effected THP-
1 and HL-60 the most among all the cell lines tested. Compounds 7,
13, 15, 17, and 19 were able to cause maximum inhibition (60e65%)
of cell proliferation against HL-60 compared to THP-1 where the
effect was only 50e55%. For liver (HEP-2) cancer cell line, only two
compounds 5 and 20 were able to sensitize the liver cell line at
10
mM, and maximum inhibition of 71% was observed for com-
pound 20. For lung (A-549) cell line, only three compounds (5, 7,
and 17) showed cytotoxic effects with maximum effect displayed
by 7 (60% inhibition). Among prostate (DU-145) and breast (MCF-7)
cancer cell lines, baring compound 12 which showed inhibition
(70%) against MCF-7, the rest of the compounds failed to exhibit any
significant inhibitory effect. In case of CNS cell line, only compound
Compound 1 and its derivatives (3e20) were screened against a
panel of nine human cancer cell lines namely A-549, PC-3, DU-145,
SF-295, MCF-7, THP-1, HCT-15 and HL-60 cells (Table S1, Fig. S1) to
COOH
RN3, t-BuOH:H2O (1:1)
Br
COOH
COOH
CuSO4, Sod. Ascorbate
N
NaH, Dry THF,
O
N
O
HO
RT, 76%
N
R
2
3-20
1
OH
HO
OMe
CN
MeO
CH2CN
CN
4
7
9
3
6
8
5
OMe
O
AcO
AcO
OAc
MeO
MeO
O
I
R =
HO
AcO
15
OH
14
12
13
10
11
Cl
OAc
O2N
I
O
O
O
AcO
AcO
AcO
19
17
16
18
20
Scheme 1. Propargylation of betulinic acid 1 and preparation of its 1,2,3-trizole derivatives.

784
R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
19 showed cytotoxic effect displaying 52% inhibition (at 10
concentration). For colon cancer cell line, only compounds 3 and 4
exhibited cytotoxic effect (10 M conc.) with latter displaying
m
M
30
minimal concentration inducing DNA fragmentation was observed
20 M (Fig. 2, Sections 1 and 3). Camptothecin used as a positive
control showed fragmentation of DNA in HL-60 cells after treat-
ment of cells with 5 M camptothecin for 6 h. DNA isolated from
untreated and treated normal monkey kidney CV-1 cells did not
show any DNA ladder (Fig. 2, Sections 2 and 4) confirming the effect
of the molecules specific only for cancer cells sparing the normal
cells.
In addition, the effect of 7 and 13 on mitochondrial functioning
was also demonstrated and found responsible for the disruption of
mitochondrial membrane along with subsequent loss of mito-
chondrial membrane potential (DJm) in a concentration depen-
dent manner (Fig. 3).
In further study, the clonogenic assay was performed using
another leukemia cell line i.e. THP-1 cells which is an adherent
cell line so that the colonies could be visualized. Both 7 and 13
produced concentration dependent inhibitory effect on the ability
of the cells to reproduce and form large colonies. With respect
to the untreated control, the number of colonies formed at
lower concentrations of 7 and 13 was comparable but at higher
concentration the number of colonies formed was negligible
(Fig. 4a and b).
Further in vitro cell migration assay was performed in order to
analyze the capacity of tumor cells to degrade the extracellular
matrix proteins, compounds of the basement membrane and sur-
rounding tissues. Such capacity could be directly correlated with
the metastatic potential of tumor cells [19]. Cell cultures treated
with 7 and 13 were photographed and cell migration was assessed
by comparing the gap sizes between the control and the treatment
wells. Representative photomicrographs of tumor cell migration
were taken and as depicted in the respective figures, the wound got
completely healed in the control wells at the lower concentration of
7 and 13 but at higher concentration the numbers of invasive cells
that penetrated the respective wound were inhibited and cell
migration got significantly stopped due to the inhibitory effect of
the 7 and 13 on cell migration and invasion (Fig. 5a and b). The
above study conclusively established the apoptotic character of 7
and 13. However, kinetic and in vivo studies in the preclinical
models need to be explored in order to ascertain their therapeutic
potency.
mM. The laddering pattern was concentration dependent and the
m
m
marginally better activity profile (Fig. S1, Table S1).
Though no clear cut structure activity relationship (SAR) could
be established, some inferences could still be drawn. Monoalkyloxy
(9) and hydroxymethyl (3 and 5) analogs in general showed better
cytotoxic effect than the parent and di- as well as trialkyloxy
compounds (16 and 10). Among ortho- and para-cyano (7 and 8)
isomers, better inhibitory effect was observed for compound 7.
Similar type of effect was also observed for the derivatives bearing
phenolic group in the aryl part of the molecules with compound 13
showing maximum inhibitory effects (Table S1). Halogen bearing
aryl moiety also showed significant inhibitory effect similar to that
of compound 7.
With the advantage of having more potent compounds than
betulinic acid, their IC50 values were determined along with betu-
linic acid (1) against cancer cells of different tissue origin (50%
growth inhibition) by plotting the graph between concentration vs
growth inhibition (Table 1).
m
In leukemia cancer cell lines promising IC50 values 2.5, 4.5, 5.5,
5.5, 7, 8, and 8
and 4 respectively against HL-60, similarly promising IC50 values
4.5, 8, and 9 M were also observed for compounds 7, 13, and 19
mM were observed for compounds 7, 13, 19, 15, 17, 5,
m
respectively against THP-1. Among all the cell lines, leukemia cells
(HL-60 and THP-1) proved most sensitive toward the semi-
synthetic analogs in particular compounds 7 and 13 showed
maximum cytotoxic effect and were chosen for further detailed
study. To verify whether the cancer cell death induced by 7 and 13
was apoptotic, as it has now become increasingly evident that
although the primary intracellular targets and the pharmacological
mechanisms of action of the anti-cancer drugs vary vastly, the drug
induced cell killing is generally mediated by apoptosis [18]. Both
compounds were found potent apoptosis inducers, as proved by the
measurement of DNA fragmentation. The apoptotic potential of the
two cytotoxic agents was further confirmed through the induction
of DNA fragmentation in HL-60 cells. Apoptosis typically involves
intra-nucleosomal chromatin cleavage by endonucleases in multi-
ples of 180 bp leading to a typical DNA ladder. Both the molecules
induced this laddering pattern at a concentration of 20 mM and
3. Conclusion
Table 1
IC50 values in
lines.
mM of betulinic acid and its analogs on the panel of human cancer cell
The overall results showed high potency of two semi-synthetic
derivatives 7 and 13 along with substantial evidence for their
apoptotic mode of action against HL-60 and THP-1 cancer cell lines.
In addition, the induction of apoptosis by these molecules is evi-
denced by the loss in mitochondrial membrane potential and
appreciable DNA fragmentation. Inhibition of cell migration and
inhibitory effect on the ability of the cells to reproduce and form
large colonies further substantiated our findings. These studies
provide sufficient evidences to advance the compounds (7 and 13)
for in vivo testing in models of human leukemia.
Compound Leukemia
Prostate
Liver Breast Lung CNS
Colon
THP-1 HL-60 DU-145 PC-3 HEP-2 MCF-7 A-549 SF-295 HCT-15
1
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
20 17
15 10
22
16
48
23
23
37 16
49 14
49 23
37
10
14
17
12
31
14
50
32
25
22
17
44
53
13
15
48
32
27
12
10
8
25
46
20
>50
26
>50
>50
26
15
>50
28
50
13
27
28
39
10
10
8
7
50
8
12 11
4.5 2.5
>50 32
47 37
39 37
22 18
18 14
32 13
14 12
18
4.8
5
>50
>50
>50
39
28
14
>50 32
>50 29
>50 >50
>50 >50
13 >50
16 13
>50 >50 >50
>50 40
43 26
43 44
49
12
10
27
3.8
9
>50
>50
>50
23 >50
26
16
36 >50
>50 >50
>50
8
4. Experimental
19
25
8
3.5
44 40
50
34 30
4.1. Chemistry
50
5.5 >50
45
13
15
All reagents used for chemical synthesis were purchased from
SigmaeAldrich. Solvents used were distilled before use. The prog-
ress of all reactions were monitored by TLC on silica gel 60 F254
plates (E. Merck) using 2% ceric ammonium sulfate solution for
detection of the spots. Purification of the products was carried out
by column chromatography. All NMR spectra (1H NMR and 13C
30
34
>50
24
18
>50
10
20
9
5.5
8
4.5
>50 >50 >50
13 15
39 3.8
>50 >50
15
>50
38
8
8
44
46 43
25
Bold values are shown for those compounds bearing single digit IC50 value.

R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
785
Fig. 2. Compounds 7 and 13 induced DNA fragmentation in HL-60 cells. Cells 2 ꢁ 106/mL/well were treated with indicated concentration of 7 and 13 for 24 h. Data are repre-
sentative of one of two similar experiments. In Sections 1 and 3, HL-60 cells and in Sections 2 and 4, normal monkey CV-1 cells treated with 7 and 13.
NMR) were recorded on Bruker DPX 200, DPX 400 and DPX 500
instruments using CDCl3 as solvent with TMS as internal standard.
4.1.1. Isolation of betulinic acid (1)
Betulinic acid was isolated in bulk quantity from 90% ethanolic
extract of the stem bark of Platanus orientalis (duly authenticated by
the Taxonomist of our institute). Betulinic acid used in the present
study was isolated by repeated column chromatography over silica
gel in 15% EtOAc in petroleum ether. Further purification was car-
ried out by crystallization. Purity was obtained >97% which was
well characterized by spectroscopic study (data were found in
agreement with reported in literature) [8].
Chemical shifts are expressed in
d and coupling constant in Hertz.
High resolution mass spectra (HRMS) were recorded on Agilent
Technologies 6540 instrument and mass spectra were recorded on
ESI-esquire 3000 Bruker Daltonics instrument. IR recorded on an
FT-IR Bruker (270-30) spectrophotometer. Melting points (uncor-
rected) of compounds were recorded on Buchi melting point
apparatus B-542.
Fig. 3. Compounds 7 and 13 induced loss of mitochondrial membrane potential (DJm) in HL-60. Cells (6 ꢁ 104/mL/well) incubated with 7 and 13 at different concentrations in
6 well plates for 24 h. Before 30 min of the completion of the experiment cells were treated with Rodamine-123 (1 mM) in serum free media. Cells were washed with PBS,
centrifuged, finally suspended in 1 mL of PBS and analyzed under confocal microscopy. Data are representative of one of two similar experiments.

786
R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
Fig. 4. THP-1 cells were seeded in 6 well plates. After 24 h the cells were treated with indicated concentrations of 7 and 13 for 24 h. After the completion of the treatment the plates
were placed in an incubator for a time equivalent to at least six potential cell divisions (to give colonies of >50 cells). After fixation the cells were stained with 0.5% crystal violet for
30 min and allowed to dry at room temperature.
4.1.2. Preparation of 3-O-propargyl-betulinic acid (2)
followed by evaporation yellow syrup was obtained. This syrup was
dissolved in dry DMF and to the stirring mixture NaN3 was added.
The mixture was stirred at room temperature for 3 h. On comple-
tion, the reaction was worked up by usual method to give the azide
product. Further purification was carried out by re-crystallization in
methanol to yield pure azides.
The compound prepared by the propargylation of compound 1
(5.0 g, 11 mmol) using the propargyl bromide (2.2 g, 16 mmol)
and NaH in dry THF under nitrogen atmosphere for 24 h, after
usual work to give the propargylated product 2 colorless solid
(4.15 g, 76% yield), mp 223 ꢂC [20]. 1H NMR (200 MHz, CDCl3):
d
0.68 (1H, m, H-5), 0.75 (3H, s, H-25), 0.83 (3H, s, H-24), 0.88 and
1.61 (1H each, m, H-1), 0.93 (3H, s, H-26), 0.97 (6H, s, H-27 and H-
23), 1.17 and 2.43 (1H each, m, H-11), 1.21 and 1.99 (1H each, m, H-
12), 1.27 and 1.94 (1H each, m, H-15), 1.34 and 1.51 (1H each, m,
H-6), 1.36 and 1.41 (1H each, m, H-7), 1.37 and 2.14 (1H each, m,
H-21), 1.38 (1H, m, H-9), 1.47 and 2.20 (1H each, m, H-22), 1.46
and 2.25 (1H each, m, H-16), 1.61 (1H, m, H-18), 1.69 (3H, s, H-30),
1.74 (2H, m, H-2), 2.31 (1H, m, H-13), 2.35 (1H, s, eOCH2CCHe),
2.98 (2H, m, H-3, H-19), 4.20 (2H, m, eOCH2e), 4.61 and 4.74 (1H
4.1.5. General experimental procedure for preparation 1,2,3-triazoles
of betulinic acid (3e20)
The title compounds were prepared by the reaction of
substituted aryl and sugar azide (say 1 equiv), 3-O-propargyl-
betulinic acid (ꢀ1 equiv), CuSO4 (0.1 equiv) in t-BuOH:water (1:1)
mixture. Sodium ascorbate (0.5 equiv) was added to the reaction
mixture and the contents stirred vigorously at room temperature
for 2e8 h till completion of the reaction (monitored by TLC anal-
ysis) [20]. The reaction was worked up by dilution of the contents
with water and extraction with ethyl acetate (3 times). The com-
bined ethyl acetate extract was washed with brine solution, dried
over anhydrous Na2SO4 and evaporated under reduced pressure on
a rotavapor. The crude product obtained thus subjected was put to
column chromatography (silica gel) with EtOAc:Hexane (1:4)
mixture as eluent to afford the desired pure products in 92e98%
yields.
each, s, H-29). 13C NMR (100 MHz, CDCl3):
d 182.10, 150.43, 109.69,
85.88, 80.96, 73.42, 56.42, 56.42, 55.93, 50.49, 49.31, 46.93, 42.43,
40.74, 38.61, 38.57, 38.44, 37.17, 37.06, 34.34, 32.18, 30.60, 29.70,
28.00, 25.53, 22.69, 20.89, 19.40, 18.22, 16.17, 16.10, 16.04, 14.12. IR
gmax (neat): 3434, 3310, 2942, 2868, 1713, 1453, 1317, 1149, 1123,
1043, 1009, 983, 885 cmꢃ1. MS (%) for C33H50O3 at m/z 495.7497
[M þ 1]þ 495 (19.3), 477 (5.3), 429 (4.3), 379 (29.0), 360 (22.5),
341 (24.7), 317 (67.7), 350 (21.0), 299/300 (21.0), 279 (100),
250 (15), 228 (19), 205 (24), 202 (34), 148 (23.6), 110 (19.6), 80
(15). HRMS m/z calcd. for
found 495.38213.
C
33H50O3 [M
þ
H]þ 495.38327,
4.1.5.1. Synthesis of 3{1N(2-hydroxymethyl phenyl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (3). The title compound prepared by
the reaction of propargylated betulinic acid (100 mg, 0.2 mmol) and
1-azido-2-hydroxymethyl benzene (40 mg, 0.25 mmol) in t-
BuOH:water (1:1) mixture (5 mL) as per the method described in
Section 4.1.5 to furnish 3 colorless solid (117 mg, 97% yield), mp
4.1.3. General procedure for synthesis of aromatic azides
The aromatic azides are prepared (Scheme 2) by addition of 6 N
HCl solution to stirring dichloromethane solution of the appro-
priate amine at ꢄ0 ꢂC followed by drop wise saturated aqueous
solution of NaNO2 and the contents stirred for 30 min. To the re-
action mixture, added NaN3 stirred the contents for further 30 min.
The contents were allowed to attain room temperature, the two
phases were separated, and the aqueous phase extracted with
DCM. The combined organic layers were washed with aqueous
solution of NaHCO3, followed by then brine solution, dried over
sodium sulfate, filtered and concentrated under reduced pressure
to give the aryl azides which were used in the next step without
further purification.
215 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.65 (1H, m, H-5), 0.70 (3H, s,
H-25), 0.73 (3H, s, H-24), 0.74 (3H, s, H-26), 0.88 and 1.50 (1H each,
m, H-1), 0.94 (6H, s, H-23 and H-27), 1.13 and 1.85 (1H each, m, H-
11), 1.21 and 1.59 (1H each, m, H-12), 1.17 and 1.45 (1H each, m, H-
15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.41 (1H each, m, H-7),
1.27 and 1.68 (1H each, m, H-21), 1.18 (1H, m, H-9), 1.47 and 1.86 (1H
each, m, H-22), 1.46 and 2.15 (1H each, m, H-16), 1.49 (1H, m, H-18),
1.54 (2H, m, H-2), 1.69 (3H, s, H-30), 2.30 (1H, m, H-13), 2.96 (1H, m,
H-19), 3.16 (1H, m, H-3), 4.47 (2H, s, eCH2OH), 4.61 and 4.73 (1H
each, s, H-29), 5.29 and 5.36 (1H each, d, J ¼ 12.1 Hz, eOCH2e), 7.38
(1H, d, J ¼ 8.10 Hz, AreH), 7.48e7.53 (2H, m, AreH), 7.65 (1H, d,
J ¼ 8.11 Hz, AreH), 8.04 (1H, s, NeCH). 13C NMR (125 MHz, CDCl3):
4.1.4. General procedure for synthesis of 2,3,4,6-tetra acetyl sugar
azides
d
176.18,150.37,143.56,135.72,135.56,131.55,130.16,129.12,125.52,
2,3,4,6-Tetra acetyl sugar azides were prepared (Scheme 2) by
dissolving acetylated sugar in DCM and HBr in acetic acid was
added drop wise with stirring under inert conditions at 0 ꢂC. The
mixture was stirred for another 15 min and on usual workup
124.37, 109.78, 78.91, 61.69, 56.93, 56.59, 55.26, 50.43, 49.40, 46.96,
42.33, 40.63, 38.83, 38.67, 38.29, 37.12, 36.91, 34.18, 31.95, 30.53,
29.60, 27.97, 27.31, 25.44, 20.82, 19.34, 18.20, 16.06, 15.81, 15.38,
14.68. IR gmax (neat): 3413, 2938, 2856, 1720, 1638, 1617, 1465,

R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
787
Fig. 5. a. THP-1 cells were seeded in six wells plate. When a tight cell monolayer has formed a wound was created using a 1000
mL tip, cells were then treated with indicated
concentrations of compound 7. The number of cells that migrated toward the wound after the treatment was visualized using 10ꢁ objective Olympus. b. THP-1 cells were seeded in
six wells plate. When a tight cell monolayer has formed a wound was created using a 1000 L tip, cells were then treated with indicated concentrations of compound 13. The
number of cells that migrated toward the wound after the treatment was visualized using 10ꢁ objective Olympus.
m
1376, 1244, 1165, 1131, 1099, 1061, 1011, 886, 759 cmꢃ1. MS (%) for
C
(17.3), 612 (50), 595 (19.4), 571 (16.6), 554 (52.7), 545 (100), 539
(52.7), 452 (15), 201 (43), 102 (38). HRMS m/z calcd. for C40H57N3O4
[M þ H]þ 644.4422, found 644.4388.
1.13 and 1.87 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12),
40H57N3O4 at m/z 666.9045 [M þ Na]þ, 667 (7), 644 (100), 626
1.17 and 1.45 (1H each, m, H-15), 1.24 and 1.52 (1H each, m, H-6),
1.26 and 1.41 (1H each, m, H-7), 1.27 and 1.67 (1H each, m, H-21),
1.18 (1H, m, H-9), 1.47 and 1.89 (1H each, m, H-22), 1.46 and 2.12
(1H each, m, H-16), 1.51 (1H, m, H-18), 1.55 (2H, m, H-2), 1.69 (3H, s,
H-30), 2.29 (1H, m, H-13), 3.02 (1H, m, H-19), 3.16 (1H, m, H-3),
3.87 (3H, s, eOCH3), 4.60 and 4.73 (1H each, s, H-29), 5.25 and 5.34
(1H each, d, J ¼ 16.0 Hz, eOCH2e), 7.03 (2H, d, J ¼ 8.0 Hz, AreH),
7.62 (2H, d, J ¼ 8.0 Hz, AreH), 7.99 (1H, s, NeCH). 13C NMR
4.1.5.2. Synthesis of 3{1N(4-methoxyphenyl)-1H-1,2,3-triazol-4yl}
methyloxy betulinic acid (4). The title compound prepared by the
reaction of propargylated betulinic acid (115 mg, 0.23 mmol) and
1-azido-4-methoxy benzene (45 mg, 0.3 mmol) as per the method
described in Section 4.1.5 to furnish 4 colorless solid (145 mg, 98%
(100 MHz, CDCl3):
d 176.20, 159.93, 150.42, 143.70, 130.38, 122.57,
122.22, 114.76, 109.67, 78.92, 57.09, 56.55, 55.66, 55.29, 50.47,
49.51, 47.04, 42.33, 40.63, 38.83, 38.68, 38.37, 37.14, 36.87, 34.18,
31.99, 30.60, 29.71, 27.96, 27.36, 22.69, 20.85, 19.37, 18.21, 16.03,
16.01, 16.0, 14.65. IR gmax (neat): 3472, 2936, 2872, 1707, 1636, 1615,
yield), mp 238 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.62 (1H, m, H-5),
0.64 (3H, s, H-25), 0.72 (3H, s, H-24), 0.73 (3H, s, H-26), 0.87 and
1.51 (1H each, m, H-1), 0.90 and 92 (3H each, s, H-23 and H-27),

788
R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
1518, 1451, 1388, 1259, 1171, 1109, 1054, 1030, 834, 760 cmꢃ1. MS (%)
for C40H57N3O4 at m/z 644.9252 [M þ H]þ, 644 (100), 601 (11.5),
541 (7.6), 473 (18.4), 387 (13), 339 (17), 233 (16.9), 451 (26), 282
(46), 102 (13.8). HRMS m/z calcd. for C40H57N3O4 [M þ H]þ
644.4422, found 644.4387.
4.1.5.5. Synthesis
of
3{1N(2-cyanophenyl)-1H-1,2,3-triazol-4yl}
methyloxy betulinic acid (7). The title compound prepared by the
reaction of propargylated betulinic acid (100 mg, 0.2 mmol) and 2-
azido benzonitrile (40 mg, 0.27 mmol) as per the method described
in Section 4.1.5 to furnish 7 (120 mg, 95% yield), mp 243e245 ꢂC. 1H
NMR (400 MHz, CDCl3): d 0.65 (1H, m, H-5), 0.69 (3H, s, H-25), 0.73
4.1.5.3. Synthesis of 3{1N(3-hydroxymethylphenyl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (5). The title compound prepared by
the reaction of propargylated betulinic acid (125 mg, 0.25 mmol)
and 1-azido-3-hydroxymethyl benzene (45 mg, 0.3 mmol) as per
the method described in Section 4.1.5 to furnish 5 (151 mg, 94%
(3H, s, H-24), 0.74 (3H, s, H-26), 0.88 and 1.50 (1H each, m, H-1),
0.94 and 0.95 (3H each, s, H-23 and H-27), 1.09 and 1.85 (1H each,
m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and 1.45 (1H each,
m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.38 (1H each, m,
H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20 (1H, m, H-9), 1.47 and
1.86 (1H each, m, H-22), 1.46 and 2.14 (1H each, m, H-16), 1.49 (1H,
m, H-18), 1.54 (2H, m, H-2), 1.69 (3H, s, H-30), 2.29 (1H, m, H-13),
3.01 (1H, m, H-19), 3.17 (1H, m, H-3), 4.59 and 4.73 (1H each, s, H-
29), 5.31 and 5.36 (1H each, d, J ¼ 12.0 Hz, eOCH2e), 7.64 (1H, d,
yield), mp 250e252 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.61 (1H, m,
H-5), 0.63 (3H, s, H-25), 0.70 (3H, s, H-24), 0.71 (3H, s, H-26), 0.87
and 1.50 (1H each, m, H-1), 0.92 and 0.93 (3H each, s, H-23 and
H-27), 1.09 and 1.85 (1H each, m, H-11), 1.21 and 1.59 (1H each, m,
H-12), 1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m,
H-6), 1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m,
H-21), 1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46
and 2.09 (1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2),
1.67 (3H, s, H-30), 2.28 (1H, m, H-13), 3.01 (1H, m, H-19), 3.17 (1H,
m, H-3), 4.60 and 4.73 (1H each, s, H-29), 4.80 (2H, s, eCH2OH),
5.28 and 5.35 (1H each, d, J ¼ 12.1 Hz, eOCH2e), 7.44 (1H, d,
J ¼ 8.10 Hz, AreH), 7.50 (1H, dd, J ¼ 8.10, 8.0 Hz, AreH), 7.63 (1H,
d, J ¼ 8.0 Hz, AreH), 7.77 (1H, s, AreH), 8.11 (1H, s, NeCH). 13C
J ¼ 8.0 Hz, AreH), 7.82e7.89 (3H, m, AreH), 8.31 (1H, s, NeCH). 13
C
NMR (100 MHz, CDCl3):
d 175.99, 150.43, 144.14, 138.40, 134.41,
134.28, 129.67, 125.42, 129.53, 115.51, 109.66, 106.73, 78.93, 56.81,
56.59, 55.28, 50.48, 49.50, 46.93, 42.34, 40.67, 38.84, 38.68, 38.34,
37.15, 37.87, 34.20, 31.99, 30.58, 29.64, 27.96, 27.36, 25.48, 20.82,
19.38, 18.23, 16.04, 15.74, 15.37, 14.68. IR gmax (neat): 3506, 3401,
2945, 2870, 2231, 1719, 1638, 1609, 1463, 1376, 1249, 1175, 1109,
1042, 882, 843, 618 cmꢃ1. MS (%) for C40H54N4O3 at m/z 637.4305
[M ꢃ H]þ, 637 (18.9), 601 (18), 505 (23.8), 403 (28), 323 (100), 310
(85.6), 252 (62.4), 241 (85.6). HRMS m/z calcd. for C40H54N4O3
[M þ H]þ 639.4268, found 639.4269.
NMR (125 MHz, CDCl3):
d 176.23, 150.39, 143.81, 143.43, 136.95,
129.82, 127.09, 122.65, 119.43, 119.22, 109.74, 78.96, 64.15, 56.95,
56.55, 55.23, 50.41, 49.46, 46.98, 42.30, 40.59, 38.80, 38.65, 38.34,
37.09, 36.86, 34.13, 31.96, 30.55, 29.72, 27.26, 25.45, 22.72, 20.81,
19.38, 18.12, 16.01, 15.64, 15.39, 14.67. IR gmax (neat): 3457, 3315,
2929, 2869, 1714, 1687, 1639, 1618, 1461, 1376, 1236, 1107, 1099,
1041, 975, 881, 795 cmꢃ1. MS (%) for C40H57N3O4 at m/z 666.9448
[M þ Na]þ, 667 (80), 644 (77.4), 626 (48.3), 602 (20.9), 598 (25.8),
594 (41.9), 578 (41.9), 566 (19.3), 556 (83.8), 549 (100), 400
(34.9), 398 (41.2), 324 (68.2), 254 (30), 207 (28), 154 (25.3), 112
(15.8). HRMS m/z calcd. for C40H57N3O4 [M þ H]þ 644.4422,
found 644.4383.
4.1.5.6. Synthesis of 3{1N(4-cyanophenyl)-1H-1,2,3-triazol-4yl}meth-
yloxy betulinic acid (8). The title compound prepared by the reac-
tion of propargylated betulinic acid (75 mg, 0.15 mmol) and 4-azido
benzonitrile (30 mg, 0.2 mmol) as per the method described in
Section 4.1.5 to furnish 8 (90 mg, 94% yield), mp 231e233 ꢂC. 1H
NMR (400 MHz, CDCl3): d 0.62 (3H, s, H-25), 0.64 (1H, m, H-5), 0.71
(3H, s, H-24), 0.74 (3H, s, H-26), 0.88 and 1.50 (1H each, m, H-1), 0.94
and 0.95 (3H each, s, H-23 and H-27), 1.09 and 1.85 (1H each, m, H-
11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and 1.45 (1H each, m, H-
15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.38 (1H each, m, H-7),
1.27 and 1.64 (1H each, m, H-21), 1.20 (1H, m, H-9), 1.47 and 1.86 (1H
each, m, H-22), 1.46 and 2.15 (1H each, m, H-16), 1.49 (1H, m, H-18),
1.54 (2H, m, H-2),1.69 (3H, s, H-30), 2.28 (1H, m, H-13), 3.02 (1H, m,
H-19), 3.19 (1H, m, H-3), 4.62 and 4.74 (1H each, s, H-29), 5.27 and
5.36 (1H each, d, J ¼ 12.0 Hz, eOCH2e), 7.83 (1H, d, J ¼ 8.0 Hz, AreH),
7.93 (2H, d, J ¼ 8.0 Hz, AreH), 8.11 (1H, s, NeCH). 13C NMR (100 MHz,
4.1.5.4. Synthesis of 3{1N(4-cyanomethylphenyl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (6). The title compound prepared by
the reaction of propargylated betulinic acid (100 mg, 0.2 mmol) and
1-azido-4-cyanomethyl benzene (40 mg, 0.25 mmol) as per the
method described in Section 4.1.5 to furnish 6 (127 mg, 97% yield),
mp 202e203 ꢂC. 1H NMR (500 MHz, CDCl3):
d 0.61 (3H, s, H-25),
0.63 (1H, m, H-5), 0.72 (3H, s, H-24), 0.73 (3H, s, H-26), 0.89 and 1.50
(1H each, m, H-1), 0.93 and 0.94 (3H each, s, H-23 and H-27), 1.09
and 1.85 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16
and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26
and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20
(1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.17 (1H
each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2), 1.69 (3H, s,
H-30), 2.27 (1H, m, H-13), 3.03 (1H, m, H-19), 3.19 (1H, m, H-3), 3.67
(2H, s, eCH2CN), 4.60 and 4.74 (1H each, s, H-29), 5.28 and 5.37 (1H
each, d, J ¼ 12.0 Hz, eOCH2e), 7.85 (2H, d, J ¼ 8.0 Hz, AreH), 7.97
(2H, d, J ¼ 8.0 Hz, AreH), 8.17 (1H, s, NeCH). 13C NMR (100 MHz,
CDCl3): d 176.92,150.31,144.66,139.66,133.96,122.27,120.60,117.67,
112.60, 109.81, 78.91, 56.81, 56.57, 55.23, 50.40, 49.45, 47.01, 42.32,
40.61, 38.83, 38.65, 38.40, 37.11, 36.85, 34.14, 31.94, 30.55, 29.72,
27.95, 27.33, 25.44, 20.82, 19.34, 18.19, 16.03, 15.60, 15.39, 14.69. IR
gmax (neat): 3470, 3230, 2946, 2872, 2232, 1707, 1636, 1611, 1465,
1378, 1248, 1176, 1110, 1043, 885, 845, 619 cmꢃ1. MS (%) for
C
40H54N4O3 at m/z 661.4311 [M þ Na]þ, 661 (41.66), 638 (16.6),
614 (4), 506 (20.8), 404 (25), 324 (100), 311 (91.6), 253 (66.6), 242
(83.3). HRMS m/z calcd. for C40H54N4O3 [M þ H]þ 639.4268,
found 639.4262.
CDCl3):
d
176.35, 150.30, 144.26, 135.33, 130.21, 129.43, 127.60,
4.1.5.7. Synthesis of 3{1N(3-methoxyphenyl)-1H-1,2,3-triazol-4yl}
methyloxy betulinic acid (9). The title compound prepared by the
reaction of propargylated betulinic acid (125 mg, 0.25 mmol) and 1-
azido-3-methoxy benzene (45 mg, 0.3 mmol) as per the method
described in Section 4.1.5 to furnish 9 (155 mg, 96% yield), mp
122.38, 120.17, 120.73, 109.77, 79.23, 60.50, 56.83, 56.61, 55.26,
50.43, 49.51, 47.01, 42.34, 40.63, 38.82, 38.66, 38.42, 37.12, 36.88,
34.17, 31.98, 31.59, 29.69, 27.95, 27.21, 25.48, 22.69, 20.97, 20.07,
19.34, 16.31, 16.23, 16.16, 14.83. IR gmax (neat): 3387, 3213, 2930,
2869, 2245, 1716, 1617, 1463, 1376, 1244, 1165, 1131, 1109, 1042, 881,
806 cmꢃ1. MS (%) for C41H56N4O3 at m/z 675.4389 [M þ Na]þ, 675
(12), 636 (43.7), 617 (26.5), 599 (39.5), 553 (39), 488 (45.2), 461
(35.9), 442 (54.6), 416 (84.3), 387 (93.7), 348 (100), 282 (39.0), 174
(17). HRMS m/z calcd. for C41H56N4O3 [M þ H]þ 653.4425,
found 653.4403.
233 ꢂC. 1H NMR (200 MHz, CDCl3):
d 0.62 (1H, m, H-5), 0.63 (3H, s,
H-25), 0.71 (3H, s, H-24), 0.72 (3H, s, H-26), 0.88 and 1.50 (1H each,
m, H-1), 0.92 and 0.94 (3H each, s, H-23 and H-27), 1.09 and 1.85
(1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and 1.45
(1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.38
(1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20 (1H, m, H-

R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
789
9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.09 (1H each, m, H-
16),1.49 (1H, m, H-18),1.54 (2H, m, H-2),1.70 (3H, s, H-30), 2.28 (1H,
m, H-13), 3.03 (1H, m, H-19), 3.17 (1H, m, H-3), 3.89 (3H, s, eOCH3),
4.60 and 4.74 (1H each, s, H-29), 5.25 and 5.36 (1H each, d,
J ¼ 12.0 Hz, eOCH2e), 6.98 (1H, d, J ¼ 8.01 Hz, AreH), 7.26 (1H, d,
J ¼ 8.0 Hz, AreH), 7.33 (1H, s, AreH), 7.42 (1H, dd, J ¼ 8.0, 8.01 Hz,
(1H, d, J ¼ 1.80 Hz, AreH), 7.74 (1H, dd, J ¼ 8.0, 1.80 Hz, AreH), 7.85
(1H, s, NeCH). 13C NMR (100 MHz, CDCl3):
176.17, 150.34, 143.25,
d
138.87, 137.24, 134.54, 133.26, 133.05, 125.66, 109.71, 90.08, 78.91,
56.91, 56.57, 55.34, 50.46, 49.44, 46.95, 42.33, 40.70, 38.85, 38.70,
38.31, 37.17, 36.91, 34.23, 31.95, 30.55, 29.60, 27.99, 27.37, 25.49,
20.85, 19.38, 18.33, 17.68, 16.35, 15.85, 15.45, 14.68. IR gmax (neat):
3345, 3221, 2992, 2868, 1711, 1617, 1463, 1376, 1244, 1192, 1133,
1077, 1039, 941, 883, 810, 620 cmꢃ1. MS (%) for C40H56IN3O3 at m/z
752.3531 [M ꢃ H]þ, 752 (100), 725 (4.2), 670 (9.1), 645 (29.5), 610
(7.7), 580 (21.1), 567 (23.9), 518 (25.3), 493 (90), 455 (55.6), 374
(28.1), 340 (19.7), 327 (73.2), 310 (71.8), 282 (97.1), 265 (32.3), 254
(76.0), 235 (57.7), 198 (59.1), 134 (25.5). HRMS m/z calcd. for
AreH), 8.08 (1H, s, NeCH). 13C NMR (100 MHz, CDCl3):
d 176.24,
160.61, 150.43, 143.86, 137.90, 130.54, 122.60, 114.74, 112.44, 109.71,
106.43, 78.95, 57.02, 56.65, 56.56, 55.26, 50.44, 49.48, 47.00, 42.31,
40.61, 38.83, 38.66, 38.35, 37.12, 36.87, 34.15, 31.98, 30.58, 29.68,
27.96, 27.35, 25.47, 20.83, 19.38, 18.19, 16.00, 15.68, 15.35, 14.67. IR
gmax (neat): 3514, 3335, 2942, 2869, 1721, 1631, 1611, 1462, 1376,
1256, 1157, 1107, 1086, 1042, 855, 776, 684 cmꢃ1. MS (%) for
C
40H56IN3O3 [M þ H]þ 754.3439, found 754.3389.
C
40H57N3O4 at m/z 643.4449 [M ꢃ H]þ, 643 (53.4), 576 (17), 526
(36.9), 519.9 (17.8), 486 (10.2), 453 (17.6), 439 (17.8), 429.7 (54.7),
377 (31.5), 365 (31.5), 347.9 (23.2), 339 (35.6), 325 (58.9), 313 (64.3),
278 (72.6), 226 (34.4), 256 (34.2), 248 (63), 226 (31.5), 174 (69.8),
112 (37.6), 278 (72.6), 248 (64.3). HRMS m/z calcd. for C40H57N3O4
[M þ H]þ 644.4422, found 639.4390.
4.1.5.10. Synthesis of 3{1N(3-methyl-5-hydroxyphenyl)-1H-1,2,3-
triazol-4yl}methyloxy betulinic acid (12). The title compound pre-
pared by the reaction of propargylated betulinic acid (100 mg,
0.20 mmol) and 3-azido-5-methylphenol (45 mg, 0.3 mmol) as per
the method described in Section 4.1.5 to furnish 12 (121 mg, 94%
yield), mp 267e270 ꢂC. 1H NMR (200 MHz, CDCl3):
d 0.64 (1H, m, H-
4.1.5.8. Synthesis of 3{1N(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (10). The title compound prepared by
the reaction of propargylated betulinic acid (120 mg, 0.24 mmol)
and 1-azido-3,4,5-methoxy benzene (52 mg, 0.3 mmol) as per the
method described in Section 4.1.5 to furnish 10 (155 mg, 92% yield),
5), 0.67 (3H, s, H-25), 0.72 (3H, s, H-24), 0.73 (3H, s, H-26), 0.89 and
1.51 (1H each, m, H-1), 0.93 and 0.95 (3H each, s, H-23 and H-27),
1.09 and 1.84 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12),
1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6),
1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21),
1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.09
(1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2), 1.69 (3H, s,
H-30), 2.13 (3H, s, AreCH3), 2.26 (1H, m, H-13), 3.01 (1H, m, H-19),
3.16 (1H, m, H-3), 4.61 and 4.75 (1H each, s, H-29), 5.25 and 5.36
(1H each, d, J ¼ 12.0 Hz, eOCH2e), 7.01 (1H, s, AreH), 7.18 (1H, s,
AreH), 7.33 (1H, s, AreH), 8.08 (1H, s, NeCH). 13C NMR (125 MHz,
mp 221e223 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.62 (1H, m, H-5),
0.63 (3H, s, H-25), 0.71 (3H, s, H-24), 0.72 (3H, s, H-26), 0.88 and
1.50 (1H each, m, H-1), 0.93 and 0.94 (3H each, s, H-23 and H-27),
1.09 and 1.85 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12),
1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6),
1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21),
1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.06
(1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2), 1.70 (3H, s,
H-30), 2.28 (1H, m, H-13), 3.03 (1H, m, H-19), 3.18 (1H, m, H-3), 3.89
(6H, s, 2ꢁ eOCH3), 3.82 (3H, s, eOCH3), 4.60 and 4.74 (1H each, s, H-
29), 5.25 and 5.36 (1H each, d, J ¼ 12.0 Hz, eOCH2e), 6.93 (2H, s,
CDCl3):
d 179.63, 154.53, 151.54, 147.25, 138.60, 130.23, 126.68,
124.08, 120.36, 118.24, 109.68, 86.75, 56.62, 55.99, 55.77, 50.48,
49.29, 46.90, 43.26, 40.07, 38.54, 38.47, 38.39, 37.42, 37.15, 34.32,
32.41, 30.48, 29.59, 28.09, 27.19, 25.51, 22.96, 20.89, 19.35, 18.12,
16.26, 16.15, 16.07, 14.68. IR gmax (neat): 3544, 2993, 2871, 1699,
1619, 1465, 1377, 1246, 1195, 1131, 1097, 1009, 945, 891, 868,
723 cmꢃ1. MS (%) for C40H57N3O4 at m/z 644.9847 [M þ H]þ, 644
(6.4), 621 (65.6), 561 (66.0), 621 (65.6), 536 (51.5), 501 (48.4), 471
(100), 414 (65.6), 356 (56.2), 324 (31.2), 28 (56.2), 208 (34.3), 178
(37.5). HRMS m/z calcd. for C40H57N3O4 [M þ H]þ 644.4422,
found 644.4393.
AreH), 8.08 (1H, s, NeCH). 13C NMR (125 MHz, CDCl3):
d 176.36,
153.89 (2ꢁ C), 150.34, 143.75, 138.29, 132.73, 122.62, 109.74, 98.31
(2ꢁ CH), 78.96, 61.07, 56.64, 56.54, 56.12 (2ꢁ OCH3), 55.21, 50.37,
49.42, 47.01, 42.30, 40.59, 38.80, 38.63, 38.33, 37.09, 36.85, 34.12,
31.95, 30.55, 29.70, 28.42, 27.28, 25.76, 20.82, 19.34, 18.20, 16.07,
15.60, 15.35, 14.66. IR gmax (neat): 3468, 3236, 2940, 2869, 1715,
1623, 1615, 1512, 1472, 1376, 1233, 1129, 1042, 1007.5, 881, 828,
618 cmꢃ1. MS (%) for C42H61N3O6 at m/z 702.4517 [M ꢃ H]þ, 702
(100), 657 (57.1), 611 (53.9), 551 (57.1), 490 (87.3), 464 (69.8), 417
(76.1), 412 (71.4), 315 (50.7), 264 (36.5), 204 (41.2), 152 (58.7).
4.1.5.11. Synthesis of 3{1N(5-hydroxy-naphth-1yl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (13). The title compound prepared by
the reaction of propargylated betulinic acid (75 mg, 0.15 mmol) and
5-azidonaphthalen-1-ol (37 mg, 0.2 mmol) as per the method
described in Section 4.1.5 to furnish 13 (98 mg, 97% yield), mp 238e
HRMS m/z calcd. for
found 704.4593.
C
42H61N3O6 [M
þ
H]þ 704.4633,
240 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.63 (1H, m, H-5), 0.68 (3H, s,
4.1.5.9. Synthesis of 3{1N(5-iodo-2-methylphenyl)-1H-1,2,3-triazol-
4yl}methyloxy betulinic acid (11). The title compound prepared by
the reaction of propargylated betulinic acid (85 mg, 0.17 mmol) and
2-azido-4-iodo-1-methylbenzene (55 mg, >0.2 mmol) as per the
method described in Section 4.1.5 to furnish 11 (122 mg, 96% yield),
H-25), 0.70 (3H, s, H-24), 0.73 (3H, s, H-26), 0.89 and 1.51 (1H each,
m, H-1), 0.93 and 0.95 (3H each, s, H-23 and H-27), 1.09 and 1.84
(1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and 1.45
(1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.38
(1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20 (1H, m, H-
9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.19 (1H each, m, H-
16),1.49 (1H, m, H-18),1.54 (2H, m, H-2),1.69 (3H, s, H-30), 2.29 (1H,
m, H-13), 3.01 (1H, m, H-19), 3.18 (1H, m, H-3), 4.16 and 4.58 (1H
each, s, H-29), 5.35 and 5.44 (1H each, d, J ¼ 12.0 Hz, eOCH2e), 6.97
(1H, d, J ¼ 8.0 Hz, AreH), 7.05 (1H, d, J ¼ 8.0 Hz, AreH), 7.28 (1H, d,
J ¼ 8.0 Hz, AreH), 7.50e7.57 (2H, m, AreH), 8.05 (1H, s, NeCH), 8.45
mp 230e233 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.65 (1H, m, H-5),
0.69 (3H, s, H-25), 0.74 (3H, s, H-24), 0.79 (3H, s, H-26), 0.88 and
1.50 (1H each, m, H-1), 0.94 and 0.95 (3H each, s, H-23 and H-27),
1.09 and 1.85 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12),
1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6),
1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21),
1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.09
(1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2), 1.70 (3H, s,
H-30), 2.17 (3H, s, AreCH3), 2.28 (1H, m, H-13), 3.01 (1H, m, H-19),
3.17 (1H, m, H-3), 4.60 and 4.73 (1H each, s, H-29), 5.25 and 5.37 (1H
each, d, J ¼ 12.0 Hz, eOCH2e), 7.12 (1H, d, J ¼ 8.0 Hz, AreH), 7.67
(1H, d, J ¼ 8.0 Hz, AreH). 13C NMR (100 MHz, CDCl3):
d 176.28,
152.67, 150.36, 143.07, 133.05, 129.75, 128.23, 127.03, 125.73, 125.08,
124.10, 123.76, 113.75, 109.74, 109.64, 79.16, 60.53, 57.03, 56.65,
55.27, 50.46, 49.47, 46.99, 42.34, 40.66, 38.82, 38.66, 38.33, 37.12,
36.94, 34.17, 32.01, 30.58, 29.64, 27.98, 27.29, 25.47, 21.08, 20.83,

790
R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
19.36, 18.22, 16.04, 15.92, 15.37, 14.66. IR gmax (neat): 3544, 3469,
3413, 2927, 2869,1711,1638,1617,1444,1378,1280,1208,1181,1152,
1080, 1071, 1039, 979, 883, 782, 617 cmꢃ1. MS (%) for C43H57N3O4 at
m/z 678.9357 [M ꢃ H]þ, 679 (3.1), 660 (18.7), 623 (20.0), 633 (20.3),
599 (32.8), 539 (40.6), 491 (54.6), 364 (100), 314 (15.6), 279 (16.4),
232 (7.0), 202 (26.5). HRMS m/z calcd. for C43H57N3O4 [M þ H]þ
680.4422, found 680.4384.
C
47H69N3O12 at m/z 868.4912 [M þ H]þ, 868 (100), 825 (1.8), 783
(2.6), 741 (25), 699 (9.6), 642 (5.2), 635 (1.8), 483 (4.2), 480 (3.6), 396
(2.4), 394 (3.9), 365 (6.4), 319 (6.9), 271 (7.5), 212 (3.3), 186 (4.1), 169
(4.1), 162 (3.1), 130 (5.1). HRMS m/z calcd. for C47H69N3O12 [M þ H]þ
868.4954, found 868.4895.
4.1.5.14. Synthesis of 3{1N(3,4-methylenedioxyphenyl)-1H-1,2,3-
triazol-4yl}methyloxy betulinic acid (16). The title compound pre-
pared by the reaction of propargylated betulinic acid (175 mg,
0.35 mmol) and 1-azido-3,4-methylenedioxy benzene (70 mg,
0.43 mmol) as per the method described in Section 4.1.5 to furnish
16 (221 mg, 97% yield), mp 227e229 ꢂC. 1H NMR (400 MHz, CDCl3):
4.1.5.12. Synthesis of 3{1N(4-benzoylphenyl)-1H-1,2,3-triazol-4yl}
methyloxy betulinic acid (14). The title compound prepared by the
reaction of propargylated betulinic acid (100 mg, 0.20 mmol) and 1-
azido-4benzoyl benzene (45 mg, 0.3 mmol) as per the method
described in Section 4.1.5 to furnish 14 (133 mg, 93% yield), mp
d
0.64 (1H, m, H-5), 0.65 (3H, s, H-25), 0.73 (3H, s, H-24), 0.73 (3H, s,
261e263 ꢂC. 1H NMR (400 MHz, CDCl3):
d
0.62 (3H, s, H-25), 0.64
H-26), 0.89 and 1.51 (1H each, m, H-1), 0.93 and 0.94 (3H each, s, H-
23 and H-27), 1.09 and 1.84 (1H each, m, H-11), 1.21 and 1.59 (1H
each, m, H-12), 1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H
each, m, H-6), 1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H
each, m, H-21), 1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22),
1.46 and 2.05 (1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-
2), 1.69 (3H, s, H-30), 2.29 (1H, m, H-13), 3.01 (1H, m, H-19), 3.18
(1H, m, H-3), 4.60 and 4.73 (1H each, s, H-29), 5.23 and 5.34 (1H
each, d, J ¼ 12.0 Hz, eOCH2e), 6.91 (1H, d, J ¼ 8.0 Hz, AreH), 7.13
(1H, dd, J ¼ 2.0, 8.0 Hz, AreH), 7.24 (1H, d, J ¼ 2.0 Hz, AreH), 7.97
(1H, m, H-5), 0.71 (3H, s, H-24), 0.72 (3H, s, H-26), 0.88 and 1.51 (1H
each, m, H-1), 0.93 and 0.94 (3H each, s, H-23 and H-27), 1.10 and
1.85 (1H each, m, H-11), 1.22 and 1.58 (1H each, m, H-12), 1.17 and
1.46 (1H each, m, H-15), 1.23 and 1.51 (1H each, m, H-6), 1.25 and
1.39 (1H each, m, H-7),1.28 and 1.65 (1H each, m, H-21),1.21 (1H, m,
H-9), 1.46 and 1.87 (1H each, m, H-22), 1.47 and 2.21 (1H each, m, H-
16),1.50 (1H, m, H-18),1.55 (2H, m, H-2),1.68 (3H, s, H-30), 2.28 (1H,
m, H-13), 3.02 (1H, m, H-19), 3.17 (1H, m, H-3), 4.61 and 4.74 (1H
each, s, H-29), 5.27 and 5.38 (1H each, d, J ¼ 12.0 Hz, eOCH2e),
7.50e7.54 (2H, m, AreH), 7.62e7.64 (1H, m, AreH), 7.82 (2H, d,
J ¼ 8.0 Hz, AreH), 7.90 (2H, d, J ¼ 8.15 Hz, AreH), 7.99 (2H, d,
J ¼ 8.15 Hz, AreH), 8.19 (1H, s, NeCH). 13C NMR (125 MHz, CDCl3):
(1H, s, NeCH). 13C NMR (100 MHz, CDCl3):
d 176.20, 150.41, 148.66,
148.12, 143.72, 131.40, 122.74, 114.26, 109.69, 108.48, 102.85, 102.16,
78.94, 57.04, 56.56, 55.28, 50.47, 49.50, 46.99, 42.32, 40.64, 38.83,
38.68, 38.37, 37.14, 36.86, 34.18, 32.81, 30.59, 29.70, 27.96, 27.36,
25.48, 20.85, 19.37, 18.21, 16.02, 15.72, 15.35, 14.67. IR gmax (neat):
3415, 2942, 2869, 1711, 1639, 1616, 1508, 1465, 1376, 1245, 1181,
1106, 1077, 1038, 934, 884, 807, 612 cmꢃ1. MS (%) for C40H55N3O5 at
m/z 658.2445 [M þ H] þ, 658 (12), 630 (4), 617 (7.5), 589 (11.2), 535
(13.6), 456 (9.4), 428 (17.3), 426 (21.1), 414 (23.1), 385 (100), 360
(27.3), 300 (33.5), 282 (16.3), 121 (47.2), 92 (13.9). HRMS m/z calcd.
for C40H55N3O5 [M þ H]þ 658.4214, found 658.4176.
d
195.21, 176.27, 150.37, 144.34, 139.45, 137.63, 136.98, 132.98, 131.79
(2ꢁ CH), 130.02 (2ꢁ CH), 128.56 (2ꢁ CH), 122.44, 119.71 (2ꢁ CH),
109.78, 78.92, 56.91, 56.57, 55.24, 50.42, 49.49, 47.02, 42.32, 40.61,
38.82, 38.65, 38.41, 37.11, 36.87, 34.14, 31.97, 30.58, 29.60, 27.95,
27.32, 22.73, 20.83, 19.37, 18.20, 16.05, 15.61, 15.40, 14.69. IR gmax
(neat): 3446, 3272, 2929, 2869, 1712, 1631, 1618, 1464, 1375, 1247,
1195, 1135, 1071, 1044, 945, 885, 809, 618 cmꢃ1. MS (%) for
C
46H59N3O4 at m/z 741.1351 [M þ Na]þ, 717 (18.3), 625 (16.9), 638
(11.2), 546 (21), 563 (71.8), 566 (46.6), 593 (19.7), 493 (21.1), 448
(13.3), 324 (45.0), 263 (71.8), 241.5 (100), 198 (16.9), 172 (25.3), 137
(9.8). HRMS m/z calcd. for C46H59N3O4 [M þ H]þ 718.4578,
found 718.4531.
4.1.5.15. Synthesis of 3{1N(4-chlorophenyl)-1H-1,2,3-triazol-4yl}meth-
yloxy betulinic acid(17). The title compound prepared by the reaction
of propargylated betulinic acid (100 mg, 0.20 mmol) and 4-azido-
chlorobenzene (40 mg, 0.26 mmol) as per the method described in
Section 4.1.5 to furnish 17 (122 mg, 94% yield), mp 245e246 ꢂC. 1H
4.1.5.13. Synthesis of 3{1N(2,3,4,6-tetraacetylgalactoso-1yl)-1H-1,2,3-
triazol-4yl}methyloxy betulinic acid (15). The title compound pre-
pared by the reaction of propargylated betulinic acid (125 mg,
0.25 mmol) and 1-azido-2,3,4,6-tetra acetyl galactose (114 mg,
0.3 mmol) as per the method described in Section 4.1.5 to furnish 15
(212 mg, w98% yield), mp 215e217 ꢂC. 1H NMR (200 MHz, CDCl3):
NMR (400 MHz, CDCl3):
d 0.62 (3H, s, H-25), 0.63 (1H, m, H-5), 0.72
(3H, s, H-24), 0.73 (3H, s, H-26), 0.88 and 1.50 (1H each, m, H-1), 0.92
and 0.94 (3H each, s, H-23 and H-27), 1.09 and 1.85 (1H each, m, H-
11),1.22 and 1.61 (1H each, m, H-12),1.17 and 1.46 (1H each, m, H-15),
1.25 and 1.51 (1H each, m, H-6), 1.27 and 1.39 (1H each, m, H-7), 1.28
and 1.65 (1H each, m, H-21),1.21 (1H, m, H-9),1.46 and 1.87 (1H each,
m, H-22), 1.47 and 2.10 (1H each, m, H-16), 1.49 (1H, m, H-18), 1.55
(2H, m, H-2),1.69 (3H, s, H-30), 2.29 (1H, m, H-13), 3.01 (1H, m, H-19),
3.18 (1H, m, H-3), 4.60 and 4.73 (1H each, s, H-29), 5.26 and 5.35 (1H
each, d, J ¼ 12.0 Hz, eOCH2e), 7.51 (2H, d, J ¼ 8.0 Hz, AreH), 7.69 (2H,
d, J ¼ 8.0 Hz, AreH), 8.06 (1H, s, NeCH). 13C NMR (125 MHz, CDCl3):
d
0.64 (1H, m, H-5), 0.72 (3H, s, H-25), 0.76 (3H, s, H-24), 0.77 (3H, s,
H-26), 0.88 and 1.51 (1H each, m, H-1), 0.93 and 0.94 (3H each, s, H-
23 and H-27), 1.09 and 1.84 (1H each, m, H-11), 1.21 and 1.59 (1H
each, m, H-12), 1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H
each, m, H-6), 1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H
each, m, H-21), 1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22),
1.46 and 2.18 (1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-
2), 1.69 (3H, s, H-30), 1.91, 2.03, 2.05, 2.25 (3H each, s, 4ꢁ eOCOCH3),
2.27 (1H, m, H-13), 3.02 (1H, m, H-19), 3.18 (1H, m, H-3), 4.12e4.15
(1H, m, sugareH), 4.18e4.25 (2H, m, sugareH), 4.60 and 4.75 (1H
each, s, H-29), 5.22e5.26 (3H, m, eOCH2e and sugareH), 5.51 (1H, d,
J ¼ 8.0 Hz, sugareH), 5.55 (1H, d, J ¼ 2.0 Hz, sugareH), 5.83 (1H, d,
J ¼ 9.24 Hz, sugareH), 7.92 (1H, s, NeCH). 13C NMR (100 MHz,
d
176.23, 150.36,144.17, 135.40, 134.75, 129.95 (2ꢁ CH), 122.35,121.71
(2ꢁ CH), 109.72, 80.99, 56.95, 56.57, 55.29, 50.46, 49.51, 47.00, 42.34,
40.64, 38.83, 38.69, 38.40, 37.14, 36.86, 34.19, 31.98, 30.60, 29.69,
27.95, 27.36, 25.49, 20.85, 19.36, 18.21, 16.01, 15.66, 15.34, 14.67. IR
gmax (neat): 3470, 2943, 2868,1716,1617,1509,1466,1375,1246,1183,
1109, 1081, 1039, 935, 889, 811, 617 cmꢃ1. MS (%) for C39H54ClN3O3 at
m/z 647.3895 [Mþ, 35Cl], 649 [Mþ, 35Cl], 649 (12.6), 647 (33.3), 622
(5.5), 620 (16.1), 611 (19.0), 609 (8.7), 578 (44.4), 580 (15.8), 536
(50.7), 508 (60.3), 483 (37.3), 458 (33.3), 423 (47.6), 344 (47.6), 319
(34.9), 295 (7.1), 222 (47.6). HRMS m/z calcd. for C39H54ClN3O3
[M þ H]þ 648.3926, found 648.3888.
CDCl3):
d 175.93, 170.23, 169.99, 169.93, 168.90, 150.42, 143.86,
122.31, 109.72, 86.33, 78.93, 74.01, 70.72, 67.90, 66.73, 60.95, 56.81,
56.54, 55.31, 50.51, 49.39, 46.92, 42.37, 40.65, 38.83, 38.70, 38.21,
37.16, 36.85, 34.25, 31.92, 30.46, 29.59, 27.95, 27.35, 25.48, 20.87,
20.68, 20.61, 20.50, 20.21, 19.27, 18.27, 16.15, 15.76, 15.35, 14.68. IR
gmax (neat): 3555, 3369, 2927, 2869, 1711, 1633, 1444, 1378, 1280,
1208, 1181, 1152, 1071, 979, 883, 806, 782, 617 cmꢃ1. MS (%) for
4.1.5.16. Synthesis of 3{1N(2,3,4,6-tetraacetylglucoso-1yl)-1H-1,2,3-
triazol-4yl}methyloxy betulinic acid (18). The title compound

R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
791
prepared by the reaction of propargylated betulinic acid (110 mg,
0.22 mmol) and 1-azido-2,3,4,6-tetra acetyl glucose (100 mg,
0.27 mmol) as per the method described in Section 4.1.5 to furnish 3
(185 mg, 97% yield), mp 163e165 ꢂC. 1H NMR (500 MHz, CDCl3):
1.86 (1H each, m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and
1.45 (1H each, m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and
1.38 (1H each, m, H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20 (1H,
m, H-9), 1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.09 (1H each, m,
H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-2), 1.69 (3H, s, H-30), 2.29
(1H, m, H-13), 3.02 (1H, m, H-19), 3.19 (1H, m, H-3), 4.61 and 4.74
(1H each, s, H-29), 5.26 and 5.38 (1H each, d, J ¼ 12.0 Hz, eOCH2e),
7.25 (1H, m, AreH), 7.58 (1H, d, J ¼ 8.0 Hz, AreH), 7.71 (1H, d,
J ¼ 1.82 Hz, AreH), 7.78 (1H, dd, J ¼ 8.0, 1.82 Hz, AreH), 7.86 (1H, s,
d
0.65 (1H, m, H-5), 0.68 (3H, s, H-25), 0.74 (3H, s, H-24), 0.78 (3H, s,
H-26), 0.88 and 1.51 (1H each, m, H-1), 0.89 and 0.90 (3H each, s, H-
23 and H-27), 1.09 and 1.84 (1H each, m, H-11), 1.21 and 1.59 (1H
each, m, H-12), 1.16 and 1.45 (1H each, m, H-15), 1.24 and 1.50 (1H
each, m, H-6), 1.26 and 1.38 (1H each, m, H-7), 1.27 and 1.64 (1H
each, m, H-21), 1.20 (1H, m, H-9), 1.47 and 1.86 (1H each, m, H-22),
1.46 and 2.18 (1H each, m, H-16), 1.49 (1H, m, H-18), 1.54 (2H, m, H-
2), 1.64 (3H, s, H-30), 1.78, 1.94, 1.99, 2.01 (3H each, s, 4ꢁ eOCOCH3),
2.29 (1H, m, H-13), 3.01 (1H, m, H-19), 3.17 (1H, m, H-3), 4.12 (1H,
m, sugareH), 4.18 (1H, m, sugareH), 4.28 (1H, m, sugareH), 4.53
and 4.64 (1H each, s, H-29), 5.11 and 5.18 (1H each, d, J ¼ 12.76 Hz, e
OCH2e), 5.19e5.22 (1H, m, sugareH), 5.47e5.52 (2H, m, 2ꢁ sugare
H), 6.10 (1H, d, J ¼ 8.95 Hz, sugareH), 8.22 (1H, s, NeCH). 13C NMR
NeCH). 13C NMR (100 MHz, CDCl3):
d 176.17, 150.34, 143.25, 138.78,
133.24, 135.42, 134.25, 133.01, 125.16, 109.68, 93.18, 78.75, 56.93,
56.54, 55.36, 50.47, 49.45, 46.97, 42.35, 40.74, 38.87, 38.71, 38.34,
37.19, 36.93, 34.25, 31.96, 30.54, 29.61, 28.01, 27.36, 25.51, 20.87,
19.40, 18.34, 16.36, 15.86, 15.46, 14.67. IR gmax (neat): 3444, 2929,
2868, 1699, 1631, 1618, 1464, 1377, 1245, 1191, 1135, 1079, 1038, 943,
885, 811, 618 cmꢃ1. MS (%) for C39H54IN3O3 at m/z 738.3271
[M þ H]þ, 738 (7), 698 (2.5), 662 (28.9), 644 (28.1), 628 (12.5), 605
(26.5), 589 (50), 535 (43.7), 486 (32.8), 462 (79.6), 442 (21.8), 437
(31.8), 410 (39), 369 (28.1), 294 (32.8), 252 (37.2), 220 (35.9), 168
(100). HRMS m/z calcd. for C39H54IN3O3 [M þ H]þ 740.3282,
found 740.3215.
(125 MHz, CDCl3):
d 175.84, 170.33, 169.88, 169.31, 168.73, 150.41,
144.01,122.04,109.72, 85.80, 78.94, 75.22, 72.57, 70.35, 67.68, 61.68,
56.87, 56.54, 55.31, 50.52, 49.42, 46.89, 42.38, 40.67, 38.84, 38.71,
38.24, 37.16, 36.84, 34.27, 31.92, 30.49, 29.61, 27.97, 27.36, 25.50,
20.85, 20.69, 20.51, 20.49, 20.14, 19.30, 18.27, 16.12, 15.80, 15.35,
14.68. IR gmax (neat): 3437, 2942, 2870, 1756, 1641, 1453, 1375, 1228,
1151, 1104, 1041, 924, 887, 756 cmꢃ1. MS (%) for C47H69N3O12 at m/z
868.4954 [M þ H]þ, 868 (100), 642 (1.9), 635 (1.3), 483 (3.7), 480
(2.6), 396 (1.9), 394 (3.5), 365 (2.4), 319 (6.4), 271 (1.5), 212 (0.7),
186 (1.2), 169 (1.8), 162 (1.4), 130 (3.4). HRMS m/z calcd. for
4.2. Biology
RPMI-1640 medium, Rhodamine-123 (Rh-123), Propidium io-
dide (PI), Proteinase K, Penicillin, Streptomycin, Camptothecin,
Fetal bovine serum, Mitomycin, Sodium bicarbonate, Phosphate
buffer saline (PBS), Sulpharhodamine (SRB), Trypsin, Paclitaxel, 5-
Fluorouracil (5-FU), Doxorubicin, Gentamycin sulfate, electropho-
resis reagents, were purchased from Sigma chemical Co. Tris buffer,
Bromophenol blue were procured from Himedia. Glacial acetic acid
was purchased from Fisher Scientific and Trichloroacetic acid (TCA)
from Merck Specialties Private Ltd. All these chemicals used in the
present study were of molecular biology grade.
C
47H69N3O12 [M þ H]þ 868.4954, found 868.49543.
4.1.5.17. Synthesis of 3{1N(4-nitrophenyl)-1H-1,2,3-triazol-4yl}meth-
yloxy betulinic acid (19). The title compound prepared by the re-
action of propargylated betulinic acid (125 mg, 0.25 mmol) and 1-
azido-4-nitro benzene (50 mg, 0.3 mmol) as per the method
described in Section 4.1.5 to furnish 19 (157 mg, 95% yield), mp 250e
253 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.62 (3H, s, H-25), 0.63 (1H, m,
H-5), 0.70 (3H, s, H-24), 0.72 (3H, s, H-26), 0.87 and 1.51 (1H each, m,
H-1), 0.93 and 0.94 (3H each, s, H-23 and H-27), 1.09 and 1.84 (1H
each, m, H-11), 1.21 and 1.59 (1H each, m, H-12), 1.16 and 1.45 (1H
each, m, H-15), 1.24 and 1.50 (1H each, m, H-6), 1.26 and 1.38 (1H
each, m, H-7), 1.27 and 1.64 (1H each, m, H-21), 1.20 (1H, m, H-9),
1.47 and 1.86 (1H each, m, H-22), 1.46 and 2.19 (1H each, m, H-16),
1.49 (1H, m, H-18), 1.68 (3H, s, H-30), 1.54 (2H, m, H-2), 2.29 (1H, m,
H-13), 3.01 (1H, m, H-19), 3.15 (1H, m, H-3), 4.61 and 4.74 (1H each,
s, H-29), 5.28 and 5.35 (1H each, d, J ¼ 12.0 Hz, eOCH2e), 7.98 (2H, d,
J ¼ 8.0 Hz, AreH), 8.21 (1H, s, NeCH), 8.44 (2H, d, J ¼ 8.0 Hz, AreH).
4.2.1. Cell culture, growth conditions and treatment
Human promyelocytic leukemia cell line (HL-60), human breast
cancer cell line (MCF-7), human neuroblastoma cancer cell line (SF-
295), human acute monocytic leukemia cell line (THP-1), human
liver cancer cell lines (HEP-2) and normal kidney cell line of mon-
key (CV-1) were procured from National Centre for Cell Sciences
(NCCS), Pune, India. Human lung carcinoma cell line A-549, and
human colon cancer cell line (HCT-15) were obtained from National
Cancer Institute, Frederick, USA. Human prostate cancer cell line
(PC-3) and human prostate cancer cell line (DU-145), were obtained
from National Cancer Institute (NCI), Bethesda, USA. All the cells
that were used were grown in RPMI-1640/MEM medium contain-
13C NMR (125 MHz, CDCl3):
d 176.31, 150.30, 147.33, 144.80, 141.01,
125.59 (2ꢁ CH), 122.42, 120.55 (2ꢁ CH), 109.83, 78.95, 56.79, 56.59,
55.23, 50.40, 49.45, 47.01, 42.34, 40.62, 38.82, 38.65, 38.42, 37.11,
36.87, 34.15, 31.95, 30.55, 29.61, 27.94, 27.32, 25.48, 20.82, 19.34,
18.20, 16.04, 15.59, 15.37, 14.70. IR gmax (neat): 3468, 2929, 2868,
1712, 1616, 1566, 1445, 1367, 1281, 1209, 1183, 1153, 1081, 1073, 1043,
981, 881, 783, 618 cmꢃ1. MS (%) for C39H54N4O5 at m/z 659.4195
[M þ H]þ, 659 (100), 631 (6), 569 (10), 543 (10), 525 (11), 399 (20.3),
365 (12.5), 321 (20.3), 233 (18.7), 185 (25), 174 (20), 156 (26.5), 135
(14), 102 (12.5). HRMS m/z calcd. for C39H54N4O5 [M þ H]þ 659.4167,
found 659.4111.
ing 10% FCS, 100 unit Penicillin/100 mg Streptomycin per mL me-
dium. Cells were allowed to grown in CO2 incubator (Thermo
Scientific USA) at 37 ꢂC with 98% humidity and 5% CO2 gas
environment.
4.2.2. Sulforhodamine B assay for % growth inhibition
The sulforhodamine B (SRB) assay was used to screen betulinic
acid and its structurally modified derivatives for cytotoxicity. The
assay is based on the ability of SRB dye to bind to basic protein of
cells that have been fixed to tissue-culture plates by trichloroacetic
acid (TCA). SRB is a bright-pink aminoxanthene dye with two sul-
fonic groups that bind to basic amino-acid residues under mild
acidic conditions, and dissociate under basic conditions. As the
binding of SRB is stoichiometric, the amount of dye extracted from
stained cells is directly proportional to the cell number. In the
present case, to determine the effect of structurally modified de-
rivatives of betulinic acid on cell number over time, SRB assays
were performed as described. Cells were seeded in flat-bottomed
4.1.5.18. Synthesis of 3{1N(3-iodophenyl)-1H-1,2,3-triazol-4yl}meth-
yloxy betulinic acid (20). The title compound prepared by the re-
action of propargylated betulinic acid (100 mg, 0.20 mmol) and 1-
azido-3-iodo benzene (62 mg, 0.25 mmol) as per the method
described in Section 4.1.5 to furnish 20 (136 mg, 92% yield), mp
236e237 ꢂC. 1H NMR (400 MHz, CDCl3):
d 0.64 (1H, m, H-5), 0.68
(3H, s, H-25), 0.73 (3H, s, H-24), 0.78 (3H, s, H-26), 0.88 and 1.51 (1H
each, m, H-1), 0.93 and 0.94 (3H each, s, H-23 and H-27), 1.09 and

792
R. Majeed et al. / European Journal of Medicinal Chemistry 63 (2013) 782e792
96 welled plates. The cells were allowed to adhere overnight, and
then media containing different structural analogs of betulinic acid
at different concentrations were added. The plates were assayed for
4.2.6. In vitro cell migration assay
The wound-healing assay is simple, inexpensive, and one of the
earliest developed methods to study directional cell migration
in vitro. The basic steps involve creating a “wound” in a cell
monolayer, capturing the images at the beginning and at regular
intervals during cell migration to close the wound and comparing
the images to quantify the migration rate of the cells. 3 ꢁ 105 cells/
mL/well were seeded in 6 wells plate. Cells were then wounded by
48 h. The cells were fixed by adding 50 mL of ice-cold 50% TCA to
each well for 60 min in case of adherent cells and with 80% TCA in
case of HL-60 cells which is a suspension cell line. Suspension cells
are then centrifuged at 1500 rpm for 15 min to pallet down the
cells. The plates were washed five times in running tap water and
stained with 100
m
L per well SRB reagent (0.4% w/v SRB in 1% acetic
scratching with a 1000 mL pipette tip cell was then washed three
acid) for 30 min. The plates were washed five times in 1% acetic acid
to remove unbound SRB and allowed to dry overnight. SRB was
solubilized with 100 mL per well 96 wells plate 10 mM Trisebase,
shaken for 5 min and the OD was measured at 570 nm with
reference wavelength of 620 nm [21]. The results are given in
Table S1 (Fig. S1). Further, the IC50 values in the presence of
different compounds on the cancer cells of different tissue origin
used for screening were determined by plotting the graph between
concentration vs %age growth inhibition (Table 1).
times with PBS to remove cell debris. The test samples were added
at the desired concentration and the plates were incubating in the
CO2 incubator after another 24 h. After the completion of the
treatment, the fresh medium was added into the plates and the
plates were again incubated till the control wound gets completely
healed. The wounds were photographed (10ꢁ objective) at 0 h and
24 h and healing was quantified by measuring the distance be-
tween the edges of the wound [26].
Acknowledgements
4.2.3. DNA agarose gel electrophoresis for evaluating DNA
fragmentation
The authors are thankful to Dr. SN Sharma and Mr. S. Kitchlu
(Taxonomists, IIIM Jammu) for providing authentic Platanus ori-
entalis plant material. Authors (RM, PKC, IK and NAD) thank Council
of Scientific and Industrial Research (CSIR-UGC), New Delhi for the
award of research fellowships. Staff of instrumentation division
(NMR) of our institute is well acknowledged for recording the
spectroscopic data.
HL-60 cells (2 ꢁ 106 cells/well/2 mL) were grown in 6 welled
plates and treated with indicated concentration of compound 7
and 13 for 24 h. After treatment, cells were centrifuged at
1500 rpm for 10 min, and washed in PBS. The pellet was lysed in
250
pH 8.0, 5% Triton X-100) containing (200
incubated at 50 ꢂC for 1 h followed by 90 min incubation with
400 g/mL DNase-free RNase. The DNA was extracted with 100 mL
mL of lysis buffer (100 mM NaCl, 5 mM EDTA, 10 mM TriseHCl,
mg/mL) proteinase-K and
m
Appendix A. Supplementary data
phenol:chloroform:isoamylalcohol (25:24:1) and centrifuged. DNA
was precipitated from aqueous phase with 3 volumes of chilled
alcohol and 0.3 M sodium acetate at 20 ꢂC overnight. The pre-
cipitate was centrifuged at 13,000ꢁ g for 10 min. The DNA pellet
Supplementary data related to this article can be found at
http://dx.doi.org/10.1016/j.ejmech.2013.03.028.
was washed in 80% alcohol, dried, dissolved in 50 mL Tris EDTA
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serum free media. After 24 h the cells were washed in PBS and
centrifuged at 1500 rpm for 5 min and suspended in PBS. The
decrease in intensity of fluorescence because of mitochondrial
membrane potential loss was analyzed using confocal microscopy
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4.2.5. In vitro clonogenic assay
Clonogenic assay was performed to evaluate the ability of a cell
to grow into a colony. The cells were harvested from logarithmically
growing stock cultures and plated at the required final clonogenic
dilutions prior to treatment. After 24 h the cells were treated with
indicated concentrations of the test molecules for another 24 h.
After treatment, the plates were placed in an incubator for a time
equivalent to at least six potential cell divisions (to give colonies of
>50 cells). After this the medium was aspirated from the plates so
as not to disturb the colonies. Plates are then washed with PBS and
then a mixture of 6% glutaraldehyde and 0.5% crystal violet were
added for 30 min to allow sufficient staining. The mixture was
removed after 30 min and the plates were washed with water and
allowed to dry at room temperature [24,25].