Search for MDR modulators: Design, syntheses and evaluations of N-substituted acridones for interactions with p-glycoprotein and Mg2+

Article abstract of DOI:10.1016/j.bmc.2009.02.002

By combining the structural features of acridone based anti-cancer drugs (like amsacrine) and MDR modulator propafenone, acridones with hydroxyl amine chain at N-10 have been designed and synthesized. These molecules exhibit appreciable interactions with p-gp and Mg²⁺ indicating their suitability to modulate p-gp mediated multi drug resistance.

Full text of DOI:10.1016/j.bmc.2009.02.002

Bioorganic & Medicinal Chemistry 17 (2009) 2423–2427
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Search for MDR modulators: Design, syntheses and evaluations of N-substituted
acridones for interactions with p-glycoprotein and Mg2+
a
b
b
Palwinder Singh a, , Jatinder kaur , Prabhjit Kaur , Satwinderjeet Kaur
*
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
b Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar 143 005, India
a r t i c l e i n f o
a b s t r a c t
Article history:
By combining the structural features of acridone based anti-cancer drugs (like amsacrine) and MDR mod-
ulator propafenone, acridones with hydroxyl amine chain at N-10 have been designed and synthesized.
These molecules exhibit appreciable interactions with p-gp and Mg2+ indicating their suitability to mod-
ulate p-gp mediated multi drug resistance.
Received 9 December 2008
Revised 3 February 2009
Accepted 4 February 2009
Available online 8 February 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Multi drug resistance
p-Glycoprotein
Hybrid molecules
Acridone derivatives
Modulators
1. Introduction
the energy supply to p-gp. Here, taking acridone as the heterocyclic
moiety (present as the central core of a number of anti-tumor
Today, most drug therapies involve multiple agents or multiple
target agents, as it is almost universally the case that single drugs
or single-target drugs encounter resistance. Drug resistance (Mul-
tiple Drug Resistance, MDR)1 which emanates due to the decrease
in the intracellular drug concentration is a great hurdle in the suc-
cessful practice of chemotherapy of various diseases like cancer,
AIDS and even malaria. It is becoming a matter of great concern
to develop such chemical entities (MDR reversers) which could
maintain the chemotherapeutic level of the drug inside the cell
by blocking p-glycoprotein (p-gp, transporter protein of the ABC
family of drug transporters)2–7 mediated efflux of the drug.
The planar, heterocyclic and considerably hydrophobic nature
of acridone, making it to interact with several biomolecular targets,
led to the investigations of a number of acridone derivatives for
their anti-tumor,8–10 anti-protozoan11–13 and anti-viral14 proper-
ties. Some of the acridone derivatives have also been studied for
multi drug resistance (MDR) modulating8,15,16 properties among
which GF 120918 was chosen for phase I clinical trials.
agents;8 A, Fig. 1) and introducing hydroxylamine fragment (active
part of MDR modulators;20 B, Fig. 1) at its N-10 position, molecules
C (Fig. 1) have been designed, synthesized and investigated for
their interactions with p-gp and Mg2+ and therefore a multiple tar-
get approach has been adopted for modulating the functioning of
p-gp.
A parallelism has been observed between the modulation of ba-
sal activity of p-gp by these molecules and the extent of their inter-
H3CO
HN
NHSO2Me
Ph
O
CH3
O
N
N
H
OH
B
A
Amsacrine - Anticancer
Propafenone - MDR modulator
O
N
For energy requirement, p-gp mediated drug efflux is linked
with ATP hydrolysis for which Mg2+ plays the key role.17–19 It
was envisaged that the molecules interacting with p-gp, if also
bind Mg2+, could provide an extra advantage for modulation of
p-gp mediated MDR via blockage of ATP hydrolysis and hence
HO
R2R1N
C
* Corresponding author. Fax: +91 183 2258819.
E-mail address: palwinder_singh_2000@yahoo.com (P. Singh).
Figure 1.
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.02.002

2424
P. Singh et al. / Bioorg. Med. Chem. 17 (2009) 2423–2427
actions with Mg2+. Further insight into the nature of interactions
between the acridones C and p-gp was explored by the dockings
of these molecules in the ATP binding site of p-gp.
anti-cancer drugs vinblastine, progesterone are taken for
comparison.
3. Discussion
2. Results
As per the manufacturer’s specifications for the ‘drug–p-gp
interactions’ assay kit, a 30% increase in the basal activity of p-
gp, on the addition of a compound implies that the compound is
interacting with p-gp. It is evident from the data given in Table 1
(Fig. 2), compounds 3–7 exhibit appreciable interactions with p-
gp. Six compounds evaluated in the present investigations for their
interactions with p-gp differ from one another by the nature of
amine group present at the end of N-10 substituent. Compounds
3, 4 and 7 with respectively pyrrolidine, piperidine and diethyl
moiety at the end of N-10 chain show better interactions with p-
gp in comparison to compounds 5, 6 and 8. Compound 4 with
44% increase in the basal activity of p-gp shows the best interac-
tions with p-gp followed by compounds 3 and 7. Compounds 3, 4
2.1. Chemistry
The synthesis of the target molecules have been achieved from
the commercially available materials. The Ullmann condensation
of o-chlorobenzoic acid and aniline provided the acridone skeleton
of the molecule. Treatment of acridone 1 with NaH in DMSO fol-
lowed by stirring with epichlorohydrin gave N-substituted acri-
done 2. NMR and mass spectral data confirmed the formation of
this compound. Irradiating an equimolar mixture of acridone 2
and pyrrolidine (solventless conditions) in microwave oven for
5 min resulted in the formation of compound 3 (86%) and likewise
the reactions of acridone 2 with other amines provided compounds
4–8 (74–84%) in 5–7 min (Scheme 1). Therefore, epoxy ring open-
ing with secondary amines under microwave irradiations partially
provides a green approach to the synthesis of target compounds.
and 7 exhibit significant interactions with p-gp even at 0.05 lM
concentration. It seems as if an optimum value of logP (ꢀ2) for
compounds 3, 4 and 7 (1.73, 2.14 and 1.98, respectively) contrib-
utes towards the better interactions of these compounds with p-
gp. Compounds 5, 6 and 8 with respective logP values 1.08, 2.56
and 2.58 exhibit less interactions with p-gp. Moreover, the interac-
tions of compounds 3 and 4 with p-gp are similar as exhibited by
the known MDR modulator propafenone and better than some of
the anti-cancer drugs taken in the present investigations. There-
fore, these results support the design of acridones 3–8 and also
identify compounds 3 and 4 as suitable leads for their development
into MDR modulators.
2.2. Biology
The interactions of compounds 3–8 with p-gp were studied
using ‘Drug–p-glycoprotein Interaction’ assay kit which contains
the p-gp vesicles prepared from highly resistant MDR cells, the
DC-3F/ADX line. The interactions of compounds with p-gp are as-
sessed in terms of modulation of basal activity (MgATP hydrolysis
activity in the absence of drug) of p-gp measured by spectrophoto-
metric method by continuous monitoring of ADP formation in the
vesicle suspension medium. The interactions of added compound
(test compound) with p-gp result in the inhibition of ATPase activ-
ity of p-gp—slowing down of conversion of phosphoenolpyruvate
to pyruvate and slow formation of lactate. This will decrease the
conversion of NADH to NAD+ and hence higher absorption at
340 nm (due to NADH). Therefore, the absorption of NADH at
340 nm, in the wells (96 well plate) where compound–p-gp inter-
actions are better is higher which is manifested as increase in the
basal activity of p-gp. Compounds are tested for their interactions
Since sequestering of Mg2+ could result in slowing down of ATP
hydrolysis and hence the supply of energy to p-gp during drug
effluxing, the new designed acridones were investigated for their
interactions with Mg2+ with the help of UV spectral studies. Com-
pounds 3–8 at 10ꢁ4 M concentrations (prepared in HEPES buffer
(10ꢁ2 M) at pH 7.2) were titrated with Mg2+ solutions (0–
0.5 ꢂ 10ꢁ4 M). All these compounds exhibit a hyperchromicity in
the region 395–405 nm on addition of Mg2+ solution (Fig. 3) with
a concomitant hypochromicity in the region 320–330 nm.
The association constants of compounds 3–8 with Mg2+ (Table
2) indicate the extent of their bindings. Compound 3, 4, 6, 7 and
8 show appreciable interactions with Mg2+. Compound 4 (which
also shows best interaction with p-gp) exhibits strongest binding
with p-gp at 0.5
concentrations as 0.05
wells). Two MDR modulators propafenone, verapamil and two
lM, 5
l
M and 50
l
M concentrations making final
l
M, 0.5 M and 5
l
lM (after dilutions in the
O
O
COOH
OH
ii
i
+
H2N
Cl
N
H
N
H
1
O
N
O
1
8
7
9
2
3
iii
iv
10
N
6
5
Hd
He
Hc
4
11
O
12
OH
Ha
13
% yield mp
3-8:
3
NR1R2
Hb
NR1R2
2
86
76
82
84
81
74
130
150
80
3-8
N
N
N
N
4
5
6
7
8
O
110
120
135
N
N(C2H5)2
N(i-pr)2
Scheme 1. Reagents and reaction conditions: (i) K2CO3, CuO, reflux; (ii) concd H2SO4, heat; (iii) NaH, DMSO, epichlorohydrin, 60–70 °C; (iv) NHR1R2, MWI, 5–7 min.

P. Singh et al. / Bioorg. Med. Chem. 17 (2009) 2423–2427
2425
Table 1
interacts with p-gp weakly irrespective of its appreciable binding
with Mg2+
Percentage increase of basal activity of p-gp by compounds 3–8
.
Therefore, these investigations viz. p-gp interaction studies and
Mg2+ binding studies indicate the potential of the acridones 3–8,
especially compounds 3 and 4, to act as MDR modulators. Parallel
trends of the results of both these investigations indicate the pos-
sibilities of modulations of p-gp activities by these molecules
through Mg2+ binding along with their interactions with p-gp.
To get further insight into the nature of interactions between
the acridones and p-gp and to supplement the experimental re-
sults, dockings21 of acridones 3–8 in the ATP binding site of p-gp
were performed. The crystal structure of p-gp in complexation
with ATP and ADP was taken from protein data bank (pdb ID
1MV5) and refined for docking studies. ATP molecule is bound to
p-gp through H-bonds between its phosphate residue and S383,
L382, G381 and G380 amino acids of p-gp. The adenine moiety of
ATP is present in a parallel position to the phenyl ring of Y352, at
Compound
Percentage increase of basal activity of p-gp
5 (
lM)
0.5 (l
M)
0.05 (lM)
3
4
5
6
7
8
38
44
30
31
36
28
40
33
35
34
34
40
27
32
32
21
31
30
31
30
31
33
24
25
29
18
—
—
—
—
Propafenone
Verapamil
Vinblastine
Progesterone
a distance of 4.12 Å, sufficiently close to exhibit
p–p interactions.
Docking programme was validated by docking ATP in the binding
site of p-gp (Fig. 4) where a close overlapping between the docked
ATP (ATP1) and one present with the crystal of p-gp (ATP) was
observed.
Since the drug binding site of p-gp is near to the ATP binding
site (cavity between the intracellular binding domain and nucleo-
side binding domain),22 we have taken 5 Å around ATP as the bind-
ing pocket of p-gp for the docking purpose. Dockings of compounds
3–8 in the binding site pocket of p-gp indicate that all these mole-
cules are held in the binding site through H-bond and p–p interac-
tions between the acridones and amino acid residues (Fig. 5).
Compounds 3–5 show H-bonds with Y393 through their carbonyl
group. The acridone moiety of compounds 3–8 exhibit p–p interac-
tions with Y352. However, compounds 6 and 8, after docking in p-
gp are placed in a position parallel to ATP. Therefore, the docking
studies also support the better interactions of compounds 3 and
4 with p-gp due to their H-bondings with active site amino acid
residues.
Figure 2. Percentage increase in basal activity of p-gp on interaction with
compounds 3–8.
4. Conclusions
In conclusion, we have synthesized the rationally designed acri-
done derivatives following a convenient synthetic methodology.
The investigations of these molecules for their interactions with
p-gp and Mg2+ have identified compounds 3 and 4 as suitable can-
didates for p-gp mediated MDR modulation. Moreover, these stud-
Figure 3. Absorption spectra of compound
3 in the presence of increasing
concentration of Mg2+ (0–0.5 ꢂ 10ꢁ4 M). Arrows denote the change in absorption
with increasing concentration of Mg2+
.
Table 2
Association constants for Mg2+ binding in HEPES buffer (Mꢁ1
)
Compound
Ka
3
4
5
6
7
8
8.3 ꢂ 104
1.08 ꢂ 105
6.8 ꢂ 103
8.3 ꢂ 104
2.2 ꢂ 104
2.22 ꢂ 104
with Mg2+ (Ka 1.08 ꢂ 105 Mꢁ1). Small differences in the bindings of
these compounds with Mg2+ are almost in the same trend as ob-
served in their interactions with p-gp except in compound 6 which
Figure 4. Validation of docking programme. ATP1 (ATP docked in the ATP binding
site of p-gp) closely overlaps with the ATP molecule present in the crystal structure
of the protein. Hs’ are suppressed for clarity.

2426
P. Singh et al. / Bioorg. Med. Chem. 17 (2009) 2423–2427
5.2.1. 10-(2-Hydroxy-3-pyrrolidin-1-yl-propyl)-10H-acridin-9-
one (3)
Yellowish Solid, mp 130 °C, yield 86%; 1H NMR (300 MHz,
CDCl3): d 1.78–1.84 (br m, 4H, C16H2/C17H2), 2.59–2.91 (m, 6H,
C15H2/C18H2, C13H2), 4.31–4.36 (m, 1H, C12H), 4.40–4.46 (dd,
J2 = 15.75 Hz, J3 = 3.45 Hz, 1H, C11H), 4.50–4.58 (dd, J2 = 16.05 Hz,
J3 = 7.35 Hz, 1H, C11H), 7.17–7.26 (m, 2H, ArH), 7.63–7.72 (m, 2H,
ArH), 8.40–8.43 (m, 2H, ArH), 8.52–8.56 (dd, 2H, J = 8.4 Hz,
J = 1.8 Hz, ArH); 13C NMR (normal/DEPT-135): d 23.56 (ꢁve CH2),
50.33 (ꢁve, CH2), 54.22 (ꢁve, CH2), 59.80 (ꢁve, CH2), 67.81 (+ve,
CH), 115.46 (+ve, ArC), 121.26 (+ve, ArC), 127.52 (+ve, ArC),
133.57 (+ve, ArC), 142.53 (C@O); FAB-MS m/z 323 (M++1). Anal.
Calcd for C20H22N2O2: C, 74.51; H, 6.88; N, 8.69. Found: C, 74.86;
H, 7.03; N, 8.68. IR (KBr cmꢁ1): 1593 (C@O), 3301 (OH).
5.2.2. 10-(2-Hydroxy-3-piperidin-1-yl-propyl)-10H-acridin-9-
one (4)
Yellow crystalline solid, mp 150 °C, yield 76%; 1H NMR
(300 MHz, CDCl3): d 1.25–1.60 (m, 6H, C16H2/C17H2/C18H2), 2.45–
2.60 (m, 6H, C15H2/C19H2,C13H2), 4.30 (m, 1H, C12H), 4.39–4.46
(dd, J2 = 16.05 Hz, J3 = 3.75 Hz, 1H, C11H), 4.51–4.58 (dd,
J2 = 16.05 Hz, J3 = 7.05 Hz, 1H, C11H), 7.23–7.28 (m, 2H, ArH),
7.67–7.72 (m, 2H, ArH), 8.49–8.52 (d, J = 8.1, 2H, ArH), 8.56–8.60
(dd, 2H, J = 8.4 Hz, J = 1.8 Hz, ArH); 13C NMR (normal/DEPT-135):
d 25.86 (ꢁve, CH2), 50.24 (ꢁve, CH2), 54.74 (ꢁve, CH2), 62.36
(ꢁve, CH2), 65.98 (+ve, CH), 115.41 (+ve, ArC), 121.34 (+ve, ArC),
127.66 (+ve, ArC), 133.66 (+ve, ArC), 142.53 (C@O); FAB- MS m/z
337 (M++1). Anal. Calcd for C21H24N2O2: C, 74.97; H, 7.19; N,
8.33. Found: C, 74.66; H, 7.27; N, 8.47. IR (KBr cmꢁ1): 1693
(C@O), 3334 (OH).
Figure 5. Compounds 3, 4, 5 and 7 docked in the binding site pocket of p-gp. H-
bonds between the carbonyl oxygens of 3, 4, 5 and OH of Y393 are visible. Hs’ are
suppressed for clarity.
ies show that Mg2+ sequestering behavior of these compounds
along with their interactions with p-gp could prove as an appropri-
ate approach for developing multiple target agents as MDR
modulators.
5. Experimental
Melting points were determined in capillaries and uncorrected.
1H and 13C NMR spectra were run on JEOL 300 MHz and 75 MHz
NMR spectrometer respectively using CDCl3 as solvent. Chemical
shifts are given in ppm with TMS as an internal reference. J values
are given in hertz. Chromatography was performed with silica
100–200 mesh and reactions were monitored by thin layer chro-
matography (TLC) with silica plates coated with silica gel HF-
254. In 13C NMR spectral data, +ve, ꢁve terms correspond to CH3,
CH, CH2 signals in DEPT-135 NMR spectra.
5.2.3. 10-(2-Hydroxy-3-morpholin-4-yl-propyl)-10H-acridin-9-
one (5)
Light yellow solid, mp 80 °C; yield 82%; 1H NMR (300 MHz
CDCl3): d 2.59–2.71 (m, 6H, C15H2/C18H2,C13H2), 3.65–3.77 (m, 4H,
C16H2/C17H2), 4.55 (m, 3H, C12H/C11H2), 7.05–7.52 (m, 2H, ArH),
7.56–7.59 (m, 2H, ArH), 7.61–7.70 (m, 2H, ArH) 8.16–8.26 (dd,
J = 8.6 Hz, J = 1.5 Hz, 2H, ArH); 13C NMR (normal/DEPT-135): d
50.5 (ꢁve, CH2), 53.98 (ꢁve, CH2), 62.36 (ꢁve, CH2), 66.41 (ꢁve,
CH2), 66.89 (+ve, CH), 115.44 (+ve, ArC), 121.24 (+ve, ArC),
127.20 (+ve, ArC), 133.56 (+ve, ArC), 177.70 (C@O); FAB-MS m/z
339 (M++1). Anal. Calcd for C20H22N2O3: C, 70.09; H, 6.55; N,
8.28. Found: C, 70.12; H, 6.10; N, 8.64. IR (KBr cmꢁ1): 1593
(C@O), 3323 (OH).
5.1. 10-Oxiranylmethyl-10H-acridin-9-one (2)
Acridone 1 (1 mmol) was treated with NaH (1.2 mol) in DMSO
followed by the addition of epichlorohydrin (1.2 mmol) and stirred
at 60–70 °C until the completion of reaction (TLC). The reaction
mass was treated with water and extracted with ethyl acetate
(4 ꢂ 25 ml). Organic layer was dried over Na2SO4 and concentrated
under vacuum. Column chromatography of the crude residue pro-
vided brownish solid, mp 180 °C, yield 47%, 1H NMR (300 MHz,
CDCl3): d 2.67–2.70 (dd, 1H, J2 = 4.5 Hz, J3 = 2.7 Hz, Hb), 2.92–2.95
(dd, 1H, J2 = 4.5 Hz, J3 = 4.5 Hz, Ha), 3.48–3.52 (m, 1H, (8 lines are
visible), Hc), 4.37–4.44 (dd, 1H, J2 = 13.2 Hz, J3 = 4.8, He), 4.83–
4.89 (dd, 1H, J2 = 17.2 Hz, J3 = 2.1 Hz, Hd), 7.26–7.33 (m, 2H, ArH),
7.55–7.60 (m, 2H, ArH), 7.68–7.75 (m, 2H, ArH), 8.51–8.54 (dd,
2H, J = 8.4 Hz, J = 1.8 Hz, ArH); 13C (normal/DEPT-135): d 44.98
(ꢁve, CH2), 47.55 (ꢁve, CH2), 50.17 (+ve, CH), 115.06 (+ve, ArC),
121.70 (+ve, ArC), 127.73 (+ve, ArC), 133.98 (+ve, ArC), 178.15
(C@O), MS (FAB): m/z 252 (M++1). Anal. Calcd for C16H13NO2: C,
76.48; H, 5.21; N, 5.57. Found: C, 75.04; H, 5.60; N, 5.79. IR (KBr,
cmꢁ1): 1604 (C@O).
5.2.4. 10-(3-[1,40]Bipiperidinyl-10-yl-2-hydroxy-propyl)-10H-
acridin-9-one (6)
Yellowish solid, mp 110 °C, yield 84%; 1H NMR (300 MHz,
CDCl3): d 1.43–1.67 (m, 8H, C22H2/C24H2/C16H2/C18H2), 1.79–1.90
(m, 2H, C23H2), 2.22–2.34 (m, 2H, C21H2), 2.48–2.59 (br m, 6H,
C25H2/C19H2/C15H2), 2.00–2.07 (m, 1H, C17H), 2.97–3.72 (m, 2H,
C13H2), 4.27–4.30 (m, 1H, C12H), 4.40–4.46 (dd, J2 = 15.9 Hz,
J3 = 3.3 Hz, 1H, C11H), 4.50–4.58 (dd, J2 = 15.9 Hz, J3 = 7.2 Hz, 1H,
C11H), 7.21–7.26 (m, 2H, ArH), 7.66–7.70 (m, 4H, ArH), 8.46–8.49
(d, J = 8.1 Hz, 2H, ArH); 13C NMR (normal/DEPT-135): d 25.88
(ꢁve, CH2), 28.07 (ꢁve, CH2), 50.14 (ꢁve, CH2), 50.33 (ꢁve, CH2),
52.48 (ꢁve, CH2), 54.78 (ꢁve, CH2), 61.69 (+ve, CH), 66.42 (+ve,
CH), 121.29 (+ve, ArC), 127.56 (+ve, ArC), 133.62 (+ve, ArC),
178.00 (C@O), FAB-MS m/z 420 (M++1). Anal. Calcd for
C26H33N3O2: C, 74.43; H, 7.93; N, 10.82. Found: C, 74.03; H, 8.01;
N, 10.52.
5.2. General procedure for synthesis of compounds 3–8
An equimolar mixture of compound 2 and appropriate amine
was irradiated in a domestic oven for 5 min and the completion
of the reaction monitored by TLC. The reaction mixture was
washed with diethyl ether to get pure compounds 3–8.
5.2.5. 10-(3-(Diethylamino)-2-hydroxypropyl)acridin-9(10H)-
one (7)
Yellowish solid, mp 120 °C, yield 81%; 1H NMR (300 MHz,
CDCl3): d 1.04–1.27 (m, 6H, C16H3/C18H3), 2.53–2.74 (m, 6H,

P. Singh et al. / Bioorg. Med. Chem. 17 (2009) 2423–2427
2427
Ka = 1/Kd; C0 is the initial concentration of ligand, Cm is the concen-
tration of Mg2+
A is the increase in absorbance at the wavelength
of maximum absorption upon addition of each mole fraction of
Mg2+
Amax is the increase in absorbance when the ligand is totally
bound to Mg2+
C15H2/C17H2/C13H2), 4.19–4.27 (m, 1H, C12H), 4.38–4.45 (dd,
J2 = 16.2 Hz, J3 = 3.45 Hz, 1H, C11H), 4.49–4.57 (dd, J2 = 16.05 Hz,
J3 = 7.35 Hz, 1H, C11H), 7.21–7.26 (m, 2H, ArH), 7.65–7.74 (m, 4H,
ArH), 8.46–8.49 (d, J = 7.5 Hz, 2H, ArH); 13C NMR (normal/DEPT-
135): d 11.94 (+ve, CH3), 47.27 (ꢁve, CH2), 50.44 (ꢁve, CH2),
57.31 (ꢁve, CH2), 66.74 (+ve, CH), 115.4 4 (+ve, ArC), 121.30 (+ve,
ArC), 127.57 (+ve, ArC), 133.63 (+ve, ArC), 142.52 (C@O); FAB-MS
m/z 325 (M++1). Anal. Calcd for C20H24N2O2: C, 74.04; H, 7.46; N,
8.64. Found: C, 74.14; H, 7.89; N, 8.93. IR (KBr): 1593 (C@O),
3342 (OH).
,
D
,
D
.
Acknowledgements
DST, UGC, CSIR New Delhi are gratefully acknowledged for
financial assistance and CDRI Lucknow for recording mass spectra
and CHN analysis. JK thanks UGC for fellowship.
5.2.6. 10-(3-(Diisopropylamino)-2-hydroxypropyl)acridin-
9(10H)-one (8)
References and notes
Creamish solid, mp 135 °C, yield 74%; 1H NMR (300 MHz,
CDCl3): d 1.04–1.10 (m, 12H, C16H3/C17H3/C19H3/C20H3), 2.67–2.69
(m, 1H, C13H), 2.80–2.93 (m, 1H, C13H), 2.95–3.10 (m, 1H, C15H),
3.46–3.50 (m, 1H, C18H), 4.37–4.89 (m, 3H, C12H/C11H2), 7.23–
7.32 (m, 2H, ArH),7.56–7.59 (m, 2H, ArH), 7.69–7.75 (m, 2H,
ArH), 8.51–8.59 (m, 2H, ArH); 13C NMR (normal/DEPT-135): d
19.88 (+ve CH3), 22.06 (+ve, CH3), 45.05 (ꢁve, CH2), 47.59 (ꢁve,
CH2), 50.23 (+ve, CH), 50.89 (+ve, CH), 66.61 (+ve, CH), 115.10
(+ve, ArC), 115.49 (+ve, ArC), 121.31 (+ve, ArC), 122.39 (+ve, ArC),
178.08 (C@O); FAB-MS m/z 353 (M++1). Anal. Calcd for
C22H28N2O2: C, 74.97; H, 8.01; N, 7.95. Found: C, 74.64; H, 8.17;
N, 8.26.
1. Teodori, E.; Dei, S.; Scapecchi, S.; Gualtieri, F. Il Farmaco 2002, 57, 385.
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5.3. Biological studies
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The modulating activities of compounds 3–8 were studied using
‘drug–p-gp interaction’ assay kit purchased from CEA, SPI-BIO
mother company. The bioassay for studying the interactions of
the test compounds with p-gp was performed in triplicate in accor-
dance with the previously reported procedure.23
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21. The dockings were carried out using ‘Dock in active site’ module of BioMed
CaChe 7.0.5.85.
5.4. Mg2+ ion binding studies
Stock solutions (10ꢁ3 M concentrations) of compounds 3–8
were prepared by dissolving in two drops of ethanol and diluting
with HEPES buffer (10ꢁ2 M) at pH 7.2. The complex formation
was studied by continuous addition of increasing mole fraction of
metal ion to 100 lL of ligand solution, making final volume 1 ml
(final concn of solution was 10ꢁ4 M). After plotting the Job plot,
binding constants of compounds 3–8 with Mg2+ were calculated
using following equation.
22. Battisti, R. F.; Zhong, Y.; Fang, L.; Gibbs, S.; Shen, J.; Nadas, J.; Zhang, G.; Sun, D.
Mol. Pharm. 2007, 4, 140.
Kd ¼ ½C0 ꢁ ð
D
A=D
AmaxÞC0ꢃ½Cm ꢁ ð
D
A=D
AmaxÞC0ꢃ=½
D
A=
D
AmaxÞC0ꢃ
23. Singh, P.; Paul, K. Bioorg. Med. Chem. 2006, 14, 7183.