Antitumor activity of (-)-α-bisabolol-based thiosemicarbazones against human tumor cell lines

Article abstract of DOI:10.1016/j.ejmech.2010.03.026

A series of thiosemicarbazones deriving from the natural sesquiterpene (-)-α-bisabolol were synthesized and tested against a panel of eight human tumor cell lines to evaluate their anti-tumor potential. Some of the compounds exhibited inhibitory effects on the growth of a wide range of cancer cell lines, but myeloid leukemia cells (K-562) were especially sensitive to all tested thiosemicarbazones (GI₅₀ 0.01-4.22 μM). Among the analogues, the ketone derivative 3l was the most active, exhibiting potent antitumoral activity (GI₅₀ 0.01 μM) and high selectivity for K-562 cells (δTGI 505). It also demonstrated high cytotoxicity, with an LC₅₀ of 1.55 μM for the K-562 cells, but it showed only moderate selectivity (δLC₅₀ 38.5 μM). Through structure-activity relationship studies, we identified some structural requirement for the antitumoral activity exhibited by these promising compounds.

Full text of DOI:10.1016/j.ejmech.2010.03.026

European Journal of Medicinal Chemistry 45 (2010) 2987e2993
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Antitumor activity of (ꢀ)-
a-bisabolol-based thiosemicarbazones against
human tumor cell lines
Alan P. da Silva a, Manuele V. Martini a, Cecília M.A. de Oliveira b, Silvio Cunha c,
,
João E. de Carvalho d, Ana L.T.G. Ruiz d, Cleuza C. da Silva a
*
a Universidade Estadual de Maringá, Departamento de Química, Av. Colombo 5790, Maringá-PR 87020-900, Brazil
b Universidade Federal de Goiás, Instituto de Química, CP 131, Campus II, Samambaia, Goiânia-GO 74001-970, Brazil
c Universidade Federal da Bahia, Instituto de Química, Campos de Ondina, Salvador-BA 40170-290, Brazil
d Centro Pluridisciplinar de Pesquisas Químicas, Biológicas e Agrárias, CP 6171, Campinas-SP 13083-970, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of thiosemicarbazones deriving from the natural sesquiterpene (ꢀ)-
a-bisabolol were synthe-
Received 13 October 2009
Received in revised form
15 March 2010
Accepted 16 March 2010
Available online 25 March 2010
sized and tested against a panel of eight human tumor cell lines to evaluate their anti-tumor potential.
Some of the compounds exhibited inhibitory effects on the growth of a wide range of cancer cell lines,
but myeloid leukemia cells (K-562) were especially sensitive to all tested thiosemicarbazones (GI50
0.01e4.22
antitumoral activity (GI50 0.01
high cytotoxicity, with an LC50 of 1.55
LC50 38.5 M). Through structureeactivity relationship studies, we identified some structural
requirement for the antitumoral activity exhibited by these promising compounds.
Ó 2010 Elsevier Masson SAS. All rights reserved.
m
M). Among the analogues, the ketone derivative 3l was the most active, exhibiting potent
M) and high selectivity for K-562 cells ( TGI 505). It also demonstrated
M for the K-562 cells, but it showed only moderate selectivity
m
d
m
Keywords:
Thiosemicarbazones
(
d
m
a
-Bisabolol
Antitumoral activity
1. Introduction
convenient starting materials in synthesis because they are
commercially available, inexpensive, and generally accessible in
enantiomeric forms.
In continuation of our research on structures endowed with
anti-cancer activity derived from the abundant natural products
Both thiosemicarbazones and their metal complexes have been
known to possess potent antitumoral [1e4], antiviral [5e8], anti-
parasitic [9e12] and antibacterial [13e16] properties. The core
structure is found in compounds used clinically, such as the
important chemotherapeutic anti-cancer agent, 3-aminopyridine-
2-carboxaldehyde-thiosemicarbazone (Triapine) [17e19]. The vast
majority of active thiosemicarbazones have the simplest aryl or
alkyl groups at the N-terminal and the more diverse R1 and R2
groups on the carbon at the imine moiety. Recently, reports on
thiosemicarbazones have shown that the presence of bulky groups
at the N(4) position enhances their biological activities [4].
Terpenes are a class of naturally occurring molecules that have
demonstrated therapeutic potential with a wide spectrum of
biological activity, including anti-inflammatory, anti-tumor and
fungicidal properties [20e26]. These molecules have been
utilized as starting materials for the synthesis of a large and
structurally diverse collection of bioactive compounds [27e29].
According to this approach, terpenes can be considered
found in Brazilian flora [27,28], we selected (ꢀ)-
a-bisabolol as
a chiral building block to construct thiosemicarbazones because of
the inherent reactivity of the double bonds towards acid addition.
Also, in an effort to find more active anti-cancer agents we
consider (ꢀ)-a-bisabolol because itself is known to suppress
proliferation of various cancer cells [22,23,29]. Following this
approach, previous results from our laboratory [30e32] have
shown that the reaction between terpenes and HNCS is a very
useful method to prepare the isothiocyanoterpenes, while retain-
ing the chiral integrity of the original natural products. We
envisaged that the successful regioselective reaction used to
introduce an NCS group in the bisabolol tertiary carbon could be
exploited as a key step in the synthesis of thiosemicarbazones
with NH2 substitutions by the chiral and aliphatic moieties [33].
Herein we describe an efficient three-step route for the synthesis
of a representative set of the bisabolol-based thiosemicarbazones
derivatives with good yield and high purity, and their in vitro
evaluation for anti-tumor activity against several human tumor
cell lines of various histological origins.
* Corresponding author. Tel.: þ55 44 3011 3674; fax: þ55 44 3011 4125.
E-mail address: ccsilva@uem.br (C.C. da Silva).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.03.026

2988
A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
2. Results and discussion
(NH), 1590e1600 cmꢀ1 (C]N) and 790e900 cmꢀ1 (C]S). The 1D
NMR spectra showed signals at dH
dC 5.33e5.35 (1H, brs, H-30)/
/
2.1. Chemistry
120.6e120.8 (C-30), 1.54e1.59 (3H, s, H-120)/27.3e27.8 (C-120),
1.54e1.60 (3H, s, H-130)/27.3e27.8 (C-130), 1.09e1.12 (3H, s, H-140)/
23.5e23.7 (C-140) and 1.61e1.64 (3H, s, H-150)/23.5e23.7 (C-150),
which were attributed to the terpene moiety, and signals at dH
9.15e8.41 and 7.40e7.82 (NH groups), dH/dC 7.44e8.46 (CH]N)/
136.2e148.5 (C]N) and dC 175.1e176.3 (C]S) were attributed to
The synthesis of the target compounds was accomplished using
the reaction sequence in Scheme 1. The synthesis of the thio-
semicarbazones 3aem was based on isothiocyanate (1) as a key
intermediate, which in turn was obtained by direct addition of an
excess of in situ generated HNCS to bisabolol at room temperature
(rt). Subsequently, thiosemicarbazide 2 was obtained quantitatively
by reacting hydrazine with compound 1 in an ethanol/water solu-
tion at 90 ꢁC. After isolation, the ethanol solution of compound 2
and benzaldehyde derivatives 3, acetophenone or benzophenone
were stirred at room temperature in the presence of catalytic
amounts of 30% sulfuric acid until complete consumption of 2
occurred. The thiosemicarbazones 3aem were obtained in very
high yield after purification of the resulting reaction mixture by
silica gel column chromatography.
the thiosemicarbazone groups.
2.2. Pharmacology
Following the synthesis of this group of compounds, their in
vitro antitumoral activity was assessed using eight different human
tumor cell lines: leukemia (K-562), melanoma (UACC-62), breast
(MCF7), breast resistant (NCI-ADR), lung (NCI-460), ovarian
(OVCAR), prostate (PCO-3) and colon (HT-29). The compounds were
used at concentrations ranging from 0.25 to 250
doxorubicin (DOX) at the same concentrations was introduced as
a positive control. The anti-cancer activity ( M) of a tested
mg/mL, and
Compounds 3aem were characterized by the combined use of
IV, MS, 1D and 2D NMR and literature data [29,32]. The IR spectrum
of thiosemicarbazones showed absorption at 3100e3490 cmꢀ1
m
compound is given by three parameters for each cell line: GI50
15'
4'
15
4
3'
2'
5'
6'
3
2
5
6
a
b
1'
7'
1
13'
S
3
13
H
1
H
H
11'
2
NH2
4
11
7
16
10'
8'
N
N
9'
10
8
NCS
HO
9
HO
HO
12'
H
14'
H
12
14
4'
(2)
(1)
15'
5''
6''
3'
2'
5'
6'
R
7''
2''
1''
c
4''
1'
7'
13'
S
3
H
3''
1
11'
2
N
4
10'
8'
N
H
N
9'
R'
HO
12'
H
14'
(3a-m)
H
H
H
H
H
N
N
N
N
N
N
CH3
OH
OCH3
CH3
H3C
H
3d:
3a:
3b:
3c:
3e:
H
H
H
N
N
N
N
NO2
Cl
NO2
NO2
3f:
3g:
3h:
3i:
H
H
CH3
N
N
N
N
Cl
Cl
Scheme 1. Reagents and conditions: (a) KHSO4, KSCN, CHCl3, rt, 48 h; (b) NH2NH2$2HCl/NaHCO3/H2O, EtOH, reflux, 2 h; (c) RCOR0, acidified with solution of H2SO4 30%, rt, 2 h.
3j:
3k:
3l:
3m:

A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
2989
100
100
75
3l
2
75
50
25
0
50
25
0
-25
-25
-50
-75
-100
UACC62
UACC62
MCF7
NCIADR
NCI460
PCO3
OVCAR03
HT29
K562
MCF7
NCIADR
-50
NCI460
PCO3
OVCAR03
-75
HT29
K562
-100
0
0,25
2,5
25
250
0
0,25
2,5
25
250
Concentration (µg mL-1)
Concentration (µg mL-1)
Fig. 1. Graphics with results of antitumoral activity for the most active compounds.
(molar concentration of the compound that inhibits 50% cell
growth), TGI (molar concentration of the compound leading to total
inhibition of the cell growth), and LC50 value (molar concentration
of the compound leading to 50% cell death). A mean graph
midpoint (MG-MID) is calculated for each of the parameters, giving
an averaged activity for each compound from the doseeresponse
curves. For the measurement of selectivity, the MG-MID (mM)
values for each compound were divided by their GI50, TGI or LC50
values for a particular cell line. Selectivity was considered low if
effects on K-562 cells at concentrations of 10- to 40-fold lower than
the derivatives with electron-donating substituents 3b, 3c, 3d and
3e. Although the compounds 3g, 3j and 3k were markedly more
active, with a TGI ranging from 0.56 to 1.06
mM, they showed
moderate selectivity for the leukemia cells ( TGI 18.3e36.7).
d
Considering our interest in searching for molecules with anti-
tumor activity and finding structureeactivity relationships, two more
ketone-derived thiosemicarbazones (3l and 3m), were included for
evaluation against the panel of tumor cell lines. Both ketone deriva-
tives 3l and 3m were able to significantly induce growth inhibition in
d
< 10, moderate if 10 <
d < 100, and high if d > 100.
All of the tested compounds dramatically inhibited the growth of
the K-562 cell at concentrations of 0.01
mM and 1.94 mM, respectively
the cell lines in a dose-dependent manner, as exemplified in Fig. 1
with the most active compounds 2 and 3l. For the benzaldehyde
thiosemicarbazones3aek, theresults showed thatthemajorityof the
compounds were able to induce growth inhibition in the cancer cell
lines (Table 1). However, K-562 (leukemia) cells were more sensitive
to all derivatives than the other cells assayed within the range of
(Table 1). With TGI values of 0.07 M, compound 3l was 60-fold
more cytostatic than 3m and exhibited even higher antitumoral
activity than the standard drug, DOX. Also, compound 3l showed
m
activity against NCI-ADR cells and had a GI50 value of 0.75 mM.
Taking the LC50 values into account, compounds 3g, 3i, 3k and 3l
were more lethal to K-562 cells (Table 3) than to the others cell
lines. Again, compound 3l was outstanding in its potent cytotox-
0.02e0.22
mM and showed high selectivity for the compounds 3e, 3g,
3i, 3j and 3k, with
d
GI50 values ranging of 97e187.
icity, with an LC50 value of 1.54
selectivity ( LC50 38.5).
Having identified the thiosemicarbazones as cancer cell line
inhibitors, we wished to examine which structural features were
required for their activity. The incorporation of the NCS group into the
mM, but with only moderate
The nature of the substituent on the phenyl ring influences the
antitumoral activity of the benzaldehyde derivatives of thio-
semicarbazones (Table 2). Notably, the derivatives with electron-
withdrawing substituents, 3g, 3i, 3j and 3k, exhibited cytostatic
d
Table 1
GI50 values (in
m
M), GI50 (MG-MID) (in
Cancer cell lines
mM) and dGI50 (values in parentheses) for tested compounds.
Compounds
Melanoma
UACC-62
Breast
MCF-7
Breast resistant
NCI-ADR
Lung
NCI-H460
Prostate
PCO-3
Ovarian
OVCAR-3
Colon
HT-29
Leukemia
K-562
MG-MIDa
a
1
2
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
-bisabolol
>100
9.96
18.50
12.70
11.57
7.42
8.87
>100
6.05
>100
16.01
15.31
7.72
7.23
>100
16.72
0.76
6.97
6.51
6.73
8.39
25.2
20.38
6.72
12.77
>100
7.35
7.58
0.75
3.31
5.99
>100
9.25
12.76
38.35
10.12
5.10
>100
11.03
26.80
8.47
>100
12.09
17.23
6.97
6.02
6.50
6.23
3.60
7.39
8.51
13.44
42.02
8.27
>100
11.38
49.44
9.96
10.36
7.42
8.15
27.65
6.94
14.11
12.32
23.65
6.89
6.37(11.7)
16.66
70.88
12.57
5.78
6.13
4.88
4.37
4.35
9.65
8.09
3.75
12.51
18.09
4.95
3.86
5.02
27.40
0.14
0.02 (289)
0.13 (47.1)
0.14 (34.9)
0.22 (19.9)
0.60
0.08 (121)
0.19 (42.6)
0.02 (187)
4.22
0.15 (121)
0.03 (165)
0.04 (97)
0.01 (502)
1.94 (14.1)
0.03
6.75
7.66
6.23
6.50
6.23
1.46
13.95
18.59
6.72
17.70
31.23
7.35
19.57
20.61
8.29
10.08
24.57
44.31
8.72
12.60
13.46
0.05
13.72
39.87
5.60
18.14
18.83
11.25
7.58
19.95
>100
0.17
7.84
20.83
53.27
7.81
7.35
6.89
6.66
7.35
28.36
>100
0.18
22.36
>100
0.18
23.61
36.73
0.04
14.26
>100
0.07
3m
doxorubicin
a
GI50 (in
m
M) mean-graph midpoint (MG-MID) ¼ average sensitivity of all cell lines toward the tested compounds.

2990
A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
Table 2
TGI values (in
m
M), TGI (MG-MID) (in
Cancer cell lines
mM) and dTGI (values in parentheses) for tested compounds.
Compounds
Melanoma
UACC-62
Breast
MCF-7
Breast resistant
NCI-ADR
Lung
NCI-H460
Prostate
PCO-3
Ovarian
OVCAR-3
Colon
HT-29
Leukemia
K-562
MG-MIDa
a
1
2
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
-bisabolol
>100
42.53
>100
43.83
39.04
22.11
40.05
>100
16.62
24.66
62.20
>100
18.14
13.82
93.3
>100
63.13
84.15
28.68
>100
94.94
21.20
>100
>100
18.26
>100
>100
19.54
>100
>100
29.04
23.76
30.51
56.98
6.07
>100
>100
37.95
>100
>100
31.94
36.37
>100
>100
>100
>100
>100
84.02
>100
>100
>100
20.72
>100
>100
68.61
>100
>100
>100
>100
>100
>100
1.42
>100
71.96
>100
36.16
45.66
76.05
13.89
>100
>100
20.67
>100
>100
37.79
22.71
>100
>100
2.30
>100
93.74
>100
12.87
11.76
15.80
17.39
>100
16.22
40.77
88.64
>100
26.50
12.77
59.52
>100
8.11
>100
>100
>100
0.38 (108)
20.87
7.95
34.85
31.08
41.96
>100
73.68
40.88
31.83
37.71
45.26
19.96
89.71
37.06
20.53
65.31
67.10
19.38
15.76
35.36
67.26
3.77
47.94
>100
36.51
80.36
35.15
31.46
>100
16.84
57.05
62.81
>100
16.53
22.59
>100
>100
46
7.84
0.56 (36.7)
9.56
4.11 (16.3)
1.06 (18.3)
0.73 (21.6)
0.07 (505)
4.19 (16.0)
0.55
15.82
62.87
>100
1.84
3m
doxorubicin
>100
0.33 (11.4)
a
TGI (in
mM) mean-graph midpoint (MG-MID) ¼ average sensitivity of all cell lines toward the tested compounds.
bisabolol structure has a favorable impact on the pharmacological
properties of the isothiocyanate derivatives against all the tested cells.
In addition, the incorporation of hydrazine into the isothiocyanate
structure drastically increases the activity of the thiosemicarbazide (2)
3. Conclusion
Wehavesynthesized a series of thiosemicarbazones derivingfrom
-bisabolol. Some of these compounds
the natural sesquiterpene (ꢀ)-
a
on the growth of the K-562 cells (GI50 0.02
TGI 289). Compound 2 also exhibits significant cytostatic and cyto-
toxic effects, with TGI and LC50 values of 0.38 M and 9.58 M. At this
mM) with high selectivity
hadexcellentgrowthinhibitionactivityagainstmostofthecancercell
lines tested. Among the examined series, the thiosemicarbazone (3l)
exhibited the best anti-cancer activity and had high selectivity, which
(d
m
m
point, it was important to understand whether the bisabolol moiety
was solely responsible for this biological activity because anti-cancer
greatly enhanced the pre-existent activity of (ꢀ)-
a-bisabolol against
the K-562 cells. The results of this investigation have prompted us to
continue the development and testing of novel terpene thio-
semicarbazone derivatives and to carry out further studies to inves-
tigate the SAR and their mechanisms of action.
activity for
However, in our study,
cells with GI50 values of 6.37
lines presented GI50, TGI and LC50 values higher than 100
a
-bisabolol has been reported in the literature [22,23,29].
-bisabolol was cytostatic against K-562 cancer
M, but had low selectivity. The other cell
M.
a
m
m
In comparison to the other thiosemicarbazones, 3l and the
electron-withdrawing substituent-containing derivatives 3k and
3g were the most active against K-562 cancer cells, but again the
latter were 10 times less active and less selective than 3l. Therefore,
replacing hydrogen with a methyl group on the imine moiety must
play a significant role in the growth inhibitory activity of these
compounds on K-562 cells.
4. Experimental
4.1. General methods
All melting points were determined using a Microquímica
model MQAPF-301 apparatus. IR spectra were obtained using KBr
pellets on an FT-IR BOMEM spectrophotometer. Low resolution
Table 3
LC50 values (in
m
M), LC50 (MG-MID) (in
Cancer cell lines
m
M) and dLC50 (values in parentheses) for tested compounds.
Compounds
Melanoma
UACC-62
Breast
MCF-7
Breast resistant
NCI-ADR
Lung
NCI-H460
Prostate
PCO-3
Ovarian
OVCAR-3
Colon
HT-29
Leukemia
K-562
MG-MIDa
a
1
2
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
-bisabolol
>100
>100
>100
48.38
52.29
48.49
55.63
>100
49.33
49.33
>100
>100
42.71
40.64
>100
>100
0.46 (89.2)
>100
>100
>100
60.35
>100
>100
56.35
>100
>100
47.31
>100
>100
>100
59.85
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
>100
37.90
>100
>100
>100
>100
>100
>100
50.12
>100
>100
52.45
>100
>100
56.95
48.45
>100
>100
>100
>100
>100
>100
43.64
45.30
46.17
54.44
>100
41.93
>100
>100
>100
47.99
40.64
>100
>100
>100
>100
90.3
>100
>100
9.58
>100
98.73
74.59
67.66
83.52
82.94
68.77
>100
74.20
59.34
90.93
73.48
58.57
45.17
59.35
75.26
41.102
>100
57.36
>100
>100
58.51
>100
44.40
>100
>100
>100
45.92
47.30
>100
>100
>100
>100
>100
>100
>100
>100
>100
12.56
45.52
8.50
56.26
10.33
1.54 (38.5)
10.29
>100
>100
>100
45.92
44.32
>100
>100
46.00
3m
doxorubicin
a
LC50 (in
m
M) mean-graph midpoint (MG-MID) ¼ average sensitivity of all cell lines toward the tested compounds.

A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
2991
mass spectra were recorded by means of a SHIMADZU-CG/MS
model QP 2000A spectrometer at 70 eV with a prob for solids. The
optical rotations were determined in CHCl3 as solvent with a Perkin
Elmer polarimeter 343 model at 25 ꢁC. Proton nuclear magnetic
resonance (1H NMR) spectra were recorded using CDCl3 as a solvent
at ambient temperature using a Varian Mercury (300 MHz) with
was added, with stirring, a solution of 1.92 mmol (0.20 mL) of
aldehyde and drops of an aqueous solution of sulfuric acid (30%).
The mixture was stirred at room temperature for 1.5 h. The reaction
mixture was concentrated in vacuo. The residue was extracted with
CHCl3 and purified by column chromatography using hexane:ethyl
acetate (80:20 v/v). Very viscous oil brown-clear translucent; yield
TMS as an internal standard. The chemical shifts (
d
) are given in
85%; [
a
]
ꢀ11.2; IR (KBr): 3342 and 3131 (NH), 1600 (C]N), 791
D
parts per million relative to TMS. Carbon-13 nuclear magnetic
resonance (13C NMR) spectra were recorded at 75.5 MHz with the
same internal standard. Elemental analyses were carried out on an
Elemental Analyzer Perkin Elmer 2400 Series II. Chromatography
was performed on silica gel Merck 230e400 mesh ASTM.
(C]S); EI-MS m/z 401 (Mþ); 1H NMR (300 MHz, CDCl3):
d 1.10 (3H,
s, H-140), 1.28 (2H, m, H-20), 1.50 (2H, m, H-80), 1.55 (2H, m, H-100),
1.57 (3H, s, H-120), 1.58 (3H, s, H-130), 1.60 (1H, m, H-10), 1.62 (3H, s,
H-150), 1.78 (2H, m, H-90), 1.90 (2H, m, H-60), 1.95 (2H, m, H-50), 5.34
(1H, m, H-30), 7.40 (3H, m, H-400/H-500/H-600), 7.49 (1H, s, HC]N, H-
100), 7.61 (2H, m, H-300/H-700), 7.79 (1H, s, NH, H-4), 9.33 (1H, s, NH,
4.2. General procedure for the preparation of compounds
H-2); 13C NMR (75.5 MHz, CDCl3): 17.9 (C-90), 23.5 (C-60), 23.6 (C-
d
140/C-150), 27.1 (C-20), 27.5 (C-120), 27.6 (C-130), 31.2 (C-50), 40.6 (C-
80), 40.9 (C-100), 43.2 (C-10), 56.4 (C-110), 74.5 (C-70), 120.8 (C-30),
127.4 (C-300/700), 129.1 (C-400/600), 130.6 (C-500), 133.6 (C-200), 134.3 (C-
40), 141.4 (C]N, C-100) and 175.8 (C]S, C-3). Anal. Calcd. for
C23H35N3SO: C, 68.79; H, 8.78; N, 10.46. Found: C, 68.50; H, 8.53; N,
10.48.
4.2.1. (ꢀ)-6-Methyl-2-[(S)-4-methylcyclohex-3-enyl]-6-
isothiocyano-heptan-2-(S)-ol (1)
The isothiocyanate was prepared according to a method previ-
ously described [30e32]. 0.045 mol (9.99 g) of
a-bisabolol was
dissolved in 10 mL of chloroform. 0.045 mol (4.37 g) of KSCN and
0.09 mol (12.25 g) of KHSO4 were previously dried, finely pulver-
ized by agate mortar and pestle, mixed and then added in the
solution. The mixture was stirred at room temperature for 2 days.
The reaction mixture was concentrated in vacuo. The residue was
purified by column chromatography using hexane:ethyl acetate
(80:15 v/v) and hexane:ethyl acetate (80:20 v/v) yielded iso-
thiocyanate (1) (46%) and thiocyanate (22%). Isothiocyanate (1):
4.2.3.2. (ꢀ)-N(1)-p-Methyl-benzaldehyde-N(4e6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3b). Very viscous oil brown-clear translucent;
yield 82%; [
a
]
ꢀ9.3; IR (KBr): 3356 and 3323 (NH), 1606 (C]N),
D
859 (C]S); EI-MS m/z 415 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.10
(3H, s, H-140), 1.28 (2H, m, H-20), 1.51 (2H, m, H-80), 1.54 (2H, m,
H-100), 1.56 (3H, s, H-120), 1.57 (3H, s, H-130), 1.60 (1H, m, H-10), 1.62
(3H, s, H-150), 1.78 (2H, m, H-90), 1.88 (2H, m, H-60), 1.92 (2H, m, H-
5000), 2.38 (3H, s, H-800), 5.34 (1H, m, H-30), 7.20 (2H, d, J ¼ 8.0 Hz, H-
4 /H-600), 7.48 (1H, s, HC]N, H-100), 7.50 (2H, d, J ¼ 8.0 Hz, H-300/H-
700), 7.82 (1H, s, NH, H-4), 9.48 (1H, s, NH, H-2); 13C NMR (75.5 MHz,
viscous oil yellow-clear translucent; [
a]
D ꢀ50.1; IR (KBr): 2092 (N]
C]S); EI-MS m/z 281 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.12 (3H, s,
H-14), 1.30 (2H, m, H-2), 1.40 (6H, s, H-12 and H-13), 1.43 (2H, m, H-
10), 1.49 (2H, m, H-8), 1.58 (1H, m, H-1), 1.66 (3H, s, H-15), 1.81 (2H,
m, H-9), 1.91 (2H, m, H-6), 1.95 (2H, m, H-5), 5.37 (1H, m, H-3); 13C
NMR (75.5 MHz, CDCl3):
d
18.5 (C-9), 23.5 (C-6), 23.5 (C-14 and C-
CDCl3): d
17.9 (C-90), 21.7 (C-800), 23.5 (C-60), 23.5 (C-140/C-150), 27.1
15), 27.0 (C-2), 29.0 (C-12), 29.2 (C-13), 31.2 (C-5), 40.1 (C-8), 43.2
(C-1), 43.9 (C-10), 61.6 (C-11), 74.3 (C-7), 120.6 (C-3), 130.5 (C]S, C-
16) and 134.4 (C-4).
(C-200), 27.5 (C-120/C-130), 31.2 (C-50), 40.6 (C-80), 40.9 (C-100), 43.2
(C-1 ), 56.3 (C-110), 74.5 (C-70), 120.7 (C-30), 127.4 (C-400/600), 129.8
(C-300/700), 130.9 (C-200), 134.3 (C-40), 140.9 (C-500), 141.8 (C]N, C-100)
and 175.6 (C]S, C-3). Anal. Calcd. for C24H37N3SO: C, 69.35; H, 8.97;
N, 10.11. Found: C, 69.48; H, 8.90; N, 9.85.
4.2.2. (ꢀ)-N(4-6)-{2-(S)-2-Hydroxyl-6-methyl-2-[1(S)-4-
methylcyclohex-3-enyl]-heptanyl}-thiosemicarbazide (2)
A solution of 0.0491 mol of hydrazine was prepared neutralizing
5.15 g of hydrazine dihydrochoride with 8,51 g (0.1013 mol) of
sodium bicarbonate in 5 mL of water, approximately. This solution
was mixed to 15 mL of ethanol, then 0.0491 mol (13.80 g) of (ꢀ)-6-
methyl-2-[(S)-4-methylcyclohex-3-enyl]-6-isothiocyano-heptan-2-
(S)-ol (1) was added. The mixture was stirred for 2 h at 90 ꢁC and
the reaction mixture was concentrated in vacuo. The residue was
extracted with CHCl3 and purified by column chromatography
using hexane:ethyl acetate (50:50 v/v). Very viscous oil yellow-
4.2.3.3. (ꢀ)-N(1)-p-Methoxy-benzaldehyde-N(4-6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3c). Very viscous oil brown-clear translucent;
yield 90%; [
a
]
ꢀ6.0; IR (KBr): 3289 and 3404 (NH), 1611 (C]N),
D
825 (C]S); EI-MS m/z 431 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.10
(3H, s, H-140), 1.30 (2H, m, H-20), 1.53 (2H, m, H-80), 1.54 (2H, m, H-
100), 1.56 (3H, s, H-120), 1.57 (3H, s, H-130), 1.61 (1H, m, H-10), 1.62
(3H, s, H-150), 1.80 (2H, m, H-90), 1.90 (2H, m, H-60), 1.95 (2H, m, H-
50), 3.85 (3H, s, H-800), 5.34 (1H, m, H-30), 6.92 (2H, d, J ¼ 8.7 Hz, H-
400/H-600), 7.45 (1H, s, HC]N, H-100), 7.55 (2H, d, J ¼ 8.7 Hz, H-300/H-
700), 7.74 (1H, s, NH, H-4), 9.20 (1H, s, NH, H-2); 13C NMR (75.5 MHz,
greenish-clear translucent; yield 71%; [
a
]
ꢀ34.6; IR (KBr): 3370
D
(NH), 1504 (C]S); EI-MS m/z 313 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.09 (3H, s, H-140), 1.30 (2H, m, H-20), 1.45 (2H, m, H-100), 1.48 (6H,
CDCl3): d
17.9 (C-90), 23.5 (C-60), 23.5 (C-140/C-150), 27.1 (C-20), 27.5
s, H-120 and H-130), 1.50 (2H, m, H-80), 1.58 (1H, m, H-10), 1.65 (3H, s,
H-150), 1.78 (2H, m, H-90), 1.90 (2H, m, H-60), 1.95 (2H, m, H-50), 3.96
(2H, brs, NH, H-1), 5.37 (1H, m, H-30), 7.49 (1H, s, NH, H-2), 7.75 (1H,
(C-120/C-130), 31.2 (C-50), 40.6 (C-80), 40.9 (C-100), 43.3 (C-10), 55.6
(C-800), 56.4 (C-110), 74.5 (C-70), 114.6 (C-400/600), 120.7 (C-30), 126.2
(C-200), 129.0 (C-300/700), 134.3 (C-40), 141.6 (C]N, C-100), 161.7 (C-500)
and 175.4 (C]S, C-3). Anal. Calcd. for C24H37N3SO2: C, 66.78; H,
8.64; N, 9.74. Found: C, 66.50; H, 8.40; N, 9.65.
s, NH, H-4); 13C NMR (75.5 MHz, CDCl3):
d
17.7 (C-90), 23.5 (C-60),
23.5 (C-140 and C-150), 27.1 (C-20), 27.8 (C-120 and C-130), 31.2 (C-50),
40.3 (C-80), 40.6 (C-100), 43.3 (C-10), 55.5 (C-110), 74.5 (C-70), 120.7
(C-30), 134.3 (C-40) and 180.4 (C]S, C-3).
4.2.3.4. (ꢀ)-N(1)-p-Hydroxy-benzaldehyde-N(4-6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3d). Very viscous oil brown translucent; yield
4.2.3. Thiosemicarbazones 3(aem)
4.2.3.1. Representative procedure for (ꢀ)-N(1)-benzaldehyde-N
(4e6)-{2-(S)-2-hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-
enyl]-heptanyl}-thiosemicarbazone (3a). To a solution of 1.92 mmol
(0.60 g) of (ꢀ)-N(4e6)-{2-(S)-2-hydroxyl-6-methyl-2-[1(S)-4-
methylcyclohex-3-enyl]-heptanyl} thiosemicarbazide (2) in ethanol,
86%; [
a
]
D ꢀ5.9; IR (KBr): 3469 and 3358 (NH),1598 (C]N), 830 (C]
S); EI-MS m/z 417 (Mþ); 1H NMR (300 MHz, CDCl3):
d 1.10 (3H, s, H-
140), 1.30 (2H, m, H-20), 1.50 (2H, m, H-80), 1.52 (2H, m, H-100), 1.54
(3H, s, H-120/H-130), 1.61 (1H, m, H-10), 1.61 (3H, s, H-150), 1.79 (2H,
m, H-90), 1.91 (2H, m, H-60), 1.97 (2H, m, H-50), 5.34 (1H, m, H-30),

2992
A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
6.85 (2H, d, J ¼ 8.5 Hz, H-400/H-600), 7.37 (2H, d, J ¼ 8.5 Hz, H-300/H-
700), 7.40 (1H, s, NH, H-4), 7.47 (1H, s, HC]N, H-100), 9.15 (1H, s, NH,
4.2.3.8. (ꢀ)-N(1)-p-Nitro-benzaldehyde-N(4-6)-{2-(S)-2-hydroxyl-
6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thio-
H-2); 13C NMR (75.5 MHz, CDCl3):
d
17.8 (C-90), 23.1 (C-60), 23.6 (C-
semicarbazone (3h). Orange solid; yield 98%; [
166e168 ꢁC; IR (KBr): 3424 and 3241 (NH), 1602 (C]N), 898 (C]S),
1500 (NeO); EI-MS m/z 446 (Mþ); 1H NMR (300 MHz, CDCl3):
1.11
a]
ꢀ4.0; mp.
D
140/C-150), 27.2 (C-20), 27.8 (C-120/C-130), 31.1 (C-50), 40.4 (C-80), 40.5
(C-100), 43.5 (C-10), 56.3 (C-110), 74.4 (C-70), 116.3 (C-400/600), 120.6
(C-30), 125.5 (C-200), 129.3 (C-300/700), 134.4 (C-40), 142.1 (C]N, C-100),
158.8 (C-500) and 175.2 (C]S, C-3). Anal. Calcd. for C23H35N3SO2: C,
66.15; H, 8.45; N, 10.06. Found: C, 66.47; H, 8.40; N, 10.21.
d
(3H, s, H-140), 1.27 (2H, m, H-20), 1.51 (2H, m, H-80), 1.55 (2H, m, H-
100), 1.59 (1H, m, H-10), 1.59 (3H, s, H-120), 1.60 (3H, s, H-130), 1.62
(3H, s, H-150), 1.79 (2H, m, H-90), 1.87 (2H, m, H-60), 1.90 (2H, m, H-
50), 5.34 (1H, m, H-30), 7.48 (1H, s, NH, H-4), 7.77 (2H, d, J ¼ 9.0 Hz,
H-300/H-700), 7.87 (1H, s, HC]N, H-100), 8.26 (2H, d, J ¼ 9.0 Hz, H-400/
4.2.3.5. (ꢀ)-N(1)-p-Dimethylamino-benzaldehyde-N(4-6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3e). Very viscous oil yellow-dark translucent;
H-600), 9.69 (1H, s, NH, H-2); 13C NMR (75.5 MHz, CDCl3):
d 17.8 (C-
90), 23.5 (C-60), 23.5 (C-140/C-150), 27.2 (C-20), 27.3 (C-120/C-130), 31.2
(C-50), 40.5 (C-80), 40.9 (C-100), 43.3 (C-10), 56.8 (C-110), 74.5 (C-70),
120.7 (C-30), 124.4 (C-300/700), 127.8 (C-400/600), 134.4 (C-40), 138.2 (C]
N, C-100), 139.7 (C-200), 148.6 (C-500) and 175.8 (C]S, C-3).
yield 92%; [
a
]
ꢀ6.0; IR (KBr): 3415 and 3378 (NH), 1592 (C]N),
D
852 (C]S); EI-MS m/z 444 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.10
(3H, s, H-140), 1.28 (2H, m, H-20), 1.52 (2H, m, H-80), 1.54 (2H, m, H-
100), 1.56 (3H, s, H-120), 1.57 (3H, s, H-130), 1.62 (1H, m, H-10), 1.62
(3H, s, H-150), 1.79 (2H, m, H-90), 1.87 (2H, m, H-60), 1.88 (2H, m, H-
50), 3.02 (6H, s, H-800/H-900), 5.34 (1H, m, H-30), 6.67 (2H, d,
J ¼ 9.0 Hz, H-400/H-600), 7.40 (1H, s, NH, H-4), 7.44 (1H, s, HC]N, H-
100), 7.48 (2H, d, J ¼ 9.0 Hz, H-300/H-700), 9.15 (1H, s, NH, H-2); 13C
4.2.3.9. (ꢀ)-N(1)-o-Chloro-benzaldehyde-N(4-6)-{2-(S)-2-hydroxyl-
6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thio-
semicarbazone (3i). Very viscous oil brown-clear translucent; yield
89%; [
S), 1075 (CeCl); EI-MS m/z 435 (Mþ); 1H NMR (300 MHz, CDCl3):
1.10 (3H, s, H-140), 1.30 (2H, m, H-20), 1.50 (2H, m, H-80), 1.54 (2H,
a
]D ꢀ6.0; IR (KBr): 3322 and 3149 (NH), 1595 (C]N), 763 (C]
NMR (75.5 MHz, CDCl3): d
17.9 (C-90), 23.5 (C-60), 23.6 (C-140/C-150),
27.1 (C-20), 27.5 (C-120/C-130), 31.2 (C-50), 40.3 (C-700/800), 40.6 (C-80),
40.9 (C-100), 43.2 (C-10), 56.1 (C-110), 74.5 (C-70), 112.0 (C-400/600),
120.8 (C-30), 121.1 (C-200), 128.9 (C-300/700), 134.2 (C-40), 142.6 (C]N,
C-100), 151.9 (C-500) and 175.1 (C]S, C-3). Anal. Calcd. for
C25H40N4SO: C, 67.53; H, 9.07; N, 12.60. Found: C, 67.39; H, 9.19; N,
12.58.
d
m, H-100), 1.56 (3H, s, H-120), 1.57 (3H, s, H-130), 1.61 (1H, m, H-10),
1.62 (3H, s, H-150), 1.75 (2H, m, H-90), 1.87 (2H, m, H-60), 1.90 (2H, m,
H-50), 5.34 (1H, m, H-30), 7.31 (1H, t, J ¼ 7.8 Hz, H-600), 7.34 (1H, dd,
J ¼ 7.8 and 1.0 Hz, H-500), 7.39 (1H, dd, J ¼ 7.8 and 1.0 Hz, H-700), 7.47
(1H, s, NH, H-4), 7.84 (1H, dd, J ¼ 7.8 and 1.0 Hz, H-400), 8.21 (1H, s,
HC]N, H-100), 9.41 (1H, s, NH, H-2); 13C NMR (75.5 MHz, CDCl3):
d
17.9 (C-90), 23.5 (C-60), 23.5 (C-140/C-150), 27.1 (C-20), 27.4 (C-120/C-
4.2.3.6. (ꢀ)-N(1)-o-Nitro-benzaldehyde-N(4-6)-{2-(S)-2-hydroxyl-
6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thio-
semicarbazone (3f). Very viscous oil yellow translucent; yield 98%;
130), 31.2 (C-50), 40.6 (C-80), 40.8 (C-100), 43.2 (C-10), 56.5 (C-110),
74.5 (C-70), 120.7 (C-30), 127.1 (C-700), 127.2 (C-500), 130.3 (C-600), 131.2
(C-400), 134.3 (C-40), 134.6 (C-200), 137.9 (C]N, C-100), 137.9 (C-300) and
175.9 (C]S, C-3). Anal. Calcd. for C23H34N3SOCl: C, 63.35; H, 7.86; N,
9.64. Found: C, 63.40; H, 7.72; N, 9.48.
[
a]
D ꢀ12.8; IR (KBr): 3424 and 3241 (NH), 1591 (C]N), 844 (C]S),
1150 (NeO); EI-MS m/z 446 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.10
(3H, s, H-140), 1.29 (2H, m, H-20), 1.51 (2H, m, H-80), 1.53 (2H, m, H-
100), 1.56 (3H, s, H-120), 1.57 (3H, s, H-130), 1.60 (1H, m, H-10), 1.62
(3H, s, H-150), 1.77 (2H, m, H-90), 1.88 (2H, m, H-60), 1.91 (2H, m, H-
50), 5.34 (1H, m, H-30), 7.40 (1H, s, NH, H-4), 7.54 (1H, td, J ¼ 8.0 and
1.2 Hz, H-600), 7.66 (1H, td, J ¼ 8.0 and 1.2 Hz, H-500), 7.89 (1H, dd,
J ¼ 8.0 and 1.2 Hz, H-700), 8.00 (1H, dd, J ¼ 8.0 and 1.2 Hz, H-400), 8.26
(1H, s, HC]N, H-100), 9.30 (1H, s, NH, H-2); 13C NMR (75.5 MHz,
4.2.3.10. (ꢀ)-N(1)-m-Chloro-benzaldehyde-N(4-6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3j). Very viscous oil brown-clear translucent;
yield 84%; [
872 (C]S), 1083 (CeCl); EI-MS m/z 435 (Mþ); 1H NMR (300 MHz,
CDCl3):
1.10 (3H, s, H-140), 1.30 (2H, m, H-20), 1.51 (2H, m, H-80),
a]
ꢀ15.2; IR (KBr): 3633 and 3231 (NH), 1603 (C]N),
D
d
17.9 (C-90), 23.5 (C-60), 23.6 (C-140/C-150), 27.1 (C-20), 27.3
d
CDCl3):
1.55 (2H, m, H-100), 1.58 (3H, s, H-120/H-130), 1.60 (1H, m, H-10), 1.62
(3H, s, H-150), 1.80 (2H, m, H-90), 1.87 (2H, m, H-60), 1.90 (2H, m, H-
50), 5.33 (1H, m, H-30), 7.33 (1H, t, J ¼ 8.0 Hz, H-600), 7.37 (1H, dd,
J ¼ 8.0 and 0.7 Hz, H-700), 7.45 (1H, m, H-300), 7.48 (1H, m, H-500), 7.60
(1H, s, NH, H-4), 7.78 (1H, s, HC]N, H-100), 9.59 (1H, s, NH, H-2); 13C
(C-120), 27.4 (C-130), 31.2 (C-50), 40.6 (C-80), 40.8 (C-100), 43.3 (C-10),
56.7 (C-110), 74.5 (C-70), 120.7 (C-30), 125.1 (C-700), 128.4 (C-200), 128.8
(C-500), 130.5 (C-600), 133.4 (C-400), 134.3 (C-40), 136.2 (C]N, C-100),
148.3 (C-300) and 176.1 (C]S, C-3).
NMR (75.5 MHz, CDCl3): d
17.8 (C-90), 23.5 (C-60), 23.5 (C-140/C-150),
4.2.3.7. (ꢀ)-N(1)-m-Nitro-benzaldehyde-N(4-6)-{2-(S)-2-hydroxyl-
27.1 (C-20), 27.3 (C-120), 27.4 (C-130), 31.2 (C-50), 40.3 (C-80), 41.0 (C-
100), 43.3 (C-10), 56.5 (C-110), 74.5 (C-70), 120.7 (C-30), 125.8 (C-600),
126.8 (C-700), 130.3 (C-500), 130.4 (C-300), 134.3 (C-40), 135.1 (C-400),
135.5 (C-200), 139.9 (C]N, C-100) and 175.7 (C]S, C-3).
6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thio-
semicarbazone (3g). Yellow solid; yield 83%; [
159e161 ꢁC; IR (KBr): 3491 and 3364 (NH), 1600 (C]N), 832 (C]S),
1300 (NeO); EI-MS m/z 446 (Mþ); 1H NMR (300 MHz, CDCl3):
1.10
a
]
D
ꢀ18.5; mp.
d
(3H, s, H-140), 1.28 (2H, m, H-20), 1.52 (2H, m, H-80), 1.57 (2H, m, H-
100), 1.58 (1H, m, H-10), 1.59 (3H, s, H-120), 1.60 (3H, s, H-130), 1.62
(3H, s, H-150), 1.78 (2H, m, H-90), 1.89 (2H, m, H-60), 1.91 (2H, m, H-
50), 5.33 (1H, m, H-30), 7.48 (1H, s, NH, H-4), 7.60 (1H, t, J ¼ 8.3 Hz, H-
600), 7.91 (1H, s, H-300), 7.94 (1H, d, J ¼ 8.3 Hz, H-700), 8.23 (1H, ddd,
J ¼ 8.1, 2.4 and 0.9 Hz, H-500), 8.46 (1H, t, J ¼ 1.8 Hz, HC]N, H-100),
4.2.3.11. (ꢀ)-N(1)-p-Chloro-benzaldehyde-N(4-6)-{2-(S)-2-
hydroxyl-6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thi-
osemicarbazone (3k). Very viscous oil brown-clear translucent;
yield 90%; [
800 (C]S), 1095 (CeCl); EI-MS m/z 435 (Mþ); 1H NMR (300 MHz,
CDCl3):
1.09 (3H, s, H-140), 1.28 (2H, m, H-20), 1.53 (2H, m, H-80),
a
]
D
ꢀ21.3; IR (KBr): 3390 and 3155 (NH), 1595 (C]N),
9.96 (1H, s, NH, H-2); 13C NMR (75.5 MHz, CDCl3): 17.8 (C-90), 23.5
d
d
1.55 (2H, m, H-100), 1.57 (3H, s, H-120), 1.58 (3H, s, H-130), 1.60 (1H,
m, H-10), 1.61 (3H, s, H-150), 1.81 (2H, m, H-90), 1.88 (2H, m, H-60),
1.92 (2H, m, H-50), 5.33 (1H, m, H-30), 7.37 (2H, d, J ¼ 8.8 Hz, H-300/H-
700), 7.44 (1H, s, NH, H-4), 7.55 (2H, d, J ¼ 8.8 Hz, H-400/H-600), 7.74
(1H, s, HC]N, H-100), 9.31 (1H, s, NH, H-2); 13C NMR (75.5 MHz,
(C-60), 23.5 (C-140/C-150), 27.1 (C-20), 27.3 (C-120/C-130), 31.2 (C-50),
40.3 (C-80), 41.0 (C-100), 43.3 (C-10), 56.7 (C-110), 74.4 (C-70), 120.7
(C-30), 121.8 (C-600), 124.6 (C-700), 130.1 (C-500), 132.9 (C-300), 134.3 (C-
40), 135.6 (C-200), 138.6 (C]N, C-100), 148.9 (C-400) and 175.7 (C]S, C-
3). Anal. Calcd. for C23H34N4SO3: C, 61.86; H, 7.67; N, 12.54. Found:
C, 61.38; H, 7.52; N, 12.53.
CDCl3):
d
17.8 (C-90), 23.5 (C-60), 23.5 (C-140/C-150), 27.2 (C-20), 27.4

A.P. da Silva et al. / European Journal of Medicinal Chemistry 45 (2010) 2987e2993
2993
(C-120/C-130), 31.2 (C-50), 40.6 (C-80), 40.9 (C-100), 43.3 (C-10), 56.5
(C-110), 74.5 (C-70), 120.7 (C-30), 128.5 (C-300/700), 129.4 (C-400/600),
132.1 (C-500), 134.3 (C-40), 136.4 (C-200), 140.0 (C]N, C-100) and 175.8
(C]S, C-3).
Citróleo e Indústria e Comércio de Óleos Essenciais Ltda., for the
-bisabolol for the accomplishment of this work and
EMBRAPA (Goiânia) for C, H, N analyses.
supply of (ꢀ)
a
4.2.3.12. (ꢀ)-N(1)-Methyl-phenyl-ketone-N(4-6)-{2-(S)-2-hydroxyl-
6-methyl-2-[1(S)-4-methylcyclohex-3-enyl]-heptanyl}-thio-
References
semicarbazone (3l). Very viscous oil brown-clear translucent; yield
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84%; [
a]
ꢀ25.7; IR (KBr): 3361 and 3155 (NH), 1575 (C]N), 771
D
(C]S); EI-MS m/z 415 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.10 (3H,
s, H-140), 1.28 (2H, m, H-20), 1.51 (2H, m, H-80), 1.54 (2H, m, H-100),
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H-150), 1.80 (2H, m, H-90), 1.89 (2H, m, H-60), 1.97 (2H, m, H-50), 2.26
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500), 7.40 (2H, t, J ¼ 8.1 Hz, H-400/H-600), 7.67 (2H, dd, J ¼ 8.1 and
2.1 Hz, H-300/H-700), 7.70 (1H, s, NH, H-4), 8.41 (1H, s, NH, H-2); 13C
NMR (75.5 MHz, CDCl3):
d
13.6 (C-800), 17.8 (C-90), 23.4 (C-60), 23.5
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a
]
ꢀ21.3; IR (KBr): 3400 and 3202 (NH), 1601 (C]N),
D
822 (C]S); EI-MS m/z 477 (Mþ); 1H NMR (300 MHz, CDCl3):
d
1.12
(3H, s, H-140), 1.29 (2H, m, H-20), 1.50 (2H, m, H-80), 1.55 (2H, m, H-
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d 17.9
(C-90), 23.6 (C-60), 23.7 (C-140/C-150), 27.2 (C-20), 27.4 (C-120/C-130),
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Acknowledgments
We are thankful to CNPq for the scholarship to A.P.S. and
SESu e MEC (Brazil) for the scholarship to M.V.M. We also thank