Gallic acid-based indanone derivatives as anticancer agents.

Abstract

Gallic acid-based indanone derivatives have been synthesised. Some of the indanones showed very good anticancer activity in MTT assay. Compounds 10, 11, 12 and 14 possessed potent anticancer activity against various human cancer cell lines. The most potent indanone (10, IC(50)=2.2 microM), against MCF-7, that is, hormone-dependent breast cancer cell line, showed no toxicity to human erythrocytes even at higher concentrations (100 microg/ml, 258 microM). While, indanones 11, 12 and 14 showed toxicities to erythrocytes at higher concentrations.

Full text

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Gallic acid-based indanone derivatives as anticancer agentsq
Hari Om Saxenaa, Uzma Faridib, Suchita Srivastavab, J. K. Kumarb, M. P. Darokarb, Suaib Luqmanb,
C. S. Chanotiyab, Vinay Krishnab, Arvind S. Negib,*, S. P. S. Khanujab
aRain Forest Research Institute, Jorhat, India
bCentral Institute of Medicinal and Aromatic Plants (CIMAP), PO CIMAP, Kukrail Road, Lucknow 226 015, India
a r t i c l ei n f o
Article history:
Received 28 March 2008
Revised 15 May 2008
Accepted 11 June 2008
Available online 14 June 2008
Keywords:
Gallic acid
Indanones
Anticancer
Osmotic fragility
HMQC
a b s t r a c t
Gallic acid-based indanone derivatives have been synthesised. Some of the indanones showed very good
anticancer activity in MTT assay. Compounds 10, 11, 12 and 14 possessed potent anticancer activity
against various human cancer cell lines. The most potent indanone (10, IC50= 2.2 lM), against MCF-7,
that is, hormone-dependent breast cancer cell line, showed no toxicity to human erythrocytes even at
higher concentrations (100 lg/ml, 258 lM). While, indanones 11, 12 and 14 showed toxicities to
erythrocytes at higher concentrations.
? 2008 Elsevier Ltd. All rights reserved.
Indanones and related compounds are important bioactive mol-
ecules. These compounds have been studied for various biological
activities including cancer and Alzheimer’s type of diseases. Inda-
nones are also used as drug intermediates, ligands of olefinic poly-
merisation catalysts2a,band discotic liquid crystals.3Indanocine (1,
Fig. 1) and its analogues are being developed to combat drug-resis-
tant malignancies.4Another indanone analogue Donepezil hydro-
chloride (2, Fig. 1) has been approved by US-FDA for the
treatment of mild to moderate Alzheimer’s disease. This drug acts
as an AChE (Acetylcholinesterase) inhibitor.5Dilemmaone A6(3,
Fig. 1) and some other indanones have been isolated from natural
products. Being such a useful moiety, several synthetic strategies
have also been developed for their synthesis.7a–j
In continuation of our studies on modification of plant pheno-
lics,8a–ewe modified gallic acid to an indanone moiety (4, Fig. 1).
Gallic acid (5), a plant phenolic acid is present as hydrolysable
tannins in almost all woody perennials. The modified gallic acid
moiety i.e., a 3,4,5-trimethoxy phenyl unit has been established
as an essential structural requirement for several anticancer leads9
like Combretastatin A4, Podophyllotoxin, Colchicine, etc. (Fig. 2). In
the present letter, gallic acid-based indanone derivatives have been
synthesised and evaluated for their anticancer activity. One of the
potent indanone (10) has further been modified to establish its
structure and activity relationship (SAR). All the compounds show-
ing potent anticancer activity were further evaluated for toxicity
tohumanerythrocytesbyperforming
test.
The synthetic strategy was as depicted in Scheme 1, gallic acid
(5) was taken as the starting material. It was fully methylated at
phenolic as well as carboxylic acid positions by refluxing it with di-
methyl sulphate in 20% aqueous alkali to get 3,4,5-trimethyl gallic
acid methyl ester (6) in 60% yield. The ester 6 underwent Grignard
reaction with methylmagnesium iodide to yield the desired sub-
strate 3,4,5-trimethoxyacetophenone (7). The acetophenone 7
and aldehyde 8 were condensed together in 3% aqueous methano-
lic sodium hydroxide to get a corresponding chalcone10(9). Simi-
larly, other aldehydes were condensed with 7 to get respective
chalcones first and then modified to corresponding indanones
(11–14).11,12All these chalcones were further modified to corre-
sponding indanones by heating with trifluoroacetic acid in a sealed
glass tube (Borosil).13aHowever, indanone 15 was obtained on
condensation of 3,4-dimethoxyacetophenone with 8 to get the
respective chalcone and further modified to corresponding inda-
none (15) as described for other indanones (11–14). Chalcones
lacking an electron releasing groups in the phenyl ring of benzoyl
group did not undergo Nazarov’s cyclisation reaction, due to deac-
tivation by the carbonyl group. Therefore, chalcones synthesised
from simple acetophenones could not be transformed into inda-
nones. All the compounds were characterised by spectroscopic
means.17
All these indanones were evaluated for in vitro anticancer
activity by MTT assay14(Table 1) against various human cancer
erythrocytefragility
0960-894X/$ - see front matter ? 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.06.039
qSee Ref. 1.
* Corresponding author. Tel.: +91 522 2717529x327; fax: +91 522 2342666.
E-mail address: arvindcimap@rediffmail.com (A.S. Negi).
Bioorganic & Medicinal Chemistry Letters 18 (2008) 3914–3918
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
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cell lines i.e., KB403 (oral and mouth cancer cells), WRL68 (liver
cancer cells), CaCO2 (colon cancer cells), HepG2 (liver cells) and
MCF7 (hormone-dependent breast cancer cells). Taxol (Paclit-
axel) and Podophyllotoxin were used as reference compounds.
Amongalltheseindanone
(IC50= 0.022 lM) showed the highest level of activity followed
by 12 (IC50= 0.023 lM) against WRL liver cancer cell lines, while
indanone 10 (IC50= 2.2 lM) was found to be most active against
MCF-7 hormone-dependent breast cancer cell lines. Indanones
11 and 12 possessed highest anticancer activity against KB-403
oral and mouth cancer cell lines. Indanone 13 was found to be
inactive against almost all the cell lines. Rest of the compounds
showed moderate to low level of activity against these human
cancer cell lines.
Compound 10 having trimethoxyphenyl units identical to gallic
acid in both the rings possessed potent anticancer activity against
MCF-7, HEPG2 and WRL68 human cancer cell lines. To establish
structure and activity relationship (SAR) of compound 10, it was
further modified by simple derivatisations (Scheme 2).13b,cCom-
pound 10 was refluxed with selenium dioxide in 1,4-dioxane to
introduce another keto group at 2-position. On oxidising com-
pound 16 was obtained as 1,2-keto-enol derivative rather than a
1,2-diketo derivative. An unexpected polycyclic derivative 17
derivativescompound
14
(Fig. 3) was also obtained, which was characterised by various
spectroscopic means. Compound 10, on refluxing with hydroxyl-
amine hydrochloride in ethanol and pyridine transformed to its
oxime in excellent yields (94%). On sodium borohydride reduction
in methanol, a corresponding secondary alcohol 19 was formed in
quantitative yield, while sodium borohydride reduction in trifluo-
roacetic acid yielded a 1-deoxy derivative 20 in good yield. But
all these derivatives possessed either lower cytotoxicities or were
found to be inactive as compared to the parent molecule 10. From
this, it was concluded that in indanone 10, all the above modifica-
tions are not favourable. Hence, a keto group at 1-position along
with no such substitutions at 2-position is desirable for its better
activity.
The structure proposed for compound 17 has been confirmed
by spectroscopic means using IR, NMR experiments like1H NMR,
13C NMR, DEPT 135 and HMBC correlation experiments and fi-
nally by mass spectrometry. The proton spectra taken on
300 MHz FT NMR in CDCl3showed six distinct singlets at 3.90,
3.96, 3.98, 4.00, 4.03 and 4.07 ppm for six methoxy groups.
Two singlet protons were also observed in the aromatic region
at 7.04 and 8.07 ppm. The
of total 21 carbons in 17.
ments clearly indicated the presence of six methyls (all oxygen-
ated) and two methines (aromatic) and 13 quaternary (nine
oxygenated) carbons. Absence of one of the aromatic proton of
ring C (which is otherwise a singlet for two enantiotopic pro-
tons) and enolic hydroxyl suggested the possibility of cyclisation.
It was further indicated by the downfield shifts of both the aro-
matic protons and presence of one more quaternary carbon at
the loss of one aromatic methine as compared to the
trum of 16. It was further ascertained by HMBC correlations of
compound 17 (Fig. 3).
Indanone derivatives 10, 11, 12 and 14 showing potent antican-
cer activity were also evaluated for erythrocyte osmotic fragility
(Fig. 4) to determine their toxicity.15Among these indanone 10
showing most potent activity against MCF-7 was found to be
non-toxic to human erythrocytes even at higher concentrations
(100 lg/ml, 258 lM). Indanones 11, 12 and 14 increased the haem-
olysis of erythrocytes, hence these may be considered toxic at
higher concentrations.
In conclusion, gallic acid-based indanone derivatives showed
potent anticancer activity against hormone-dependent breast can-
cer, oral and liver cancer cell lines. As one of the potent molecules
was found non-toxic to human erythrocytes, this compound may
further be optimised to better anticancer leads with no or low tox-
icities to normal cells.
13C NMR spectra showed presence
13C coupled with DEPT 135 experi-
13C spec-
NH2
H3CO
H3CO
O
CH3
OH
CH3
1
N
O
H3CO
H3CO
HCl.
2
O
H3CO
H3CO
OCH3
4
NH
O
H3C
OCH3
3
R
Figure 1. Structures of Indanocine (1), Donepezil hydrochloride (2), Dilemmaone A (3) and gallic acid-based indanone (4).
OCH3
H3CO
H3CO
OCH3
OH
Combretastatin A4
O
O
O
OH
H3CO
OCH3
OCH3
O
Podophyllotoxin
H3CO
H3CO OCH3
O
OCH3
NH
CH3
O
Colchicine
OCH3
OCH3
H3CO
3,4,5-Trimethoxyphenyl unit
Figure 2. Structures of some lead molecules possessing 3,4,5-trimethoxyphenyl
moiety as a common unit.
H. O. Saxena et al./Bioorg. Med. Chem. Lett. 18 (2008) 3914–3918
3915

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R1=
R2=
10: 4,5,6-trimethoxy- ,
11: 4,5,6-trimethoxy- , H;
12: 4,5,6-trimethoxy- ,
13: 4,5,6-trimethoxy- , 3'-methoxy-;
14: 4,5,6-trimethoxy- ,
15: 5,6-dimethoxy- ,
3',4',5'-trimethoxy;
2',3',4'-trimethoxy-;
2',4',6'-trimethoxy-;
3',4',5'-trimethoxy- .
COOH
HO
HO
HO
COOCH3
H3CO
H3CO
H3CO
C
H3CO
H3CO
H3CO
CH3
O
OCH3
H3CO OCH3
+
CHO
OCH3
OCH3
H3CO
OCH3
H3CO
H3CO
O
OCH3
OCH3
H3CO
H3CO
OCH3
O
OCH3
OCH3
5
iii
iii
iv
OCH3
OCH3
O
R2
R1
O
R2
R1
iv
CH3
O
6
7
7
8
9
10
+
C
CH3
H3CO
H3CO
H3CO
CH3
OH
Minor
Scheme 1. Reagents and conditions: (i) 20% aq alkali, dimethyl sulphate, refluxed for 3 h, 60%; (ii) CH3I, Mg turnings, THF, 20 min at RT then reflux for 1 h, 42%; (iii) 3% aq
methanolic NaOH, RT, overnight 16–18 h, 62–84% respective acetophenones and aldehydes used; (iv) TFA, refluxed in a sealed tube, 3–4 h, 28–52%.
Table 1
Cytotoxicitiesaof indanones and their analogues against various human cancer cell lines by MTT assay
Compound Human cancer cell lines
KB403 IC50(lM)WRL68 IC50(lM)CaCO2 IC50(lM)HEPG2 IC50(lM)MCF7 IC50(lM)
10
11
12
13
14
15
16
17
18
19
20
Taxol
Podophyllotoxin
10.3
0.84
1.54
Inactive
12.90
139.6
Inactive
Inactive
136.4
192.3
Inactive
0.001
20.5
12.8
Inactive
0.023
Inactive
0.022
195.5
124.3
62.5
223.3
192.3
153.8
0.004
4.8
Inactive
Inactive
206
Inactive
226
139.6
Inactive
112.5
49.6
6.4
115.3
0.008
0.002
9.0
188
Inactive
Inactive
1.49
111.7
74.6
Inactive
124
102.5
89.7
0.009
4.8
2.20
Inactive
Inactive
Inactive
211
Inactive
Inactive
50
Inactive
243.5
Inactive
0.006
8.5
aIC50P 250 lM was considered as inactive.
3916
H. O. Saxena et al./Bioorg. Med. Chem. Lett. 18 (2008) 3914–3918

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Acknowledgment
The financial support from the CSIR Networking Project (NWP-
09) is duly acknowledged.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmcl.2008.06.039.
References and notes
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Refs. 2–9 cited in the paper.
8. (a) Negi, A. S.; Darokar, M. P.; Chattopadhyay, S. K.; Garg, A.; Bhattacharya, A.
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OCH3
H3CO
H3CO
O
OCH3
OCH3
OCH3
v
vi
vii
viii
OCH3
H3CO
H3CO
NOH
OCH3
OCH3
OCH3
OCH3
H3CO
H3CO
OCH3
OCH3
OCH3
OH
OCH3
H3CO
H3CO
OCH3
OCH3
OCH3
OCH3
16
H3CO
H3CO
OCH3
OCH3
OCH3
O
OH
OCH3
H3CO
H3CO
+
O
O
OCH3
OCH3
OCH3
10
18
19
20
17
Scheme 2. Reagents and conditions: (v) SeO2, 1,4-Dioxane, refluxed for 3 h, 16: 67%, 17: 14%; (vi) NH2OH?HCl, Ethanol, Pyridine, refluxed for 2 h, 94%; (vii) NaBH4–MeOH,
58%; (viii) NaBH4–TFA, 0 ?C–RT, 6 h, 72%.
O
H
H3CO
H3CO
OCH3
OCH3
OCH3
H3CO
H
O
Figure 3. HMBC correlations of compound 17.
0
20
40
60
80
100
120
0.85 0.65 0.40.20.1
Percent Phosphate Buffer Saline
Percent Hemolysis
10 121411 CONTROL
Figure 4. Osmotic haemolysis curve of erythrocytes.
H. O. Saxena et al./Bioorg. Med. Chem. Lett. 18 (2008) 3914–3918
3917

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(b) Negi, A. S.; Chattopadhyay, S. K.; Srivastava, S.; Bhattacharya, A. K. Synth.
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Sisodia, B. S.; Darokar, M. P.; Luqman, S.; Khanuja, S. P. S. Bioorg. Med. Chem.
Lett. 2006, 16, 911; (d) Srivastava, V.; Saxena, H. O.; Shanker, K.; Kumar, J. K.;
Luqman, S.; Gupta, M. M.; Khanuja, S. P. S.; Negi, A. S. Bioorg. Med. Chem. Lett.
2006, 16, 4603; (e) Srivastava, V.; Darokar, M. P.; Fatima, A.; Kumar, J. K.;
Chowdhury, C.; Dwivedy, G. R.; Shrivastava, K.; Gupta, V.; Chattopadhyay, S. K.;
Luqman, S.; Saxena, H. O.; Gupta, M. M.; Negi, A. S.; Khanuja, S. P. S. Bioorg. Med.
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9. Srivastava, V.; Negi, A. S.; Kumar, J. K.; Gupta, M. M.; Khanuja, S. P. S. Bioorg.
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10. Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchel, A. R.. In Book, Vogel’s Text
Book of practical organic chemistry; Addison-Wesley Longman, Inc.: Reading,
MA, 1998; p 1034.
11. Lawrence, N. J.; Armitage, E. S. M.; Greedy, B.; Cook, D.; Ducki, S.; McGown, A. T.
Tetrahedron Lett. 2006, 47, 1637.
12. Saxena, H. O.; Faridi, U.; Kumar, J. K.; Luqman, S.; Daroker, M. P.; Shanker, K.;
Chanotiya, C. S.; Gupta, M. M.; Negi, A. S. Steroids 2007, 72, 892.
13. (a) Syntheses: Generalprocedure for preparing indanone derivatives from
chalcones: Synthesis of3-(30,40,50-Trimethoxyphenyl)-4,5,6-trimethoxy-
indan-1-one (10). In a Borosil test tube, chalcone 9 (150 mg, 0.39 mmol) was
taken in trifluoroacetic acid (0.5 ml) and the tube was sealed carefully with
flame. The reaction mixture was heated at 120 ?C for 4 h. The reaction mixture
was poured into crushed ice and extracted with ethyl acetate, organic layer
was washed with water, dried over anhydrous sodium sulphate and
evaporated in vacuo. The crude residue thus obtained was purified through
column chromatography on silica gel using ethylacetate–hexane as eluent. The
desired indanone 10 was obtained as a solid. It was recrystallised with
chloroform–hexane (1:3) to get 10 as a light brown solid.
(b) Synthesis of3-(30,40,50-Trimethoxyphenyl)-4,5,6-trimethoxy-indan (20).
Indanone 10 (100 mg, 0.26 mmol) was taken in trifluoroacetic acid (2.5 ml) and
the reaction flask was stirred in an ice-bath. After stirring for 5 min sodium
borohydride (100 mg, 2.6 mmol) was added in portions with maintaining the
bath temperature 0–15 ?C for an hour. After that the reaction mixture was
stirred at room temperature for 6 h. On completion, 10 ml water was added to
reaction mixture and it was extracted with ethyl acetate, organic layer was
washed with water, dried over anhydrous sodium sulphate and evaporated in
vacuo. The crude residue thus obtained was purified through column
chromatography on silica gel using ethyl
desired indan 20 was obtained as oil.
(c) 2-Hydroxy,3-(30,40,50-trimethoxyphenyl)-4,5,6-trimethoxy-ind-2-en-1-one
(16). Indanone 10 (100 mg, 0.26 mmol) was taken in a round-bottomed flask
with1,4-dioxane (10 ml) and selenium dioxide (290 mg, 2.6 mmol). The
reaction mixture was refluxed for 6 h. On completion, reaction mixture was
filtered and filtrate was evaporated in vacuo. The crude mass thus obtained
was purified through column chromatography on silica gel using ethyl
acetate–hexane as eluent. The cyclised product 17 was first obtained
followed by the desired derivative 16.
14. In-vitro anticancer activity using MTT assay. In-vitro cytotoxicity testing was
performed as per reported method.162 ? 103cells/well were incubated in the
5% CO2incubator for 24 h to enable them to adhere properly to the 96-well
polystyrene microplates (Grenier, Germany). Test compound dissolved in
dimethyl sulphoxide (DMSO, Merck, Germany), in at least five concentrations,
were added into the wells and left for 4 h. After the incubation, the compound
plus media was replaced with fresh media and the cells were incubated for
another 48 h in the CO2incubator at 37 ?C. The concentration of DMSO were
always kept below 1.25%, which was found to be non-toxic to cells. Then, 10 lL
MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
added to each well and plates were incubated at 37 ?C for 4 h. DMSO
(100 lL) was added to all wells and mixed thoroughly to dissolve the dark blue
crystals. The plates were read on SpectraMax 190 Microplate reader (Molecular
Devices Inc. USA) at 570 nm within 1 h of DMSO addition.
15. Determination of osmotic haemolysis of erythrocytes: Blood from healthy human
male volunteers (n = 3) with informed consent was collected for experiments
using heparin (10 U/ml) as the anti-coagulant. The collected blood was stored
at 4 ?C and was used for experiments within 4 h of collection.18Experiments
were carried in-vitro by adding heparinised blood to hypotonic solutions of
varying concentrations of phosphate buffered saline (0.85% to 0.10%).
Phosphate-buffered saline stock (10%) was prepared by dissolving 5 g of
sodium chloride, 1.3655 g of disodium hydrogen orthophosphate and 0.243 g
of sodium dihydrogen orthophosphate in 100 ml of autoclaved double distilled
water. From this stock, working standards of 0.85% to 0.10% were prepared. The
tubes were incubated at 37 ?C for 60 min with mild shaking and the extent of
haemolysis was measured colorimetrically at 540 nm.19Results are expressed
in terms of mean erythrocyte fragility (MEF50), which is the level of haemolysis
of the erythrocytes at 50% saline concentrations. Similarly, prior to the
experiment, heparinised blood was incubated with effective concentration of
acetate–hexane as eluent. The
bromide] was
indanone derivatives (5–100 lg/ml) at 37 ?C for 60 min. The concentrations of
indanones were chosen higher than the concentrations at which the
compounds showed anticancer activity.
Aliquots of saline solutions of decreasing concentration (from 10 to 1 g/L) were
prepared as described earlier.19,20The test compound treated erythrocytes
were then transferred to tubes containing decreasing concentrations of saline
solutions. After careful mixing, the cell suspensions were left to equilibrate for
30 min and then centrifuged at 3000 rpm for 5 min. The absorbance of
supernatants was read at 540 nm, with the standardised against an assay blank
(the 10 g/L saline supernatant corresponds to 0% haemolysis). The recorded
optical density (OD) of the supernatant reflects the degree of haemolysis of the
erythrocytes. The percentage lysis was calculated by dividing the OD of the
supernatant obtained from a particular saline concentration by the OD of
the standard (1 g/L) representing 100% haemolysis.21Osmotic fragility curves
were constructed by plotting the percentage lysis against the concentration of
saline solutions. The MEF50(mean erythrocyte fragility) value, which is the
saline concentration at which 50% of the cells haemolyse at standard pH and
temperature, was then obtained from the curve.
16. Woerdenbag, H. J.; Moskal, T. A.; Pras, N.; Malingré, T. M.; Farouk, S.; EI-Feraly,
H.; Kampinga, H.; Konings, A. W. T. J. Nat. Prod. 1993, 56, 849.
17. Selected physical data:Compound 10:
cm?1): 2938, 1705, 1591, 1509, 1500, 1129.1H NMR(CDCl3, 300 MHz) d 2.58–
2.65 (dd, 1H, 2-CH, J = 2.58, 19.29 Hz), 3.13–3.22(dd, 1H, 2-CH, J = 7.98,
19.26 Hz), 3.42 (s, 3H, OCH3), 3.78 (s, 6H, 2? OCH3), 3.81 (s, 3H, OCH3), 3.91
(s, 3H, OCH3), 3.93 (s, 3H, OCH3), 4.50–4.53 (dd, 1H, 3-CH, J = 7.95, 2.49 Hz),
6.31 (s, 2H, aromatic protons), 7.09 (s, 1H, aromatic proton);13C NMR(CDCl3,
75.46 MHz) d 42.30, 47.48, 56.58, 56.68, 56.68, 60.44, 61.14, 61.14, 100.81,
105.03, 132.65, 137.75, 140.42, 140.42, 144.38, 149.21, 150.89, 153.84, 153.84,
155.45, 205.08. EI Mass GC–MS (CH3CN): 388 [M+], 373, 357, 181.
Compound 12: Yield = 71%; mp = 119–123 ?C; IR (KBr, cm?1): 2936, 2838, 1704,
1599, 1498, 1470, 1101.1H NMR(CDCl3, 300 MHz) d 2.54–2.61 (dd, 1H, 2-CH,
J = 1.99, 19.07 Hz), 3.07–3.16 (dd, 1H, 2-CH, J = 8.03, 19.09 Hz), 3.38 (s, 3H,
OCH3), 3.69 (s, 3H, OCH3), 3.81 (s, 3H, OCH3), 3.84 (s, 3H, OCH3), 3.88 (s, 3H,
OCH3), 3.90 (s, 3H, OCH3), 4.75–4.78 (br d, 1H, -CH, J = 7.95, 2.49 Hz), 6.53–6.58
(br s, 2H, aromatic protons), 7.08 (s, 1H, aromatic proton); EI mass GC–MS
(CH3CN): 388 [M+], 357, 373, 358, 342.
Compound 13: Yield: 48%; mp = 112–115 ?C;1H NMR(CDCl3, 300 MHz) d 2.58–
2.65 (dd, 1H, 2-CH, J = 2.42, 19.26 Hz), 3.14–3.23(dd, 1H, 2-CH, J = 7.97,
19.27 Hz), 3.39 (s, 3H, OCH3), 3.76 (s, 3H, OCH3), 3.91 (s, 3H, OCH3), 3.93 (s,
3H, OCH3), 4.54–4.58 (dd, 1H, –CH, J = 2.36 and 7.90 Hz), 6.66–7.23 (m, 8H,
aromatic protons); EI mass GC–MS (CH3CN): 328 [M+], 313, 207.
Compound 16: Yield = 67%; mp = oil; IR (KBr, cm?1): 3444, 2939, 1727, 1594,
1499, 1466, 1126.1H NMR(CDCl3, 300 MHz) d 3.33 (s, 3H, OCH3), 3.78 (s, 6H,
2? OCH3), 3.84 (s, 3H, OCH3), 3.86 (s, 3H, OCH3), 6.65 (s, 2H, aromatic protons),
6.97 (s, 1H, aromatic proton);13C NMR(CDCl3, 75 MHz) d 42.30, 47.48, 56.58,
56.68, 56.68, 60.44, 61.14, 61.14, 100.81, 105.03, 132.65, 137.75, 140.42,
140.42,144.38, 149.21, 150.89, 153.84, 153.84, 155.45, 205.08. EI Mass GC–MS
(CH3CN): 402 [M+], 387, 195.
Compound 17: Yield = 16%; mp = 145–148 ?C; IR (KBr, cm?1): 2933, 1697, 1474,
1384, 1096.1H NMR(CDCl3, 300 MHz) d 3.90 (s, 3H, OCH3), 3.95 (s, 3H, OCH3),
3.98 (s, 3H, OCH3), 4.00 (s, 3H, OCH3), 4.03 (s, 3H, OCH3), 4.07 (s, 3H, OCH3),
7.04 (s, 1H, aromatic proton), 8.07 (s, 1H, aromatic proton);13C NMR(CDCl3,
75 MHz) d 56.55, 56.93, 61.10, 61.37, 61.51, 62.09, 105.96, 106.96, 127.09,
130.38, 133.06, 136.87, 137.10, 141.73, 147.17, 147.52, 149.42, 153.86, 154.26,
156.33, 187.84. EI Mass GC–MS (CH3CN): 400 [M]+.
Compound 19: Yield = 58%; mp = 132–136 ?C ; IR (KBr, cm?1): 3516, 2941, 1593,
1503, 1463, 1419, 1335, 1120.1H NMR(CDCl3, 300 MHz) d 1.92–2.01 (m, 1H, 2-
CH), 2.94–2.99 (m, 1H, 2-CH), 3.45 (s, 3H, OCH3), 3.79 (s, 12H, 4? OCH3), 3.90
(s, 3H, OCH3), 4.22–4.27 (m, 1H, 3-CH), 5.16–5.20 (m, 1H, 1-CH), 6.48 (s, 2H,
aromatic protons), 6.81 (s, 1H, aromatic proton);13C NMR(CDCl3, 75.46 MHz) d
46.35, 47.58, 56.45, 56.53, 60.21, 60.42, 60.94, 60.98, 75.35, 103.54, 105.24,
105.88, 130.49, 137.01, 141.54, 142.30, 142.82, 150.36, 153.31, 154.46. EI Mass
GC–MS (CH3CN): 390 [M+], 372, 357. ½a?28
Compound 20: Yield = 72%; mp = 71–74 ?C ;1H NMR(CDCl3, 300 MHz) d 1.99–
2.06 (m, 1H, 2-CH), 2.52–2.59 (m, 1H, 2-CH), 2.85–2.89 (m, 1H, 1-CH), 2.99–
3.06 (m, 1H, 1-CH), 3.51 (s, 3H, OCH3), 3.77 (s, 6H, 2? OCH3), 3.80 (s, 3H, OCH3),
3.81 (s, 3H, OCH3), 3.87 (s, 3H, OCH3), 4.37–4.42 (m, 1H, 3-CH), 6.33 (s, 2H,
aromatic proton), 6.63 (s, 1H, aromatic proton);13C NMR(CDCl3, 75.46 MHz) d
22.66, 29.67, 31.93, 49.43, 56.35, 56.35, 60.15, 60.73, 60.81, 104.01, 105.19,
130.84, 139.95, 142.38, 150.29, 153.93, 153.76. EI Mass GC–MS (CH3CN): 390
[M+], 372, 357.
18. Luqman, S.; Rizvi, S. I. Asia Pacific J. Pharmacol. 2004, 16, 53.
19. Luqman, S.; Obli Prabu, K. V.; Pal, A.; Saikia, D.; Darokar, M. P.; Khanuja, S. P. S.
Nat. Prod. Commun. 2006, 1, 481.
20. Luqman, S.; Kumar, N.; Rizvi, S. I. University Allahabad Studies 2004, 3, 29.
21. Dacie, J. V.; Lewis, S. M. Practical Hematology, 1984; Orient Longman, p
152.
Yield = 64%; mp = 107–110 ?C; IR (KBr,
589þ 6:99?(1.04, MeOH).
3918
H. O. Saxena et al./Bioorg. Med. Chem. Lett. 18 (2008) 3914–3918