C. N. Reddy et al. / Bioorg. Med. Chem. Lett. xxx (2015) xxx–xxx
7
death.17,18 In this context, DU-145 cells were treated with com-
pounds 6b and 6u at 1.5 and 3 M concentration for 48 h. Results
indicate that there was nearly 2 to 3-fold induction in caspase-3
l
levels compared to the control (Fig. 6).
In summary, we report the synthesis and anticancer activity of a
series of spiro[cyclopropane-1,30-indolin]-20-ones against five
human cancer cell lines, namely HT-29 (colon), DU-145 (prostate),
Hela (cervical), A549 (lung) and MCF-7 (breast). The experimental
results suggested the 1,3-dipolar cycloaddition/ring contraction
mechanism for the diastereoselective cyclopropanation of 3-
methyleneindolin-2-ones. Compound 6b and 6u showed signifi-
cant anticancer activity against human prostate cancer cell line,
DU-145. Detailed biological studies like, cell cycle analysis showed
that these compounds arrest the cell cycle at G0/G1 phase and
induced cell death by apoptosis. It was further confirmed by mito-
chondrial membrane potential, Annexin V-FITC analysis and Cas-
pase-3 activity.
Acknowledgments
R.A.M. is thankful to the Department of Science and Technology,
India for financial support (GAP 0378 & GAP 0470). Financial sup-
port in part from IICT Project Affordable Cancer Therapeutics ‘CSC-
0301’ is also acknowledged. C.N.R. and P.R.A. acknowledge CSIR-
New Delhi for their fellowships.
General experimental procedure for the synthesis of compounds 5a–y, 3a–f
and 8b: To a 25 ml round bottom flask, 3-methyleneindolin-2-ones (1 mmol),
ethyl diazoacetate (1.1 mmol), and tetrahydrofuran (10 ml) were taken and the
reaction mixture was refluxed overnight. After completion, the reaction
mixture was evaporated to yield crude product which was further purified
by column chromatography using ethyl acetate-hexane in increasing polarity
to yield desired compounds. Characterization data for ethyl-2-benzoyl-20-
oxospiro[cyclopropane-1,30-indoline]-3-carboxylate 8b: Physical appearance:
white solid; mp 169–170 °C; Rf = 0.30 (50% EtOAc/n-Hexane); IR (KBr, cmꢀ1):
3219, 3059, 2978, 2925, 1734, 1708, 1688, 1617, 1471, 1447, 1362, 1342, 1310,
1201, 1165; 1H NMR (300 MHz, CDCl3) d 8.14 (s, 1H), 7.84 (d, J = 7.8 Hz, 2H),
7.56–7.49 (m, 2H), 7.39–7.31 (m, 3H), 7.12 (t, J = 7.3 Hz, 1H), 6.95 (d, J = 7.8 Hz,
1H), 4.36–4.08 (m, 2H), 3.84 (d, J = 7.9 Hz, 1H), 3.49 (d, J = 7.8 Hz, 1H), 1.27 (t,
J = 7.1 Hz, 3H); 13C NMR (75 MHz, CDCl3 + DMSO) d 189.56, 171.90, 166.84,
142.21, 135.25, 132.83, 128.01, 127.88, 127.49, 123.61, 121.88, 121.22, 109.60,
60.87, 38.84, 38.78, 33.93, 13.45. HRMS calcd for C20H18NO4; 336.1236, found
336.1246. General experimental procedure for the reduction of carbonyl
compounds: To a 25 mL round bottom flask, carbonyl compound (1 mmol) and
ethanol (10 mL) was taken under nitrogen atmosphere. Next NaBH4 (5 mmol)
was added to the reaction mixture in portions with stirring. After the reaction
was complete, the reaction mixture was concentrated and extracted with
EtOAc/saturated aq. NaHCO3. The organic layer was separated, dried over
anhydrous sodium sulfate, and concentrated to yield pure products.
Characterization data for ethyl 3-(hydroxy(4-methoxyphenyl)methyl)-20-
oxospiro[cyclopropane-1,30-indoline]-2-carboxylate 7c: Physical appearance:
white solid; mp 202–204 °C; Rf = 0.38 (50% EtOAc/n-Hexane); IR (KBr, cmꢀ1) :
3469, 3078, 2950, 2873, 1739, 1696, 1251; 1H NMR (300 MHz, CDCl3) d 8.90 (s,
1H), 7.50 (d, J = 8.6 Hz, 2H), 7.21 (t, J = 7.6 Hz, 1H), 7.14 (d, J = 7.4 Hz, 1H), 7.02
(t, J = 7.5 Hz, 1H), 6.91 (dd, J = 12.8, 8.3 Hz, 3H), 4.82 (d, J = 9.7 Hz, 1H), 4.11 (q,
J = 7.1 Hz, 2H), 3.82 (s, 3H), 3.14–2.95 (m, 1H), 2.90 (s, 1H), 2.72 (d, J = 8.1 Hz,
1H), 1.18 (t, J = 7.1 Hz, 3H). 13C NMR (75 MHz, CDCl3+DMSO) d 174.22, 166.16,
158.34, 141.85, 134.84, 127.02, 126.79, 126.64, 126.21, 120.77, 113.10, 109.51,
69.11, 60.33, 54.55, 40.50, 36.75, 35.61, 13.43. HRMS calcd. for C21H22NO5;
368.1498, found 368.1503. Characterization data for ethyl 50-bromo-3-
(hydroxy(4-nitrophenyl)methyl)-20-oxospiro [cyclopropane-1,30-indoline]-2-
carboxylate 7y: Physical appearance: orange solid; mp 207–208 °C; Rf = 0.48
(50% EtOAc/n-Hexane); IR (KBr, cmꢀ1) : 3412, 3005, 1731, 1682, 1620, 1526,
1320, 1218; 1H NMR (300 MHz, CDCl3+DMSO) d 9.91 (s, 1H), 8.09 (d, J = 8.8 Hz,
2H), 7.59 (d, J = 8.7 Hz, 2H), 7.34 (d, J = 1.7 Hz, 1H), 7.23 (dd, J = 8.3, 1.9 Hz, 1H),
6.74 (d, J = 8.3 Hz, 1H), 5.23 (d, J = 4.3 Hz, 1H), 4.91 (dd, J = 8.0, 4.8 Hz, 1H), 4.04
(q, J = 7.1 Hz, 2H), 2.79 (dt, J = 16.3, 8.2 Hz, 1H), 1.11 (t, J = 7.1 Hz, 3H). 13C NMR
Supplementary data
Supplementary data associated with this article can be found, in
References and notes
(75 MHz, CDCl3+DMSO)
d 174.11, 166.38, 150.56, 141.57, 130.33, 128.71,
126.96, 126.68, 125.00, 123.53, 122.07, 113.91, 111.53, 69.34, 61.35, 41.12,
36.99, 36.36, 29.59, 14.05. HRMS calcd. for C20H18BrN2O6; 461.0348, found
461.0363.