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Synthesis and antitumor activity of novel 10-amino acids ester homocamptothecin analogues
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Chinese Chemical Letters 19 (2008) 811–813 www.elsevier.com/locate/cclet
Synthesis and antitumor activity of novel 10-amino acids ester homocamptothecin analogues Liang You, Wan Nian Zhang *, Zhen Yuan Miao, Wei Guo, Xiao Ying Che, Wen Ya Wang, Chun Quan Sheng, Jiang Zhong Yao, Ting Zhou School of Pharmacy, Second Military Medical University, Shanghai 200433, China Received 7 March 2008
Abstract Nine racemic homocamptothecin derivatives were synthesized and in vitro antitumor activities were evaluated by standard MTT method. The results showed that some of the compound had higher antitumor activity than iritecan. # 2008 Wan Nian Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Homocamptothecin; Amino acids ester; Antitumor activity; Synthesis
20(S)-Camptothecin (CPT), an antitumor alkaloid, was first isolated by Wall and Wani in 1966 from Camptotheca acuminate a tree native to China [1]. The cellular target of the drug is DNA topoisomerase I, a nuclear enzyme that is required for topological manipulation of DNA during cellular events such as replication, transcription and repair [2]. In 1997 Lavergne and coworkers first described a novel class of camptothecin analogues named homocamptothecin, which showed much higher cytotoxicity than CPT [3]. The homocamptothecin derivatives such as diflomotecan, homosilatecan DB-90 are undergoing clinical trial and first results are encouraging. Most structural modification of camptothecin have focused on rings A and B and achieved potent antitumor agents of 10-substituted derivatives of camptothecin. Zu et al. have exploited a series of compounds which placed the several water-solubilizing groups in the position C-10 of CPT as aromatic quarternary ammonium salts. These salt showed specially lower cytotoxicity in vitro than CPT and impressive tumor inhibiting activities [4]. Christoph et al. have also invented specific phospholipid ester of 7-ethyl-10-hydroxycamptothecin. The water solubility and antitumor activity of those compounds were enhanced remarkably compared with CPT [5]. So we recently synthesized a series of 10-substituted racemic homocamptothecin analogues, hoping that these derivatives might have high antitumor activity and water solubility. The synthetic route started from the mhydroxyacetophenone to 10-amino acids ester derivatives homocamptothecin in good yield was showed in Scheme 1. A solution of of m-hydroxyacetophenone 1, tetrahydrofuran and triethylamine stirred at 0 8C, then triphosgene (BTC) was added slowly. The carbonate 2 was then formed. The carbonate was reacted with H2SO4 and HNO3 to get 3, which was hydrogenated to give 4 [6]. Friedlander condensation of the tricyclic 5 [7] with 4 in the presence of an acid
* Corresponding author. E-mail address: [email protected] (W.N. Zhang). 1001-8417/$ – see front matter # 2008 Wan Nian Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.05.011
812
L. You et al. / Chinese Chemical Letters 19 (2008) 811–813
Scheme 1. Reagents and conditions: (a) BTC, ET3N, THF, rt, 4 h, 0 8C, 85%; (b) H2SO4, HNO3, rt, 1 h, 5 8C, 65%; (c) H2, Pd, rt, 6 h, 95%; (d) toluene, p-TSA, 110 8C, 6 h, 70%; (e) CH2Cl2, DCC, DMAP, 6 h, 25–30%; (f) CH2Cl2, TFA, rt, 1 h, 85–96%.
catalyst gave 7-methy-10-hydroxylhomocamptothecin 6, which was reacted with different N-protected racemic amino acids to give the 10-amino acids ester derivatives of 7a–g [8]. 7a and 7c stirred in trifluoroacetic acid to give 8a and 8c [8]. We used BTC instead of phosgene because of its high toxicity and the yield was not degraded. All of the synthesized 10-substituted analogues of racemic homocamptothecin were evaluated on their antitumor activities in vitro by MTT assay, and the result is summarized in Table 1. It was found that many of them exhibited more potent cytotoxic activity against A-549, LOVO and MDA-MB-435 cell line than iritecan. Among them 7a, 7c and 7e showed better activity against MDA-MB-435 cell line slightly lower than topotecan. From the cytotoxicity values (IC50) it emerged that some of the compound might use as prodrug and further biological evaluations are currently in progress and will be reported later. Table 1 Structure and in vitro antitumor activity of the target compounds Compound
6 7a 7b 7c 7d 7e 7f 7g 8a 8c Topotecan Iritecan
R
Benz-CH2– H (CH2)2CH– (CH2)2CHCH2– (Boc)NH(CH2)4– (Boc)NHCOCH2CH2– CH3SCH2CH2– Benz-CH2– H
IC50 (mg/mL) A-549
MDA-MB-435
LOVO
0.0303 1.700 2.170 1.851 2.179 1.921 5.79 2.72 1.53 1.95 0.0179 2.81
<0.001 0.00578 0.001 0.0102 0.0164 0.0123 0.211 0.0102 0.135 0.135 <0.001 0.694
0.0132 0.104 0.0308 0.111 0.151 0.0872 0.406 0.00838 0.597 0.332 0.00755 3.04
L. You et al. / Chinese Chemical Letters 19 (2008) 811–813
813
Acknowledgments This research was supported by the National Natural Science Foundation of China (No. 30371689), Shanghai Major Program Science and Technology Foundation (No. 064319009) and Shanghai Leading Academic Discipline Project (No. B906). References [1] [2] [3] [4] [5] [6] [7] [8]
M.E. Wall, M.C. Wani, C.E. Cook, et al. J. Am. Chem. Soc. 88 (1966) 3888. N. Osheroff, Pharmacology 41 (1989) 223. L. Olivier, L.G. Laurence, P.R. Francesc, Bioorg. Med. Lett. 7 (1997) 2235. Q.Y. Li, Y.G. Zu, R.Z. Shi, et al. Bioorg. Med. Chem. 14 (2006) 7175. M. Christoph, H.O. Brigitte, B. Joris, et al., WO Patent 082053 (2006). A.R. Osborn, K. Schofield, J. Chem. Soc. (1955) 2100. Z.Y. Miao, W.N. Zhang, J.Z. Yao, et al. Chin. Chem. Lett. 17 (2006) 720. Selected spectral data. 6: yellow powder, mp > 255 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H), 1.86 (q, 2H), 2.76 (s, 3H), 3.06 (d, 1H), 3.49 (d, 1H), 5.28 (s, 2H), 5.39 (d, 1H), 5.53 (d, 1H), 6.03 (s, 1H), 7.42 (s, 1H), 7.72 (t, 1H), 7.87 (t, 1H), 8.15 (q, 2H), 8.69 (s, 1H), 10.32 (s, 1H); ESI-MS m/z: 391.3 [M H] . 7a: yellow powder, mp 235–238 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.2 Hz), 1.40 (s, 9H), 1.86 (q, 2H, J = 7.5 Hz), 2.73 (s, 3H), 3.14 (d, 2H, J = 9.3 Hz), 3.27 (d, 2H, J = 13.8 Hz), 4.50 (q, 1H, J = 7.8 Hz), 5.30 (s, 2H), 5.47 (d, 2H, J = 15.4 Hz), 6.04 (s, 1H), 7.29 (s, 1H), 7.37–7.40 (m, 5H), 7.51 (d, 1H, J = 8.75 Hz), 7.69 (d, 1H, J = 6.7 Hz), 7.72 (s, 1H), 8.20 (d, 1H, J = 9.3 Hz); ESI-MS m/z: 638.6 [M H] . 7c: yellow powder, mp 252–254 C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.06 (d, 6H, J = 7.33 Hz), 1.46 (s, 9H), 1.87 (q, 2H, J = 7.5 Hz), 2.18 (q, 1H, J = 7.5 Hz), 2.75 (s, 3H), 3.28 (d, 2H, J = 13.8 Hz), 4.17 (t, 1H, J = 6.73 Hz), 5.31 (s, 2H), 5.47 (d, 2H, J = 15 Hz), 6.04 (s, 1H), 7.41 (s, 1H), 7.55 (d, 1H, J = 7.4 Hz), 7.61 (d, 1H, J = 9.14 Hz), 7.90 (s, 1H), 8.22 (d, 1H, J = 9.1 Hz); ESI-MS m/z: 590.3[M H] . 7e: yellow powder, mp 203–205 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.38 (s, 9H), 1.44 (s, 9H), 1.23–1.72 (m, 6H), 1.84 (q, 2H, J = 7.0 Hz), 1.87 (q, 2H, J = 7.5 Hz), 2.75 (s, 3H), 3.27 (d, 2H, J = 14.2 Hz), 4.22 (s, 1H), 5.30 (s, 2H), 5.47 (d, 2H, J = 15.1 Hz), 6.03 (s, 1H), 6.83 (s, 1H), 7.40 (s, 1H), 7.56 (d, 1H, J = 6.85 Hz), 7.60 (d, 1H J = 8.5 Hz), 7.91 (s, 1H), 8.20 (d, 1H, J = 9.1 Hz); ESI-MS m/z: 719.7 [M H] . 8a: yellow powder; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.86 (q, 2H, J = 7.5 Hz), 2.72 (s, 3H), 3.21 (d, 2H, J = 13.8 Hz), 3.34 (d, 2H, J = 9.3 Hz), 4.65–4.70 (m, 1H), 5.31 (s, 2H), 5.47 (d, 2H, J = 15.4 Hz), 6.04 (s, 1H), 7.39–7.65 (m, 7H), 7.65 (s, 1H), 8.25 (d, 1H, J = 9.2 Hz), 8.65 (s, 2H); ESI-MS m/z: 538.6 [M H] .
Chinese Chemical Letters 19 (2008) 811–813 www.elsevier.com/locate/cclet
Synthesis and antitumor activity of novel 10-amino acids ester homocamptothecin analogues Liang You, Wan Nian Zhang *, Zhen Yuan Miao, Wei Guo, Xiao Ying Che, Wen Ya Wang, Chun Quan Sheng, Jiang Zhong Yao, Ting Zhou School of Pharmacy, Second Military Medical University, Shanghai 200433, China Received 7 March 2008
Abstract Nine racemic homocamptothecin derivatives were synthesized and in vitro antitumor activities were evaluated by standard MTT method. The results showed that some of the compound had higher antitumor activity than iritecan. # 2008 Wan Nian Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Homocamptothecin; Amino acids ester; Antitumor activity; Synthesis
20(S)-Camptothecin (CPT), an antitumor alkaloid, was first isolated by Wall and Wani in 1966 from Camptotheca acuminate a tree native to China [1]. The cellular target of the drug is DNA topoisomerase I, a nuclear enzyme that is required for topological manipulation of DNA during cellular events such as replication, transcription and repair [2]. In 1997 Lavergne and coworkers first described a novel class of camptothecin analogues named homocamptothecin, which showed much higher cytotoxicity than CPT [3]. The homocamptothecin derivatives such as diflomotecan, homosilatecan DB-90 are undergoing clinical trial and first results are encouraging. Most structural modification of camptothecin have focused on rings A and B and achieved potent antitumor agents of 10-substituted derivatives of camptothecin. Zu et al. have exploited a series of compounds which placed the several water-solubilizing groups in the position C-10 of CPT as aromatic quarternary ammonium salts. These salt showed specially lower cytotoxicity in vitro than CPT and impressive tumor inhibiting activities [4]. Christoph et al. have also invented specific phospholipid ester of 7-ethyl-10-hydroxycamptothecin. The water solubility and antitumor activity of those compounds were enhanced remarkably compared with CPT [5]. So we recently synthesized a series of 10-substituted racemic homocamptothecin analogues, hoping that these derivatives might have high antitumor activity and water solubility. The synthetic route started from the mhydroxyacetophenone to 10-amino acids ester derivatives homocamptothecin in good yield was showed in Scheme 1. A solution of of m-hydroxyacetophenone 1, tetrahydrofuran and triethylamine stirred at 0 8C, then triphosgene (BTC) was added slowly. The carbonate 2 was then formed. The carbonate was reacted with H2SO4 and HNO3 to get 3, which was hydrogenated to give 4 [6]. Friedlander condensation of the tricyclic 5 [7] with 4 in the presence of an acid
* Corresponding author. E-mail address: [email protected] (W.N. Zhang). 1001-8417/$ – see front matter # 2008 Wan Nian Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.05.011
812
L. You et al. / Chinese Chemical Letters 19 (2008) 811–813
Scheme 1. Reagents and conditions: (a) BTC, ET3N, THF, rt, 4 h, 0 8C, 85%; (b) H2SO4, HNO3, rt, 1 h, 5 8C, 65%; (c) H2, Pd, rt, 6 h, 95%; (d) toluene, p-TSA, 110 8C, 6 h, 70%; (e) CH2Cl2, DCC, DMAP, 6 h, 25–30%; (f) CH2Cl2, TFA, rt, 1 h, 85–96%.
catalyst gave 7-methy-10-hydroxylhomocamptothecin 6, which was reacted with different N-protected racemic amino acids to give the 10-amino acids ester derivatives of 7a–g [8]. 7a and 7c stirred in trifluoroacetic acid to give 8a and 8c [8]. We used BTC instead of phosgene because of its high toxicity and the yield was not degraded. All of the synthesized 10-substituted analogues of racemic homocamptothecin were evaluated on their antitumor activities in vitro by MTT assay, and the result is summarized in Table 1. It was found that many of them exhibited more potent cytotoxic activity against A-549, LOVO and MDA-MB-435 cell line than iritecan. Among them 7a, 7c and 7e showed better activity against MDA-MB-435 cell line slightly lower than topotecan. From the cytotoxicity values (IC50) it emerged that some of the compound might use as prodrug and further biological evaluations are currently in progress and will be reported later. Table 1 Structure and in vitro antitumor activity of the target compounds Compound
6 7a 7b 7c 7d 7e 7f 7g 8a 8c Topotecan Iritecan
R
Benz-CH2– H (CH2)2CH– (CH2)2CHCH2– (Boc)NH(CH2)4– (Boc)NHCOCH2CH2– CH3SCH2CH2– Benz-CH2– H
IC50 (mg/mL) A-549
MDA-MB-435
LOVO
0.0303 1.700 2.170 1.851 2.179 1.921 5.79 2.72 1.53 1.95 0.0179 2.81
<0.001 0.00578 0.001 0.0102 0.0164 0.0123 0.211 0.0102 0.135 0.135 <0.001 0.694
0.0132 0.104 0.0308 0.111 0.151 0.0872 0.406 0.00838 0.597 0.332 0.00755 3.04
L. You et al. / Chinese Chemical Letters 19 (2008) 811–813
813
Acknowledgments This research was supported by the National Natural Science Foundation of China (No. 30371689), Shanghai Major Program Science and Technology Foundation (No. 064319009) and Shanghai Leading Academic Discipline Project (No. B906). References [1] [2] [3] [4] [5] [6] [7] [8]
M.E. Wall, M.C. Wani, C.E. Cook, et al. J. Am. Chem. Soc. 88 (1966) 3888. N. Osheroff, Pharmacology 41 (1989) 223. L. Olivier, L.G. Laurence, P.R. Francesc, Bioorg. Med. Lett. 7 (1997) 2235. Q.Y. Li, Y.G. Zu, R.Z. Shi, et al. Bioorg. Med. Chem. 14 (2006) 7175. M. Christoph, H.O. Brigitte, B. Joris, et al., WO Patent 082053 (2006). A.R. Osborn, K. Schofield, J. Chem. Soc. (1955) 2100. Z.Y. Miao, W.N. Zhang, J.Z. Yao, et al. Chin. Chem. Lett. 17 (2006) 720. Selected spectral data. 6: yellow powder, mp > 255 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H), 1.86 (q, 2H), 2.76 (s, 3H), 3.06 (d, 1H), 3.49 (d, 1H), 5.28 (s, 2H), 5.39 (d, 1H), 5.53 (d, 1H), 6.03 (s, 1H), 7.42 (s, 1H), 7.72 (t, 1H), 7.87 (t, 1H), 8.15 (q, 2H), 8.69 (s, 1H), 10.32 (s, 1H); ESI-MS m/z: 391.3 [M H] . 7a: yellow powder, mp 235–238 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.2 Hz), 1.40 (s, 9H), 1.86 (q, 2H, J = 7.5 Hz), 2.73 (s, 3H), 3.14 (d, 2H, J = 9.3 Hz), 3.27 (d, 2H, J = 13.8 Hz), 4.50 (q, 1H, J = 7.8 Hz), 5.30 (s, 2H), 5.47 (d, 2H, J = 15.4 Hz), 6.04 (s, 1H), 7.29 (s, 1H), 7.37–7.40 (m, 5H), 7.51 (d, 1H, J = 8.75 Hz), 7.69 (d, 1H, J = 6.7 Hz), 7.72 (s, 1H), 8.20 (d, 1H, J = 9.3 Hz); ESI-MS m/z: 638.6 [M H] . 7c: yellow powder, mp 252–254 C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.06 (d, 6H, J = 7.33 Hz), 1.46 (s, 9H), 1.87 (q, 2H, J = 7.5 Hz), 2.18 (q, 1H, J = 7.5 Hz), 2.75 (s, 3H), 3.28 (d, 2H, J = 13.8 Hz), 4.17 (t, 1H, J = 6.73 Hz), 5.31 (s, 2H), 5.47 (d, 2H, J = 15 Hz), 6.04 (s, 1H), 7.41 (s, 1H), 7.55 (d, 1H, J = 7.4 Hz), 7.61 (d, 1H, J = 9.14 Hz), 7.90 (s, 1H), 8.22 (d, 1H, J = 9.1 Hz); ESI-MS m/z: 590.3[M H] . 7e: yellow powder, mp 203–205 8C; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.38 (s, 9H), 1.44 (s, 9H), 1.23–1.72 (m, 6H), 1.84 (q, 2H, J = 7.0 Hz), 1.87 (q, 2H, J = 7.5 Hz), 2.75 (s, 3H), 3.27 (d, 2H, J = 14.2 Hz), 4.22 (s, 1H), 5.30 (s, 2H), 5.47 (d, 2H, J = 15.1 Hz), 6.03 (s, 1H), 6.83 (s, 1H), 7.40 (s, 1H), 7.56 (d, 1H, J = 6.85 Hz), 7.60 (d, 1H J = 8.5 Hz), 7.91 (s, 1H), 8.20 (d, 1H, J = 9.1 Hz); ESI-MS m/z: 719.7 [M H] . 8a: yellow powder; 1H NMR (500 MHz, DMSO-d6, d, ppm): 0.87 (t, 3H, J = 7.4 Hz), 1.86 (q, 2H, J = 7.5 Hz), 2.72 (s, 3H), 3.21 (d, 2H, J = 13.8 Hz), 3.34 (d, 2H, J = 9.3 Hz), 4.65–4.70 (m, 1H), 5.31 (s, 2H), 5.47 (d, 2H, J = 15.4 Hz), 6.04 (s, 1H), 7.39–7.65 (m, 7H), 7.65 (s, 1H), 8.25 (d, 1H, J = 9.2 Hz), 8.65 (s, 2H); ESI-MS m/z: 538.6 [M H] .