Research Article Synthesis and Biological Evaluation of New (-)-Gossypol-Derived Schiff Bases and Hydrazones Vu Van Vu, 1 Trinh Thi Nhung, 1 Nguyen Thi Thanh, 1 Luu Van Chinh, 2 Vu Dinh Tien, 1 Vu Thu Thuy, 1 Do Thi Thao, 3 Nguyen Hai Nam, 4 Angela Koeckritz, 5 and Tran Khac Vu 1 1 School of Chemical Engineering, Hanoi University of Science and Technology, No. 1 Dai Co Viet, Hai Ba Trung, Hanoi, Vietnam 2 Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam 3 Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam 4 Hanoi University of Pharmacy (HUP), 13-15 Le Tanh Tong, Hanoi, Vietnam 5 Leibniz Institute for Catalysis at the University of Rostock, Albert-Einstein-Str. 29A, 18059 Rostock, Germany Correspondence should be addressed to Tran Khac Vu; vu.trankhac@hust.edu.vn Received 8 June 2017; Revised 19 August 2017; Accepted 13 September 2017; Published 17 October 2017 Academic Editor: Mire Zloh Copyright © 2017 Vu Van Vu et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A series of 14 new (−)-gossypol Schif bases and hydrazones have been synthesized via an in situ procedure in high yields. Structural data showed that all target compounds exist as the enamine tautomer. Bioassays showed that several compounds exhibited cytotoxic efects against three human cancer cell lines. Compound 8a showed the greatest cytotoxic efect against hepatocellular carcinoma (HepG2), lung carcinoma (LU-1), and breast cancer (MCF-7) cell lines with IC 50 values of 20.93, 13.58, and 9.40 M, respectively. However, in an antibacterial test, compounds 8a and 8b inhibited Staphylococcus aureus and Bacillus cereus and compound 8e inhibited only Staphylococcus aureus at the same MIC values of 1024 g/ml. 1. Introduction Cancer is characterized by uncontrolled cell growth, metas- tasis, and invasion and is responsible for approximately 13% of all human deaths throughout the world [1]. Te three most common and fatal types are lung, liver, and breast cancer. Currently, although there has been a lot of success in both cancer chemotherapy and anticancer drug development research, cancer remains a signifcant challenge in the future because of the drug resistance and adverse side efects of chemotherapy [2]. Novel antitumor agents based on natural products are becoming increasingly more popular in order to overcome these limitations and develop more efective anticancer agents [3]. Gossypol (1) (Figure 1), a polyphenolic dialdehyde found in high concentrations in the pigment glands of the cotton plant Gossypium, has recently received increased attention due to its wide range of biological activities, especially anticancer [4–7], contraceptive [8], antiviral [9–11], and antimicrobial [12] activities. However, the application of gossypol as a therapeutic agent has been limited because of a number of serious side efects [13] that have been shown to be associated with the aldehyde groups. More recently, signifcant attention has been focused on the potential therapeutic value of gossypol as a promising starting point for the development of antitumor or antiviral derivatives for medicinal applications with enhanced bioactivity and reduced side efects [14–18], in which the aldehyde groups are altered to give gossypol derivatives (e.g., Schif bases, esters, and ethers). Many of these derivatives exhibit a variety of unusual disease-inhibiting activities, especially anticancer activity [19]. Research regarding the biological efects of gossypol both in vitro and in vivo showed that the (−)- enantiomer is more potent than the (+)-enantiomer or the racemic mixture (1) [20]. It has also been hypothesized that while low doses of (−) gossypol are selective, higher doses of either enantiomer result in nonselective action [21, 22]. Also related to the mechanism of action, (−)-gossypol has been reported to target Bcl-2, Bcl-xL, and Mcl-1 proteins with high afnities and is now in clinical trials as an orally administered Hindawi Journal of Chemistry Volume 2017, Article ID 3687182, 8 pages https://doi.org/10.1155/2017/3687182