Synthesis, angiopreventive activity, and in vivo tumor inhibition of novel benzophenone–benzimidazole analogs V. Lakshmi Ranganatha a , B.R. Vijay Avin b , Prabhu Thirusangu b , T. Prashanth a , B.T. Prabhakar b , Shaukath Ara Khanum a, ⁎ a Department of Chemistry, Yuvaraj's College (Autonomous), University of Mysore, Mysore 570 005, Karnataka, India b Molecular Biomedicine Laboratory, Postgraduate Department of Studies and Research in Biotechnology, Sahyadri Science College (Autonomous), Kuvempu University, Shimoga 577203, Karnataka, India abstract article info Article history: Received 9 July 2013 Accepted 1 October 2013 Keywords: Benzophenone–benzimidazoles Methoxy group Cytotoxicity Angioprevention Aim: The development of anticancer drugs with specific targets is of prime importance in modern biology. This study investigates the angiopreventive and in vivo tumor inhibition activities of novel synthetic benzophenone– benzimidazole analogs. Main methods: The multistep synthesis of novel benzophenone–benzimidazole analogs (8a–n) allowing substitution with methoxy, methyl and halogen groups at different positions on the identical chemical backbone and the variations in the number of substituents were synthesized and characterized. The newly synthesized compounds were further evaluated for cytotoxic and antiproliferative effects against Ehrlich ascites carcinoma (EAC) cells. The potent lead compounds were further assessed for antiangiogenic effects in a CAM model and a tumor-induced vasculature in vivo model. The effect of angioprevention on tumor growth was verified in a mouse model. Key findings: The cytotoxicity studies revealed that compounds 8f and 8n are strongly cytotoxic. Analyzing the structure–activity relationship, we found that an increase in the number of methyl groups in addition to methoxy substitution at the para position of the benzoyl ring in compound 8n resulted in higher potency compared to 8f. Furthermore, neovessel formation in in vivo systems, such as the chorioallantoic membrane (CAM) and tumor-induced mice peritoneum models, was significantly suppressed and reflected the tumor inhibition observed in mice. Significance: These results suggest the potential clinical application of compound 8n as an antiangiogenic drug for cancer therapy. Crown Copyright © 2013 Published by Elsevier Inc. All rights reserved. Introduction The identification of novel molecular targets for cancer therapy has led to a paradigm shift in drug development, and more emphasis is now placed on molecules that can effectively inhibit the angiogenesis process, in which new blood vessels are formed from preexisting ones to support the growth of tumors and the development of cancer (Folkman, 2007; Albini et al., 2012). Angiogenesis inhibitors are desirable anticancer targets and minimize the side effects of chemotherapy. Specificity in targeting tumor endothelial cells and the formation of neovessels are unique properties that could be incorporated into a potential antiangiogenic drug for cancer therapy (Alicia Chung et al., 2010; Johannessen et al., 2013). Benzophenone derivatives obtained from natural (Henry Jacobs et al., 1999) and synthetic (Karrer et al., 2000) methods are pharmacologically active molecules (Tzvetomira et al., 2009; Yamazaki et al., 2012) and even display antitumor activity (Sakowski et al., 2001; Hsieh et al., 2003; Balasubramanyam et al., 2004; Prabhakar et al., 2006a, 2006b). Several benzophenones are under study; combretastatin A-4 is known to exhibit antiangiogenic effects and is being studied in clinical trials (Tozer et al., 2008). The presence of a benzimidazole nucleus in numerous categories of therapeutic agents has made it an indispensable anchor for the development of new antiangiogenic therapeutics (Yogita and Silakari, 2012). Previously, we reported the synthesis and antitumor and antiangiogenic properties of (2- aroyl-4-methylphenoxy)acetamides 4a–e, which are benzophenone analogs (Prabhakar et al., 2006a, 2006b). More specifically, the benzophenone derivative [2-(4-methoxybenzoyl)-4-methylphenoxy]- N-(4-chlorophenyl) acetamide (BP-1, IC 50 : 42.50 μM) was shown to inhibit angiogenesis, thereby preventing angiogenesis-dependent disorders, such as mammary carcinoma and rheumatoid arthritis, both in vivo and in vitro, where it down-regulated the vascular endothelial growth factor (VEGF) gene expression responsible for angiogenesis (Prabhakar et al., 2006a, 2006b; Shankar et al., 2009). The promising Life Sciences 93 (2013) 904–911 ⁎ Corresponding author at: Department of Chemistry, Yuvaraj's College, University of Mysore, Mysore, India. Tel.: +91 99018 88755; fax: +91 821 2419239. E-mail address: shaukathara@yahoo.co.in (S.A. Khanum). 0024-3205/$ – see front matter. Crown Copyright © 2013 Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.lfs.2013.10.001 Contents lists available at ScienceDirect Life Sciences journal homepage: www.elsevier.com/locate/lifescie