Polymeric seven-coordinated organotin(IV) complexes derived from 5-amino-2-chlorobenzoic acid and in vitro anti-cancer studies

Abstract

Cancer cases are alarmingly increasing worldwide, and newer chemotherapeutic agents are needed. Recent analogs of cisplatin (carboplatin, lobaplatin, nedaplatin and oxaliplatin) and their marketing as advanced chemotherapeutic drugs have furthered the interest in metal-based anti-cancer drugs. In the current study, two new polymeric organotin(IV) carboxylate complexes (1 and 2) have been synthesized and characterized. Spectroscopic studies showed that coordination took place via carboxylates. Furthermore, X-ray crystallographic study on 1 indicated that it possesses a monomeric structure and exists in polymeric formation due to additional Sn–N coordination, assigning seven coordinations to each metal ion. Both the complexes were tested against three cancerous (human colon cancer, HCT 116; breast cancer, MCF-7; and leukemia, K562) and one non-cancerous (3T3-L1) cell lines. Complex 1 showed exceptional cytotoxicity against cancerous cell lines (IC₅₀ = 1.0 μM for HCT 116; 258.7 nM for MCF-7; and 46.7 nM K562) and remained comparatively non-toxic against normal cells (IC₅₀ = 37.0 μM). This shows that both complexes have selective cytotoxicity against cancer cells.

Graphical Abstract

Keywords:

• Organotin(IV) carboxylate complexes
• 5-Amino-2-chlorobenzoic acid
• Cytotoxicity
• Anti-cancer

Acknowledgments

The authors would like to thank Ministry of Higher Education for the Fundamental Research Grant Scheme (Project No.: FRGS/1/2012/SG01/UTAR/02/1), Universiti Tunku Abdul Rahman and Universiti Sains Malaysia for financial support as well as technical assistance and facilities. Dr Muhammad Adnan Iqbal is the recipient of USM-Postdoctoral Fellowship in research.