Antibacterial and antitumoral activities of new organotin(IV)-Schiff bases derivatives

This preliminary report shows eight complexes of triorganotin(IV): Ph3SnOH and (CH3)3SnOH with four chelating imines on new synthesis. Of these ligands, two are salen-like (four coordination sites, two imidic, two phenoxidic) [1], one is a tetradentate pyrrole derivative [2] while the fourth, a vita- min B6 derivative, is pentadentate [3]. Ligands have been characterized by means of FT-IR, UV-Vis, Fluorescence, 1H- and 13C-NMR, LC-MS ESI triple quadrupole; complexes by means FT-IR, 1H- and 119Sn-NMR, LC-MS ESI, using the isotopic distribution pattern as a discriminant [4]. Geometry and nature of coordination complexes have been also evaluated using the 119Sn chemical shifts. Solid-state synthesis of the complexes (with a ball mill [5]) was also explored; such method reduces both solvent consumption and time – from 8-10 h under controlled atmosphere to about 1 h, with results identical to the wet synthesis. Antitumoral and antibacterial activities of the triorganotin (IV) complexes (BS01M, BS01P, BS02M, BS02P, BS03M, BS03P, BS04M, BS04P) were tested in vitro. In both analyses, the Shiff bases alone showed no biological activity. Antimicrobial activity was evaluated by Kirby-Bauer method against the Gram-negative Escherichia coli, and the two Gram-positive Kocuria rizophila and Staphylococcus aureus strains. All the ML2 complexes were active in inhibiting bacterial growth, with BS02P and BS03P showing the best antibacterial performance. Among the ML complexes, BS01M was not active, BS02M showed a weak antibacterial activity only against the Gram-positive bacteria, BS04M was mainly active against the Gram-negative E. coli and BS03M was active against all the tested strains. Antitumor activity was evaluated by MTT assay against cervical (HeLa), colon adenocarcinoma (HT- 29) and breast (MDA-MB231) cancer cell lines. Results showed that ML2 complexes are more active than ML ones, with HeLa cells more sensitive to treatments. These complexes (especially the ML2) showed promising results; their mechanism of action is under investigation. References 1. K. Tayade, S.K. Sahoo, S. Chopra, N. Singh, Inorganica Chimica Acta, 421, 538-543 (2014); https://doi.org/10.1016/j. ica.2014.05.014 2. S. Meghdadi, M. Amirnasr, K. Mereiter, Polyhedron, 30, 1651-1656 (2011); https://doi.org/10.1016/j.poly.2011.03.041 3. D. Sharma, S.K. Sahoo, S. Chaudhary, R. Kanta Bera, J.F. Callan, Analyst, 138, 3646-3650 (2013); https://doi.org/10.1039/ C3AN00199G 4. G. Lawson, R.H. Dahm, N. Ostah, E.D. Woodland, Applied Organometallic Chemistry, 10, 125-133 (1996); https://doi. org/10.1002/(SICI)1099-0739(199603)10:2<125::AID-AOC491>3.0.CO;2-1 5. G.A. Bowmaker, Chemical Communications, 49, 334-348 (2013); http://doi.org/10.1039/C2CC35694E 6. R. Di Stefano, M. Scopelliti, C. Pellerito, G. Casella, T. Fiore, G.C. Stocco, R. Vitturi, L. Ronconi, I.D. Sciacca, L. Pellerito, Journal of Inorganic Biochemistry, 98, 534-546 (2004); https://doi.org/10.1016/j.jinorgbio.2003.12.013 7. C. Pellerito, L. Nagy, L. Pellerito, A. Szorcsik, Journal of Organometallic Chemistry, 691, 1733-1747 (2006); https://doi. org/10.1016/j.jorganchem.2005.12.025