Cytotoxicity and enzyme inhibition studies of polyoxometalates and their chitosan nanoassemblies

Polyoxometalates (POMs) have become very significant in biomedical research for their structural diversity which renders them highly active against bacterial, viral and cancer diseases. In this study three different POMs were synthesized and nanoassemblies were made with chitosan (CTS), a natural biodegradable polymer with excellent drug carrier properties. The compounds were tested on two isoenzymes of alkaline phosphatases including tissue specific calf intestine alkaline phosphatase (CIAP) and tissue non-specific alkaline phosphatase (TNAP). Compound [TeW6O24](6-) (TeW6) showed the highest activity (45.4 +/- 11.3 mu M) among tested compounds against TNAP. Similarly, chitosan-[TeW6O24](6-) (CTS-TeW6) was proved to be a potent inhibitor of CIAP with Ki value of 22 +/- 7 nM. A comparative study was made to evaluate their cytotoxic potential against HeLa cells. Among all tested compounds, Chitosan-[NaP5W30O110](14-) (CTS-P5W30) has showed higher percent cytotoxicity (88 +/- 10%) at 10 M when compared with the standard anticancer drug vincristine (72 +/- 7%). The study revealed that selected POMs proved excellent anticancer potential and were equally effective against alkaline phosphatase enzyme, an increased level of which may indicate cancer metastasis. (C) 2014 The Authors. Published by Elsevier Ireland Ltd.