Antioxidant and cytotoxic properties of novel spirocyclic benzothiazolines

Abstract

In this work, we report the synthesis, structural characterization and evaluation of in vitro antioxidant and cytotoxic properties of novel spirobenzothiazolines (1a-e, 2a-e). 5-nonsubstituted spirobenzothiazolines (1a-e) demonstrated notable inhibitory capacity on lipid peroxidation (LPO), reducing power and scavinging effects on diphenylpicryl hydrazine (DPPH.) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS. +) radicals, that were similar to that of alpha-tocopherol. The most potent antioxidant was compound 1a (incorporating an ethyl group on the cyclohexane ring) with an anti-LPO activity 2-fold higher than that of alpha-tocopherol. Compound 1a exhibited anti-LPO and DPPH. scavenging activities at concentrations lower than those cytotoxic for mouse normal fibroblast (NIH/3T3) cells and was also found to be slightly more selective for cancer cells (human prostat adenocarcinoma cell/PC-3) than normal mammalian cells.