Antioxidant and Cytotoxic Activity Studies in Series of Higher Amino Acid Schiff Bases

Abstract

In this work, the antioxidant activity of the higher amino acid Schiff bases, which were preparedas the monosodium salts (1a–3a) and the neutral forms (1b–3b) was determined by DPPHscavenging assay. In pure MeOH solution, the scavenging ability of Schiff bases 1a-3a werehigher than 1b-3b, but lower than ascorbic acid. The activity followed the order 3 (a,b) > 2 (a,b)> 1 (a,b). On the other hand, Schiff bases 2a and 3a behaved as the most effective scavengers ofthe DPPH radical in methanol-water mixture (v:v, 1:3). And, they were found to be have lowerSC50 values in this mixture compared to pure methanol. In vitro cytotoxicity of these Schiff baseswas studied against human cervical cancer cells (HeLa), human breast adenocarcinoma cells(MCF-7), and human normal embryonic kidney cells (HEK293). For HeLa cell line, Schiff bases1a-3a exhibited a litttle high activity than 1b, but very low activity than doxorubicin. Schiff bases2b and 3b had no cytotoxicity against HeLa cell. For MCF-7 cell line, Schiff bases 1a, 3a, 1b and3b nearly were inactive at 100 μM, whereas 2a increased cell proliferation in the all testedconcentration range. Differently, Schiff base 2b showed the highest cytotoxicity and killed 90percent of MCF-7 cells at concentration of 100 μM. For HEK-293, doxorubicin was stronglycytotoxic. Despite this, Schiff bases 1a, 3a and 3b were inactive, whereas the others showed littleweak toxicity.