Cytotoxicity and Antimicrobial Activity Studies of an Ellagic Acid-Zinc Layered Hydroxide Intercalation Compound

Abstract

An ellagic acid (EA)-zinc layered hydroxide (ZLH) intercalation compound (EAN) was synthesized using zinc oxide as the starting material at two different concentrations of EA: 0.01 and 0.025 mol/L. The resulting EAN have the same basal spacing of 10.4 A. The cytotoxicity of EAN was determined using a total protein content assay against two normal cell lines (murine fibroblast 3T3 cells and human breast epithelial MCF-10a cells) and two human cancer cell lines (breast cancer MCF-7 cells and liver cancer HepG2 cells). The results suggest that EAN displays cytotoxicity and anti-proliferative activity in MCF-7 and HepG2 cancer cells while impacting less on the growth of normal cells at all concentrations tested. The activities of three caspase enzymes were quantified for both of the cancer cell lines that were treated with the EAN. It was found that caspase-3 and caspase-9, but not caspase-8, were activated, which in turn indicated that apoptosis via the mitochondrial (intrinsic) pathway had taken place. In the MCF-7 and HepG2 cells, the EAN increased DNA fragmentation in a time- and concentration-dependent manner. The morphology of treated cells was also studied, and the EAN-treated HepG2 cells showed more dramatic changes than MCF-7 cells. In addition, we investigated the antimicrobial activity of EAN using minimum inhibitory concentration (MIC) determination by the agar dilution method. It was found that EAN has enhanced antimicrobial activity compared to ellagic acid.