Topoisomerase I and II Enzyme Inhibitory Aqueous Extract of Ardisia compressa and Ardisin Protect against Benomyl Oxidation of Hepatocytes

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Abstract
Tea preparations of Ardisia compressa (AC) have been used in folk medicine against liver disorders. The objective of this study was to evaluate the in vitro topoisomerase I and II enzyme inhibition and the antioxidant effect of an aqueous extract from dry leaves of AC and a pure component (ardisin) purified from AC on benomyl (Be)-induced cytotoxicity in primary culture rat hepatocytes. Lipid peroxidation (malondialdehyde), antioxidant enzyme activities of glutathione reductase, glutathione peroxidase, and superoxide dismutase, and glutathione levels were studied. Topoisomerase I and II enzyme inhibition was used to guide purification of ardisin, which was purified using TLC, MPLC, and preparative and analytical HPLC methods. Benomyl increased malondialdehyde (58% change in comparison to the control) and glutathione peroxidase (10%), producing a significant consumption of endogenous antioxidant glutathione (65%, P < 0.05). A 94% hepatocyte protection was observed when cells were first exposed to ardisin (0.27 microg/mL), followed by Be (35 microg/mL). Cell protection by the tea extract of AC (AE) was greater than that by (-)-epigallocatechin 3-gallate (EGCG). Ardisin showed a clear inhibition of topoisomerases I and II catalytic activity in Saccharomyces cerevisiae mutant cells JN 394, JN394t(-)(1), and JN394t-(2)(-)(5). The potency of ardisin was superior to that of AE and EGCG as an antioxidant, protecting rat hepatocytes when exposed to Be. On the basis of the effective concentrations of equivalents to [+]catechin found in the present study, it can be estimated that, in order to gain antioxidative protection, a person would need to ingest approximately 1 L of AC tea per day, with a total content of 10.8 g of plant material.