Abstract

Every part of Vernonia cinerea Less. has been reported for medicinal uses as they all have various therapeutic values with many kinds of pure compounds isolated. The aim of the present study is to investigate the cytoprotective effect and mechanisms of a whole plant extract on human umbilical vein endothelial cells (HUVECs) from nicotine toxicity. Cytotoxic ability of nicotine and V. cinerea extract to HUVECs were determined by proliferation assay using the 3-(4,5-dimethylthia-zol,2-yl)-2,5-diphenyltetrazolium bromide (MTT) reagent. After that, the cytoprotective effect of V. cinerea was assessed by examining the presence of vacuole-like structures in cells exposed to 5 or 7.5 mM nicotine with and without V. cinereawater extract and stained them with crystal violet. Reverse transcription-polymerase chain reaction (RT-PCR) was used to confirm the mRNA levels of genes involved in intracellular antioxidant system. Although 0.1 to 5 mM nicotine showed no toxic effect on HUVECs during 7 days treatment, abnormal features, that is, the vacuole-like structures were found in the cytoplasm of exposed HUVECs. V. cinerea water extract of 100, 500 and 1,000 µg/ml mixed with 5 mM nicotine reduced the numbers of cells containing vacuole-like structures in the cytoplasm of HUVECs with the dose- and time-dependent fashion. The mRNA of catalase and catalase activity in HUVECs exposed to 5 mM nicotine was significantly down-regulated, but recovered when the cells were treated with V. cinerea extract. V. cinereaextract could be useful in protecting endothelial cells from nicotine toxicity possibly via intracellular antioxidant mechanism, catalase.

Key words: Vernonia cinerea, cytoprotective effect, nicotine toxicity, catalase.