Protective effects of kahweol and cafestol against hydrogen peroxide-induced oxidative stress and DNA damage

There is an increasing evidence that oxidative stress is implicated in the processes of inflammation and carcinogenesis. It has been shown that kahweol and cafestol, coffee-specific diterpenes, exhibit chemoprotective effects. This study investigated the effects of kahweol and cafestol, coffee-specific diterpenes, on the hydrogen peroxide (H2O2)-induced oxidative stress and DNA damage in NIH3T3 cells. When the cells were treated with kahweol or cafestol, cytotoxicity, lipid peroxidation, and reactive oxygen species production induced by H2O2 were markedly reduced in a dose-dependent manner. Moreover, kahweol and cafestol were shown to be highly protected against H2O2-induced oxidative DNA damage as determined by the Comet (single cell gel electrophoresis) assay and the measurement of 8-oxoguanine content in N1H3T3 cells. Kahweol and cafestol also protected hydroxyl radical-induced 2-deoxy-D-ribose degradation by ferric ion-nitrilotriacetic acid and H2O2 In addition, kahweol and cafestol efficiently removed the superoxide anion generated from the xanthine/xanthine oxidase system. These results suggest that kahweol and cafestol are effective in protecting against H2O2-induced oxidative stress and DNA damage, probably via scavenging free oxygen radicals, and that kahweol and cafestol act as antioxidants. (C) 2007 Elsevier Ireland Ltd. All rights reserved.