Expression of Inducible Nitric Oxide Synthase by
α-Hederin in Macrophages

Abstract

α-Hederin, a triterpene saponin, is reported to have antitumor activities; however, the mechanism underlying its therapeutic effects is not known. In this study, we examine the effects of α-hederin on the release of nitric oxide (NO) and the level of inducible nitric oxide synthase (iNOS) gene expression in mouse macrophages. α-Hederin elicited a dose-dependent increase in NO secretion. Reverse-transcription polymerase chain reaction showed that the increased NO secretion was due to an increase in iNOS mRNA. Transient expression assays with NF-κB binding sites linked to the luciferase gene revealed that the increased level of iNOS mRNA induced by α-hederin was mediated by the NF-κB transcription factor complex. These results demonstrate that α-hederin stimulates NO release and is able to upregulate iNOS expression through NF-κB transactivation, which may be a mechanism, whereby α-hederin elicits its biological effects.

α-Hederin - iNOS - expression - macrophages

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