A study of an endothelin antagonist from a Chinese anti-snake venom medicinal herb

Because it is well known that endothelin (ET) plays an important role in the pathogenesis of cardiovascular diseases, antagonists of ET for clinical use are very important. Because ET and some snake toxins have a homologous structure and similar biologic actions the effect of Chinese anti-snake venom herbal medicines on ET bioactivity was investigated both in vivo and in vitro. Hong Bei Si Chou [Cissus assamica (Laws.) Craib] is a herbal medicine used to treat snake bite in Guangxi province. It was found that all the different fractions of EtOH extraction, the EtOAc part of the EtOH extraction, and resverotrol (3,4'5-trihydroxytransstilbene) isolated from the EtOAc part could antagonize ET both in vivo and in vitro. These three fractions transiently relaxed ET-contracted isolated rat aortic ring in a dose-dependent manner. They also antagonized the lethal effects of ET-1 in mice and inhibited blood pressure elevation induced by ET-1. The results have shown that it is possible to find ET antagonists in Chinese anti-snake venom medicinal herbs. In the future, our work should shed new light on the treatment of cardiovascular diseases in which ET is involved.