A natural vascular alpha 1-adrenoceptor antagonist but less prevalent than the D-isomer. It markedly inhibits the contraction of rat stomach muscle strips induced by 5-HT, histamine, K+ and Ca2+ after high K+ depolarization, showing a non-competitive antagonism and could be a potential muscle relaxant. Studies suggest that it has protective effect of on acute myocardial Iichemia and anoxia lesion.
