Isotetrandrine is a biscoclaurine alkaloid inhibitor of G protein activation of PLA2 but not PLC or PLD. It has been suggested that isotetrandrine suppresses the receptor-mediated phospholipase A2 activation by uncoupling a GTP-binding protein from the enzyme. Isotetrandrine has been reported to inhibit collagen, thrombin, and arachidonic acid-induced platelet aggregation. Isotetrandrine has been found to inhibit arachidonic acid liberation of platelets induced by compound 48/80, antigen, GTPβS and Ca2+. Isotetrandrine is an inhibitor of AR (α1 adrenoceptor).
