Terpenoids of Salvia hydrangea: two new, rearranged 20-norabietanes and the effect of oleanolic acid on erythrocyte membranes.

Four abietane-type terpenoids, including two known royleanones and two new, rearranged 20-norabietanes, were isolated from the roots of the Iranian medicinal plant Salvia hydrangea DC. ex Bentham (Lamiaceae), which is used as an anthelmintic and antileishmanial remedy. Their structures were established using COSY, NOESY, HSQC, and HMBC spectral data. The possible identity of one of the 20-norabietanes with demethylmulticauline, previously reported from a different Salvia species, is discussed. A moderate in vitro antiplasmodial effect of the extract of S. hydrangea flowers was found to be associated with the presence of large amounts of pentacyclic triterpenes, mainly oleanolic acid. The observed antiplasmodial activity of oleanolic acid is apparently due to its incorporation into the erythrocyte membrane, which adversely affects the growth of Plasmodium falciparum parasites. Thus, oleanolic acid caused transformation of erythrocytes into stomatocytes in the concentration range where the in vitro antiplasmodial activity was observed.