Local variation in the content of angiotensin II and arginine vasopressin receptor antagonistic terpenoids in the rhizomes of Alisma orientale.

The aqueous extract of the Chinese crude drug Alismatis rhizoma, a dried rhizome of Alisma orientale Juzepczuk, exhibited in vitro inhibitory activities on angiotensin II and arginine vasopressin binding to their receptors. A fractionation study on the extract clarified that the known terpenoidal constituents; i.e., alisols A and B, 23-O-acetylalisol B, and alismol, were responsible for the activities. Furthermore, investigation of commercial samples of the crude drug demonstrated striking differences in their activities dependent on their locality of origin due to a difference in the amounts of these active principles. Therefore, the content of these principles could be utilized as a criteria of quality of the crude drug Alismatis rhizoma.