Protostane‐Type Triterpenoids from Alisma orientale

Twenty‐eight protostane triterpenoids, including a new degraded one ( 1 ), nine new ones ( 2 – 10 ), and two new natural ones ( 11 and 12 ), have been isolated from the dried rhizomes of Alisma orientale . Alisol R ( 1 ) was the first 20,21,22,23,24,25,26,27‐octanorprotostane triterpenoid. The absolute configurations of 25‐methoxyalisol F ( 2 ) and 16 β ‐hydroperoxyalisol B 23‐acetate ( 3 ) were determined by X‐ray diffraction analysis. In addition, alismaketone‐B 23‐acetate ( 28 ) showed potent vasorelaxant activity on endothelium‐intact thoracic aorta rings precontracted with KCl.