Withangulatin A, a New Withanolide from Physalis angulata

A new rithanolide as a topoisemerase I1 inhibitor, withangulatin A was isolated from the whole herb o f P h y r a l i s angulata L .(Salanaceae).The structure of withangulatin A was established as (2OS,ZZR)-15a-acetory-5B,6Bepony-4B,lk-dihydr0xy-l-oxowitha-2,16,24-trienolide ( I ) on the basis of spectroscopic and chemical evidence.P h y s a l i s angulata L ., known as an antipyretic, diuretic and antitumor folk-medicine, is one o f the cormon solanaceous plants in air an.' Various physalins' and withanolides5 together with acetylcho-6 7