New withanolides and other constituents from the fruit of Withania somnifera

Abstract

Two new steroidal lactones of the withanolide-type, 5beta, 6alpha, 14alpha, 17beta, 20beta-pentahydroxy-1-oxo-20 S, 22R-witha-2, 24-dienolide (1)and 6alpha, 7alpha-epoxy-5alpha, 14alpha, 17alpha, 23beta-tetrahydroxy-1-oxo-22R-witha-2, 24-dienolide (2), were isolated from the fruit of Withania somnifera (L.) Dunal (Solanaceae) growing in Southern Egypt, together with two known coumarins, scopoletin (3)and aesculetin (4), a known triterpene, viz. Beta-amyrin (5), and two known phytosterols, viz. stigmasterol (6) and sitosterol (7). The structures of the isolated compounds have been elucidated by spectroscopic methods including UV, IR, (1)H-, (13)C-NMR, DEPT experiments, HRFAB-, FAB-, and EI-mass spectrometry. The in vitro antimicrobial activity of the new withanolide (1) and the alcoholic fruit extract are discussed.