Novel steroids from the seeds of Centratherum anthelminticum

Two novel and two known steroids were isolated respectively from benzene: acetone and ethanolic extracts of the seeds of C. anthelminticum and, identified as (24alpha/R)-Stigmasta-7-en-3-one (1), (24alpha/R)-Stigmasta-7, 9(11)-dien-3-one (2), (24alpha/S)-Stigmasta-5, 22-dien-3beta-ol (3) and (24alpha/S)-Stigmasta-7, 22-dien-3beta-ol (4). The structures were assigned on the basis of their IR, 1H NMR, 13C NMR (DEPT), 2D NMR (1H-1H COSY and 1H-13C COSY), mass spectra, chemical analyses and on comparison with literature values. The novel steroids (1) and (2) were also tested against several human pathogenic bacteria and fungi.