Antimicrobial activities of sterols from Pycnarrhena manillensis
The dichloromethane extract of the air-dried leaves of Pycnarrhena manillensis afforded stigmast-4-en-3,6-dione (1) and stigmast-4-en-3-one (2) by silica gel chromatography. Their structures were elucidated by extensive 1D and 2D NMR spectroscopy. 1 and 2 exhibited moderate antifungal activity against C. albicans and low antibacterial activity against E. coli and P. aeruginosa. 2 was slightly active against S. aureus, while 1 was inactive against this bacterium. Both compounds were inactive against B. subtilis, T. mentagrophytes and A. niger.