Chemical constituents from stems and leaves of Diospyros gracilipes Hiern and the antimicrobial and cytotoxic principles

Abstract

The ethanolic extract from stems and leaves of Diospyros gracilipes Hiern showed moderate antimicrobial activity against Staphylococcus aureus (9 mm), Klebsiella pneumonia (7 mm) and Candida albicans (11 mm) using the disc diffusion assay. Fractionation of the extract led to the isolation of lupenone, ursolic acid, corosolic acid, a mixture of 3I±- and 3I²- taraxerols, 3I²-E-coumaroyltaraxerol, pinocembrin, scopoletin, plumbagin and elliptinone as established by spectroscopic techniques. Plumbagin exhibited potent antimicrobial activity against the three test microorganisms with inhibitory zones ranging between 30 and 43 mm at 50 µg/disc, and 21 and 28 mm at 10 µg/disc. Plumbagin displayed significant cytotoxicity (IC50=0.26 µg/mL) against HT-29 colon cancer cell line in the sulforhodamine B assay, whereas elliptinone showed weaker activity (IC50=13.29 µg/mL) compared to plumbagin. The reported anti-progestational activity of plumbagin provides a rationale for the popular use of this plant as abortifacient.