Chemical constituents of Dissotis perkinsiae (Melastomaceae) and their antimicrobial activity

Abstract

The phytochemical study of the Methanol/dichloromethane extract of the leaves of Dissotis perkinsiae led to the isolation and identification seven compounds: Ursolic acid (1); Sitosterol-β-D-glucoside (2); Isoquercitrin (3);Quercetin-3-O-β-galactoside (4);Kaempferol-3-O-β-D-glucoside (5); Kaempferol-7-O-β-D-glucoside (6); Trans-Tiliroside (7). Their structures were elucidated on the basis of spectroscopic analysis and by comparison of their spectral data with those reported in the literature. The results of antimicrobial activity indicated that the MIC vary from >0.5 to 0.00078 mg/mL on yeasts and from >0.5 to 0.25 mg/mL on bacteria. Sitosterol-β-D-glucoside was the most active with the broad spectrum (MIC=0.125mg/mL on C. albicans, MIC=0.0625 mg/mL on C. kruseiand MIC=0.0078 mg/mL on C. parapsilosis). Kaempferol-7-O-β-D-glucoside was the most active on C. krusei (MIC=0.0039 mg/mL). The anti yeat activity of Sitosterol-β-D-glucoside and Kaempferol-7-O-β-D-glucoside were better thanfluconazole (0.032mg/mL) on C. parapsilosis (MIC 0.0078 mg/mL) and C. krusei (0.0039 mg/mL) respectively. Sitosterol-β-D-glucoside and Trans-Tiliroside showed weak inhibitotry activity against S. enteric and S. aureus with MIC value of 0.5mg/mL. Respectively this inhibitory effect was lower activities observed with Chloremphenicol and Ampicillin (0.000488 mg/mL). The results of this study suggest that Dissotis perkinsiae represent an untapped source of compounds with potential antimicrobial activity that could be explored in the development of new therapeutic natural products.