Polyphenolic constituents and antimicrobial activity of Rhapis excels (Arecaceae, Coryphoideae).

Abstract

The chromatographic fractionation of Rhapis excelsa f.,Arecaceae, leaves extract, a plant known as lady palm, resulted in the isolation of four flavonoids: Apigenin-8-C-glucoside (vitexin), Apigenin-6,8-Di-C-βglucopyranoside (vicenin-2), Luteolin-6-C-glucoside (isoorientin) and Luteolin-8-C-glucoside (orientin). The structural elucidations of these compounds were performed by means of the comparison of their spectral data (UV systematic identification and 1 NMR) with those ones of the literature. Ethyl acetate and butanol fractions showed remarkable antioxidant activity (86.2 and 75.6 respectively), when investigated for their DPPH (2,2- diphenyl-1-picrylhydrazyl) radical scavenging activity. The major polyphenols were identified, as benzoic acid, ferulic acid with others by means of RP-HPLC, they were quantified in methanolic crude extract. Also, the antibacterial activity of the extract was assessed against Staphylococcus aureusstrains, including methicillinresistant S. aureus (MRSA). The extracts had no antimicrobial activity alone but they revealed ability to potentiate the antibacterial activity of ciprofloxacin, tetracycline and oxacillin.