Efficient method for the screening and identification of anti-diabetic components in the leaves of Olea europaea L.

Abstract

In this article, an efficient method of high speed counter-current chromatography (HSCCC) coupled with post-column on-line evaluation was developed to screen, isolate and identify the major anti-diabetic compounds present in the leaves of Olea europaea L. The HSCCC separation employed a two-step process: first, an optimized two-phase system composed of ethyl acetate–water (1 : 1) was used to separate the extraction; then, a solvent system composed of butanol–water–acetic acid (1 : 1 : 0.1) was applied to further separate the anti-diabetic active compounds. The eluant was detected by post-column evaluation with α-amylase used in both steps. It was found that five major constituents of the O. europaea L. leaf extracts displayed potential anti-diabetic activity. Their structures were identified by ¹H- and ¹³C-Nuclear Magnetic Resonance (NMR) as Oleuropein, Ligstroside, Hydroxytyrosol, Tyrosol and Luteolin-7-O-β-D-glucoside.