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

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 antidiabetic 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 a-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 H-1- and C-13-Nuclear Magnetic Resonance (NMR) as Oleuropein, Ligstroside, Hydroxytyrosol, Tyrosol and Luteolin-7-O-beta-D-glucoside.