A new combined technology: Macroporous adsorption resin and high speed counter current chromatography for hydroxytyrosol separation from olive leaf enzymatic hydrolysate.

Due to three free hydroxyl groups, hydroxytyrosol (HT) presents strong bioactivity and has broad food and drug application prospects. However, there is no good separation and purification technology. In this study, separation and purification technology of HT from the ethyl acetate extraction of enzymatic hydrolysate from olive leaf (EEEH) was investigated with macroporous adsorption resin (MAR) and high-speed counter-current chromatography (HSCCC) and the separation factors were optimized. First, the adsorption properties of eight MARs (AB-8, S-8, D-101, X-5, XAD-1, XAD-5, NKA-Ⅱ, H-103) for HT enrichment were studied. The results showed that H-103 macroporous resin was adsorbent, sample concentration was 1.5 mg/mL, eluent was 30 % ethanol solution, sample loading rate was 3.0 BV/h, elution velocity was 2.0 BV/h, and HT purity of EEEH was increased from 10.23 % to 40.78 %. Then, solvent systems were examined according to partition coefficients of target component and petroleum ether: ethyl acetate: methanol: water (4:6:4:6, v/v) system was chosen. The critical experimental parameters of HSCCC were optimized as following: revolution speed was 1200 rpm and flow rate was 3 mL/min. The HT purity of macroporous resin purified EEEH was increased from 40.78 % to 85.7 %. Therefore, MAR-HSCCC combined technology could be a very effective approach to separate and purify HT from EEEH.