Analysis and evaluation of hydroxytyrosol in olive leaf extract

ABSTRACT

There is a group of phenolic compounds and their glycosidic forms responsible of antioxidant effect in the olive leaf extract. Hydroxytyrosol is one of these compounds considered as building unit for the other phenolic molecules in the extract. A normal phase chromatographic methodwas established for analysis of hydroxytyrosol. It generates clean chromatograms suitable for analytical and preparative purposes and better resolved than those obtained from reversed phase systems. Mobile phase of [11] acetonitrile and 1% acetic acid aqueous solution was used. Flow rate was kept constant at 0.5 mL/min. Injection volume was 20 uL and UV detector was set at A=280 nm. The developed HPLC method was found linear within the range of 0.82-4.12 mg%, precise with RSD less than 2% and accurate with a range of 97.6-101.2%. LOQ and LOD of the method were calculated to be 8 and 0.8 jig/ml respectively.Furthermore, antioxidant degree of hydroxytyrosol and its derivatives in the extract was evaluated by Follin-ciocalteu'sreagent and found equivalent to 40 mg gallic acid