Polyphenolic content and antioxidant activity of Eugenia pollicina leaf extract in vitro and in model emulsion systems

The polyphenolic profile of a leaf extract of the Mauritian endemic plant, Eugenia pollicina, was assessed as a source of natural antioxidants. The amounts of flavan-3-ol derivatives determined by HPLC, were in the order of (-)-epicatechin (EC) > (-)-epigallocatechin gallate (EGCG) > (+)-catechin (C) > (-)-epicatechin gallate (ECG) with the levels of Procyanidin B2 and B1 dimers ranging from 1 to 3 mg g(-1) FW. The trolox equivalent antioxidant capacity and ferric reducing antioxidant power values were 796 mu mol g(-1) FW and 302 mu mol g(-1) FW respectively. E. pollicina extracts also strongly inhibited the FeCl3 and ascorbate-dependent microsome lipid peroxidation, a function that is linked to their flavonoid contents. The extent of DNA damage induced by the extract under study in the copper-phenanthroline assay was lower than the effect of a reference of 240 mu M ascorbate. E. pollicina extracts also inhibited lipid autoxidation in the 30% (v/v) olive oil and soybean oil oil-in-water (O/W) emulsions and was effective in slowing down the formation of hydroperoxides in the emulsions during 13 days storage at 40 degrees C as determined by the peroxide, conjugated diene and para-anisidine values. The high levels of total phenolics, flavonoids and procyanidins measured indicate that E. pollicina is a potential source of antioxidants relevant to the maintenance of oxidative stability of the food matrix, cosmetics and/or pharmaceutical preparations. (C) 2010 Elsevier Ltd. All rights reserved.