Abstract:

Based on centrifugal partition chromatography(CPC) and thin-layer chromatography(TLC), preparative high performance liquid chromatography(Pre-HPLC) and so on, the total polyphenol extract(TPF) of olive oil was extracted from extra virgin olive oil, and then TPF was used as raw material to separate and prepare 2-(4-hydroxyphenyl) ethyl(E)-4-formyl-3-(2-oxoethyl)hex-4-enoate(oleocanthal, OLEO) and 2-(3, 4-dihydroxyphenyl)ethyl(Z)-4-formyl-3-(2-oxoethyl)hex-4-enoate(oleacein, OLEA) monomer compounds. Their structures were characterized by ¹H NMR and their antioxidant activities were also investigated. The results showed that 14 fractions were obtained during the process of CPC with the solvent system of n-hexane/ethyl acetate/ethanol/water volume ratio of 3∶2∶3∶2 from 9 g extract in 20 mL of methanol. After purification, 422.3 mg OLEO and 163.0 mg OLEA with the purity of ≥95% were obtained, respectively; the antioxidant activities of OLEO and OLEA at different concentrations(0-1 g/L) were evaluated by their free radical scavenging capacity on ABTS⁺·, DPPH· and total antioxidant capacity(T-AOC), it indicated that OLEA had stronger antioxidant activity than OLEO, and the 50% inhibition concentration(IC₅₀) values of OLEO and OLEA for DPPH· were 0.029 and 1.85×10^-11 g/L, respectively, the scavenging capacties of OLEO and OLEA against ABTS⁺· were 0.765 5 and 0.894 2 mmol/L(calculated by the concentration of Trolox); and their total antioxidant capacities reached 0.157 1 and 0.646 2 mmol/L(calculated by the concentration of FeSO₄), respectively.

Key words: fractions, gradient elution, oleocanthal, oleacein, evaluation