Abstract

Leaves, epicarp and seeds of Garcinia madruno (Kunth) Hammel were extracted by percolation using consecutively n-hexane, dichloromethane, ethyl acetate, and methanol until exhaustion. Then, fractions were screened for their phenolic content (Folin-Ciocalteu method) and antioxidant properties (DPPH, ABTS, FRAP methods). The phenolic content ranged from 2404 ± 121 (hexane fraction) to 9097 ± 275 mg GAE/100 g d.w. (ethyl acetate fraction) for seeds, 2372 ± 153 (dichloromethane fraction) to 11292 ± 962 mg GAE/100 g d.w. (ethyl acetate fraction) for epicarp, and 3659 ± 180 (dichloromethane fraction) to 23510 ± 255 mg GAE/100 g d.w. (ethyl acetate fraction) for leaves. The antioxidant activity was significantly depending on the nature of the extracting solvent and the organ of the plant. The highest values of antioxidant activity were displayed for ethyl acetate and hexane fractions. For ABTS assay, ethyl acetate fraction reached 57069 ± 1350, 67768 ± 2990, and 377848 ± 6039 mg AAE/100 g d.w. for seeds, epicarp, and leaves, respectively. From the most active fractions (ethyl acetate and hexane), three compounds were isolated by chromatographic techniques and their structures were elucidated by spectroscopic methods corresponding to the biflavonoids morelloflavone and volkensiflavone (from ethyl acetate fraction); and the polyisoprenylated benzophenone garcinol (from hexane fraction), first time reported in this species. These metabolites were quantified by high performance liquid chromatography and their antioxidant properties (DPPH, ABTS, FRAP, ORAC) evaluated. The highest concentration of the biflavonoids and the polyisoprenylated benzophenone was found in ethyl acetate and hexane, respectively. The biflavonoid morelloflavone displayed the highest antioxidant activity with 209216 ± 11723 (ABTS) and 293842 ± 22026 (ORAC) μmol Trolox/100 g. The results suggested that G. madruno might be a good source of metabolites with antioxidant activity.

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