Identification and assessment of antioxidant capacity of phytochemicals from kiwi fruits.

The kiwi fruit is the edible berry of a cultivar group of the woody vine of several Actinidia species. The most common commercially available, green-fleshed kiwi fruit is the cultivar 'Hayward', which belongs to the Actinidia deliciosa species. An antioxidative screening of kiwi fruit components (peel and pulp) crude extracts was carried out using specific assay media characterized for the presence of highly reactive species such as 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH(•)), H(2)O(2), and O(2)(•-). The Mo(VI) reducing power of the samples was also determined. The phenol and flavonoid contents were quantified. Phytochemical analysis of kiwi peel crude extracts led to the isolation of vitamin E, 2,8-dimethyl-2-(4,8,12-trimethyltridec-11-enyl)chroman-6-ol, as well as α- and δ-tocopherol, 7 sterols, the triterpene ursolic acid, chlorogenic acid, and 11 flavonoids. Chemical fractionation of pulp crude extracts led to the isolation of two caffeic acid glucosyl derivatives and two coumarin glucosydes, besides the three vitamin E, β-sitosterol, stigmasterol, and its Δ(7) isomer, campesterol, chlorogenic acid, and some flavone and flavanol molecules. All of the compounds were tested for their radical scavenging and antioxidant capabilities by measuring their capacity to scavenge DPPH and anion superoxide radical and to reduce a Mo(VI) salt.