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, ß-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.

Isolation and structure elucidation of antioxidant polyphenols from quince (Cydonia vulgaris) peels.

Thirteen new compounds, as well as 16 already known, have been isolated from organic extracts of peels of Cydonia vulgaris, a fruit of a shrub belonging to the same tribe as the apple. All of the structures were elucidated by EI- or ESI-MS and (1)H and (13)C NMR after purification of individual compounds by HPLC. Thirteen fatty acid esters of cinnamyl alcohols, three fatty acid esters of hydroxybenzoic acid, three fatty acid esters of hydroxybenzaldehyde, three glucosides of aromatic acids, four chlorogenic acids, two flavonols, and a benzylamine have been identified. The fatty acid moieties have been identified by GC-MS analysis of the methanolysis products. All of the compounds were tested for their radical scavenging and antioxidant activities by measuring their capacity to scavenge the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and anion superoxide radical and to induce the reduction of Mo(VI) to Mo(V). The chlorogenic acids and the flavonols exhibited more antioxidant and radical scavenger capacity than the positive standards alpha-tocopherol and ascorbic acid. The results of the tests were analyzed by cluster analysis that grouped all of the compounds on the basis of the substituents on the aromatic ring.

Reactive oxygen species scavenging activity of flavone glycosides from Melilotus neapolitana.

One new and six known flavone glycosides were isolated from the MeOH extract of Melilotus neapolitana Ten. The new compound, identified as 7-O-beta-D-glucopyranosyloxy-4',5-dihydroxy-3-[O-alpha-L-rhamnopyranosyl-(1-->6)-3-O-beta-D-glucopyranosyloxy]flavone (1) by 1D and 2D NMR techniques and mass spectra, was isolated along with kaempferol-3-O-rutinoside (2), kaempferol-3-O-glucoside (3), rutin (4), quercetin-3-O-glucoside (5), isorhamnetin-3-O-rutinoside (6), and isorhamnetin-3-O-glucoside (7). The antioxidant and radical scavenging activities of these compounds and the whole crude methanol extract were evaluated. The organic extract can inhibit MDA marker's synthesis by 57%. All the metabolites displayed good reducing power, with the kaempferol (2,3) and isorhamnetin derivatives (6,7) being less active than the corresponding quercetin derivatives 4,5.

Isolation, structure elucidation, and antioxidant evaluation of cydonioside A, an unusual terpenoid from the fruits of Cydonia vulgaris.

A novel terpenoid, cydonioside A (1), was isolated from the fruits of Cydonia vulgaris Pers. Its structure and relative configuration were elucidated on the basis of in-depth spectroscopic analyses, including 2D-NMR experiments as well as MM+ calculations. Compound 1 was assayed for its radical-scavenging activity towards the DPPH radical and the superoxide radical anion (O2*-), as well as for its overall antioxidant activity, as assessed by the formation of a phosphomolybdenum complex.

Spectroscopic identification and antioxidant activity of glucosylated carotenoid metabolites from Cydonia vulgaris fruits.

Carotenoid metabolites are common plant constituents with significant importance for the flavor and aroma of fruits. Three new carotenoid derivatives, (2E,4E)-8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 1-O-beta-D-glucopyranosyl ester (1), (2Z,4E)-8-beta-D-glucopyranosyloxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid (3), and 3,9-dihydroxymegastigmast-5-ene-3-O-[beta-D-glucopyranosyl-(1-->6)]-beta-D-glucopyranoside (5), as well as three known compounds, have been isolated from the ethanolic extract of peels of Cydonia vulgaris, the fruit of a shrub belonging to the same family as the apple. All the compounds were identified by spectroscopic techniques, especially 1D and 2D NMR. Antioxidant activities of all the isolated metabolites were assessed by measuring their ability to scavenge DPPH radical and superoxide radical (O2*-) and to induce the reduction of Mo(VI).

Distachyasin: A new antioxidant metabolite from the leaves of Carex distachya.

A novel antioxidant prenylated stilbenoid, distachyasin, has been isolated from the leaves of Carex distachya. Its structure has been elucidated on the basis of the spectroscopic characteristics. Bidimensional NMR, and crystallographic data and computational calculations have furnished important data useful for the characterization and the stereochemistry of the molecule. The compound has a tetracyclic skeleton derived from carexane. The compound has been assayed, for the antioxidant activity, by measuring its capacity to scavenge the H(2)O(2), nitric oxide, superoxide radical and to inhibit formation of TBARS (thiobarbituric acid reactive species).

Free-radical-scavenging and antioxidant activities of secondary metabolites from reddened cv. Annurca apple fruits.

Forty-three secondary metabolites were isolated and characterized from cv. Annurca apple fruit, an apple variety cultivated in the south of Italy. This apple cultivar undergoes a typical reddening treatment after collection. All of the compounds were characterized on the basis of their spectroscopic data. The compounds were tested for their radical-scavenging and antioxidant activities by measuring their capacity to scavenge DPPH* (2,2'-diphenyl-1-picrylhydrazyl radical), H2O2, and NO (nitric oxide) and to inhibit the formation of methyl linoleate conjugated diene hydroperoxides or TBARS (thiobarbituric acid reactive species).