procyanidin-b1 and 2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid

In the present study the structure of proanthocyanidins from Polyalthia longifolia leaves was characterized with (13)C nuclear magnetic resonance, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses. The results showed that the proanthocyanidins were mixture of homopolymers of B-type procyanidins with degree of polymerization up to 14-mer. Furthermore, the antioxidant activity of the proanthocyanidins was studied through 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free-radical scavenging activities, and ferric reducing/antioxidant power assays. In addition, antityrosinase activity of the proanthocyanidins was investigated. The IC50 for 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free-radical scavenging activity of the proanthocyanidins were 89.32 ± 12.07 and 76.79 ± 5.88 μg/mL, respectively; the ferric reducing/antioxidant power value was 710.54 ± 142.82 mg ascorbic acid equivalent/g dry weight. The IC50 for antityrosinase activity was 773.09 ± 1.47 μg/mL. In conclusion, the proanthocyanidins from P. longifolia leaves exhibited potent antioxidant and antityrosinase activities. This research would provide scientific evidence for the use of proanthocyanidins from P. longifolia leaves as antioxidant and antityrosinase agents.

Topics: Antioxidants; Ascorbic Acid; Benzothiazoles; Biflavonoids; Biphenyl Compounds; Catechin; Chromatography, High Pressure Liquid; Enzyme Inhibitors; Free Radical Scavengers; Inhibitory Concentration 50; Magnetic Resonance Spectroscopy; Monophenol Monooxygenase; Oxidation-Reduction; Picrates; Plant Leaves; Polyalthia; Proanthocyanidins; Reducing Agents; Spectrometry, Mass, Electrospray Ionization; Sulfonic Acids

The contribution of each phytochemical to the total antioxidant capacity of apples was determined. Major phenolic phytochemicals of six apple cultivars were identified and quantified, and their contributions to total antioxidant activity of apples were determined using a 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay and expressed as vitamin C equivalent antioxidant capacity (VCEAC). Average concentrations of major phenolics and vitamin C in six apple cultivars were as follows (mg/100 g of fresh weight of apples): quercetin glycosides, 13.20; procyanidin B(2), 9.35; chlorogenic acid, 9.02; epicatechin, 8.65; phloretin glycosides, 5.59; vitamin C, 12.80. A highly linear relationship (r (2) > 0.97) was attained between concentrations and total antioxidant capacity of phenolics and vitamin C. Relative VCEAC values of these compounds were in the order quercetin (3.06) > epicatechin (2.67) > procyanidin B(2) (2.36) > phloretin (1.63) > vitamin C (1.00) > chlorogenic acid (0.97). Therefore, the estimated contribution of major phenolics and vitamin C to the total antioxidant capacity of 100 g of fresh apples is as follows: quercetin (40.39 VCEAC) > epicatechin (23.10) > procyanidin B(2) (22.07) > vitamin C (12.80) > phloretin (9.11) > chlorogenic acid (8.75). These results indicate that flavonoids such as quercetin, epicatechin, and procyanidin B(2) rather than vitamin C contribute significantly to the total antioxidant activity of apples.

Topics: Antioxidants; Ascorbic Acid; Benzothiazoles; Biflavonoids; Catechin; Flavonoids; Free Radicals; Fruit; Malus; Phenols; Proanthocyanidins; Quercetin; Sulfonic Acids