procyanidin-b1 and 1-1-diphenyl-2-picrylhydrazyl

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

Six galloyl-substituted procyanidin B1 and B2, 3-O-gallate, 3''-O-gallate, and 3,3''-di-O-gallate, were systematically synthesized with the condensation method using TMSOTf as a catalyst. Their ability of DPPH radical scavenging activity and DNA polymerase inhibitory activity were also investigated. The results indicated that the galloyl group of these compounds is very important for both activities. 3,3''-Di-O-gallate dimers acted as strong inhibitor against DNA polymerase alpha and beta, whereas the desgalloyl and monogalloyl compounds did not exhibit any appreciable inhibitory activity against the DNA polymerase beta.

Topics: Animals; Biflavonoids; Biphenyl Compounds; Catalysis; Catechin; Cattle; Enzyme Inhibitors; Free Radical Scavengers; Gallic Acid; Molecular Conformation; Nucleic Acid Synthesis Inhibitors; Picrates; Proanthocyanidins; Rats; Structure-Activity Relationship

A 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-generating system was used to evaluate the antioxidant properties of Korean medicinal plants that have been used widely as folk medicines for several disorders, as well as compounds isolated from them. Among the Rosaceae, Rosa rugosa and Rosa davurica showed strong DPPH radical-scavenging activity. The most effective medicinal plant from families other than Rosaceae was Cedrela sinensis, followed in order by Nelumbo nucifera, Eucommia ulmoides, Zanthoxylum piperitum, Cudrania tricuspidata and Houttuynia cordata. These results serve as a good index of the free radical-scavenging activities of Korean medicinal plants. Furthermore, the polyphenols isolated from these plants, procyanidin B-3, (+)-catechin, gallic acid, methyl gallate, quercetin, quercetin-3-O-beta-D-glucoside, quercetin-3-O-beta-galactoside, quercetin-3-O-rutinose and kaempferol, exerted strong DPPH radical-scavenging activity. These results suggest that the Korean medicinal plants and the polyphenols isolated from them that exhibited effective radical-scavenging activity may be promising agents for scavenging free radicals and treating diseases associated with excess free radicals.

Topics: Biflavonoids; Biphenyl Compounds; Catechin; Flavonoids; Free Radical Scavengers; Fruit; Humans; Korea; Medicine, Traditional; Phenols; Phytotherapy; Picrates; Plant Extracts; Plant Leaves; Plant Roots; Plant Stems; Polyphenols; Proanthocyanidins; Rosaceae

We induced lipid peroxidation in rat heart mitochondria with ferrous sulphate (FeSO4) and compared the inhibitory effect of various tannins on the peroxidation. Oxygen consumption and malondialdehyde (MDA) formation were used to quantitate the amount of lipid peroxidation, and the free radical scavenger activity of tannins was measured with a diphenyl-p-picryl hydrazyl (DPPH) method. Of 25 tannins and related compounds tested, catechin benzylthioether and procyanidin B-2 benzylthioether were the most potent in inhibiting lipid peroxidation, with inhibitory effects stronger than that of trolox, a water soluble analogue of vitamin E. The concentrations (IC50) required for catechin benzylthioether and procyanidin B-2 benzylthioether to inhibit oxygen consumption to 50% of control values were 0.85 and 2.0 microM, respectively, while their IC50 values from the inhibition of MDA formation were 0.9 and 1.70 microM, respectively. The IC50 values for catechin, and procyanidin B-2 to inhibit oxygen consumption were 34.0 and 11.0 microM. Both compounds were less potent than their benzylthioether derivatives. However, the ability of catechin and procyanidin B-2 to scavenge DPPH were similar to that of their benzylthioether derivatives. We conclude that conjugation with a benzylthioether group enhances the inhibitor effect of tannins on lipid peroxidation, and that the mechanism is not an increase in its scavenger activity.

Topics: Animals; Bepridil; Biflavonoids; Biphenyl Compounds; Catechin; Dose-Response Relationship, Drug; Ferrous Compounds; Free Radical Scavengers; Free Radicals; Lipid Peroxidation; Male; Malondialdehyde; Mitochondria, Heart; Oxygen Consumption; Picrates; Proanthocyanidins; Rats; Structure-Activity Relationship; Tannins