Showing papers on "DPPH published in 1996"
TL;DR: It is suggested that the galloyl moiety attached to flavan-3-ol at 3 position has a strong scavenging ability on the DPPH radical as well as the ortho-trihydroxyl group in the B ring, which elevates the radical scavenging efficiency above that of the orthosylated group; as has been recognized in other flavonoids such as flavones.
768 citations
TL;DR: Evidence is provided that hydroxy-flavones exhibit interesting antioxidant properties expressed either by the capacity to scavenge free radicals or to competitively inhibit xanthine oxidase (for 7-hydroxy-Flavones), which may be drug candidates for treating pathologies related to free radical oxidation.
675 citations
Journal Article•
TL;DR: It is shown that curcumin is the most potent scavenger of superoxide radicals followed by demethoxycurcumin and bisdemethoxyCurcumin, and the presence of methoxy group further increases the activity.
Abstract: Three natural curcuminoids (curcumin (CAS 458-37-7), demethoxycurcumin, bisdemethoxycurcumin) and acetylcurcumin were compared for their ability to scavenge superoxide radicals and to interact with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radicals. The results showed that curcumin is the most potent scavenger of superoxide radicals followed by demethoxycurcumin and bisdemethoxycurcumin. Acetylcurcumin was inactive. Interaction with DPPH showed a similar activity profile. The study indicates that the phenolic group is essential for the free radical scavenging activity and presence of methoxy group further increases the activity.
497 citations
Journal Article•
TL;DR: In this paper, the results suggest that at least six plants including Eugenia caryophyllata, Alpinia offiicinarum, Rhus verniciflua, Curcuma longa, Rheum palmatvm and Evodia officinalis may be the potential sources of antioxidant.
Abstract: Methanolic aqueous extracts of 100 plants were screened for antioxidative activity using Fenton's reagen/ethyl linoeate system and free radical scavenging activity using DPPH free radical generating system. The results suggest that at least six plants including Eugenia caryophyllata, Alpinia offiicinarum, Rhus verniciflua, Curcuma longa, Rheum palmatvm and Evodia officinalis may be the potential sources of antioxidant, But only one plant, Cornus officinalis, may be the potential source of free radical scavenger from natural plants.
102 citations
TL;DR: The antioxidant activity of Ecklonia stolonifera was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at 37°C, using 2-thiobarbituric acid (TBA) and the radical scavenging effect on 1,2-diphenyl-2-picrylhydrazyl (DPPH) radical.
Abstract: The antioxidant activity ofEcklonia stolonifera was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at 37°C, using 2-thiobarbituric acid (TBA) and the radical scavenging effect on 1,2-diphenyl-2-picrylhydrazyl (DPPH) radical. The methanol extract ofEcklonia stolonifera showed strong antioxidant activity. And the methanol extract was fractionated with several solvents. With regard their fractions, the antioxidative activity were in the order of ethyl acetate>dichloromethane insoluble intermediated phase>dichloromethane>n-butanol>water fraction. The ethyl acetate soluble fraction exhibiting the strongest antioxidant activity was further purified by repeated silica gel and Sephadex LH-20 column chromatography. Antioxidant phloroglucinol was isolated and identified by1H-NMR and13C-NMR. Its antioxidant activity was similar to that of L-ascorbic acid.
49 citations
TL;DR: In this article, cyclization of the corresponding 3,5-bis(1,1-dimethylethyl)-4-hydroxy-N-2-(sulphamoylphenyl)benzamides (12,22 ) was used as free radical scavengers by reaction with DPPH using UV and ESR spectrometry.
20 citations
TL;DR: In this article, the free radical scavenging activity of Thea sinensis leaf extract was evaluated with a chemical test involving diphenylpicrylhydrazyl radical (DPPH).
Abstract: The free radical scavenging activity of Thea sinensis leaf extract was evaluated with a chemical test involving diphenylpicrylhydrazyl radical (DPPH). The hot aqueous green tea extract demonstrated antiradical activity comparable with rutin and vitamin E used as a standard. Liquid-liquid fractionation monitored by scavenging radical bioassay followed by preparative high pressure liquid chromatography led to catechin derivatives. The antiradical activity of the main component of tea leaves was identified as epigallocatechin gallate the major component demonstrating activity.
16 citations