Shizuo Toda

Inhibitory effects of chlorogenic acids on linoleic acid peroxidation and haemolysis

Abstract Antioxidant activities of chlorogenic acid and related catechols were investigated by both the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system and the superoxide anion-mediated linoleic acid peroxidation system. At 10 μM, chlorogenic acid, 3,5-dicaffeoylquinic acid, caffeic acid and protocatechuic acid showed more scavenging activities on DPPH than dl -α-tocopherol or ascorbic acid. DPPH radical scavenging activities of these compounds increased dose-dependently at concentrations ranging from 1 to 50 μM; 1 mol of chlorogenic acid reacted with ca 4 mol of radical, and 1 mol of 3,5-dicaffeoylquinic acid with ca 6 mol of radical. Chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeic acid inhibited the formation of conjugated diene from linoleic acid. The inhibitory activity of 3,5-dicaffeoylquinic acid was stronger than that of chlorogenic acid or caffeic acid; dl -α-tocopherol was the most inhibitory of the other catechols tested. Effects on the haemolysis and peroxidation of mouse erythrocytes induced by H 2 O 2 was also examined. Cafreic acid, chlorogenic acid, 3,5-dicaffeoylquinic acid and dl -α-tocopherol exhibited strong inhibitory activities, but cinnamic acid, p -coumaric acid, ferulic acid, protocatechuic acid and vanillic acid were ineffective. Caffeic acid (25 μM) inhibited the rupture and haemolysis of erythrocytes.

Inhibitory effects of Astragali Radix, a crude drug in Oriental medicines, on lipid peroxidation and protein oxidative modification by copper.

Effects of Astragali Radix, the root of Astragalus membrauaceus Bunge, were investigated on oxidative stress such as lipid peroxidation and protein oxidative modification by copper. The results showed that these effects are similar to those of mannitol and superoxide dismutase as a free radical scavenger. It was demonstrated that Astragali Radix have inhibitory effects on oxidative stress induced by copper.

Inhibitory effects of isoflavones in roots of Astragalus membranaceus BUNGE (Astragali Radix) on lipid peroxidation by reactive oxygen species

Possible inhibitory effects were investigated of isoflavones in the roots of Astragalus membranaceus BUNGE (Astragali Radix), afrormosin, calycosin, formononetin and odoratin on lipid peroxidation by reactive oxygen species. Calycosin inhibited lecithin peroxidation which was induced by hydroxy radical‐generation by interaction of haemoglobin and hydrogen peroxide. Calycosin and formononetin inhibited lecithin peroxidation which was induced by superoxide anion generation by xanthine‐xanthine oxidase. Other isoflavones had no inhibitory effects on lecithin peroxidations. These results demonstrated that the antioxidant properties of isoflavones, which have a methoxy group at the 4′ position, are derived from hydroxy groups at the 7 and 4′ position.

Inhibitory effects of Astragali Radix, crude drug in Oriental medicines on lipid peroxidation and protein oxidative modification of mouse brain homogenate by copper

Astragali Radix, the root of Astragalus membranaceus Bunge, is a crude drug used widely in Oriental medicines. It is a major component of Ougi‐Keishi‐gomotsu‐to, a traditional herbal medicine, used for neurop patients with abnormal sensations and neuropathic pain of the legs. It was shown to have inhibitory effects on lipid peroxidation and protein oxidative modification by copper. The effects were similar to and stronger than those of mannitol and superoxide dismutase as free radical scavengers. These results demonstrated that Astragali Radix has inhibitory effects on oxidative stress induced by metal.

Effect of aluminum on iron-induced lipid peroxidation and protein oxidative modification of mouse brain homogenate

In the present study the authors report on the enhancing effect of aluminum(III) (Al[III]) on iron(II)(Fe[II])-induced lipid peroxidation (LPO) of mice brain homogenate, which occurs in a concentration and time-dependent manner. No evidence of LPO caused by Al alone was found.Both Al(III) and Fe(II) ions induced protein oxidative modifications in mice brain homogenate, in a time and concentrationdependent manner. Aluminum enhances Fe(II)-induced protein oxidative modification at a concentration of 2:1 and 1:1 Al:Fe molar ratios. However, Al suppress Fe(II)-induced protein oxidative modification at a concentration of 0.5:1 Al:Fe molar ratio.Addition of ethylenediaminetetraacetic acid (EDTA) inhibits both LPO and protein oxidative modifications induced by Al(III) and Fe(II) ions. Addition of mannitol and of Superoxide dismutase (SOD) did not show such effects.It is concluded that in mice brain homogenate, Al accelerates Fe(II)-induced LPO. Protein oxidative modifications caused by Fe(II) and/or Al ions are enhanced at high, but suppressed at low concentrations of Al ions. The latter observation suggests a possible biological role of Al as an antioxidant.

Antioxidative components isolated from the roots of Astragalus membranaceus Bunge (Astragali Radix)

Antioxidative components in the methanol extract of the root of Astragalus membranaceus Bunge were investigated by using an evaluation method based on the air oxidation of linoleic acid. Afrormosin, calycosin and odoratin were found to be active components. These antioxidative activities are superior or similar to those of butyl hydroxytoluene and α‐tocopherol.

Comparison of antioxidative and chelating effects of daidzein and daidzin on protein oxidative modification by copper in vitro.

Daidzein and its glycoside daidzin are isoflavones. Their antioxidative effects were compared in vitro. Although both compounds inhibited protein oxidative modification by copper, the inhibitory effect of daidzein was stronger than that of daidzin. Because daidzein showed a greater affinity for Cu2+, the antioxidant effect of these isoflavones may be dependent on their respective copper-chelating abilities.

Inhibition in vitro linoleic acid peroxidation and haemolysis by caffeoyltryptophan

Antioxidant activities of caffeoyltryptophan were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system, the superoxide anion generation system and the superoxide anion-mediated linoleic acid peroxidation system. At 10 microM, caffeoyltryptophan showed greater scavenging activity on DPPH than dl-alpha-tocopherol or ascorbic acid. DPPH radical scavenging activity of caffeoyltryptophan increased dose-dependently at concentrations ranging from 1 to 50 microM; 1 mol of caffeoyltryptophan reacted with ca 4 mol of radical. Caffeoyltryptophan caused 80% inhibition of superoxide anion generation at 50 microM. The inhibitory activity of caffeoyltryptophan was as strong as that of 5-caffeoylquinic acid. Caffeoyltryptophan inhibited the formation of conjugated diene from linoleic acid. The inhibitory activity increased in the order caffeic acid < 5-caffeoylquinic acid < caffeoyltryptophan < dl-alpha-tocopherol. Effects on the in vitro haemolysis and peroxidation of mouse erythrocytes induced by H2O2 were also examined. Caffeoyltryptophan exhibited strong inhibitory activities; Tryptophan was ineffective in these systems. These data suggest that caffeoyltryptophan may be a natural antioxidant in the human diet and, as such, may intervene in toxicological processes that are mediated by radical mechanisms.

Inhibitory effects of phenylpropanoid metabolites on copper-induced protein oxidative modification of mice brain homogenate, in vitro

We present the results of an in vitro investigation of the inhibitory effects of phenylpropanoid metabolites on copper-induced protein oxidative modification of mice brain homogenate. The effects of caffeic acid, 3-(3, 4-dihydroxyphenyl)-l-alanine, esculetin, ferulic acid, and scopoletin were stronger than that of mannitol as a free-radical scavenger, whereas the effects of other phenylpropanoid metabolites, cinnamic acid, coniferyl alcohol, p-coumaric acid, coumarin, phenylalanine, tyrosine, and umbelliferone, were weak. These results demonstrated that phenolic carboxylic acids with 3,4-dihydroxy or 4-hydroxy-3-methoxy substituents and benzo-α-pyrons with 6,7-dihydroxy or 7-hydroxy-6-methoxy substituents in phenylpropanoid metabolites inhibit metal-induced protein oxidative modification of the brain.

Induction of neutrophil accumulation by red ginseng.

The present paper attempts to document the effect of an extract of red ginseng (RG), the root of Panax ginseng C.A. Meyer (family Araliaceae) neutrophil accumulation in mice after intraperitoneal injection