Antioxidative activity of oren-gedoku-to (TJ-15) and toki- shakuyaku-san (TJ-23) in the liver microsomes of rats]

TJ-15 (Oren-Gedoku-To) inhibited enzymatically (NADPH or CumOOH) and non-enzymatically (Fe-askorbate) induced lipid peroxidation in the rat liver microsomes as assessed by the TBA-reactive product accumulation. TJ-23 (Toki-Shakuyaku-San) had little effect on either system. The protective effect of TJ-15 against lipid peroxidation could not be fully accounted for by its action on microsomal electron transfer, as evaluated by studying the kinetics of reduction of cytochrome C. In a free solution TJ-15 and TJ-23 effectively scavenged OH., radicals, as indicated by the inhibition of ethylene production from KMBA, and O2-. anion radicals, as assessed by the inhibitory effect on the rate of NBT reduction. The present results suggest that TJ-15, yet not TJ-23, is capable to reach hydrophobic intra-membrane sites at concentrations at which it is an effective antioxidant. Thus TJ-15 may be a potentially useful protective agent against free radical-mediated damage.     

Antioxidative properties of the kampo drugs TJ-9, TJ-15, TJ-23, TJ-96 and TJ-114]

Plant extracts from Kampo medicines TJ-9 (A), TJ-15 (B), TJ-23 (C), TJ-114 (D) and TJ-96 (E) inhibited peroxidation of low-density lipoprotein (LDL) in vitro and peroxidation of multilamellar liposomes formed by total lipids isolated fro the rat brain. The order of relative efficacy of the extracts in both experiments was as follows: C < D equal to or greater than A < B. Using EPR spectroscopy, the Kampo extracts were found to be oxidated by means of PbO2 and to become relatively stable radicals, which shows that they possess electro-donor properties. A relationship between their ability to inhibit peroxidation of LDL and liposomes and their ability to become a radical was found. The Kampo medicines which produced more radicals inhibited peroxidation of LDL and liposomes more effectively. By means of EPR spectroscopy, Kampo B was found to reduce the vitamin E radical. The results contribute to the understanding of the positive effects of Kampo extracts in the diseases in which a negative influence of free radicals is assumed.     

The preventive inhibition of chondroitin sulfate against the CCI<Subscript>4</Subscript>-lnduced oxidative stress of subcellular level

Our work in this study was made in the microsomal fraction to evaluate the lipid peroxidation by measuring superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) and to elucidate the preventive role of CS in the CCl4-induced oxidative stress. The excessive lipid peroxidation by free radicals derived from CCl4 leads to the condition of oxidative stress which results in the accumulation of MDA. MDA is one of the end-products in the lipid peroxidation process and oxidative stress. MDA, lipid peroxide, produced in this oxidative stress causes various diseases related to aging and hepatotoxicity, etc. Normal cells have a number of enzymatic and nonenzymatic endogenous defense systems to protect themselves from reactive species. The enzymes in the defense systems, for example, are SOD, CAT, and GPx. They quickly eliminate reactive oxygen species (ROS) such as superoxide anion free radical *O2(-), hydrogen peroxide H2O2 and hydroxyl free radical *OH. CS inhibited the accumulation of MDA and the deactivation of SOD, CAT and GPx in the dose-dependent and preventive manner. Our study suggests that CS might be a potential scavenger of free radicals in the oxidative stress originated from the lipid peroxidation of the liver cells of CCl4-treated rats.     

丹酚酸B镁盐对自由基的清除作用和对脂质过氧化的抑制作用(英文)

AIM: To study the effect of magnesium lithospermate B (MLB) on the lipid peroxidation and on its free radical scavenging activity. METHODS: MLB was incubated in rat tissue homogenate or in a free radical generating system. MLB induced inhibition of lipid peroxidation and its scavenging activity on superoxide anions and hydroxyl radicals was studied using colorimetric estimation. RESULTS: MLB inhibited the lipid peroxidation induced by either an auto-oxidant or Fe2+/VitC in vitro, in the liver homogenate, the inhibitory rate of MLB (10 mg/L) being 69.2% and 57.7%, respectively. MLB (25 and 50 mg/kg) decreased the amount of thiobarbituric acid reactive substances (TBARS) in rat serum, liver, kidney, and heart. However, it did not inhibit the lipid peroxidation of brain homogenate ex vivo. MLB scavenged superoxide anions generated from xanthine/xanthine oxidase system and iron-dependent hydroxyl radicals. CONCLUSION: MLB is an inhibitor of lipid peroxidation and scavenge superoxide anions and hydroxyl radicals both in vitro and ex vivo.     

茶多酚清除氧自由基及抑制脑脂质过氧化反应的体外试验

目的研究茶多酚对羟自由基（·ＯＨ）、超氧阴离子自由基（Ｏ·２）的清除作用及其对脂质过氧化的抑制作用。方法茶多酚与自由基发生体系或大鼠脑线粒体共浴后，比色法测定·ＯＨ、Ｏ·２及丙二醛生成量。结果茶多酚对Ｆｅｎｔｏｎ反应生成的·ＯＨ及黄嘌呤－黄嘌呤氧化酶系统产生的Ｏ·２具有较强的清除作用，ＩＣ５０分别为９１９．６ｍｇ·Ｌ－１和８３６ｍｇ·Ｌ－１。茶多酚对·ＯＨ诱导的离体大鼠脑线粒体产生的脂质过氧化有明显的抑制作用。结论茶多酚的抗脂质过氧化作用与其清除氧自由基作用有关     

Inhibition of lipid peroxidation by pindolol

Among beta-blockers, including atenolol, metaproterenol, pindolol and propranolol, only pindolol strongly inhibited lipid peroxidation induced by xanthine oxidase-hypoxanthine in the presence of adenosine-5'-phosphate-Fe3+. In the reaction system, superoxide predominantly reduced iron because superoxide dismutase strongly prevented the iron reduction. However, pindolol had no effect on the superoxide-dependent iron reduction. Adding superoxide dismutase immediately stopped the lipid peroxidation, indicating that superoxide is closely connected with forming the initiator of xanthine oxidase-hypoxanthine-induced lipid peroxidation. On the other hand, pindolol also inhibited lipid peroxidation, whereas it did not react with superoxide, indicating that it inhibited xanthine oxidase-hypoxanthine-induced lipid peroxidation by an independent mechanism of superoxide. Pindolol sharply scavenged 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) radical cations, but the ability of pindolol to scavenge peroxyl radicals of 2,2'-azobis(2-amidinopropane)-dihydrochloride and 2,2'-diphenyl-p-picrylhydrazyl radicals was low. In addition, pindolol did not scavenge hydroxyl radicals at physiologically significant concentrations. These results suggest that the ability of pindolol to inhibit lipid peroxidation was due to scavenging carbon-centered radicals rather than peroxyl radicals.     

Inhibitory activity of epigallocatechin gallate (EGCg) in paraquat-induced microsomal lipid peroxidation--a mechanism of protective effects of EGCg against paraquat toxicity

Recently we have reported that epigallocatechin gallate (EGCg), a major component of Japanese green tea, significantly increased the survival rate of paraquat (Pq) poisoned mice. This paper describes two biochemical activities of EGCg, which relate to its protective effects against Pq toxicity. EGCg inhibited Pq-induced microsomal malondialdehyde (MDA) productions in rat liver microsome system containing 40 microM FeSO(4). Forty micromolar EGCg inhibited MDA production significantly. EGCg may inhibit the Pq-induced MDA production by at least two mechanisms. One may be iron-chelating activity as the inhibition disappeared when excess amounts of FeSO(4) were added to the reaction mixture, which indicated that EGCg reduced iron driven lipid peroxidation by pulling out available irons in the reaction mixture. The other is radical scavenging activity. EGCg scavenged DMPO-OOH spin adducts generated by the microsome-Pq system. The dose response curve of EGCg was similar to that obtained by ascorbic acid which is a typical water-soluble radical scavenger. Although ascorbic acid had a potential activity of scavenging superoxide radicals, it can not be recommended to use for the treatment of Pq poisoning, because ascorbic acid acts as a pro-oxidant in the presence of free transition metal ions by accelerating the Fenton reaction (Fe(2+)+H(2)O(2)-->Fe(3+)+OH(-)+OH*), which is responsible for lipid peroxidation. On the contrary, EGCg inhibited iron-driven lipid peroxidation presumably not only by chelating to Fe ions but also by scavenging superoxide radicals, which are responsible for the reduction of ferric (Fe(3+)) to ferrous (Fe(2+)) that catalyzes the Fenton reaction. Chelating and radical scavenging activity of EGCg can be expected simultaneously in the occurrence of Pq toxicity, which may explain the protective effects of EGCg against Pq toxicity.     

An investigation of the novel anti-inflammatory agents ONO-3144 and MK-447. Studies on their potential antioxidant activity

Oxygen-derived free radicals have been implicated as contributors to inflammatory disorders and it has been suggested that certain anti-inflammatory drugs act by scavenging free radicals. In this paper we have studied the free radical scavenging activity of two such experimental anti-inflammatory drugs MK-447 and ONO-3144. Using the technique of pulse radiolysis we have been able to obtain rate constants for the reactions of these compounds with specific free radicals including OH and O2-. We have also investigated the antioxidant capacity of these compounds using rat liver microsomal lipid peroxidation systems. It is suggested that this approach yielding quantitative data concerning defined free radical species will lead to a better understanding of the role of radical scavenging in anti-inflammatory activity.     

Inhibition by uric acid of free radicals that damage biological molecules

To clarify the antioxidative role of uric acid, its ability to scavenge carbon-centered and peroxyl radicals and its inhibitory effect on lipid peroxidation induced by various model systems were examined. Uric acid efficiently scavenged carbon-centered and peroxyl radicals derived from the hydrophilic free radical generator 2,2'-azobis-(2-amidinopropane)-dihydrochloride (AAPH). All damage to biological molecules, including protein, DNA and lipids induced by AAPH, was strongly prevented by uric acid. In contrast, alpha-tocopherol had little effect on damage to biological molecules. Lipid peroxidation by the lipophilic free radical generator 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) was little inhibited by uric acid, but not by alpha-tocopherol. Copper-induced lipid peroxidation was inhibited by uric acid and alpha-tocopherol. NADPH- and ADP-Fe(3+)-dependent microsomal lipid peroxidation was efficiently inhibited by alpha-tocopherol, but not by uric acid. Uric acid seems to scavenge free radicals in hydrophilic conditions to inhibit lipid peroxidation on the lipid-aqueous boundary, and the antioxidation is only little in lipophilic conditions.     

The effect of kampo preparations and their effect on peptidase activity in damage caused by free radicals]

The activity of peptidases (trypsin from bovine pancreas and trypsin-like enzymes from the liver rat homogenate) was influenced by five preparation of Kampo medicine, TJ-9 (Sho-Saiko-To), TJ-15 (Oren-Gedoku-To), TJ-23 (Toki-Shakuyaku-San), TJ-96 (Saiboku-To), and TJ-114 (Sairei-To) and studied in relation to their effect on the uptake of free oxygen radicals demonstrated earlier. On the basis of increased activity of trypsin and trypsin-like enzymes and the previously found capability of uptaking free oxygen radicals, the mechanism of action of the Kampo preparations may be assumed to be connected not only with a direct support of enzymes of digestion and increased activity of peptidases, capable of eliminating oxidatively damaged proteins, but with an antioxidative effect as well, which prevents increased cumulation of oxidatively damaged macromolecules and the action of superoxide radicals developed earlier by the well-known and trypsin-stimulated conversion of xanthinedehydrogenase to xanthinoxidase.     

Free radical scavenging activities of yellow gentian (Gentiana lutea L.) measured by electron spin resonance

Yellow gentian (Gentiana lutea L.) is a herbal species with a long-term use in traditional medicine due to its digestive and stomachic properties. This paper presents an investigation of the free radical scavenging activity of methanolic extracts of yellow gentian leaves and roots in two different systems using electron spin resonance (ESR) spectrometry. Assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the superoxide radicals (O2*-) generated by the xanthine/xanthine oxidase (X/XO) system. The results of gentian methanolic extracts were compared with the antioxidant capacity of synthetic antioxidant butylated hydroxyanisole (BHA). This study proves that yellow gentian leaves and roots exhibit considerable antioxidant properties, expressed either by their capability to scavenge DPPH or superoxide radicals.     

Effect of sex hormones on lipid peroxidation in rat liver

The role of sex hormones in hepatic lipid peroxidation, and in hepatic aldehyde oxidase and xanthine oxidase activities were investigated using rat liver homogenates. It was observed that male rat had a significantly greater content of malondialdehyde in liver than female. Among the sex hormones tested, estradiol, one of female hormones, markedly inhibited the formation of lipid peroxides in liver tissues in vitro. Especially, the inhibitory effect of estradiol appeared more remarkably in Fe+2-induced lipid peroxidation. The hepatic xanthine oxidase activity was decreased about 15% by 10(-6) M estradiol, whereas, the aldehyde oxidase activity was almost completely disappeared at the same concentration of estradiol. It implies that sex differences in lipid peroxidation is attributed to the suppression of free radical generating system by estradiol.     

Effect of diltiazem isomers and thiamine on piglet liver microsomal peroxidation using dichlorofluorescein.

PURPOSE: We investigated a potential hepatoprotective role of d-cis diltiazem, l-cis diltiazem, thiamine and the combination d-cis diltiazem and thiamine against lipid peroxidation in a piglet liver microsomal model. A modified in vitro dichlorofluorescein assay was developed to assess the extent of peroxidative damage induced by reactive oxygen species in the piglet liver microsomal fraction. METHODS: Microsomal membrane fraction, obtained from 3 week old female piglets, was treated with either the biologically vasoactive d-cis diltiazem or the non-vasoactive stereoisomer l-cis diltiazem (5-1000 microM) for 1 hour at 37 degrees C followed by one hour incubation with the free radical generator AAPH (2,2'-azobis-(2-amidinopropane) dihydrochloride; 1 mM) to initiate lipid peroxidation. In a separate study, piglet liver microsomes were pre-treated with d-cis diltiazem (50 or 500 microM) and thiamine (10-100 microM) to assess the antioxidant activity of the combination. RESULTS: A dose dependant inhibition of membrane lipid peroxidation was observed with d-cis diltiazem (p<0.05) but not with l-cis diltiazem, suggesting that diltiazem is stereospecific in protecting against microsomal lipid peroxidation. Combining diltiazem with thiamine further protected microsomes against lipid peroxidation compared to use of individual drugs. CONCLUSION: We conclude that diltiazem and the combination of diltiazem and thiamine offers a hepatoprotective effect against free radicals.     

Antioxidant effect of prostaglandin E2 in the liver alcoholic steatosis

The mechanisms of the antioxidant effect of prostaglandin E2 (PGE2) in cases of chronic alcoholic intoxication were studied. It is shown that PGE2 decreases the production of hydroxyl radicals, lipoperoxides, conjugated dienes, malonic dialdehyde, and carbonyl-containing products of lipid peroxidation. In addition, PGE2 normalizes activity of the liver microsomal monooxygenase system components responsible for the free oxygen radical production.     

The influence of lipid peroxidation products (malondialdehyde, 4-hydroxynonenal) on xanthine oxidoreductase prepared from rat liver.

Depending on metabolic conditions, xanthine oxidoreductase acts as either a dehydrogenase (XDH) or an oxidase (XOD). The metabolism of hypoxanthine and xanthine by the oxidase is associated with the production of reactive oxygen radicals. Reaction of reactive oxygen radicals with polyunsaturated fatty acids (lipid peroxidation) leads to the formation of malondialdehyde (MDA) and 4-hydroxynonenal (HNE), known to modify proteins by reaction with NH2- and SH-groups. Therefore, these aldehydes could influence both the activity of xanthine oxidoreductase and the XOD/XDH ratio. We found that incubation of xanthine oxidoreductase with MDA leads to an initial increase in XDH activity and to a continuous decrease in XOD activity, whereby the total activity decreases. This was in contrast to the effects of HNE which did not alter the XDH activity; XOD was however activated. This demonstrates that the lipid peroxidation products MDA and HNE are able to modify xanthine oxidoreductase similarly to a feed-back mechanism.     

Enhancement of antioxidant and anti-inflammatory activities of bioflavonoid rutin by complexation with transition metals

The antioxidant and anti-inflammatory activities of two transition metal complexes of bioflavonoid rutin, Fe(rut)Cl(3) and Cu(rut)Cl(2), were studied. It was found that Cu(rut)Cl(2) was a highly efficient in vitro and ex vivo free radical scavenger that sharply decreased (by 2-30 times compared to the parent rutin): oxygen radical production by xanthine oxidase, rat liver microsomes, and rat peritoneal macrophages; the formation of thiobarbituric acid-reactive products in microsomal lipid peroxidation; and the generation of oxygen radicals by broncho-alveolar cells from bleomycin-treated rats. The copper-rutin complex was also a superior inhibitor of inflammatory and fibrotic processes (characterized by such parameters as macrophage/neutrophil ratio, wet lung weight, total protein content, and hydroxyproline concentration) in the bleomycin-treated rats. The antioxidant activity of Fe(rut)Cl(3) was much lower and in some cases approached that of rutin. Fe(rut)Cl(3) also stimulated to some degree spontaneous oxygen radical production by macrophages. We suggested that the superior antioxidant and anti-inflammatory activity of the copper-rutin complex is a consequence of its acquiring the additional superoxide-dismuting copper center. The inhibitory activity of Fe(rut)Cl(3) was lower, probably due to the partial reduction into Fe(rut)Cl(2) in the presence of biological reductants; however, similarly to the copper-rutin complex, this complex efficiently suppressed lung edema.     

3,3'-diselenodipropionic acid, an efficient peroxyl radical scavenger and a GPx mimic, protects erythrocytes (RBCs) from AAPH-induced hemolysis

3,3'-diselenodipropionic acid (DSePA), a derivative of selenocystine, has been synthesized and examined for antioxidant activity, glutathione peroxidase (GPx) activity, and cytotoxicity. The effect of DSePA on membrane lipid peroxidation, release of hemoglobin, and intracellular K+ ion as a consequence of erythrocyte (red blood cells or RBCs) oxidation by free radicals generated by 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) were used to evaluate the antioxidant ability. Lipid peroxidation, hemolysis, and K+ ion loss in RBCs were assessed, respectively, by formation of thiobarbituric acid reactive substances (TBARS), absorbance of hemoglobin at 532 nm and flame photometry. The IC50 values for lipid peroxidation, hemolysis, and K+ ion leakage were 45+/-5, 20+/-2, and 75+/-8 microM, respectively. DSePA treatment prevented the depletion of glutathione (GSH) levels in RBCs from free-radical-induced stress. DSePA is a good peroxyl radical scavenger and the bimolecular rate constant for the reaction of DSePA with a model peroxyl radical, trichloromethyl peroxyl radical (CCl 3O2*), was determined to be 2.7x10(8) M(-1) s(-1) using a pulse radiolysis technique. DSePA shows GPx activity with higher substrate specificity towards peroxides than thiols. The cytotoxicity of DSePA was studied in lymphocytes and EL4 tumor cells and the results showed that DSePA is nontoxic to these cells at the concentrations employed. These results when compared with two well-known selenium compounds, sodium selenite and ebselen, indicated that DSePA, although it shows lesser GPx activity, has higher free radical scavenging ability and lesser toxicity.     

Rat liver microsomal NADPH-supported oxidase activity and lipid peroxidation dependent on ethanol-inducible cytochrome P-450 (P-450IIE1)

The liver microsomal ethanol-inducible cytochrome P-450 (P-450IIE1) form is known to exhibit a high rate of oxidase activity in the absence of substrate and it was therefore of interest to evaluate whether this form of P-450 could contribute to microsomal and liposomal NADPH-dependent oxidase activity and lipid peroxidation. The rate of microsomal NADPH-consumption, O2--formation, H2O2-production and generation of thiobarbituric acid (TBA) reactive substances correlated to the amount of P-450IIE1 in 28 microsomal samples from variously treated rats. Anti-P-450IIE1 IgG inhibited, compared to control IgG, microsomal H2O2-formation by 45% in microsomes from acetone-treated rats and by 22% in control microsomes. NADPH-dependent generation of TBA-reactive products was completely inhibited by these antibodies, whereas preimmune IgG was essentially without effect. Liposomes containing reductase and P-450IIE1 were peroxidized in a superoxide dismutase (SOD) sensitive reaction at a 5-10-fold higher rate than membranes containing 3 other forms of cytochrome P-450. Lipid peroxidation in reconstituted vesicles dependent on the presence of P-450IIB1 was by contrast not inhibited by SOD. Microsomal peroxidase activities, using 15-(S)-hydroperoxy-5-cis-8,11,13-trans-eicosatetraenoic acid as a substrate were high in microsomes from phenobarbital- or ethanol-treated rats but low in membranes from isoniazid-treated rats, having the highest relative level of P-450IIE1. It is suggested that the oxidase activity of P-450IIE1 contributes to microsomal NADPH-dependent lipid peroxidation. The combined action of the oxidase activity by P-450IIE1 and the peroxidase activities by P-450IIB1 and other forms of P-450 may be important for the high rate of lipid peroxidation observed in e.g. microsomes from ethanol- or acetone-treated rats. The possible importance of cytochrome P-450IIE1-dependent lipid peroxidation in vivo after ethanol abuse is discussed.     

Studies on membrane factors in iron-supported lipid peroxidation

Lipid peroxidation in biomembranes is mediated by free radical reactions. It leads to membrane damage and has been proposed to be associated with the pathogenesis to tissue injuries. Iron is known as a catalyst of lipid peroxidation. Microsomal lipid peroxidation by both NADPH and iron-chelate, such as Fe(3+)-ADP or Fe(3+)-PPi, is believed to be enzymatically associated with iron reduction. On the other hand, the addition of free Fe2+ to microsomes or liposomes produces a lag phase before the maximal rates of lipid peroxidation. We examined the interaction of iron with membrane in iron-supported lipid peroxidation and microsomal membrane components associated with iron reduction in NADPH-supported lipid peroxidation. Iron-supported lipid peroxidation was affected by the surface charges of liposomal membrane. Liposomes containing phosphatidylserine (PS) were most sensitive to iron-supported lipid peroxidation. The effect of PS on iron-supported lipid peroxidation indicates that iron participates in binding to membrane surface charges and also indicates that Fe2+ at high level bound to membranes plays a role in producing a lag phase. The mechanism producing a lag phase in Fe(2+)-PPi-supported lipid peroxidation is discussed. In NADPH-supported lipid peroxidation in microsomes, it seemed unlikely that superoxide may be involved in iron reduction. Alternatively, under anaerobic conditions, NADPH-supported iron reduction in microsomes was not dependent on cytochrome P450 content and not inhibited by CO. A cholate-solubilized fraction of microsomes was applied to a laurate-Sepharose column and an active fraction for lipid peroxidation was obtained. Involvement of a heat-labile component, distinct from cytochrome P450, responsible for iron reduction in microsomal lipid peroxidation was demonstrated.