没食子酸丙脂对乙醇诱导鼠肝急性损伤的保护作用

本文研究没食子酸丙酯对乙醇塑造鼠急性肝损伤模型的影响。结果证实该化合物具有抑制肝组织脂质过氧化、维持鼠肝线粒体氧化磷酸化、保护其形态结构的完整性等作用。为阐明赤芍的生化药理作用提供资料。     

Impact of ursolic acid on chronic ethanol-induced oxidative stress in the rat heart

Oxidative stress plays an important role as a mediator of myocardial damage produced by ethanol. This work was designed to investigate the effect of ursolic acid (UA), a reported radical scavenger and antioxidant, on oxidative stress in the heart of chronically ethanol-administered rats. Chronic ethanol administration (7.9 g/kg/day for 60 days) caused tissue damage that was manifested by the elevation of serum lactate dehydrogenase (LDH) and creatine phosphokinase (CPK). It also induced oxidative stress in the heart by increasing the lipid peroxidation process and by decreasing the antioxidant capacity of the heart. After the induction of toxicity (i.e. initial 30 days), treatment groups received UA (10, 20 and 40 mg/kg/day) along with ethanol for another 30 days. Coadministration of UA effectively (20 mg/kg/day) restored the activities of marker enzymes. It also controlled the oxidative stress by decreasing lipid peroxidation products (manifested by decreased lipid peroxidation products such as thiobarbituric acid reactive substances--TBARS, lipid hydroperoxides--LOOH and conjugated dienes--CD), increasing the activities of free radical scavenging enzymes (superoxide dismutase--SOD, catalase--CAT, glutathione peroxidase--GPx and glutathione S-transferase--GSH) and increasing the levels of non-enzymic antioxidants such as reduced glutathione, ascorbic acid and alpha-tocopherol. These findings demonstrate that UA acts as a protective agent against ethanol-induced abnormalities in the heart by reducing the lipid peroxidation process and by enhancing the antioxidant capacity.     

Potential in vitro antioxidant and protective effects of Soymida febrifuga on ethanol induced oxidative damage in HepG2 cells

There is increasing evidence that oxidative stress is implicated in pathogenesis of various diseases, including alcoholic liver injury. In the present study, we investigated the comparative protective effects of leaf, bark, root and root bark extracts of Soymida febrifuga (Roxb.) A. Juss. (Meliaceae) against ethanol induced oxidative damage in HepG2 cells. Comparatively, methanolic and aqueous extracts of bark and leaf significantly attenuated the cytotoxicity of the ethanol, as determined by cytotoxicity, lipid peroxidation, lactate dehydrogenase, alanine aminotransferases and asparatate aminotransferases, than the root and root bark extracts. Ethanol induces liver toxicity through free radical generation so initially in vitro antioxidant activity of the extracts was evaluated. Methanolic and aqueous extracts of bark and leaf have shown higher total phenolic content, reducing power, metal chelating, superoxide, hydroxyl radical, hydrogen peroxide and nitric oxide (murine macrophage cells) scavenging activity than the root and root bark extracts.     

Tungtungmadic acid, a novel antioxidant, fromSalicornia herbacea

Tungtungmadic acid (3-caffeoyl-4-dihydrocaffeoyl quinic acid) is a new chlorogenic acid derivative that was isolated from the Salicornia herbacea. The structure of tungtungmadic acid was determined using chemical and spectral analysis. The antioxidant activity of tungtungmadic acid was evaluated using various antioxidant assays, including free radical scavenging, lipid peroxidation and hydroxyl radical-induced DNA strand breaks assays. Tungtungmadic acid (IC50 = 5.1 microM and 9.3 microM) was found to have higher antioxidant activity in the DPPH scavenging assay as well as in the iron-induced liver microsomal lipid peroxidation system. In addition, the tungtungmadic acid was also effective in protecting the plasmid DNA against strand breakage induced by hydroxyl 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.     

Free radical scavenging and antioxidant activities of Glinus oppositifolius (carpet weed) using different in vitro assay systems

Glinus oppositifolius (L.) Aug. DC. (Aizoceae), commonly called slender carpet weed, is a prostrate or diffuse herb which acts as stomachic, uterine stimulant, aperient and lochia. It is used traditionally in the treatment of earache, itch and skin diseases. Glinus oppositifolius was extracted with ethanol (70%) and used for the evaluation of various in vitro antioxidant assays which includes H-donor activity, nitric oxide scavenging, superoxide anion scavenging, reducing ability, hydroxyl radical, hydrogen peroxide scavenging, total phenolic content, total flavonoid content, total antioxidant activity by thiocyanate and phosphomolybdenum method, metal chelating, β-carotene bleaching, total peroxy radical assays. The pro-oxidant activity was measured using bleomycin-dependent DNA damage. Ex vivo models such as lipid peroxidation were used to study the antioxidant property of the extract. The various antioxidant activities were compared with suitable standard antioxidants such as ascorbic acid, butylated hydroxyl toluene (BHT), α-tocopherol, curcumin, quercetin and Trolox. The generation of free radicals, viz., O₂^·?, OH^·, H₂O₂, NO^· and peroxyl radicals, were effectively scavenged by the ethanol extract of Glinus oppositifolius. The antioxidant activity depends on concentration and increases with increasing amounts of the extract. The total phenolic content, flavonoid content and total antioxidant activity in Glinus oppositifolius were determined as microgram (μg) pyrocatechol, quercetin and α-tocopherol equivalent/mg, respectively. The extract did not exhibit any pro-oxidant activity when compared with ascorbic acid. The results obtained in this study indicate that Glinus oppositifolius scavenges free radicals and reduces lipid peroxidation, ameliorating the damage imposed by oxidative stress in different disease conditions and serve as a potential source of natural antioxidant.     

The impact of cyanoglycoside rich fraction isolated from Cassava (Manihot esculenta) on alcohol induced oxidative stress.

The effects of feeding a cassava (Manihot esculenta) rich diet on alcohol induced peroxidative damages were investigated in male albino rats. Rats were divided into four groups and maintained for 60 days as follows. (1) Control group: cassava free diet, (2) alcohol group: cassava free diet+ethanol (4 g/kg body wt/day), (3) cassava group: cassava diet and (4) alcohol+cassava group: cassava diet+ethanol (4 g/kg body wt/day). Results revealed that alcohol induced significant lipid peroxidation, since the lipid peroxidation products malondialdehyde (MDA), hydroperoxides and conjugated dienes were elevated in the liver. The activities of free radical scavenging enzymes such as superoxide dismutase (SOD), catalase and glutathione reductase were reduced and glutathione content was decreased in the liver. But the co-administration of a cassava rich diet increased the activity of free radical scavenging enzymes and glutathione content. The level of lipid peroxides in the liver was also decreased on co-administration of cassava. But the oxidative damage caused by cassava was potentiated by alcohol administration. These studies suggested that consumption of alcohol along with cassava offered some protection against the alcohol induced oxidative stress. So we isolated the cyanoglycoside rich fraction from cassava and its impact on rats administered alcohol was also investigated. The results revealed that alcohol induced oxidative stress was potentiated by the co-administration of cyanoglycoside rich fraction. These studies suggested that the fiber and antioxidant vitamins present in the cassava may be playing a protective role against the alcohol induced oxidative stress.     

Leaves of Cassia tora as a novel cancer therapeutic – An in vitro study

Cassia tora Linn (Leguminacea) is a medicinal plant traditionally used as laxative, for the treatment of leprosy and various skin disorders. Preliminary phytochemical analysis of leaf showed the presence of polyphenols (3.7 mg gallic acid equivalent per gram dried leaves). The presence of phenolic compound prompted us to evaluate its antioxidant and antiproliferative potential. In the present study C. tora methanolic leaf extract (CTME) was evaluated for its nitric oxide scavenging activity and reducing power assays using Rutin and BHT as standards. The extract was studied for its lipid peroxidation inhibition assay using rat liver and brain. In all assays, a correlation existed between concentration of extract and percentage inhibition of free radical, reducing power and inhibition of lipid peroxidation. The antiproliferative activity of CTME with Cisplatin, anticancer drug was studied using human cervical cancer cells (HeLa). Proliferation of HeLa was measured by MTT assay, cell DNA content by modified diphenylamine method and apoptosis by Caspase 3 activity. The plant extract induced a marked concentration dependent inhibition on proliferation, reduced DNA content and apoptosis in HeLa. These results clearly indicate that C. tora is effective against free radical mediated diseases.     

Antioxidant and radical scavenging properties of <Emphasis Type="Italic">Iris germanica</Emphasis>

The antioxidant activity of aqueous and ethanol extracts of iris (Iris germanica L., family Iridaceae) has been evaluated in vitro using various antioxidant assays, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Both aqueous and ethanol extracts exhibit strong total antioxidant activity, showing 95.9, 88.4, 79.9% and 90.5, 78.0, 65.3% inhibition on peroxidation of linoleic acid emulsion in concentrations of 10, 30, and 50 μg-ml, respectively. Both extracts also possess effective reducing power and exhibit free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities in concentrations of 20, 40, and 60 μg-ml. The antioxidant properties were compared to those of reference antioxidants (BHA, BHT, and α-tocopherol). In addition, the total content of phenolic compounds in both aqueous and ethanol iris extracts has been determined as gallic acid equivalent. The results indicate that iris has in vitro antioxidant properties, which can be the major factor responsible for the inhibition of lipid peroxidation. Published in Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 8, pp. 13–18, August, 2007.     

In vitro antioxidant activity and scavenging effects of Cinnamomum verum leaf extract assayed by different methodologies.

The free radical scavenging capacity and antioxidant activities of the methanolic extract of Cinnamomum verum leaf (CLE) were studied and compared to antioxidant compounds like trolox, butylated hydroxyl anisole, gallic acid and ascorbic acid. The CLE exhibited free radical scavenging activity, especially against DPPH radical and ABTS radical cation. They also exhibited reducing power and metal ion chelating activity, along with hydroxyl radical scavenging activity. The peroxidation inhibiting activity of CLE recorded using the linoleic acid emulsion system, showed very good antioxidant activity.     

Prooxidant action of gallic acid compounds: copper-dependent strand breaks and the formation of 8-hydroxy-2′-deoxyguanosine in DNA

Gallic acid and its alkylesters, polyphenolic compounds with antioxidative activity, acted as a prooxidant causing a copper-dependent DNA damage. Treatment of DNA from plasmid pBR322 and calf thymus with gallic acid plus copper ion caused strand scission and the formation of 8-hydroxy-2′-deoxyguanosine in DNA. Addition of catalase protected DNA from the gallic acid/copper-dependent strand breaks and the formation of 8-hydroxy-2′-deoxyguanosine, indicating that hydroxyl radical may participate in the DNA damage. Ethyl-, propyl- and butylgallates showed only a little DNA damage. Octyl- and laurylgallates caused negligible damage of DNA. DNA strand breaks and formation of 8-hydroxy-2′-deoxyguanosine were closely related to the reduction of copper by gallate compounds. These results imply that cuprous ion reduced by gallate derivatives may play a key role in the oxidative cleavage of DNA and the formation of base adduct. The cytotoxic effect of gallate compounds can be explained by their prooxidant action dependent on the reducing activity.     

Protection of DNA and membrane from γ-radiation induced damage by the extract of Acorus calamus Linn.: An in vitro study

Acorus calamus, an ethnomedicinally important plant, was investigated for its protecting activity against radiation induced DNA and membrane damage. The in vitro free radical scavenging activity of the extract (water:ethanol, 1:1) of A. calamus was studied by parameters viz DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical scavenging activity, hydroxyl radical scavenging activity, and superoxide radical scavenging activity. Membrane damage due to radiation exposure was measured as the peroxidation of lipids in terms of thiobarbituric acid reacting substance (TBARS). The in vitro DNA damage was monitored by assessing the radiation induced relaxation of supercoiled plasmid DNA (pBR322). Damage to cellular DNA induced by γ-radiation (6Gy) was monitored by alkaline single cell gel electrophoresis or comet assay in murine cells and human peripheral blood leukocytes. Enhancement of DNA repair mechanism was also monitored. The extract effectively scavenged free radicals in a concentration dependent manner. Presence of A. calamus extract during irradiation prevented peroxidation of membrane lipids in mouse liver homogenate. It helped to reduce the disappearance of the covalently closed circular (ccc) form of plasmid DNA following exposure to γ-radiation. Also the A. calamus extract effectively protected DNA from radiation induced strand breaks and enhanced the DNA repair process. Hence A. calamus extract can be used as a good source of natural radioprotecting agent.     

Antioxidant flavonoids and chlorogenic acid from the leaves ofEriobotrya japonica

The antioxidant activity of Eriobotrya japonica was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and lipid peroxidation produced when mouse liver homogenate was exposed to the air at 37 degrees C, using 2-thiobarbituric acid (TBA). The methanol extract and its fractions of Eriobotrya japonica leaves showed strong antioxidant activity. The antioxidant activity of EtOAc and n-BuOH soluble fractions were stronger than the others, and were further purified by repeated silica gel, MCl gel CHP-20P, and Sephadex LH-20 column chromatography. Antioxidant chlorogenic acid, quercetin-3-sambubioside from n-BuOH fraction, and methyl chlorogenate, kaempferol- and quercetin-3-rhamnosides, together with the inactive ursolic acid and 2 alpha-hydroxyursolic acid from EtOAc fraction were isolated. Antioxidant flavonoids and chlorogenic acid also showed prominent inhibitory activity against free radical generation in dichlorofluorescein (DCF) method.     

In vitro and in vivo antioxidant properties of different fractions of Moringa oleifera leaves

The antioxidant potency of different fractions of Moringa oleifera leaves were investigated by employing various established in vitro systems, such as β-Carotene bleaching, reducing power, DPPH/superoxide/hydroxyl radical scavenging, ferrous ion chelation and lipid peroxidation. On the basis of in vitro antioxidant properties polyphenolic fraction of M. oleifera leaves (MOEF) was chosen as the potent fraction and used for the DNA nicking and in vivo antioxidant properties. MOEF shows concentration dependent protection of oxidative DNA damage induced by HO and also found to inhibit the toxicity produced by CCl₄ administration as seen from the decreased lipid peroxides (LPO) and increased glutathione (GSH) levels. Among the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) levels were restored to almost normal levels compared to CCl₄ intoxicated rats. The HPLC analysis indicated the presence of phenolic acids (gallic, chlorogenic, ellagic and ferulic acid) and flavonoids (kaempferol, quercetin and rutin). Thus, it may be concluded that the MOEF possess high phenolic content and potent antioxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation.     

Saponins isolated from the root of Platycodon grandiflorum protect against acute ethanol-induced hepatotoxicity in mice

The protective effects of saponins isolated from the root of Platycodon grandiflorum (Changkil saponins: CKS) against alcoholic steatosis in liver injury induced by acute ethanol administration were investigated. Pretreatment with CKS prior to ethanol administration significantly prevented the increases in serum alanine aminotransferase activity, hepatic TNF-α level, hepatic lipid peroxidation and hepatic triglyceride level. CKS prevented ethanol-induced steatosis and necrosis, as indicated by liver histopathological studies. Additionally, CKS protected against ethanol-induced depletion of hepatic glutathione levels. CYP2E1 has been suggested as a major contributor to ethanol-induced oxidative stress and liver injury. The concurrent administration of CKS efficaciously abrogated the CYP2E1 induction and CYP2E1-dependents hydroxylation of aniline as compared to the individual treatment at higher doses. These findings suggest that CKS may prevent ethanol-induced acute liver injury, possibly through its ability to block CYP2El-mediated ethanol bioactivation and its free radical scavenging effects.     

褪黑素拮抗鼠肝线粒体自由基产生的实验研究

目的观察褪黑素拮抗氧自由基和对膜脂质过氧化损伤的保护作用。方法用电子自旋共振技术，以ＤＭＰＯ和４－ＰＯＢＮ为捕集剂，捕集Ｆｅｎｔｏｎ反应产生的羟自由基和Ｆｅ２＋启动的鼠肝线粒体膜脂质过氧化产生的脂类自由基，以脂肪酸自旋标记物５－Ｄｏｘｙｌ和１６－Ｄｏｘｙｌ标记线粒体膜，研究脂质过氧化损伤后膜流动性的变化。结果褪黑素对羟自由基和脂类自由基有良好的清除作用，５０％清除浓度分别为１８６μｍｏｌ·Ｌ－１和４５０μｍｏｌ·Ｌ－１，而且在５００μｍｏｌ·Ｌ－１浓度范围内能防止脂质过氧化引起的线粒体膜流动性降低。结论褪黑素是一个有效的抗氧化剂，能防止生物膜的脂质过氧化损伤。     

Antioxidant and antilipid peroxidation potential of supercritical fluid extract and ethanol extract of leaves of vitex negundo linn

Supercritical fluid extract and ethanol extract of Vitex negundo Linn. were subjected to the chromatographic evaluation for identification of their constituents. Free radical scavenging activity of both extracts was studied by subjecting them to DPPH assay. IC(50) values of ethanol and supercritical fluid extract of Vitex negundo indicate that ethanol extract has stronger reducing potential and ability to scavenge free radicals as compared to the supercritical fluid extract. The in vivo effect of extracts on lipid peroxidation was studied using ethanol induced oxidative stress model in rat. Ingestion of extracts for 14 days exhibited significant reduction in plasma MDA level of stressed animals. Ethanol extract exhibited higher in vivo antilipid peroxidation potential as compared to supercritical fluid extract which correlated well with radical scavenging potential of extract.     

Protective effect of caffeic acid phenethyl ester on tert-butyl hydroperoxide-induced oxidative hepatotoxicity and DNA damage

Increased oxidative stress and associated high levels of free radical generation have been described to occur during the pathogeneses of various diseases in animal models. In the present work, we investigated the protective effects of the phenethyl ester of caffeic acid (CAPE), an active component of honeybee propolis, on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in a cultured HepG2 cell line and in rat liver. CAPE was found to significantly reduce t-BHP-induced oxidative injury in HepG2 cells, as determined by cell cytotoxicity, and lipid peroxidation and reactive oxygen species (ROS) levels in a dose-dependent manner. Furthermore, CAPE protected HepG2 cells against t-BHP-induced oxidative DNA damage, as determined by the Comet assay. Consistently, CAPE reduced hydroxyl radical-induced 2-deoxy-d-ribose degradation by ferric ion-nitrilotriacetic acid and H2O2, and also removed the superoxide anion generated by a xanthine/xanthine oxidase system. Our in vivo study showed that pretreatment with CAPE prior to the administration of t-BHP significantly and dose-dependently prevented increases in the serum levels of hepatic enzyme markers (alanine aminotransferase and aspartate aminotransferase) and reduced lipid peroxidation in rat liver. Moreover, histopathological evaluation of livers consistently revealed that CAPE reduced liver lesion induction by t-BHP. Taken together, these results suggest that the protective effects of CAPE against t-BHP-induced hepatotoxicity may, at least in part, be due to its ability to scavenge ROS and protect DNA from oxidative stress-induced damage.     

Free radicals and grape seed proanthocyanidin extract: importance in human health and disease prevention

Free radicals have been implicated in over a hundred disease conditions in humans, including arthritis, hemorrhagic shock, atherosclerosis, advancing age, ischemia and reperfusion injury of many organs, Alzheimer and Parkinson's disease, gastrointestinal dysfunctions, tumor promotion and carcinogenesis, and AIDS. Antioxidants are potent scavengers of free radicals and serve as inhibitors of neoplastic processes. A large number of synthetic and natural antioxidants have been demonstrated to induce beneficial effects on human health and disease prevention. However, the structure-activity relationship, bioavailability and therapeutic efficacy of the antioxidants differ extensively. Oligomeric proanthocyanidins, naturally occurring antioxidants widely available in fruits, vegetables, nuts, seeds, flowers and bark, have been reported to possess a broad spectrum of biological, pharmacological and therapeutic activities against free radicals and oxidative stress. We have assessed the concentration- or dose-dependent free radical scavenging ability of a novel IH636 grape seed proanthocyanidin extract (GSPE) both in vitro and in vivo models, and compared the free radical scavenging ability of GSPE with vitamins C, E and beta-carotene. These experiments demonstrated that GSPE is highly bioavailable and provides significantly greater protection against free radicals and free radical-induced lipid peroxidation and DNA damage than vitamins C, E and beta-carotene. GSPE was also shown to demonstrate cytotoxicity towards human breast, lung and gastric adenocarcinoma cells, while enhancing the growth and viability of normal human gastric mucosal cells. The comparative protective effects of GSPE, vitamins C and E were examined on tobacco-induced oxidative stress and apoptotic cell death in human oral keratinocytes. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, while apoptotic cell death was assessed by flow cytometry. GSPE provided significantly better protection as compared to vitamins C and E, singly and in combination. GSPE also demonstrated excellent protection against acetaminophen overdose-induced liver and kidney damage by regulating bcl-X(L) gene, DNA damage and presumably by reducing oxidative stress. GSPE demonstrated excellent protection against myocardial ischemia-reperfusion injury and myocardial infarction in rats. GSPE was also shown to upregulate bcl(2) gene and downregulate the oncogene c-myc. Topical application of GSPE enhances sun protection factor in human volunteers, as well as supplementation of GSPE ameliorates chronic pancreatitis in humans. These results demonstrate that GSPE provides excellent protection against oxidative stress and free radical-mediated tissue injury.