2,4,8-trihydroxybicyclo [3.2.1]octan-3-one scavenges free radicals and protects against xenobiotic-induced cytotoxicity

Currently, there is a great deal of interest in the study of natural compounds with free-radical-scavenging activity because of their potential role in maintaining human health and preventing diseases. In this paper, we report the antioxidant and cytoprotective properties of 2,4,8-trihydroxybicyclo [3.2.1]octan-3-one (TBO) isolated from the aqueous extract of Decalepis hamiltonii roots. Our results show that TBO is a potent scavenger of superoxide (O₂·?), hydroxyl (·OH), nitric oxide (·NO) and lipid peroxide (LOO·) – physiologically relevant free radicals with IC₅₀ values in nmolar (42–281) range. TBO also exhibited concentration-dependent secondary antioxidant activities such as reducing power, metal-chelating activity and inhibition of protein carbonylation. Further, TBO at nmolar concentration prevented CuSO₄-induced human LDL oxidation. Apart from the in vitro free-radical-scavenging activity, TBO demonstrated cytoprotective activity in primary hepatocytes and Ehrlich ascites tumour (EAT) cells against oxidative-stress-inducing xenobiotics. The mechanism of cytoprotective action involved maintaining the intracellular glutathione (GSH), scavenging of reactive oxygen species (ROS) and inhibiting lipid peroxidation (LPO). Based on the results, it is suggested that TBO is a novel bioactive molecule with implications in both prevention and amelioration of diseases involving oxidative stress as well as in the general well-being.     

14-Aminotetradecanoic acid exhibits antioxidant activity and ameliorates xenobiotics-induced cytotoxicity

Natural compounds with free-radical scavenging activity have potential role in maintaining human health and preventing diseases. In this study, we report the antioxidant and cytoprotective properties of 14-aminotetradecanoic acid (ATDA) isolated from the Decalepis hamiltonii roots. ATDA is a potent scavenger of superoxide (O(2) (?-)), hydroxyl ((?)OH), nitric oxide ((?)NO), and lipid peroxide (LOO(?)) physiologically relevant free radicals with IC(50) values in nM (36-323) range. ATDA also exhibits concentration-dependent secondary antioxidant activities like reducing power, metal-chelating activity, and inhibition of protein carbonylation. Further, ATDA at nM concentration prevented CuSO(4)-induced human LDL oxidation. ATDA demonstrated cytoprotective activity in primary hepatocytes and Ehrlich ascites tumor cells against oxidative stress inducing xenobiotics apart from the in vitro free-radical scavenging activity. The mechanism of cytoprotective action involved maintaining the intracellular glutathione, scavenging of reactive oxygen species, and inhibition of lipid peroxidation. It is suggested that ATDA is a novel bioactive molecule with potential health implications.     

Free-radical scavenging by Ouratea parviflora in experimentally-induced liver injuries

The antioxidant potential of crude extracts and fractions from leaves of Ouratea parviflora, a Brazilian medicinal plant used for the treatment of inflammatory diseases, was investigated in vitro through the scavenging of radicals 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), hydroxyl radical (HO*), superoxide anion (O2*-), and lipid peroxidation in rat liver homogenate. The crude extract (CEOP) and hydro-alcoholic fraction (OP4) showed strong inhibitory activity toward lipid peroxidation induced by tert-butyl peroxide (IC50 = 2.3 +/- 0.2 and 1.9 +/- 0.1 microg/ml, respectively). The same products exhibited a strong concentration-dependent inhibition of deoxyribose oxidation (14.9 +/- 0.2 and 0.2 +/- 0.1 microg/ml, respectively), and also showed a considerable antioxidant activity against O2*- (87.3 +/- 0.1 and 73.1 +/- 0.4 microg/ml, respectively) and DPPH radicals (55.4 +/- 0.3 and 38.3 +/- 0.4 microg/ml, respectively). The protective effects of CEOP and OP4 were also studied in mouse liver. CCl4 significantly increased (by 90%) levels of lipid hydroperoxides, carbonyl protein content (64%), DNA damage index (133%), aspartate aminotransferase (261%), alanine aminotransferase (212%), catalase activity (23%), and also caused a decrease of 60% in GSH content. The results showed that CEOP and OP4 exerted cytoprotective effects against oxidative injury caused by CCl4 in rat liver, probably related to the antioxidant activity showed by the in vitro free radical scavenging property.     

红酵母的抗氧化机制与高产类胡萝卜素菌株的筛选*

通过聚丙烯酰胺凝胶电泳(PAGE)和超氧化物歧化酶(SOD)的鉴别性定位染色分析,表明红酵母Rhodotorula sp.仅存在线粒体中的Mn-SOD。在类胡萝卜素含量较高的时期(培养5d),红酵母SOD活力下降, 过氧化氢酶(CAT)活力升高,而此时它对外界O2-. 和H2O2的抗性均明显高于类胡萝卜素含量较低的时期(培养2d)。以上结果表明红酵母胞质中的抗氧化作用已主要由类胡萝卜素来承担,类胡萝卜素含量越高,红酵母抗氧化能力越强。由此,利用产生的O2-. 试剂TBO处理红酵母,可筛选出稳定高产的类胡萝卜素菌株,其中以培养2d的红酵母作为筛选对象更佳,所筛菌落类胡萝卜素含量可高达1740.9~2039.2g/g干重,比未处理的对照增加了28.2%~50.1%。     

Celastrus paniculatus seed oil and organic extracts attenuate hydrogen peroxide- and glutamate-induced injury in embryonic rat forebrain neuronal cells

Seed oil of Celastrus paniculatus Willd. (CP) has been reported to improve memory and the methanolic extract (ME) of CP was shown to exhibit free-radical-scavenging properties and anti-oxidant effects in human non-immortalized fibroblasts. In the present study, we have investigated the free-radical-scavenging capacity of CP seed oil (CPO) and two extracts, an ethanolic extract (EE) and a ME. CPO and EE showed dose-dependent, free-radical-scavenging capacity, but to a lesser degree than observed for ME. Oxidative stress involves the generation of free radicals and free radical scavenging is one of the mechanisms of neuroprotection. We therefore investigated the effects of CPO, ME, and EE for protection against hydrogen peroxide (H(2)O(2))- and glutamate-induced neurotoxicity in embryonic rat forebrain neuronal cells (FBNC). Pre-treatment of neuronal cells with CPO dose-dependently attenuated H(2)O(2)-induced neuronal death. Pre-treatment with ME and EE partially attenuated H(2)O(2)-induced toxicity, but these extracts were less effective than CPO for neuronal survival. In H(2)O(2)-treated cells, cellular superoxide dismutase (SOD) activity was unaffected, but catalase activity was decreased and levels of malondialdehyde (MDA) were increased. Pre-treatment with CPO, ME, or EE increased catalase activity and decreased MDA levels significantly. Also, CPO pre-treatment attenuated glutamate-induced neuronal death dose-dependently. The activity of cellular acetylcholinesterase (AChE) was not affected by CPO, ME, or EE, suggesting that the neuroprotection offered by CPO was independent of changes in AChE activity. Taken together, the data suggest that CPO, ME, and EE protected neuronal cells against H(2)O(2)-induced toxicity in part by virtue of their antioxidant properties, and their ability to induce antioxidant enzymes. However, CPO, which exhibited the least antioxidant properties, was the most effective in preventing neuronal cells against H(2)O(2)- and glutamate-induced toxicities. Thus, in addition to free-radical scavenging attributes, the mechanism of CP seed component (CP-C) neuroprotection must be elucidated.     

Potential cytoprotection: antioxidant defence by caffeic acid phenethyl ester against free radical-induced damage of lipids, DNA, and proteins

Oxidative stress is considered to be a major cause of cellular injuries in a variety of chronic health problems, such as carcinogenesis and neurodegenerative disorders. Caffeic acid phenethyl ester (CAPE), derived from the propolis of honeybee hives, possesses a variety of biological and pharmacological properties including antioxidant and anticancer activity. In the present study, we focused on the diverse antioxidative functionalities of CAPE and its related polyphenolic acid esters on cellular macromolecules in vitro. The effects on human erythrocyte membrane ghost lipid peroxidation, plasmid pBR322 DNA, and protein damage initiated by the water-soluble initiator 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) and hydrogen peroxide (H(2)O(2)) were monitored by formation of hydroperoxides and by DNA nicking assay, single-cell alkaline electrophoresis, and SDS-polyacrylamide gel electrophoresis. Our results showed that CAPE and its related polyphenolic acid esters elicited remarkable inhibitory effects on erythrocyte membrane lipid peroxidation, cellular DNA strand breakage, and protein fragmentation. The results suggest that CAPE is a potent exogenous cytoprotective and antigenotoxic agent against cell oxidative damage that could be used as a template for designing novel drugs to combat diseases induced by oxidative stress components, such as various types of cancer.     

Cytoprotective properties of traditional Chinese medicinal herbal extracts in hydrogen peroxide challenged human U373 astroglia cells

Age is the leading risk factor for many of the most prevalent and devastating diseases including neurodegenerative diseases. A number of herbal medicines have been used for centuries to ameliorate the deleterious effects of ageing-related diseases and increase longevity. Oxidative stress is believed to play a role in normal ageing as well as in neurodegenerative processes. Since many of the constituents of herbal extracts are known antioxidants, it is believed that restoring oxidative balance may be one of the underlying mechanisms by which medicinal herbs can protect against ageing and cognitive decline. Based on the premise that astrocytes are key modulators in the progression of oxidative stress associated neurodegenerative diseases, 13 herbal extracts purported to possess anti-ageing properties were tested for their ability to protect U373 human astrocytes from hydrogen peroxide induced cell death. To determine the contribution of antioxidant activity to the cytoprotective ability of extracts, total phenol content and radical scavenging capacities of extracts were examined. Polygonum multiflorum, amongst others, was identified as possessing potent antioxidant and cytoprotective properties. Not surprisingly, total phenol content of extracts was strongly correlated with antioxidant capacity. Interestingly, when total phenol content and radical scavenging capacities of extracts were compared to the cytoprotective properties of extracts, only moderately strong correlations were observed. This finding suggests the involvement of multiple protective mechanisms in the beneficial effects of these medicinal herbs.     

Isotretinoin treatment induces oxidative toxicity in blood of patients with acne vulgaris: a clinical pilot study

Acne vulgaris is the one of the most common skin diseases. Although isotretinoin (13-cis-retinoic acid) is an effective and well-tolerated medication, it has a wide range of side effects. Because the effects of isotretinoin on oxidant and antioxidant systems have not yet been clarified, we investigated plasma and erythrocyte antioxidant vitamins, lipid peroxidation (LP), reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) values in patients with acne vulgaris before and after isotretinoin treatment. The study was performed on the blood plasma and erythrocytes of 31 acne vulgaris patients. Blood samples were taken from the patients before treatment and after isotretinoin (oral and 0·5-0·7?mg·kg(-1) ) treatment for 2?months. Plasma amtioxidant vitamins, erythrocyte malondialdehyde, GSH and GSH-Px levels were measured. Plasma vitamin E (p?相似文献   

Free-radical-scavenging effect of carbazole derivatives on AAPH-induced hemolysis of human erythrocytes

Since the research on antioxidants provides theoretical information for the medicinal development, and supplies some in vitro methods for quick-optimizing drugs, it attracts more scientific attention from bioorganic and medicinal chemists. In addition to the traditional O-H bond-type antioxidant, carbazole and its related tricyclic amines (Ar2NHs), in which N-H bond functioned as the antioxidant, have attracted much research attention because Ar2NHs have always been the central structure in many currently used drugs. Thus, the investigation on the structure-activity relationship (SAR) between Ar2NHs and their free-radical-scavenging capacities in detail will benefit the development of novel radical-scavenging drugs containing Ar2NHs as the central structure. Therefore, carbazole (CazNH) and its structural analogues including phenoxazine (PozNH), phenothiazine (PtzNH), iminostilbene (IsbNH) together with diphenylamine (DpaNH) were applied to protect human erythrocytes against 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced hemolysis in vitro. By introducing the chemical kinetic formula related to free radical reaction, namely, the quantitative relationship between inhibition period (tinh) and the concentration of antioxidant (AH), tinh=(n/Ri)[AH], into AAPH-induced hemolysis, the values of stoichiometric factor (n) of Ar2NHs indicated that the free-radical-scavenging sequence of Ar2NHs is PozNH>DpaNH>CazNH>IsbNH>PtzNH >alpha-tocopherol (TocH). Another aim of this work was to investigate the antioxidative effect of Ar2NHs used together with other antioxidants including Trolox (TroH), VC, L-ascorbyl-6-laurate (VC-12), and TocH. The obtained data revealed that n value of PozNH when used together with all the other antioxidants decreases, whereas, n values of CazNH, DpaNH, IsbNH, and PtzNH when used in combination with TroH increase, demonstrating that two different interaction styles existed in the case of Ar(2)NHs used with other antioxidants. These findings may be useful for the development of agents for various ROS-mediated diseases in vivo.     

γ-氨基丁酸浸种对番茄种子及幼苗耐盐性调节的生理机制

以番茄‘金棚一号’为材料,研究了外源γ-氨基丁酸(GABA)浸种处理对NaCl胁迫下种子萌发及幼苗生长和生理代谢的影响。结果显示:(1)NaCl胁迫显著抑制了番茄种子的萌发和胚根生长,同时导致番茄幼苗体内活性氧(O2.-、H2O2)大量积累,膜脂过氧化程度加重,幼苗叶片光合系统Ⅱ活性显著降低,幼苗的生长受到严重抑制。(2)外源GABA浸种能够显著提高盐胁迫下番茄种子的萌发和胚根的生长,并以10.00mmol.L-1 GABA浸种处理效果最好。(3)外源GABA浸种处理显著提高了NaCl胁迫下番茄幼苗根系和叶片抗氧化酶(SOD、POD和CAT)活性,降低了活性氧(O2.-、H2O2)的产生和膜脂过氧化程度,通过维持较高的光合系统Ⅱ活性,促进了幼苗的生长及生物量积累,但GABA的缓解效应存在较大的浓度差异,其中以10.00mmol.L-1 GABA处理效果较好。研究表明,10.00mmol.L-1 GABA浸种处理能够通过促进番茄种子萌发和幼苗生长来缓解盐胁迫的伤害。     

Hemin-induced platelet activation and ferroptosis is mediated through ROS-driven proteasomal activity and inflammasome activation: Protection by Melatonin

Reactive oxygen species (ROS) are capable of inducing cell death or apoptosis. Recently, we demonstrated that lipid-ROS can mediate ferroptosis and activation of human platelets. Ferroptosis is an intracellular iron-mediated cell death, distinct from classical apoptosis and necrosis, which is mediated through the accumulation of ROS, lipid peroxides and depletion of cellular GSH. Lately, we demonstrated that hemoglobin degradation product hemin induces ferroptosis in platelets via ROS and lipid peroxidation. In this study, we demonstrate that hemin-induced ferroptosis in platelets is mediated through ROS-driven proteasome activity and inflammasome activation, which were mitigated by Melatonin (MLT). Although inflammasome activation is linked with pyroptosis, it is still not clear whether ferroptosis is associated with inflammasome activation. Our study for the first time demonstrates an association of platelet activation/ferroptosis with proteasome activity and inflammasome activation. Although, high-throughput screening has recognized ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) as potent ferroptosis inhibitors, having an endogenous antioxidant such as MLT as ferroptosis inhibitor is of high interest. MLT is a well-known chronobiotic hormone that regulates the circadian rhythms in vertebrates. It also exhibits potent antioxidant and ROS quenching capabilities. MLT can regulate fundamental cellular functions by exhibiting cytoprotective, oncostatic, antiaging, anti-venom, and immunomodulatory activities. The ROS scavenging capacity of MLT is key for its cytoprotective and anti-apoptotic properties. Considering the anti-ferroptotic and anti-apoptotic potentials of MLT, it could be a promising clinical application to treat hemolytic, thrombotic and thrombocytopenic conditions. Therefore, we propose MLT as a pharmacological and therapeutic agent to inhibit ferroptosis and platelet activation.     

Changes in membrane properties during energy depletion-induced cell injury studied with fluorescence microscopy.

The changes in membrane structural properties occurring during the process of ATP depletion-induced cell injury in adherent human astrocytoma cells (UC-11 MG) were studied with two epifluorescence techniques: 1) steady-state fluorescence anisotropy (r) to examine microstructural changes in the membrane phospholipids and 2) fluorescence redistribution after photobleaching (FRAP) to examine membrane fluidity changes. A new method for r measurement was established that provides the unique advantage of simultaneously monitoring both vertical and horizontal polarized fluorescence emissions needed for the calculation of r. In this study, r in the astrocytoma cells labeled with 1-(4-trimethylammonium phenyl)-6-phenyl-1,3,5-hexatriene p-toluenesulfonate was shown to remain stable for up to 90 min. However, when the cells were treated with 75 microM iodoacetic acid (IAA), a metabolic inhibitor that induces rapid depletion of cellular ATP, r continually decreased, indicating a decrease in membrane lipid order and perturbation of the bilayer structure. This decrease in r could be prevented by the pretreatment of cells with lipophilic antioxidants such as tirilazad or gossypol. Tirilazad itself caused a significant increase in r, suggesting that tirilazad intercalates into the membrane bilayer and profoundly increases the lipid order in uninjured cells. Gossypol, however, did not exhibit this property. Further investigations into these phenomena with FRAP confirmed the r results and indicated that membrane fluidity increased while its structure became less rigid during the process of ATP-induced cell injury. In addition, lipophilic antioxidants prevented the membrane structural aberrations induced by IAA. Experimental results suggest that different mechanisms of cytoprotective action may exist for tirilazad and the antioxidant gossypol. Gossypol appears to prevent or delay the observed cell injury entirely because of its antioxidant action, whereas tirilazad's protection is mediated not only via its antioxidant activity, but also by its ability to increase cell membrane lipid order.     

Assessment of antioxidative activity of extract from fermented grain food mixture using chemical and cellular systems

Fermented food is a rich source of antioxidants and micronutrients with the potential to prevent various human diseases. The increasing evidence indicates that in addition to its direct action, radical-scavenging antioxidants may modulate the cellular antioxidant system such as glutathione. In the present study, we investigated the antioxidant activity of Antioxidant Biofactor (AOB) extracts, a mixture of commercially available fermented grain food by using chemical and cellular experimental systems. In the former system, the total radical scavenging capacity was assessed from the bleaching of pyranine and pyrogallol red that is induced by free radicals generated from an azo initiator. In this assay system, the radical scavenging capacity per gram of AOB was estimated to be 95 micromol. On the other hand, the cytoprotective effect of AOB was also investigated on the basis of PC12 cell death induced by 6-hydroxydopamine. In this cellular system, AOB extract exhibited a cytoprotective effect only when the cells were pretreated with AOB. This pretreatment resulted in a significant increase in the levels of cellular glutathione as well as regulator of glutathione synthesis, such as the cystine/glutamate exchange transport system (xCT). This evidence suggests that AOB possesses both direct and indirect antioxidant activities to cope with oxidative insults.     

Senkyunolides reduce hydrogen peroxide-induced oxidative damage in human liver HepG2 cells via induction of heme oxygenase-1

Rhizoma Chuanxiong is widely used as folk medicine to treat the diseases caused by oxidative stress and inflammation. To delineate the underlying molecular mechanisms, we recently found that Rhizoma Chuanxiong extract significantly induced heme oxygenase-1 (HO-1), an enzyme that degrades intracellular heme into three bioactive products: biliverdin, carbon monoxide and free iron. The anti-inflammatory, antiapoptotic and antiproliferative actions of these products highlight HO-1 as a key endogenous antioxidant and cytoprotective gene. This study was designed to further characterize HO-1 induction of Rhizoma Chuanxiong through bioactivity-guided fractionation. All isolated fractions were assayed for HO-1 induction in human HepG2 cell line at mRNA and protein levels. Based on chromatographic profiling, nuclear magnetic resonance (NMR) and mass spectrometric analysis, the active compounds were identified as senkyunolide-H and its stereoisomer senkyunolide-I. Both senkyunolide isomers inhibited the formation of reactive oxygen species and lipid peroxidation and enhanced the cellular resistance to hydrogen peroxide-induced oxidative damage. Notably, heme oxygenase inhibitor tin protoporphyrin IX (SnPP) significantly suppressed the antioxidant activity of senkyunolide stereoisomers. Thus, this study demonstrated that senkyunolide-H and -I attenuated oxidative damage via activation of HO-1 pathway.     

Beneficial influence of fungal metabolite nigerloxin on eye lens abnormalities in experimental diabetes

Osmotic and oxidative stress have been implicated in the pathogenesis of diabetic cataract. Nigerloxin, a fungal metabolite, has been shown to possess aldose reductase inhibitory and free radical scavenging potential, in vitro. In the present study, the beneficial influence of nigerloxin was investigated on diabetes-induced alteration in the eye lens of rats treated with streptozotocin. Groups of diabetic rats were administered nigerloxin orally (100?mg·(kg body mass)(-1)·day(-1)) for 30?days. The activity of lens polyol pathway enzymes?(aldose reductase and sorbitol dehydrogenase), lipid peroxides, and advanced glycation end products (AGEs) were increased in the diabetic animals. Levels of glutathione as well as the activity of antioxidant enzymes?(superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase) were decreased in the eye lens of the diabetic animals. The administration of nigerloxin significantly decreased levels of lipid peroxides and AGEs in the lens of the diabetic rats. Increase in the activity of aldose reductase and sorbitol dehydrogenase in the lens was countered by nigerloxin treatment. The activity of glutathione and antioxidant enzyme in the lens was significantly elevated in nigerloxin-treated diabetic rats. Examination of the treated rats' eyes indicated that nigerloxin delayed cataractogenesis in the diabetic rats. The results suggest the beneficial countering of polyol pathway enzymes and potentiation of the antioxidant defense system by nigerloxin in diabetic animals, implicating its potential in ameliorating cataracts in diabetics.     

Protective effect of butin against hydrogen peroxide-induced apoptosis by scavenging reactive oxygen species and activating antioxidant enzymes

The antioxidant property of butin was investigated for cytoprotective effect against H(2)O(2)-induced cell damage. This compound showed intracellular reactive oxygen species (ROS) scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, inhibition of lipid peroxidation, and DNA damage. This radical scavenging activity of butin protected cell damage exposed to H(2)O(2). Also, butin reduced the apoptotic cells induced by H(2)O(2), as demonstrated by the decreased DNA fragmentation, apoptotic body formation, and caspase 3 activity. In addition, butin restored the activity and protein expression of cellular antioxidant enzymes, superoxide dismutase (SOD), and catalase (CAT) in H(2)O(2)-treated cells. Taken together, these findings suggest that butin protected cells against H(2)O(2)-induced cell damage via antioxidant property.     

Induction of antioxidant stress proteins in vascular endothelial and smooth muscle cells: protective action of vitamin C against atherogenic lipoproteins.

Elevated levels of lipid peroxidation and increased formation of reactive oxygen species within the vascular wall in atherosclerosis can overwhelm cellular antioxidant defence mechanisms. Accumulating evidence implicates oxidatively modified low density lipoproteins (LDL) in vascular dysfunction in atherosclerosis and oxidized LDL have been localized with in atherosclerotic lesions. We here report that human oxidatively modified LDL induce expression of 'antioxidant-like' stress proteins in vascular cells, involving increases in the activity of L-cystine transport, glutathione synthesis, heme oxygenase-1 and the murine stress protein MSP23. Moreover, treatment of human arterial smooth muscle cells with the dietary antioxidant vitamin C markedly attenuates adaptive increases in endogenous antioxidant gene expression and affords protection against smooth muscle cell apoptosis induced by moderately oxidized LDL. As vascular cell death is a key feature of atherosclerotic lesions and may contribute to the plaque 'necrotic' core, cap rupture and thrombosis, our findings suggest that the cytoprotective actions of vitamin C could limit plaque instability in advanced atherosclerosis.     

Isolation, identification, and biological evaluation of Nrf2-ARE activator from the leaves of green perilla (Perilla frutescens var. crispa f. viridis)

The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is a cellular defense system against oxidative stress. Activation of this pathway increases expression of antioxidant enzymes. Epidemiological studies have demonstrated that the consumption of fruits and vegetables is associated with reduced risk of contracting a variety of human diseases. The aim of this study is to find Nrf2-ARE activators in dietary fruits and vegetables. We first attempted to compare the potency of ARE activation in six fruit and six vegetables extracts. Green perilla (Perilla frutescens var. crispa f. viridis) extract exhibited high ARE activity. We isolated the active fraction from green perilla extract through bioactivity-guided fractionation. Based on nuclear magnetic resonance and mass spectrometric analysis, the active ingredient responsible for the ARE activity was identified as 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC). DDC induced the expression of antioxidant enzymes, such as γ-glutamylcysteine synthetase (γ-GCS), NAD(P)H: quinone oxidoreductase-1 (NQO1), and heme oxygenase-1. DDC inhibited the formation of intracellular reactive oxygen species and the cytotoxicity induced by 6-hydroxydopamine. Inhibition of the p38 mitogen-activated protein kinase pathway abolished ARE activation, the induction of γ-GCS and NQO1, and the cytoprotective effect brought about by DDC. Thus, this study demonstrated that DDC contained in green perilla enhanced cellular resistance to oxidative damage through activation of the Nrf2-ARE pathway.     

UVA诱发的1O2和O2-·产生与脂质过氧化水平关系的研究

紫外A(UVA,320 nm-400 nm)诱发的脂质过氧化反应是通过活性氧(ROS)介导的。在UVA照射之后,单线态氧(1O2)和超氧阴离子(O2-.)是细胞内最初产生的ROS,它们进一步生成过氧化氢(H2O2),羟自由基(.OH)等其它自由基。为了探讨UVA照射后最早生成的1O2和O2-.与细胞氧化损伤后果的关系,我们采用一种特异性检测1O2和O2-.的高灵敏度化学发光探针MCLA(2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimid-azo[1,2-α]pyrazin-3-one hydrochloride)检测人外周血淋巴细胞经UVA照射后的化学发光变化。发现不同剂量UVA照射后,细胞MCLA化学发光变化和MDA浓度变化一致。结果表明UVA照射后1O2和O2-.的水平与由此引发的脂质过氧化损伤存在正相关关系。因此,MCLA化学发光方法可望作为一种检测UVA诱发脂质过氧化水平的简单快速方法。     

Mitochondria induce oxidative stress, generation of reactive oxygen species and redox state unbalance of the eye lens leading to human cataract formation: disruption of redox lens organization by phospholipid hydroperoxides as a common basis for cataract disease

The aging eye appears to be at considerable risk from oxidative stress. Lipid peroxidation (LPO) is one of the mechanisms of cataractogenesis, initiated by enhanced promotion of oxygen free radicals in the eye fluids and tissues and impaired enzymatic and non-enzymatic antioxidant defenses of the crystalline lens. The present study proposes that mitochondria are one of the major sources of reactive oxygen species (ROS) in mammalian and human lens epithelial cells and that therapies that protect mitochondria in lens epithelial cells from damage and reduce damaging ROS generation may potentially ameliorate the effects of free radical-induced oxidation that occur in aging ocular tissues and in human cataract diseases. It has been found that rather than complete removal of oxidants by the high levels of protective enzyme activities such as superoxide dismutase (SOD), catalase, lipid peroxidases in transparent lenses, the lens conversely, possess a balance between peroxidants and antioxidants in a way that normal lens tends to generate oxidants diffusing from lenticular tissues, shifting the redox status of the lens to become more oxidizing during both morphogenesis and aging. Release of the oxidants (O(2)(-)·, H(2)O(2) , OH·, and lipid hydroperoxides) by the intact lenses in the absence of respiratory inhibitors indicates that these metabolites are normal physiological products inversely related to the lens life-span potential (maturity of cataract) generated through the metal-ion catalyzed redox-coupled pro-oxidant activation of the lens reductants (ascorbic acid, glutathione). The membrane-bound phospholipid (PL) hydroperoxides escape detoxification by the lens enzymatic reduction. The lens cells containing these species would be vulnerable to peroxidative attack which trigger the PL hydroperoxide-dependent chain propagation of LPO and other damages in membrane (lipid and protein alterations). The increased concentrations of primary LPO products (diene conjugates, lipid hydroperoxides) and end fluorescent LPO products were detected in the lipid moiety of the aqueous humor samples obtained from patients with cataract as compared to normal donors. Since LPO is clinically important in many of the pathological effects and aging, new therapeutic modalities, such as patented N-acetylcarnosine prodrug lubricant eye drops, should treat the incessant infliction of damage to the lens cells and biomolecules by reactive lipid peroxides and oxygen species and "refashion" the affected lens membranes in the lack of important metabolic detoxification of PL peroxides. Combined in ophthalmic formulations with N-acetylcarnosine, mitochondria-targeted antioxidants are promising to become investigated as a potential tool for treating a number of ROS-related ocular diseases, including human cataracts.