In Vitro Antioxidant And Free Radical Scavenging Potential Of Methanolic Extracts Of Uvaria Chamae Leaves And Roots

Objective: This study investigated the in vitro antioxidant and free radical potentials of methanol extracts of Uvaria chamae leaves and roots. Methods: Fresh Uvaria chamae leaves and roots were air dried, pulverized and extracted using methanol. Phytochemical, total phenolic, flavonoids, antioxidant and tannin contents, DPPH, hydroxyl, and superoxide radical scavenging properties of the extracts were determined using standard methods. Results: In vitro antioxidant potentials revealed that methanol extract of Uvaria chamae leaves contains vitamin A (4871±79.21 I. U) and vitamin C (1.72±0.02%) while the root extract contains vitamin A (673.28±0.00I. U) and vitamin C (1.66±0.01%). Both extracts had equal contents of vitamin E (8.83±0.04 mg/100g). The leaf extract scavenged 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in a concentration dependent manner with the correlation coefficient (R2) of 0.839 and effective concentration (EC50) of 31.19 µg/ml, while the root extract scavenged DPPH with R2 of0.778 and EC50 of 14.00 µg/ml. The leaf and root extracts scavenged superoxide radical and hydroxyl radical with EC50 of 5.93 µg/ml and 719.45 µg/ml; 107.89 µg/ml and 912.01 µg/ml respectively compared to the EC50 of ascorbic standard (30.27 µg/ml) and EC50 of vitamin E standard (106.66µg/ml) respectively. The leaf extract showed significantly higher (p<0.05) anti radical power (ARP) of superoxide (0.17) compared to the root extract (0.0014) and the root extract showed significantly higher (p<0.05) ARP of DPPH (0.071) compared to the leaf extract (0.032). Conclusion: The leaves and roots of Uvaria chamae are rich in natural antioxidants that can be exploited in the treatment of diseases related to oxidative stress.

Thai pigmented rice bran extracts inhibit production of superoxide, nitric oxide radicals and inducible nitric oxide synthase in cellular models

Objective: To study the inhibitory effect of rice bran extracts of Thai black Kam Muang and red Hawm Dawk Mali Deang on oxidative stress factors including superoxide (O2?-), nitric oxide (NO?), and inducible nitric oxide synthase (iNOS). Methods: Bran extracts (40% ethanol) of Kam Muang and Hawm Dawk Mali Deang were obtained and evaluated for in vitro 2-2′-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and NO? scavenging activity. Their inhibitory effects on cellular O2?- and NO? were measured in phorbol 12-myristate 13-acetate-stimulated neutrophil-like HL-60 cells and lipopolysaccharide-stimulated RAW264.7 macrophages, respectively, and their viability was monitored using the MTT assay. The effect on iNOS expression was also assessed by the Western blotting assay. Total contents of phenolics, flavonoids, and subtypes were also determined. Results: Hawm Dawk Mali Deang exhibited about 3.5-fold greater cellular O2?- inhibitory activity than Kam Muang [EC50 values of (23.57±4.54) and (81.98±1.45) μg/mL, respectively] in phorbol 12-myristate 13-acetate-stimulated HL-60 cells. Hawm Dawk Mali Deang exhibited about 2-fold higher in vitro ABTS?+ and NO? scavenging activity than Kam Muang, but it exerted cellular NO? inhibitory activity of only about 26% (undetermined EC50 value) in lipopolysaccharide-stimulated RAW264.7 cells. Conversely, Kam Muang exerted potent cellular NO? inhibitory activity [EC50 value: (281.13±59.18) μg/mL] and dose-dependently decreased iNOS levels. No cytotoxicity of both extracts was detected in both cell types. As for corresponding contents, Hawm Dawk Mali Deang contained higher contents of phenolics and flavonoids than Kam Muang. Moreover, Kam Muang and Hawm Dawk Mali Deang had a high content of total anthocyanins [(14.73±0.52) mg C3GE/g of extract] and total proanthocyanidins [(115.13±1.47) mg CE/g of extract], respectively. Conclusions: Based on these data, bran extracts of Thai black Kam Muang and red rice Hawm Dawk Mali Deang can help lower oxidative stress and inflammation attributed partly to O2?-and NO?.

Thai pigmented rice bran extracts inhibit production of superoxide, nitric oxide radicals and inducible nitric oxide synthase in cellular models

Objective: To study the inhibitory effect of rice bran extracts of Thai black Kam Muang and red Hawm Dawk Mali Deang on oxidative stress factors including superoxide (O

Study on Morphological Distribution of Photogenerated Superoxide Radicals Produced by Different Crystal Titanium Dioxide / 分析化学

Superoxide radical ( O·-2 ) , is one of reactive oxygen species ( ROS ) produced in TiO2 photocatalytic reactions, and plays an important role in the photodegradation of pollutants. In this work, we constructed two different procedures to study the generation of total O·-2 and surface-adsorbed O·-2 during TiO2 photocatalytic reaction using nitroblue tetrazolium ( NBT) as capture probe. Furthermore, three different TiO2 ( anatase, rutile and P25 ) were selected as model, and O·-2 generation and its existence form were all studied. The results showed that the generation of total O·-2 was followed by the order P25> anatase> rutile, but the surface-adsorbed O·-2 was nearly the same. The study of surface-adsorbed ROS is very important due to their probably persistence for the pollutants photodegradation or antibacterial activity.

Effects of Blending Oil of Lavender and Thyme on Oxidative Stress, Immunity, and Skin Condition in Atopic Dermatitis Induced Mice

PURPOSE: The purpose of this study was to evaluate the effects of essential oil on oxidative stress, immunity, and skin condition in atopic dermatitis (AD) induced mice. METHODS: This study was a 3x3 factorial design. Factors were oil type (Lavender, Thyme, and 2:1 mixture of lavender and thyme oil [blending oil]) and treatment period (0 day, 7 days, and 21 days). The samples were 45 mice with AD and randomly assigned to nine groups of five mice per group. The dependent variables such as superoxide radical, IgE, degranulated mast cells, and epidermal thickness were measured. Data were collected from February to April in 2014. Descriptive statistics, One-way ANOVA, Two-way ANOVA, and Tukey's HSD test were performed using the SPSS WIN 20.0 program. RESULTS: Dependent variables were not statistically significantly different by the three oil types (p >.05). Essential oils such as lavender, thyme, and blending oil were all effective in reducing AD symptoms and especially 2:1 blending oil were most effective. There were statistically significant differences by the three treatment periods in all dependent variables (p <.001). There were statistically significant interactions between oil types and treatment periods in all dependent variables (p <.01). For decreasing superoxide radical, degranulated mast cells, and epidermal thickness, 2:1 mixed oil should be applied for at least 21 days. Otherwise to reduce IgE, 2:1 mixed oil should be used for at least 7 days. CONCLUSION: These findings provide bases for developing effective interventions for AD patients to manage their AD symptoms.

Geração e desintoxicação enzimática de espécies reativas de oxigênio em plantas / Plant generation and enzymatic detoxification of reactive oxygen species

As condições de estresse biótico e abiótico impostas às plantas induzem a superprodução de espécies reativas de oxigênio (ROS), podendo causar danos às estruturas celulares e mesmo acarretar a morte da planta. As respostas bioquímicas e fisiológicas de plantas superiores ao estresse oxidativo incluem um eficiente sistema de defesa antioxidante, que envolve a atividade das enzimas superóxido dismutase, catalase, ascorbato peroxidase, peroxirredoxinas, dentre outras, além de metabólitos não enzimáticos, que, de forma conjunta, atuam na eliminação das ROS e na redução do dano oxidativo. Nesta revisão, serão abordados os principais sítios de produção de ROS e a ação de algumas enzimas do sistema de defesa antioxidante em plantas.

The biotic and abiotic stress conditions imposed on plants induces overproduction of reactive oxygen species (ROS), which can cause damage to cellular structures and even lead to the death of the plant. The biochemical and physiological responses of higher plants to oxidative stress includes an efficient antioxidant defense system, which involves the activity of the enzymes superoxide dismutase, catalase, ascorbate peroxidase, peroxiredoxines, among others, in addition to non-enzymatic metabolites, which, together, work on eliminating the ROS and in reducing oxidative damage. This review will address the main production sites of ROS and the action of some enzymes of antioxidative defense system in plants.

In vitro antioxidant evaluation and total phenolics of methanolic leaf extracts of Nyctanthes arbor-tristis L / 中国天然药物

AIM@#To investigate the in vitro antioxidant activity and total phenolic content of the methanolic leaf extract of Nyctanthes arbor-tristis L. (NA).@*METHODS@#The sample was tested using five in vitro antioxidant methods (1, 1-diphenyl-2-picryl hydrazine radical scavenging activity (DPPH), hydroxyl radical-scavenging activity (-OH), nitric oxide scavenging activity (NO), superoxide radical-scavenging activity, and total antioxidant activity) to evaluate the in vitro antioxidant potential of NA and the total phenolic content (Folin-Ciocalteu method). The extract showed good free radical scavenging property which was calculated as an IC50 value.@*RESULTS@#IC50 (Half maximal inhibitory concentration) of the methanolic extract was found to be 57.93 μg·mL(-1) for DPPH, 98.61 μg·mL(-1) for -OH, 91.74 μg·mL(-1) for NO, and 196.07 μg·mL(-1) for superoxide radical scavenging activity. Total antioxidant capacity of the extract was found to be (1198 ± 24.05) mg ascorbic acid for the methanolic extract. Free radical scavenging activity observed in the extracts of NA showed a concentration-dependent reaction. The in vitro scavenging tested for free radicals was reported to be due to high phenolic content in the leaf extract. The leaf extract of NA showed the highest total phenolic content with a value of 78.48 ± 4.2 equivalent mg TAE/g (tannic acid equivalent).@*CONCLUSIONS@#N. arbor-tristis leaf extract exhibited potent free radical scavenging activity. The finding suggests that N. arbor-tristis leaves could be a potential source of natural antioxidant.

Proton transfer from 1,4-pentadiene to superoxide radical anion: a QTAIM analysis / Transferencia de protón desde el 1,4-pentadieno al radical anión superóxido: un análisis QTAIM / Transferência de prótons de 1,4-pentadieno o ânion radical superóxido: uma análise QTAI

We studied the bis-allylic proton transfer reaction from 1,4-pentadiene to superoxide radical anion (O2.-). Minima and transition state geometries, as well as thermochemical parameters were computed at the B3LYP/6-311+G(3df,2p) level of theory. The electronic wave functions of reactants, intermediates, and products were analyzed within the framework of the Quantum Theory of Atoms in Molecules. The results show the formation of strongly hydrogen bonded complexes between the 1,4-pentadien- 3-yl anion and the hydroperoxyl radical as the reaction products. These product complexes (PCs) are more stable than the isolated reactants and much more stable than the isolated products. This reaction occurs via pre-reactive complexes which are more stable than the PCs and the transition states. This is in agreement with the fact that the net proton transfer reaction that leads to free products is an endothermic and nonspontaneous process.

Nosotros estudiamos la reacción de transferencia de protón bis-alílico del 1,4-pentadieno al radical anión superóxido (O2.--). Las geometrías de los mínimos y de los estados de transición, así como también los parámetros termoquímicos se calcularon usando el nivel de teoría B3LYP/6-311+G(3df,2p). Las funciones de onda electrónicas de los reactantes, intermedios y productos se analizaron dentro del marco de la teoría cuántica de átomos en moléculas. Nuestros resultados muestran la formación de complejos estabilizados por enlaces de hidrógeno entre el anión 1,4pentadien-3-ilo y el radical hidroperoxilo como productos de reacción. Estos complejos producto (PCs) son más estables que los reactantes aislados y mucho más estables que los productos aislados. Esta reacción ocurre vía la formación de complejos pre-reactivos, los cuales son más estables que los PCs y los estados de transición. Estos resultados están de acuerdo con el hecho de que la reacción global de transferencia de protón que conduce a la formación de los productos libres es un proceso endotérmico y no espontáneo.

Estudou-se a reação de transferência do próton bis-alílico do 1,4-pentadieno ao radical ânion superóxido (O2.-). As geometrias dos mínimos e dos estados de transição, bem como os parâmetros termoquímicos foram calculadas utilizando o nível de teoria B3LYP/6-311+G(3df, 2p). As funçÃμes de onda eletrònica dos reagentes, intermediários e produtos foram analisadas no âmbito da teoria quântica de átomos em moléculas. Os resultados obtidos demonstram a formação de complexos estabilizados por ligaçÃμes de hidrogênio entre o ânion 1,4-pentadieno- 3-ilo e o radical hidroperoxilo como produtos de reação. Estes complexos formados como produtos (PCs) são mais estáveis do que os reagentes isolados e muito mais estáveis do que os produtos isolados. Esta reação ocorre por meio de complexos pré-reativos mais estáveis do que os PCs e os estados de transição. Estes resultados estão de acordo com o fato da reação global de transferência de próton que conduz à formação dos produtos livres, é um processo endotérmico e não espontâneo.

Assessment of inflammation based on the release of oxygen radicals by granulocytes in chronic uncontrolled asthma / Avaliação da inflamação com base na liberação de radicais oxidantes por granulócitos na asma crônica não-controlada

Objetivo: Avaliar a liberação espontânea de ânion superóxidopor granulócitos de sangue periférico de pacientescomasma crônica não-controlada antes e após corticoterapia e de indivíduos sadios. Métodos: Foram estudados 32 pacientes entre 6 e 18 anos (média 12,04 anos) e 29 indivíduos sadios como grupo decomparação.Os pacientes oramagrupados de acordocomo volumeexpiratório forçado no primeiro segundo: grupo I, volume expiratórioforçado no primeiro segundo entre 60 e 80%, 19 pacientes; e grupo II, volume expiratório forçado no primeiro segundo = 60%, 13 pacientes. A liberação espontânea de superóxido por granulócitos, medida por espectrofotometria utilizando superóxido dismutase, foi avaliada nos pacientes antes e após o tratamento com prednisona por via oral e beclometasona, budesonida ou fluticasona administradas por via inalatória. Na análise estatística foramutilizados os testes de análise de variância, Tukey e de Wilcoxon.Resultados: Comparando-se a liberação de ânion superóxido por granulócitos dos pacientes asmáticos e indivíduos sadios observamosque a liberação foi maior nos asmáticos não-controladosdo grupo II (p < 0,05). Avaliando-se a liberação de superóxido pelas células dos pacientes antes e após a terapiacomcorticosteroideuma diminuição significativa foi observada apenas no grupo I. Conclusão: O impacto dos glicocorticoides sobre a modulação da inflamação ocorreu nos indivíduos asmáticos não-controlados com volume expiratório forçado no primeiro segundo entre 60 e 80%.Naqueles com volume expiratório forçado no primeiro segundo = 60não foi observada essa modulação, havendo necessidade de mais estudos para avaliar o impacto de tal achado nos pacientes asmáticos.

Objective: To evaluate spontaneous release of superoxide anion by peripheral blood granulocytes of atopic patients with uncontrolled asthma undergoing glucocorticoid therapy and of healthy subjects. Methods: We studied 32 patients, aged 6 to 18 (mean 12.04), and 29 healthy subjects as a comparative group. Patients weregrouped according to the forced expiratory vital capacity in the firstsecond. Group I, forced expiratory vital capacity in the first second of between60and80%,had 19 patients, and group II, forced expiratoryvital capacity in the first second=60%,had 13 patients. Spontaneous superoxide release by granulocytes was measured by aspectrophotometer method based on superoxide dismutase, before and after oral prednisone and beclomethasone, budesonide or fluticasone inhaled therapy. Statistical analyses were performed using ANOVA, Wilcoxon and Tukey tests. Results: Comparing the superoxide anion release bygranulocytes of asthmatic patients and healthy subjects,weobserved a higher release by cells of the uncontrolled patient group II (p < 0.05). Evaluating the superoxide release by cells of asthmatic patients before and after steroid therapy, a significant decrease was found only in patient group I.Conclusion: The impact of corticosteroids on inflammatorymodulation occurred in the uncontrolled asthmatics with forced expiratory vital capacity in the first second between 60 and 80%. In those with forced expiratory vital capacity in the first second of = 60%, this findingwas not observed. Further studies are necessary to evaluate the effect of this finding on asthmatic patients.

Effects of Some Essential Oils on Superoxide Radical Formation in the Reaction Mixture of Riboflavin under UVA Irradiation / 日本補完代替医療学会誌

<i>Objective</i>: The effects of essential oils on the formation of superoxide radicals during UVA (365 nm) irradiation were investigated.<br> <i>Methods</i>: ESR (electron spin resonance) spin-trapping experiments were performed on a reaction mixture containing 15 μM riboflavin, 0.10 M DMPO (5,5-dimethyl-l-pyrroline-<i>N</i>-oxide), 23 mM phosphate buffer (pH 7.4) and 6.3% (v/v) DMSO (dimethyl sulfoxide) (standard reaction mixture) during UVA (365 nm) irradiation.<br> <i>Results</i>: On addition of various concentrations of tea tree oil (<i>or</i> lavender super oil <i>or</i> grapefruit oil <i>or</i> peppermint oil <i>or</i> wintergreen oil) to the standard reaction mixture, the ESR peak height decreased dose-dependently.<br> <i>Conclusion</i>: This result shows that antioxidant activities increase as follows: lavender super oil<grapefruit oil<peppermint oil<tea tree oil<wintergreen oil.<br>

Effect of Pyroligneous Liquor on Oxygen Radicals and Their Scavenger Enzymes in Liver of CD Rats

This study was designed to investigate the effects of pyroligneous liquor on oxygen radicals and their scavenger enzy-mes in the liver of Cri/Bgi CD rats (7 rats per group ). Male rats were fed a basic diet prepared in our Lab., PL-0 (Control ), PL-1, PL-25, PL-50 and PL-75 groups were prepared to be 0%, 1%, 25%, 50% and 75%with distilled water using pyrolig-neous liquor (35% of Choa Co. Ltd.), and were administrated orally for 8 weeks. Superoxide radical contents in liver mi-tochondria and microsomes were significantly decreased to 12-14%, 11-15%, respectively, in these PL-25 and PL-50 groups compared with the control group. Hydroxyl radical content in mitochondria and microsomes were markedly decreased to 12-20% and 17%, respectively, in these PL-25 and PL-50% groups compared with the control group. Hydro-gen peroxide content in mitochondria and microsomes were significantly decreased about 15-12% and 22-20% in liver of PL-25 and PL-50 groups compared with the control group. Mn-SOD and Cu/Zn-SOD activities in liver of PL-25 and PL-50 groups were remarkably increased to 15-25%, 11-16%, respectively, compared with the control group. GPx activities in mitochondria and microsomes were significantly increased in the liver of PL-25 and PL-50 groups compared with the control group. CAT activities in mitochondria and cytosol were significantly increased to 12-14%, 15-27%, respectively, in the liver of PL-25 and PL-50 groups compared with the control group. These results suggest that long term administra-tion orally of 25 and 50% pyroligneous liquor may effectively inhibit the formation of oxygen free radicals, and also scavenger enzyme activities significantly increase through the administration orally.

STUDY ON FREE RADICAL SCAVENGING ACTIVITY OF PROTEINASE HYDROLYSATES FROM EGG WHITE / 营养学报

trypsin. The EWPHs with papain for 3h displayed the strongest radical scavenging activity. The values of hydroxyl radical and superoxide free radical scavenging activity were 65.63% and 38.40% respectively. Conclusion EWPHs exhibited free radical scavenging activity and the activity of scavenging hydroxyl radical were stronger than superoxide radical.

The Harmful Effects of Superoxide Radical and the Protective Effect of Ginseng Saponin on Rat Whole Bladder Contractility / 대한비뇨기과학회지

PURPOSE: We investigated the effects of the superoxide radical on rat whole bladder contractility with duroquinone (superoxide radical generator, Dq) and diethyldithiocarbamate (superoxide dismutase inhibitor, DETCA), and the effects of ginseng saponin (GS) against superoxide radical injury. MATERIALS AND METHODS: Isometric tension changes of isolated rat whole bladders were recorded in an organ bath using a force transducer. The acute effects of Dq and Dq preincubated with DETCA were assessed on resting tension, electrical field stimulation, and bethanechol-, ATP-, and KCl-induced contraction. The effects of Dq and Dq preincubated with DETCA in the presence of sodium nitroprusside and GS were investigated. RESULTS: The resting tension of the muscle was not changed by Dq and Dq preincubated with DETCA. Dq had a harmful effect on only ATP- and KCl-induced detrusor contraction, whereas Dq pretreated with DETCA attenuated the induction of detrusor contraction which was reduced in response to the exogenous NO including GS. In the presence of L-NAME, the effects of GS reduced the Dq-induced inhibition on the detrusor contractility. CONCLUSIONS: It is suggested that the superoxide radical may be the cause of voiding difficulty. GS, as a NO synthesis stimulator, seems to act as a scavenger of the superoxide anion. However further study on the effect of each subfraction of GS is needed for clinical application.

Role of hydroxyl radical in superoxide induced microsomal lipid peroxidation: Protective effect of anion channel blocker.

Treatment of bovine pulmonary artery smooth muscle microsomes with the superoxide radical generating system hypoxanthine plus xanthine oxidase stimulated iron release, hydroxyl radical production and lipid peroxidation. Pretreatment of the microsomes with deferoxamine or dimethylthiourea markedly inhibited lipid peroxidation, and prevented hydroxyl radical production without appreciably altering iron release. The superoxide radical generating system did not alter the ambient superoxide dismutase activity. However, addition of exogenous superoxide dismutase prevented superoxide radical induced iron release, hydroxyl radical production and lipid peroxidation. Simultaneous treatment of the microsomes with deferoxamine, dimethylthiourea or superoxide dismutase prevented hydroxyl radical production and liqid peroxidation. While deferoxamine or dimethylthiourea did not appreciably alter iron release, superoxide dismutase prevented iron release. However, addition of deferoxamine, dimethylthiourea or superoxide dismutase even 2 min after treatment did not significantly inhibit lipid peroxidation, hydroxyl radical production and iron release. Pretreatment of microsomes with the anion channel blocker 4,4'-dithiocyano 2,2'-disulphonic acid stilbine did not cause any discernible change in chemiluminiscence induced by the superoxide radical generating system but markedly inhibited lipid peroxidation without appreciably altering iron release and hydroxial radical production.

Effects of Cadmium on Superoxide Radical, Superoxide Dismutase, Catalase and ATPase Activity in Liver, Kidney and Testicle of Rats in Vtm and in Vivo / 예방의학회지

Production of free radicals of superoxide anion in tissues by cadmium, activities of superoxide dismutase and catalase to protect tissue damages caused by the free radicals and ATPase that plays an important role in energy metabolism at cellular level were investigated. Experiments in viro were conducted with liver, kidney and testicle tissue homogenates of rats adding 0.05~0.50 mM cadmium chloride, and in vivo experiments administering single dose of 5mg of cadmium/kg of body weight in 0.1% cadmium chloride solution intraperitoneally 48 hours prior to evisceration. Production of superoxide radicals in liver and testicle increased with addition of cadmium in vitro, but not in kidney. In vivo experiments, however superoxide radicals slightly increased in liver and kidney but not in testicle. Superoxide dismutase (Cu, Zn-SOD and Mn-SOD), catalase and ATPase (total, (Mg++)- & (Na+)- (K+)-) activity decreased in the presence of cadmium in dose dependent manner. Reduction of these enzyme activities varied not only with dosage of cadmium but also with type of tissue and between in vitro and in vivo experiment.

Scavenging of superoxide radical by ascorbic acid.

Using acetaldehyde and xanthine oxidase as the source of superoxide radical, the second order rate constant for the reaction between ascorbic acid and superoxide radical was estimated to be 8·2 × 107 M-1 s–1. In rats, the average tissue concentration of ascorbic acid was of the order of 10–3 Μ and that of superoxide dismutase was of the order of 10–6 M. So, taking together both the rate constants and the tissue concentrations, the efficacy of ascorbic acid for scavenging superoxide radical in animal tissues appears to be better than that of superoxide dismutase. The significance of ascorbic acid as a scavenger of superoxide radical has been discussed from the point of view of the evolution of ascorbic acid synthesizing capacity of terrestrial vertebrates.

EFFECT OF SELENIUM ON GENERATION OF SUPEROXIDERADICAL IN RAT HEART MITOCHONDRIA / 西安交通大学学报(医学版)

Weanling rats were fed with a low-selenium diet (Se 0.009mg/kg, — Se group) and the diet supplemented with sodium selenite (Se 0. 232mg/kg,+ Se group) for 1, 2 and 3 months respectively. The generation rate of superoxide radical(O_2~-), activity of manganese dependent superoxide dismutase (Mn-SOD) in heart mitochondria and blood Se concentration from the rats were determined. The results showed that the mitochondrial O_2~- generation rate from — Se rats was significantly higher than those from + Se rats at 2 and 3 months. During all the feeding periods, no significant difference in mitochondrial Mn-SOD activity was found between the—Se and + Se groups,while the blood Se concentration in — Se group was significantly lower than those in + Se group at each feeding time and continually decreased in the 2 and 3 month. The results suggested that selenium could depress O_2~- generation in heart mitochondria.