Pin-Der Duh

Antioxidant and pro-oxidant properties of ascorbic acid and gallic acid

Abstract The antioxidant and pro-oxidant properties of ascorbic acid (AA) and gallic acid (GA) were investigated. AA and GA, at a concentration of 1.65 mM, accelerate the oxidation of deoxyribose induced by Fe 3+ –EDTAJH 2 O 2 . The reducing power of these two compounds increased upon increasing the concentration. AA and GA showed no chelating ability toward iron (II). At a concentration of 4.17 mM, AA and GA exhibited 42.1 and 43.9% scavenging effects on DPPH radicals, respectively. They exhibited 60% scavenging effects on hydrogen peroxide at a concentration of 4.17 mM. No toxicity was found in AA and GA toward human lymphocytes. AA, at 0.82 mM, and GA, at 0.6 mM, exhibited the maximal DNA damage, the means of tail DNA% were 14.8 and 28.8%, respectively. When AA and GA were mixed with H 2 O 2 , they exhibited a slight inhibitory effect on DNA damage induced by H 2 O 2 on pre-incubating both the compounds with human lymphocytes for 30 min before exposure to H 2 O 2 . The antioxidant activities of AA and GA at a higher concentration were mainly due to the scavenging of hydrogen peroxide in this system. The pro-oxidant mechanism for AA and GA acid is most likely due to the strong reducing power and weak metalchelating ability.

Antioxidant activity of anthraquinones and anthrone

Abstract The antioxidant properties of anthraquinones (AQs) and anthrone were evaluated using different model systems. The antioxidant activity of these compounds (200 ppm) on the inhibition of peroxidation of linoleic acid was found to be in the order of BHA (96%), anthrone (95%), alizarin (93%)>aloe-emodin (78%)>rhein (71%)>emodin (36%)>anthraquinone (8%). Chrysophanol accelerated the peroxidation of linoleic acid. Anthrone and alizarin exhibited a reducing power, although the other AQs did not show any reducing power. AQs and anthrone exhibited a weak chelating ability on iron (II). At a concentration of 0.25 mg/ml, the scavenging effects of anthrone, aloe-emodin and emodin, on hydroxyl radicals produced by the Fenton reaction were 26.2, 16.6 and 41.8%, respectively. However, at the same concentration, anthraquinone, alizarin, chrysophanol and rhein accelerated the production of hydroxyl radicals. These results suggest that the antioxidant mechanism, for both emodin and aloe-emodin, possibly depends on scavenging hydroxyl radicals. The strong activity shown by anthrone could be due to its reducing power and scavenging effects on hydroxyl radicals. The pro-oxidant activity exhibited by chrysophanol might be due to the enhanced production of free radicals.

Antioxidant activity of sesame coat.

The antioxidant activity of ethanolic extracts of sesame coat (EESC) was investigated. The antioxidant activity (91.4%) of 1.0 mg EESC was equal to 1.0 mg tocopherol (90.5%) but was weaker than 1.0 mg butylated hydroxyanisole (98.6%) on peroxidation of linoleic acid. EESC showed an inhibitory effect against the formation of thiobarbituric acid reactive substances (TBARS) in a liposome model system. EESC at 10.0 mg exhibited a 94.9% scavenging effect on α,α-diphenyl-β-picrylhydrazyl radicals and marked reducing power, indicating that EESC acts as a primary antioxidant. The extracts, at a dose of 1.0 mg, showed a 50.0% scavenging effect on the hydroxyl radical. EESC also exhibited a metal-binding ability. Sesamin and sesamolin, the lignan substances, were found in EESC, by HPLC analysis. In addition, chromatographic analysis demonstrated that phenolic compounds and tetranortriterpenoids, which had positive reactions with β-carotene, indicating antioxidant activity, are present in EESC. According to these results, termination of free radical reaction, metal-binding ability and quenching of reactive oxygen are suggested to be, in part, responsible for the antioxidant activity of EESC.

Antioxidative activity of three herbal water extracts

The antioxidative activity of water extracts of three herbs, including the flower of Chrysanthemum morifolium Ramat (FCMR), the calyx of Hibiscus sabdariffa L. (CHSL) and roasted seed of Hordeum vulgare L. (RSHVL), which are commonly called Hang Chu, Lo Shen and Chao Mai in Taiwan, respectively, were investigated. FCMR, CHSL and RSHVL showed marked antioxidative activity, not only in linoleic acid but also in liposome model systems, indicating that the three herbal water extracts may protect the cell from damage by lipid peroxidation. FCMR, CHSL and RSHVL possessed high contents of phenolic compounds and exhibited reducing power, revealing that these herbal extracts may containreductones. The water extracts of the three herbs also showed good hydrogen-donating abilities, indicating that they had effective activities as radical scavengers. No mutagenicity in the water extracts of the three herbs was found in Salmonella typhimurium TA98 and TA100, either with or without S9 mix.

Comparison of Protective Effects between Cultured Cordyceps militaris and Natural Cordyceps sinensis against Oxidative Damage

The Chinese herb DongChong-XiaCao originating from Cordyceps sinensis is widely used as a traditional medicine in China for treatment of a wide variety of diseases. The extracts of Cordyceps sinensis (CSE) and Cordyceps militaris (CME) are well-known for their biological effects. In the present study, the antioxidant efficiency of CME and CSE in protecting lipid, protein, and low-density lipoprotein (LDL) against oxidative damage was investigated. CME and CSE showed weakly inhibitory effect on liposome oxidation, that of CME being superior to that of CSE. As for the protein oxidation model system, the inhibitory effect of CME on protein oxidation was inferior to that of CSE. CME and CSE at 1.0 mg/mL showed 50.5 and 67.1% inhibition of LDL oxidation, respectively. The contents of bioactive ingredients cordycepin and adenosine in CME are higher than those of CSE; however, both cordycepin and adenosine showed no significant antioxidant activity as determined by the Trolox equivalent antioxidant capacity method. Polyphenolic and flavonoid contents are 60.2 and 0.598 microg/mL in CME and 31.8 and 0.616 microg/mL in CSE, respectively, which may in part be responsible for their antioxidant activities. In addition, a polysaccharide present in CME and CSE displayed antioxidant activity, which suggested that the activity might be derived partly from polysaccharides of CME and CSE. The tendency to scavenge the ABTS(*)(+) free radical and the reducing ability of CME and CSE display concentration-dependent manners, suggesting that CME and CSE may be potent hydrogen donators. On the basis of the results obtained, the protective effects of CME and CSE against oxidative damage of biomolecules are a result of their free radical scavenging abilities.

Effects of resveratrol and 4-hexylresorcinol on hydrogen peroxide-induced oxidative DNA damage in human lymphocytes.

The protective effects of resveratrol and 4-hexylresorcinol against oxidative DNA damage in human lymphocytes induced by hydrogen peroxide were investigated. Resveratrol and 4-hexylresorcinol showed no cytotoxicity to human lymphocytes at the tested concentration (10-100 w M). In addition, DNA damage in human lymphocytes induced by H 2 O 2 was inhibited by resveratrol and 4-hexylresorcinol. Resveratrol and 4-hexylresorcinol at concentrations of 10-100 w M induced an increase in glutathione (GSH) levels in a concentration-dependent manner. Moreover, these two compounds also induced activity of glutathione peroxidase (GPX) and glutathione reductase (GR). The activity of glutathione-S-transferase (GST) in human lymphocytes was induced by resveratrol. Resveratrol and 4-hexylresorcinol inhibited the activity of catalase (CAT). These data indicate that the inhibition of resveratrol and 4-hexylresorcinol on oxidative DNA damage in human lymphocytes induced by H 2 O 2 might be attributed to increase levels of GSH and modulation of antioxidant enzymes (GPX, GR and GST).

Pro-oxidative properties of flavonoids in human lymphocytes

The pro-oxidative properties of the four flavonoids, quercetin, morin, naringenin and hesperetin, in human lymphocyte system were investigated. Naringenin and hesperetin accelerated the oxidation of deoxyribose induced by Fe3+/H2O2 in a concentration range of 0–200 μM, but quercetin and morin decreased it when the concentration was greater than 100 μM. The generation of hydrogen peroxide and the superoxide anion and the production of TBARS in lymphocytes were increased with increasing concentration of a flavonoid. Cell membrane protein thiols of the lymphocytes decreased when treated with the four flavonoids. Quercetin and hesperetin had no significant effect (p>0.05) on the activity of glutathione reductase, but morin and naringenin could inhibit the activity of the enzyme at a concentration of 200 μM, when compared to the control group. The glutathione S-transferase activity was slightly decreased by treatment with each of the four flavonoids only at a concentration of 200 μM. Therefore, the DNA damage in lymphocytes induced by the flavonoids in the model system might have been due to their stimulation of oxidative stress in the lymphocytes, which resulted in the decrease of cell membrane protein thiols, increase of lipid peroxidation in cell membrane and in the influence of the antioxidative enzyme activities.

Hepatoprotection of emodin and Polygonum multiflorum against CCl4-induced liver injury

Context: Polygonum multiflorum is known as a medicinal plant. It has been used as a folk medicine which showed antioxidative property. Objective: Protective effects of the water extracts (w/v:1/10) from fresh P. multiflorum (WEP) on carbon tetrachloride (CCl4)-induced liver damage in rats were investigated. Materials and methods: CCl4 was used for inducing liver damage of SD rats, and WEP and emodin were fed for eight consecutive weeks. Results: We found that emodin levels in fresh WEP was higher than that in ripening WEP. Rats were administered WEP and emodin, the main active compound, for 56 consecutive days. WEP significantly lowered the serum levels of hepatic enzyme markers, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and reduced the generation of malonaldehyde. Treatment with WEP recovered glutathione S-transferase and catalase activity in rats as compared to treatment with CCl4 alone. In addition, serum tumor necrosis factor-α, an inflammatory marker, was found to decrease in rats treated with WEP. In histopathological evaluation, fatty degeneration and necrosis were found to be significantly decreased in the CCl4 plus WEP treatment group. Discussion and conclusion: WEP may be effective in attenuating liver damage by reducing lipid peroxidation as well as by positively modulating inflammation.

Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress

Protective effects of sweet orange (Citrus sinensis) peel and their bioactive compounds on oxidative stress were investigated. According to HPLC-DAD and HPLC-MS/MS analysis, hesperidin (HD), hesperetin (HT), nobiletin (NT), and tangeretin (TT) were present in water extracts of sweet orange peel (WESP). The cytotoxic effect in 0.2mM t-BHP-induced HepG2 cells was inhibited by WESP and their bioactive compounds. The protective effect of WESP and their bioactive compounds in 0.2mM t-BHP-induced HepG2 cells may be associated with positive regulation of GSH levels and antioxidant enzymes, decrease in ROS formation and TBARS generation, increase in the mitochondria membrane potential and Bcl-2/Bax ratio, as well as decrease in caspase-3 activation. Overall, WESP displayed a significant cytoprotective effect against oxidative stress, which may be most likely because of the phenolics-related bioactive compounds in WESP, leading to maintenance of the normal redox status of cells.

Cytotoxic effect of Eucalyptus citriodora resin on human hepatoma HepG2 cells.

The aim of this study was to evaluate the antiproliferative effect of Eucalyptus citriodora resin (ECR) on human hepatoma HepG2 cells. The results from MTT assay and LDH leakage analysis showed that water extracts of ECR (WEECR) in the dose range of 0-500 μg/ml displayed stronger cytotoxic effects on HepG2 cells than other organic solvent extracts of ECR. By flow cytometry analysis, WEECR slowed down the cell cycle at the G0/G1 phase after 24 h of incubation. Moreover, WEECR treatment induced an apoptotic response in HepG2 cells. WEECR-induced apoptosis was in association with the attenuation of mitochondrial transmembrane potentials (ΔΨ(m)), increased Bax/Bcl-2 ratio and activation of caspase-3. In addition, WEECR contained high concentration of phenolics and flavonoids, which may be responsible for the potent cytotoxicity of WEECR on HepG2 cells. Taken together, WEECR may be a potent antihepatoma agent due to apoptosis in HepG2 cells.