Gow-Chin Yen

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.

Antioxidative properties of methanolic extracts from peanut hulls

Antioxidative properties of methanolic extracts from peanut hulls (MEPH) have been investigated. MEPH had good thermal stability and showed an 85.2% inhibition of peroxidation of linoleic acid when heated at 185°C for 2 h. Only a slight decrease in antioxidative activity of MEPH occurred when the extract was stored at different temperatures (∓20, 5 and 30°C) under air or nitrogen (30°C) for 70 d. Antioxidative activity of MEPH decreased with an increase of pH from 3 to 9. No synergistic effect of ascorbic acid, citric acid, cysteine or α-tocopherol was observed on the inhibitory effect of MEPH. The reducing power of MEPH increased with an increase in concentration and was significantly correlated (r=0.9793,P<0.05) to the extent of antioxidative activity. MEPH also showed good inhibitory activity in lard oxidation when compared with butylated hydroxyanisole.

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.

Antioxidant and radical scavenging properties of extracts from Ganoderma tsugae

Abstract The antioxidant activities and scavenging effects on free radicals of extracts from Ganoderma were investigated. The methanolic extracts of Ganoderma tsugae (MEGT) showed the strongest antioxidant activity of five species of Ganoderma tested. MEGT exhibited substantial antioxidant activity in the linoleic acid and rat liver microsome peroxidation systems. The antioxidant activity of MEGT was stronger than α-tocopherol. MEGT had a strong chelating effect on Fe 2+ . MEGT showed a marked and concentration-dependent scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl radical. MEGT also exhibited a strong scavenging effect on the hydroxyl radical as measured by electron paramagnetic resonance spectrometry. The formation of 8-hydroxy-2′-deoxyguanosine, from 2′-deoxyguanosine induced by various prooxidants, was reduced by MEGT. In view of these results, the antioxidant and radical scavenging activities of Ganoderma may have an important role on inhibition of lipid peroxidation in biological systems.

Phenolic Compounds Rutin and o-Coumaric Acid Ameliorate Obesity Induced by High-Fat Diet in Rats

Dietary fat is one of the most important environmental factors associated with the incidence of cardiovascular diseases. In this study, the antiobesity effects of rutin (R) and o-coumaric acid (oCA) were investigated. Wistar rats were divided into normal and obese groups, and obese rats were prefed a high-fat diet (HFD) containing 40% beef tallow for 4 weeks. Then, R and oCA were given as a supplement to obese rats at doses of 50 and 100 mg/kg, respectively, for a period of 8 weeks. The results showed that body, liver organ, and adipose tissue weights of peritoneal and epididymal fat pads in the HFD+ R and HFD+oCA groups were significantly decreased as compared to those in the HFD group. Serum lipid profiles, insulin, and leptin were significantly decreased in the HFD+ R (high dose, HD) and HFD+oCA (HD) groups as compared to those in the HFD group. Hepatic triacylglycerol and cholesterol levels were significantly decreased in the HFD+ R (HD) and HFD+oCA (HD) groups as compared to those in the HFD group. Moreover, the consumption of R and oCA reduced oxidative stress and glutathione disulfide (GSSG) content, and enhanced the levels of glutathione (GSH), GSH peroxidase (GPx), GSH reductase (GRd), and GSH S-transferase (GST) in the hepatic tissue of rats with HFD-induced obesity. These results demonstrate that intake of R and oCA can be beneficial for the suppression of high-fat-diet-induced dyslipidemia, hepatosteatosis, and oxidative stress in rats.

Oleanolic Acid and Ursolic Acid Induce Apoptosis in HuH7 Human Hepatocellular Carcinoma Cells through a Mitochondrial-Dependent Pathway and Downregulation of XIAP

Oleanolic acid (OA) and ursolic acid (UA) are commonly found in plants and herbs and have been reported to possess hepatoprotective, anti-inflammatory and anticancer activities. In the present study, the effects of OA and UA on induction of apoptosis in human hepatocellular carcinoma HuH7 cells and the related mechanisms were investigated. The results demonstrate that OA and UA could inhibit the growth of HuH7 cells with IC(50) values of 100 and 75 microM, respectively. Cell cycle analysis using flow cytometry indicated that the fraction of HuH7 cells in sub-G1 phase progressively increased with increasing concentrations of OA or UA from 20 to 80 microM. Treatment with OA and UA for 8 h induced a dramatic loss of the mitochondria membrane potential and interfered with the ratio of expression levels of pro- and antiapoptotic Bcl-2 family members in HuH7 cells. OA and UA-induced apoptosis involving the release of mitochondria cytochrome c into the cytosol and subsequently induced the activation of caspase-9 and caspase-3, followed by cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, HuH7 cells treated with OA and UA suppressed the activity of NF-kappaB and modulated the mRNA expression of X-linked inhibitor of apoptotic protein (XIAP) as compared with untreated cells. These results demonstrate that OA and UA induce apoptosis in HuH7 cells through a mitochondria-mediated pathway and downregulation of XIAP.

Antioxidant activity and active compounds of rice koji fermented with Aspergillus candidus

Abstract Antioxidant activity of ethyl acetate extracts from rice koji (EAERK) fermented with Aspergillus candidus CCRC 31543 was evaluated, and the antioxidant components in koji were isolated and identified. EAERK (200 μg/ml) showed a 90% inhibitory effect on peroxidation of linoleic as determined by the thiocyanate method. EAERK also showed a marked antioxidant activity on the oxidation of lard determined by using the Rancimat method. EAERK had a strong scavenging effect on the DPPH radical. Silica gel column chromatography was used to separate EAERK into eight fractions (A–H). Fractions C–F possessed significant antioxidant activity and showed more than 88% inhibition of peroxidation of linoleic acid. Fraction C was crystallized and purified to obtain compound 1. Fractions D–F were combined and re-separated by means of column chromatography and the subfraction that exhibited strong antioxidant activity was crystallized to yield purified compound 2. Compounds 1 and 2 were shown to be ergosterol and terphenyllin, respectively, on the basis of UV-vis spectral, MS and NMR analyses. Ergosterol showed no antioxidant activity on the peroxidation of linoleic acid. However, the antioxidant activity of terphenyllin was equal to that of BHA at 200 μg/ml.

EVALUATION OF THE CYTOTOXICITY, MUTAGENICITY AND ANTIMUTAGENICITY OF EMERGING EDIBLE PLANTS

This study evaluates the toxic, mutagenic and antimutagenic effects of emerging edible plants that are consumed as new leafy vegetables in Taiwan. Among eight plant extracts, only the extracts of Sol (Solanum nigrum L.) showed cytotoxicity to Salmonella typhimurium TA100 in the absence of S9 mix. The toxicity of extracts from different parts of the Sol plant, such as leaf and stem, immature fruit and mature fruit, towards S. typhimurium TA100 and human lymphocytes was also assayed. The immature fruit extracts of Sol exhibited strong cytotoxicity with dose dependence and induced significant DNA damage in human lymphocytes based on the comet assay. However, no mutagenicity was found in eight plant extracts to TA98 or TA100 either with or without the S9 mixture. Sol and Sec [Sechium edule (Jacq.) Swartz] extracts showed the strongest inhibitory effect towards the mutagenicity of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) in S. typhimurium TA98 and TA100; the ID(50) was less then 1 mg/plate. Cra [Crassocephalum creidioides (Benth.) S. Moore] extracts also expressed moderate antimutagenic activities towards IQ and benzo[a]pyrene (B[a]P) either in TA98 or in TA100; the ID(50) was 1.63-2.41 mg/plate. The extracts from Bas (Basella alba L.), Bou (Boussingaultia gracilis Miers var. pseudobaselloides Bailey), Cen (Centella asiatica L. Urban), Cor (Corchorus olitorius L.) and Por (Portulaca oleracea L.) showed weak to moderate inhibition of mutagenicity of IQ. However, the potential antimutagenicity of these plant extracts towards B[a]P was weaker than that towards IQ. For a direct mutagen, 4-nitroquinoline-N-oxide (NQNO), only the Sol extracts showed strong inhibitory effects in the TA100 system. The antimutagenic activity of water extracts of Sec was partly reduced by heating at 100 degrees C for 20 min. The heat-stable antimutagens in Sec extracts could be produced in the plant extract preparation process. Fractions with molecular weights above 30,000 showed the strongest antimutagenicity and peroxidase activity in all the fractions of the Sec extracts.

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).