Contributions of major components to the antimutagenic effect of Hsian-tsao (Mesona procumbens Hemsl.).

Our aim was to determine the antimutagenic activity of various solvent extracts from an herb Mesona procumbens Hemsl, normally called Hsian-tsao in China. We also investigated the relationships between the special components in the water extract of Hsian-tsao (WEHT) and the antimutagenic activity. It was found that the extracts at 0-0.6 mg/plate from three solvents (water, methanol, and ethyl acetate) exhibited a dose-dependent antimutagenic effect against benzo[a]pyrene [B(a)P] and 2-amino-3-methylimidazo(4,5-f)quinoline (IQ), both are indirect mutagens in Salmonella tester strains TA98 and TA100. The WEHT from three different plantations revealed a similar inhibitory effect on the mutagenicity of IQ in TA 98 at 2.5-5.0 mg/plate. The inhibitory effect of WEHT on the mutagenicity of IQ correlates with their polyphenol and ascorbic acid contents but not with their chlorophyll contents. These findings suggest that the antimutagenicity activity of WEHT may be attributed mainly to their polyphenolic compounds and ascorbic acid.

Antioxidant effects of water extracts from barley (Hordeum vulgare L.) prepared under different roasting temperatures.

The antioxidant effects of water extracts of roasted barley (WERB) were investigated under different roasting temperatures and compared with those of the water extracts of unroasted barley (WEUB). It was found that the Maillard reaction products increased upon increasing the roasting temperatures. Both WERB and WEUB exhibited significant antioxidant activities in linoleic acid and liposome model systems. Although WERB and WEUB afforded considerable protection against the damage of deoxyribose and proteins, the antioxidant efficiency of roasted samples was weaker than that of unroasted samples because of the reduction of antioxidant components (catechin, tocopherol, and lutein) with increasing roasting temperature. Unroasted samples were more effective in reducing power, quenching free radical, hydroxyl radical, and chelating iron than the roasted samples. The different antioxidant activity among roasted and unroasted barley samples may be partly attributed to the changes in catechin, tocopherol, and lutein contents.

Action of methanolic extract of mung bean hulls as inhibitors of lipid peroxidation and non-lipid oxidative damage.

The antioxidant effects of methanolic extract of mung bean hulls (MEMBH) on lipids and non-lipids, including liposome, carbohydrate, protein and 2'-deoxyguanosine (2'-dG), were investigated. MEMBH exhibited a remarkable antioxidant effect in a liposome model system, indicating that the extract was an inhibitor of lipid peroxidation. The inhibitory effect of MEMBH on deoxyribose damage was amount-dependent and it afforded considerable protection against damage to deoxyribose. In addition, MEMBH at low amounts was more effective in protecting protein oxidation. Furthermore, the oxidation of 2'-dG to 8-hydroxy-2'-deoxyguanosine (8-OH-2'dG) was inhibited by MEMBH. These results show that the extract also was an inhibitor of non-lipid oxidation damage. The extract exhibited metal binding ability and scavenging activity for hydrogen peroxide and hydroxyl radical, which may explain the mechanism of their protecting lipids and non-lipids from oxidative damage.

Antimutagenic effect of methanolic extracts from peanut hulls.

The antimutagenic effects of methanolic extracts of peanut hulls (MEPH) were evaluated by the Ames test. MEPH inhibited the mutagenicity of 4-nitroquinoline-N-oxide (NQNO), a direct-acting mutagen. MEPH also inhibited the mutagenicity of some indirect-acting mutagens and decreased in the order of 2-amino-3-methyl-imidazo(4,5-f)quinoline (IQ) > aflatoxin B1 (AFB1) > 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole (Glu-P-1) > 3 amino-1,4-dimethyl-5H-pyridol(4,3-b)indole (Trp-P-1) > benzo(a)pyrene (B(a)P for S. typhimurium TA98, and IQ > Trp-P-1 > Glu-P-1 > AFB1 > B(a)P for S. typhimurium TA100.