Beneficial effects of yam on carbon tetrachloride-induced hepatic fibrosis in rats.

BACKGROUND: In a previous study, lyophilised yam reduced brain amyloid beta-protein (Abeta) accumulation and improved the antioxidative defence system in senescence-accelerated (SAMP8) mice. Therefore, the aim of this study was to investigate the hepatic protection of yam in the carbon tetrachloride-induced hepatic fibrosis of rats. Hepatic fibrosis was induced in rats via intraperitoneal injections of CCl(4) at a dose of 1 mL kg(-1) body weight (BW) twice weekly for 8 weeks. Three groups of rats were gavaged daily with yams at doses of 0.5, 1 and 2 g kg(-1) BW for 8 weeks, respectively. RESULTS: Yam treatments significantly decreased the ratio of liver/body weight, levels of gamma-glutaminotranspeptidase (GGT), low-density lipoprotein, and triglyceride in serum when compared with those administered CCl(4) alone. Treatment with yams significantly elevated antioxidant activities of glutathione peroxidase (GSH-Px) and superoxidase dismutase (SOD) in livers. Microscopically, yam-treated groups presented with low histoscores of CCl(4)-induced liver injury and fibrosis. Additionally, yam treatment reduced the area of GGT-positive foci and the index of proliferating cell nuclear antigen (PCNA) in liver. CONCLUSION: Daily administration of yam attenuates CCl(4)-induced hepatic fibrosis in rats in a dose-dependent manner; this attenuation may be related to the antioxidant properties of yams.

Hairy root cultures of Gynostemma pentaphyllum (Thunb.) Makino: a promising approach for the production of gypenosides as an alternative of ginseng saponins.

Hairy root cultures of Gynostemma pentaphyllum were established by infecting leaf discs with Agrobacterium rhizogenes. The dry biomass of hairy roots grown in MS medium for 49 days was 7.3 g l(-1) with a gypenoside content of 38 mg g(-1) dry wt.

The hepatoprotective effect of Bupleurum kaoi, an endemic plant to Taiwan, against dimethylnitrosamine-induced hepatic fibrosis in rats.

In the present study, three materials extracted or isolated from the roots of B. kaoi, an endemic plant to Taiwan, were used to be examined the hepatoprotective effect against dimethylnitrosamine (DMN)-induced hepatic fibrosis in rats, they were water extract (BKW), polysaccharide-enriched fractions (BKP) and saponin-enriched fractions (BKS). After treated with DMN for 4 weeks, the levels of aminotrasferases (GOT, GPT) were significantly elevated in serum, and the levels of total protein (TP) and albumin were significantly decreased in serum and liver homogenates. Furthermore, the collagen contents were significantly elevated in liver homogenates and corresponded to the hepatofibrotic pathological examination. As the results showed, treated with groups of BKW, BKP, BKS markedly reduced GOT, GPT levels in rats serum. In addition, treated with groups of BKW, BKP, BKS markedly raised TP levels in rats serum and liver homogenates. Furthermore, treated with groups of BKW, BKP markedly raised albumin levels in rats serum and liver homogenates. Treated with groups of BKW, BKP, BKS markedly raised interferon-gamma (IFN-gamma) levels in rats serum, where only BKS and silymarin markedly raised interkeukin-10 (IL-10) levels in rats serum compared to that of DMN treated rats. None of test materials of B. kaoi except silymarin reduced the malondialdehyde (MDA) levels, but BKW, BKP markedly raised hepatic glutathione (GSH) levels to reveal the activity of anti-lipid peroxidation. Otherwise, treated with groups of BKW, BKP, BKS significantly reduced collagen contents in rats liver homogenates. In conclusion, B. kaoi demonstrated the anti-inflammatory and anti-fibrotic activities followed by anti-oxidant activity of enhanced GSH production, enhanced the liver cell regeneration and concerned with regulations of INF-gamma and IL-10. The ability of hepatoprotective and anti-fibrotic activities of B. kaoi are higher than B. chinense, a Bupleuri Radix imported from China to Taiwan.

Protective effect of water yam (Dioscorea alata L.) extract on the copper-driven fenton reaction and X-ray induced DNA damage in vitro.

The rhizome extract of Dioscorea has been shown to possess radical scavenging activity. In this study, the protective effect of water yam (Dioscorea alata L.) rhizome extract on calf thymus DNA and plasmid DNA strand breakage by the copper-driven Fenton reaction and X-irradiation was examined. The protective activity in vitro of four lyophilized extracts obtained from yam rhizomes: (1) aqueous extract (YAE); (2) 30% ethanolic extract (YEE); (3) aqueous extract boiled for 30 min (BYAE); and (4) 30% ethanolic extract boiled for 30 min (BYEE) were evaluated by ethidium bromide binding assay and DNA nicking assay. The YAE, YEE, and BYEE effectively inhibited the copper-driven Fenton reaction-induced damage of calf thymus DNA, while inhibition was less pronounced in the case of X-ray induced strand breakage of plasmid DNA. While BYAE potently inhibited X-ray induced strand breaks in plasmid pGL3 DNA, it failed to inhibit, and even greatly enhanced copper-H(2)O(2) induced damage of calf thymus DNA. The present results demonstrate strong copper chelating and weak hydroxyl radical scavenging activities in yam rhizome extracts, and these activities may vary depending on the procedures used in preparing the extract.

Chinese yam (Dioscorea alata cv. Tainung No. 2) feeding exhibited antioxidative effects in hyperhomocysteinemia rats.

Antioxidative effects of Dioscorea alata (D. alata) were investigated in hyperhomocysteinemia (HHcy) induced by methionine (Met) oral feeding (1 (g/kg of BW)/day). HHcy rats were fed a standard laboratory chow supplemented without or with freeze-dried D. alata powder at 1, 2.5, and 5 (g/kg of BW)/day, assigned as Met, Met + D1, Met + D2, and Met + D3 groups, respectively. Twelve weeks after D. alata feeding, plasma homocysteine levels (16.3-24.2 microM) were significantly decreased compared to that of the Met group (34.1 +/- 9.9 microM) (p < 0.01), and similar to the basal level (15.0 +/- 1.9 microM). Thrombin-induced platelet aggregation (PA) of the Met + D2 and Met + D3 groups was significantly lower than that of the Met group. Plasma malondialdehyde levels, an indicator of lipid peroxidation, and hepatic reactive oxygen species, an indicator of oxidative stress, of HHcy with D. alata feeding were significantly lower than that without D. alata feeding. The hepatic catalase in the Met + D2 and Met + D3 groups was significantly elevated compared to that in the Met group. D. alata feeding did not significantly change hepatic superoxide dismutase, glutathione peroxidase, and glutathione reductase, which were adaptively enhanced by Met feeding. The decreased glutathione/glutathione disulfide ratio in the Met group was increased after D. alata feeding. These results indicated that HHcy induced by Met could be reversed by D. alata feeding. D. alata feeding exhibited its antioxidative effects in HHcy including alleviating PA, lipid peroxidation, and oxidative stress, but did not induce activity of antioxidant enzymes which had already adaptively increased by HHcy.