Lee-Wen Chang

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.

Antioxidant and antityrosinase activity of mulberry (Morus alba L.) twigs and root bark

The antioxidant and antityrosinase activities of the ethanolic extract of mulberry twigs (EEMT) were investigated. The results showed that EEMT exhibited radical scavenging and reducing activity, as well as ferrous ion-chelating activity. In addition, EEMT also protected phospholipids against free radicals, indicating that EEMT could protect biomolecules from oxidative damage. Meanwhile, in the range of 0-60 μg/ml, the tyrosinase inhibitory activity of EEMT increased with increase in sample concentration, and was superior to that of the ethanolic extract of mulberry root bark (EEMR). High-performance liquid chromatography (HPLC) analysis was employed to determine the phenolic components, revealing that maclurin, rutin, isoquercitrin, resveratrol, and morin were present in EEMT. Acting as an antioxidant and a tyrosinase inhibitor, these bioactive constituents could contribute to the protective effects of EEMT. Overall, the results showed that EEMT might serve as a natural antioxidant and tyrosinase inhibitor.

Cytoprotective effect of white tea against H2O2-induced oxidative stress in vitro

The protective effect of water extracts of white tea (WEWT) on oxidative stress in vitro is investigated. WEWT, like water extracts of green tea (WEGT) and water extracts of Pu-erh tea (WEPT), demonstrates a marked inhibition of the oxidation of liposome, albumin and LDLmodel systems. WEWT protects against H2O2-induced cytotoxicity, in a dose-dependent manner. The inhibition of ROS generation and MDA formation by WEWT in H2O2-induced Clone 9 cells parallels the effects on cell viability. Moreover, GSH and antioxidant enzymes may play an important role in the protective effect that is associated with H2O2-induced oxidative stress. The HPLC-DAD and HPLC-MS/MS analysis, shows that sixteen bioactive compounds are present in WEWT, which may partially account for its protective effect against oxidative insult. These results suggest that the mechanism of the protective actions of WEWT is related to its antioxidant potential and the maintenance of the normal redox status of the cell.

Anti-inflammatory effects of an aqueous extract of Welsh onion green leaves in mice.

The anti-inflammatory effects of an aqueous extract of Welsh onion green leaves (WOE) in mice was investigated. Administration of WOE, in the range of 0.25-1g/kg, showed a concentration dependent inhibition on paw edema development after carrageenan treatment in mice. The anti-inflammatory effects of WOE were closely attributed to decreased levels of tissue NO and tumor necrosis factor-α (TNF-α). Further evidence for WOEs protection is shown in the reduction of lipid oxidation and the increase of antioxidant enzyme activities, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) in vivo. Further, WOE also decreased the number of acetic acid-induced writhing responses and formalin-induced pain in the late phase in mice. Overall, the results showed that WOE might serve as a natural source of anti-inflammatory compounds.

Inhibitory effects of water extract of Flos Inulae on mutation and tyrosinase.

In this study, the effects of a water extract of Flos Inulae (WFI) on antioxidant, antimutation and antityrosinase were investigated. The results showed that WFI inhibited the mutagenicity of 2-aminoanthracene (2-AA), an indirect mutagen; and 4-nitroquinoline-N-oxide (4-NQO), a direct mutagen toward Salmonella typhimurium TA 98 and TA 100. In addition, WFI, in the range of 0.2-0.6 mg/ml, showed radical scavenging, reducing activities and chelating activity as well as decreased lipid oxidative damage. Meanwhile, WFI also inhibited tyrosinase activity and NO generation in lipopolysaccharide (LPS) stimulated macrophages. High performance liquid chromatography analysis suggests that the major phenolic constituents in WFI are chlorogenic acid, rutin, quercetin, luteolin and kaempferol. These bioactive components may contribute to the protective effects of WFI. The obtained data suggests that Flos Inulae can be applied to antimutation, antityrosinase and anti-inflammation.

Protective effects of three smoke flavouring phenols on oxidative damage and nitric oxide production

In this study, the effects of three smoke flavouring phenols, including 4-methoxyphenol (4-MP), 4-ethyl-2-methoxyphenol (EMP), and 4-propenyl-2-methoxyphenol (isoeugenol), on oxidative damage and nitric oxide production, were examined. In the range 5-20μM, EMP displayed the highest inhibitory effects on radical production and biomolecule oxidation in the acellular systems of the three smoke flavouring phenols. In addition, 4-MP, EMP and isoeugenol, in the range 5-20μM, protected liver cells against tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity, correlating with protection against intracellular glutathione depletion. Meanwhile, the inhibitory effects of the three smoke flavouring phenols on nitric oxide (NO) generation, in lipopolysaccharide (LPS)-stimulated macrophages, increased with increasing concentrations. The decrease in NO production was attributed to the reduced inducible nitric oxide synthase (iNOS) expression in macrophages. These data suggested that the three smoke flavouring phenols, particularly EMP, show biological activities that contribute to antioxidation as well as anti-inflammation.