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.

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.

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 WOE's 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.

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.

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.

Antioxidant properties of roasted coffee residues.

The antioxidant activity of roasted coffee residues was evaluated. Extraction with four solvents (water, methanol, ethanol, and n-hexane) showed that water extracts of roasted coffee residues (WERCR) produced higher yields and gave better protection for lipid peroxidation. WERCR showed a remarkable protective effect on oxidative damage of protein. In addition, WERCR showed scavenging of free radicals as well as the reducing ability and to bind ferrous ions, indicating that WERCR acts as both primary and secondary antioxidants. The HPLC analyses showed that phenolic acids (chlorogenic acid and caffeic acid) and nonphenolic compounds [caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)furfuraldehyde] remained in roasted coffee residues. These compounds showed a protective effect on a liposome model system. The concentrations of flavonoids and polyphenolic compounds in roasted coffee residues were 8,400 and 20,400 ppm, respectively. In addition, the Maillard reaction products (MRPs) remaining in roasted coffee residues were believed to show antioxidant activity. These data indicate that roasted coffee residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remained in roasted coffee residues.

Effects of pu-erh tea on oxidative damage and nitric oxide scavenging.

The effects of pu-erh tea, which is prepared by fermentation of tea, on oxidative damage and nitric oxide scavenging, compared with various other brands of tea were investigated. The total antioxidant activity was determined using the Trolox equivalent antioxidant capacity (TEAC) assay. The results showed that TEAC values of the 200 microg/mL water extracts of pu-erh tea (WEPT), green tea, oolong tea, and black tea were 86.3, 85.3, 87.4, and 80.3 (microg/mL), respectively, indicating that WEPT showed a significant antioxidant activity. WEPT, like green tea extract, oolong tea extract, and black tea extract, exhibited a remarkable protective effect in lipid (liposome) and nonlipid (protein and deoxyribose) model systems, implying that it is an inhibitor of lipid and nonlipid oxidative damage. It also exhibited metal-binding ability, reducing power, and scavenging effect for free radicals. Moreover, WEPT showed a decreasing effect on nitric oxide production of lipopolysaccharide-induced RAW 264.7 macrophages. In addition, the results revealed that epicatechin (EC), flavonoid, ascorbic acid, and polyphenolic compounds are present in WEPT, which may partially account for the protective effect on oxidative damage. Thus, WEPT may have potential as an antioxidant and as a nitric oxide scavenging agent.

Identification of an antioxidant, ethyl protocatechuate, in peanut seed testa.

The antioxidant activity and identification of the antioxidant component of peanut seed testa were investigated. The antioxidant activity of peanut seed testa was studied in the linoleic acid model system by using the ferric thiocyanate method. Among the five organic solvent extracts, the ethanolic extracts of peanut seed testa (EEPST) produced higher yields and stronger antioxidant activity than other organic solvent extracts. EEPST was separated into 17 fractions on silica gel column chromatography. Fraction 17, which showed the largest yield and significant antioxidant activity, was separated by thin-layer chromatography. Four major antioxidative subfractions were present. Subfraction 17-2 was found to be effective in preventing oxidation of linoleic acid. This subfraction was further fractionated and isolated and characterized by UV, MS, IR, and (1)H NMR techniques. The active compound was identified as ethyl protocatechuate (3,4-dihydroxybenzoic acid ethyl ester).