Isolation and Identification of Myricitrin, an Antioxidant Flavonoid, from Daebong Persimmon Peel.

In this study, the antioxidant flavonoid, myricitrin, was isolated and identified from Daebong persimmon peel. The persimmon peel extract was successively fractionated with n-hexane, ethyl acetate, and n-butanol. The ethyl acetate fraction had the strongest antioxidant activities among the solvent fractions and was further fractionated by silica gel and octadecylsilane column chromatography, and preparative high performance liquid chromatography. Three antioxidant compounds were finally isolated, and compound 2 was identified as myricitrin by liquid chromatography/mass spectrometry and 1H and 13C nuclear magnetic resonance. Myricitrin had the strongest antioxidant activities by ferric ion reducing antioxidant power and α,α-diphenyl-2-picrylhydrazyl radical scavenging assays. These results suggested that myricitrin was found as a major antioxidant flavonoid responsible for the strong antioxidant activities of Daebong persimmon peels.

Antioxidant capacities and polyphenolics of Chinese cabbage (Brassica rapa L. ssp. Pekinensis) leaves.

Chinese cabbage (Brassica rapa L. ssp. Pekinensis) is a green leafy vegetable used mainly in kimchi, salted and fermented dishes. Consumer preference for the leaf portion differs according to the type of dishes. In this study, Chinese cabbage was divided into three parts, and their antioxidant activities were investigated through in vitro assays. The total phenolic contents (TPC), total flavonoid contents (TFC), and vitamin C contents were also determined as indicators of antioxidant contents. The phenolic acids and flavonoids were separated and identified using high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS). The outer leaf had the strongest antioxidant activity with the maximum antioxidant contents, followed by the mid- and inner leaves. Principal component analysis (PCA) revealed that outer leaf is positively related to caffeic acid, p-coumaric acid, ferulic acid, and myricetin contents, whereas the mid- and inner leaves are negatively related to sinapic acid contents.

Enhancing polyphenol extraction from unripe apples by carbohydrate-hydrolyzing enzymes.

The effects of process variables such as enzyme types, enzyme ratio, reaction temperature, pH, time, and ethanol concentration on the extraction of unripe apple polyphenol were investigated. The results indicated that Viscozyme L had the strongest effect on polyphenols extraction and was selected to study the polyphenol composition. The ratio of enzyme (Viscozyme L) to substrate (2 fungal beta-glucanase units (FBG)) at 0.02, reaction at pH 3.7, 50 degrees C for 12 h, and ethanol concentration of 70% were chosen as the most favorable extraction condition. Total phenolic content (TPC), reducing sugar content (RSC), and extraction yield increased by about 3, 1.5, and 2 times, respectively, compared with control. The contents of p-coumaric acid, ferulic acid, and caffeic acid increased to 8, 4, and 32 times, respectively. The enzyme-aided polyphenol extraction process from unripe apples might be applied to food industry for enhancing bioactive compound production.

Effects of ethanol extract from Saururus chinensis (Bour.) Baill on lipid and antioxidant metabolisms in rats fed a high-fat diet.

This study was performed to investigate the effect of ethanol extract from Saururus chinensis (Lour.) Baill on liver function, plasma lipid composition and antioxidant system with high-fat diet for 4 weeks. Rats were divided into the following five groups; untreated control group (normal), treated with 0.5% SE (normal + 0.5% SE), high-fat group (high-fat), high-fat group treated with 0.1% SE (high-fat + 0.1% SE), or 0.5% SE (high-fat + 0.5% SE). Weight gains showed a tendency to decrease in rat with high-fat + SE. Plasma total cholesterol showed a tendency to decrease with ethanol extract from S. chinensis (Lour.) Baill. LDL-cholesterol contents were lower in ethanol extract group than that of control group. Aspartate amino transferase and alanine amino transferase activities were increased by high-fat diet, and were decreased by 0.5% SE. Lipid peroxide level showed a tendency to increase in high-fat diet group than that of normal group. In ethanol extract from S. chinensis (Lour.) Baill groups, lipid peroxide level decreased significantly and SOD activity was also decreased progressively. These results demonstrated that the ethanol extract of S. chinensis (Lour.) Baill lowered serum cholesterol levels, tissue lipid contents and accumulation of cholesterol in the rat.

Effect of almond skin polyphenolics and quercetin on human LDL and apolipoprotein B-100 oxidation and conformation.

Almond skin polyphenolics (ASP) and vitamin C (VC) or E (VE) inhibit the Cu(2+)-induced generation of conjugated dienes in human low-density lipoprotein (LDL) in a synergistic manner. However, the mechanism(s) by which this synergy occurs is unknown. As modification of apolipoprotein (apo) B-100 is an early, critical step in LDL oxidation, we examined the effects of combining ASP or quercetin and antioxidant vitamins on the oxidation of this moiety as well as on the alteration of LDL conformation and electronegativity (LDL-). In a dose-dependent manner, ASP (0.12-2.0 micromol/L gallic acid equivalents) decreased tryptophan (Trp) oxidation by 6.7-75.7%, increased the generalized polarity (Gp) of LDL by 21.0-81.5% at 90 min and reduced the ratio of LDL- to total LDL (tLDL) by 38.2-83.8% at 5 h. The actions of ASP on these parameters were generally additive to those of VC and VE. However, a 10-25% synergy of ASP plus VC in protecting apo B-100 Trp against oxidation may result from their synergistic interaction in prolonging the lag time to oxidation. ASP and VE acted in synergy to reduce LDL-/tLDL by 24-43%. Quercetin's actions were similar to ASP, though more effective at inhibiting Trp oxidation. Thus, ASP and quercetin reduce the oxidative modification of apo B-100 and stabilize LDL conformation in a dose-dependent manner, acting in an additive or synergistic fashion with VC and VE.

Antioxidant evaluation and oxidative stability of structured lipids from extravirgin olive oil and conjugated linoleic acid.

Structured lipid (SL) was synthesized from extravirgin olive oil (EVOO) and conjugated linoleic acid (CLA) via a lipase-catalyzed reaction. CLA provides a variety of health benefits, but it is not consumed in free fatty acid form. The synthesized SL olive oil contained 42.5 mol % CLA isomers, and the major isomers were cis-9,trans-11-CLA (16.9 mol %) and trans-10,cis-12-CLA (24.2 mol %). The antioxidant activity determined by the radical scavenging capacity with the 2,2-diphenyl-1-picrylhydrazyl radical was lower in SL olive oil than in EVOO. The oxidative stability was also lower in SL olive oil since it had a higher peroxide value, rho-anisidine value, and 2-thiobarbituric acid reactive substances values during 20 days of storage at 60 degrees C. This observation could be due to the reduction in the natural phenolic compounds (97%) and tocopherols (56%), and the incorporated CLA with two conjugated double bonds in the SL olive oil. The oxidative stability of SL olive oil was increased by added rosemary extracts at concentrations of 100, 200, and 300 ppm. The present study suggests that the SL olive oil may be a suitable way to incorporate or deliver CLA into human diets. However, the addition of a proper antioxidant would be required for improving its oxidative stability.

Wisteria floribunda gall extract inhibits cell migration in mouse B16F1 melanoma cells by regulating CD44 expression and GTP-RhoA activity.

Extracts from galls grown on Wisteria floribunda are used as an anti-tumoral preparation in oriental traditional medicine. Here, we investigated the molecular mechanism of this anti-tumoral effect by first examining whether the extract inhibited cell migration in a B16 cell-based wound healing assay. The gall extract delayed wound healing in a dose- and time-dependent manner, indicating that one or more components of the fraction inhibited cell migration. Examination of two molecules known to be involved in metastasis, CD44, and RhoA-GTP, revealed that the gall extract decreased CD44 expression in a concentration-dependent manner, and also increased RhoA-GTP activity in comparison to untreated controls. Taken together, these results suggest that the Wisteria gall extract may inhibit cancer cell migration via inhibition of CD44 mRNA expression and activation of the GTP-RhoA protein.

Novel flavonol glycoside, 7-O-methyl mearnsitrin, from Sageretia theezans and its antioxidant effect.

A novel flavonol glycoside, 7-O-methylmearnsitrin (7,4'-O-dimethylmyricetin 3-O-alpha-L-rhamnopyranoside), and myricetrin, kaempferol 3-O-alpha-L-rhamnopyranoside, europetin 3-O-alpha-L-rhamnoside, and 7-O-methyl quercetin 3-O-alpha-L-rhamnopyranoside were isolated from the leaves of Sageretia theezans, and their chemical structures were identified by spectroscopic analyses including two-dimensional NMR (HSQC, HMBC). Whereas myricetrin, europetin 3-O-alpha-L-rhamnoside, and 7-O-methylquercetin 3-O-alpha-L-rhamnopyranoside showed stronger activities than ascorbic acid and alpha-tocopherol, 7-O-methylmearnsitrin showed very weak antioxidant activities by ESR and LDL oxidation inhibition tests.