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.

Amygdalin Contents in Peaches at Different Fruit Development Stages.

Amygdalin contents of the seeds, endocarps, and mesocarps from three peach cultivars (i.e., Stone Peach, Hikawa Hakuho, and Bakhyang) were measured at three stages of fruit development (stone-hardening, fruit enlargement, and ripening). The peach samples were dried and defatted with a Soxhlet apparatus, reflux extracted with methanol, and analyzed using reverse phase high-performance liquid chromatography. During all fruit development stages, the amygdalin contents in the seeds were higher than those in the endocarps and mesocarps. The amygdalin contents of the Stone Peach were comparatively higher than the Hikawa Hakuho and Bakhyang (P<0.05). Further, the amygdalin contents during ripening were very low or not detected. Overall, the amygdalin contents of the three peach cultivar samples (seed, endocarp, and mesocarp) increased until the fruit enlargement stage and either remained constant or decreased during ripening.

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.

Phosphorylation of Ser-204 and Tyr-405 in human malonyl-CoA decarboxylase expressed in silkworm Bombyx mori regulates catalytic decarboxylase activity.

Decarboxylation of malonyl-CoA to acetyl-CoA by malonyl-CoA decarboxylase (MCD; EC 4.1.1.9) is a vital catalytic reaction of lipid metabolism. While it is established that phosphorylation of MCD modulates the enzymatic activity, the specific phosphorylation sites associated with the catalytic function have not been documented due to lack of sufficient production of MCD with proper post-translational modifications. Here, we used the silkworm-based Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid system to express human MCD (hMCD) and mapped phosphorylation effects on enzymatic function. Purified MCD from silkworm displayed post-translational phosphorylation and demonstrated coherent enzymatic activity with high yield (-200 µg/silkworm). Point mutations in putative phosphorylation sites, Ser-204 or Tyr-405 of hMCD, identified by bioinformatics and proteomics analyses reduced the catalytic activity, underscoring the functional significance of phosphorylation in modulating decarboxylase-based catalysis. Identified phosphorylated residues are distinct from the decarboxylation catalytic site, implicating a phosphorylation-induced global conformational change of MCD as responsible in altering catalytic function. We conclude that phosphorylation of Ser-204 and Tyr-405 regulates the decarboxylase function of hMCD leveraging the silkworm-based BmNPV bacmid expression system that offers a fail-safe eukaryotic production platform implementing proper post-translational modification such as phosphorylation.

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.

Flavonoid-rich fraction from Sageretia theezans leaves scavenges reactive oxygen radical species and increases the resistance of low-density lipoprotein to oxidation.

To explore their bioactive fractions, Sageretia theezans leaves were extracted with 60% acetone and then fractionated sequentially with hexane, ethyl acetate, and water. Reactive oxygen radical species (ROS) (HOCl, ONOO(-), and O(2)(*-)) scavenging activity, oxygen radical absorbance capacity (ORAC) value, and total phenolic content of each fraction were investigated. The ethyl acetate fraction had the largest total phenolic content and ORAC value and displayed the strongest ROS scavenging activity. The ethyl acetate fraction at 2 mumol of gallic acid equivalents/L prolonged the lag time of low-density lipoprotein oxidation by 260% compared to the control. In the ethyl acetate fraction, 7-O-methylmearnsetin 3-O-rhamnoside and the other nine flavonols were characterized using high-performance liquid chromatography with electrochemical detection. The total flavonoid content in the ethyl acetate fraction was 460 mg/g. 7-O-Methylmyricetin 3-O-rhamnoside and 7-O-methylmearnsetin 3-O-rhamnoside were the predominant flavonoids, making up 36% and 17% of the total flavonoid content, respectively.

Antiobesity effects of wild ginseng (Panax ginseng C.A. Meyer) mediated by PPAR-gamma, GLUT4 and LPL in ob/ob mice.

The antiobesity effect of wild ginseng (WG; Panax ginseng C.A. Meyer) in male obese leptin-deficient (B6.V-Lepob, 'ob/ob') mice was evaluated. WG was administered orally to mice at doses of 100 mg/kg and 200 mg/kg daily for 4 weeks. The WG-treated ob/ob mice showed a loss of body weight and a decrease in blood glucose levels compared with control mice. WG regulated the mRNA expression level especially, it increased peroxisome proliferators-activated receptors-gamma (PPAR-gamma) and lipoprotein lipase (LPL) in adipose tissue, as well as glucose transporter 4 (GLUT4) and insulin receptor (IR) in the skeletal muscle and liver. Taken together, these results suggest that WG may play a vital role in the antiobesity effect in ob/ob mice; this has importance in insulin sensitivity. This may prove to be of clinical importance in improving the management of obesity and related metabolic syndromes.

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.

An antioxidant hispidin from the mycelial cultures of Phellinus linteus.

In the course of screening for reactive oxygen species scavengers from natural products, an antioxidant was isolated from the mycelial culture broth of Phellinus linteus and identified as hispidin. The hispidin content was reached its maximum level at 12 days after onset of inoculation. About 2.5 mg/mL of hispidin was produced by P. linteus in a yeast-malt medium (pH 5.8, 25 degrees C). Hispidin inhibited 22.6 and 56.8% of the super oxide anion radical, 79.4 and 95.3% of the hydroxyl radical, and 28.1 and 85.5% of the DPPH radical at 0.1 and 1.0 mM, respectively. The positive control alpha-tocopherol scavenged 25.6 and 60.3%, 74.6 and 96.3%, and 32.7 and 77.5% of each radical, respectively, at the same concentrations. However, hispidin showed no significant activity on the hydrogen peroxide radical.

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.

A prolyl endopeptidase-inhibiting antioxidant from Phyllanthus ussurensis.

A prolyl endopeptidase inhibitor was isolated from the ethyl acetate soluble fraction of Phyllanthus ussurensis. The active compound was identified as an ellagitannin, corilagin. It was shown to non-competitively inhibit prolyl endopeptidase (PEP) with the IC50 value of 1.17x10(-6) microM. The Ki value was 6.70x10(-7) M. Corilagin was less inhibitory to other serine proteases such as chymotrypsin, trypsin, and elastase, indicating that it was relatively a specific inhibitor of PEP. Corilagin also effectively inhibited reactive oxygen species such as hydroxide and superoxide anion radical, hydrogen peroxide, and DPPH. Especially, corilagin showed potent scavenging activity on the superoxide anion radical in the ESR method (IC50 = 3.79x10(-6) M) as well as xanthine oxidase system.

Antioxidative activity of resveratrol and its derivatives isolated from seeds of Paeonia lactiflora.

Seven stilbenes, a new cis-epsilon-viniferin and the six known stilbenes, trans-resveratrol, trans-resveratrol-4'-O-beta-D-glucopyranoside, trans-epsilon-viniferin, gnetin H, and suffruticosol A and B, were isolated and identified from seeds of Paeonia lactiflora. The antioxidative activity of these stilbene derivatives was evaluated against the 2-deoxyribose degradation and rat liver microsomal lipid peroxidation induced by the hydroxyl radical generated via a Fenton-type reaction. Among these stilbenes, trans-epsilon-viniferin and gnetin H significantly inhibited 2-deoxyribose degradation and lipid peroxidation in rat liver microsomes. In addition, cis-epsilon-viniferin, and suffruticosol A and B also exhibited moderate antioxidative activity. These results suggest that resveratrol dimers and trimers, together with resveratrol from seeds of Paeonia lactiflora may be useful as potential sources of natural antioxidants.

Effects of extract from Angelica keiskei and its component, cynaroside, on the hepatic bromobenzene-metabolizing enzyme system in rats.

The effects of Angelica keiskei Koidz. on hepatic lipid peroxide and the activities of free radical generating and scavenging enzymes were investigated in bromobenzene-induced hepatic lipid peroxidation in rats. The level of lipid peroxide elevated by bromobenzene was significantly reduced by the methanol extract from the aerial parts of A. keiskei and its component, cynaroside. Epoxide hydrolase activity was decreased significantly by the treatment of bromobenzene. However, the enzyme activity was restored in the liver of rats given the methanol extract and cynaroside. The results suggest that the reduction of bromobenzene-induced hepatic lipid peroxidation by the extract of A. keiskei and cynaroside under our experimental conditions is thought to be through enhancing the activity of epoxide hydrolase, an enzyme removing bromobenzene epoxide.