Tae-Gyu Nam

Polyphenol-rich blackcurrant extract prevents inflammation in diet-induced obese mice

Obesity is closely associated with chronic, low-grade inflammation. We investigated if polyphenol-rich blackcurrant extract (BCE) can prevent inflammation in vivo. Male C57BL/6J mice were fed a modified AIN-93M control diet containing high fat/high cholesterol (16% fat, 0.25% cholesterol by weight) or the control diet supplemented with 0.1% BCE (wt/wt) for 12 weeks. In BCE-fed mice, the percentage of body weight and adipocyte size of the epididymal fat were significantly lower than those of control mice. There were fewer crown-like structures (CLS) with concomitant decreases in F4/80, cluster of differentiation 68 and inhibitor of nuclear factor κB kinase ε (IKKε) mRNA in the epididymal adipose of BCE-fed mice. F4/80 and IKKε mRNA levels were positively correlated with CLS number. In the skeletal muscle of mice fed with BCE, mRNA expression of genes involved in energy expenditure and mitochondrial biogenesis, including PPARα, PPARδ, UCP-2, UCP-3 and mitochondrial transcription factor A, were significantly increased. When splenocytes from BCE-fed mice were stimulated by lipopolysaccharides, tumor necrosis factor α and interleukin-1β mRNA were significantly lower than control splenocytes. Together, the results suggest that BCE supplementation decreases obesity-induced inflammation in adipose tissue and splenocytes, at least in part, by modulating energy metabolism in skeletal muscle.

Flavonoid analysis of buckwheat sprouts.

It is known that common buckwheat sprouts contain several flavonoids, including orientin, isoorientin, vitexin, isovitexin, rutin, and quercetrin, whereas tartary buckwheat sprouts contain only rutin. In this study, we evaluated flavonoids present in buckwheat sprouts and identified a previously unreported flavonoid. Simultaneous detection by HPLC was used to separate rutin and a compound that was not separated in previous studies. We used a novel HPLC elution gradient method to successfully separate rutin and the previously unidentified compound, for which we performed structural analysis. The identification of six flavonoids by HPLC was confirmed using HPLC-ESI-MS/MS analysis. The newly identified compound, [M+H](+) =611.17, was identified by NMR as the rutin epimer quercetin-3-O-robinobioside. Unlike common buckwheat sprout, tartary buckwheat sprout contained rutin as a main flavonoid, whereas other flavonoids appeared only in trace amounts or were not detected. Quercetin-3-O-robinobioside was not detected in tartary buckwheat sprout.

Anthocyanins in the ripe fruits of Rubus coreanus Miquel and their protective effect on neuronal PC-12 cells

Phenolics of the fresh ripe fruits of Rubus coreanus Miquel were extracted and separated into anthocyanin and the non-anthocyanin fractions, which were used for the evaluation for antioxidant capacity and neuroprotective effects. The anthocyanin fraction accounted for approximately 47-55% of the total antioxidant capacity of the whole extract and had significantly higher free radical-scavenging capacity than the non-anthocyanin fraction. Furthermore, the anthocyanins alleviated intracellular oxidative stress, as assayed by in vitro fluorescent measurements. The anthocyanins showed neuroprotective effects on PC-12 cells in vitro against oxidative stress in a dose-dependent manner. Triple quadrupole LC/MS and Q-TOF LC/MS analyses revealed four major anthocyanins; cyanidin 3-O-sambubioside, cyanidin 3-O-glucoside, cyanidin 3-O-xylosylrutinoside, and cyanidin 3-O-rutinoside in increasing order of amounts. These results demonstrated that anthocyanins are the major components and contributors to the antioxidant capacity of ripe R. coreanus Miquel fruits. Further studies are warranted to determine whether consumption of the fruits reduces oxidative stress in the brain and promotes health.

Protective Effect of Detoxified Rhus verniciflua Stokes on Human Keratinocytes and Dermal Fibroblasts against Oxidative Stress and Identification of the Bioactive Phenolics

Oxidative stress due to the over-production of reactive oxygen species (ROS) is associated with human skin aging. This study was designed to identify the bioactive phenolics in detoxified Rhus verniciflua Stokes (DRVS) that may protect human skin against oxidative stress. Under oxidative stress caused by H2O2, the 40% (v/v) aqueous methanol extract of DRVS protected human keratinocytes in a dose-dependent manner. The expression of matrix metalloproteinase-1 (MMP-1) was also inhibited by the DRVS extract in human dermal fibroblasts-neonatal cells exposed to ultraviolet A. The major bioactive phenolics of DRVS were tentatively identified by LC/Q-TOF-ESI-MS/MS, and included gallic acid, 2-(ethoxymethoxy)-3-hydroxyphenol, fustin, a fustin isomer, tetragalloyl glucose, pentagalloyl glucose, fisetin, sulfuretin, a sulfuretin isomer, and butein. The results suggest that a DRVS extract may be effective in slowing skin aging through its antioxidative properties and by down-regulating MMP-1 expression. Further studies are needed to examine whether this effect would be mediated by the phenolics identified in this study.

New tocopherol analogue with radical-scavenging activity from the peels of Citrus unshiu Marcovich

One new tocopherol analogue, methoxytocopherol (1), and two known analogues, α-tocopherol (2) and γ-tocopherol (3), were isolated from the peels of Citrus unshiu Marcovich. The chemical structures of compounds 1–3 were determined by interpretation of spectroscopic data. All isolated compounds were evaluated for radical-scavenging capacity using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt, 1,1-diphenyl-2-picrylhydrazyl, and oxygen radical absorbance capacity assays.

Additive antioxidant capacity of vitamin C and tocopherols in combination

Vitamin C (ascorbic acid) and vitamin E (tocopherols) are water-soluble and fat-soluble essential nutrients, respectively, present ubiquitously in cellular membranes and plasma through dietary intake of fruits and vegetables. These vitamins act as antioxidants by virtue of their free hydroxyl groups. To quantitatively assess the vitamin C-tocopherol interaction in generating total antioxidant capacity, various binary mixtures of vitamin C and tocopherols (α, β, δ, and γ) were titrated with ABTS radicals. In this assay, the antioxidant capacity of tocopherols increased as follows: β-tocopherol<α-tocopherol<δ-tocopherol<γ-tocopherol. As the total concentration of mixed antioxidants vitamin C and tocopherols increased, the total antioxidant capacity increased linearly. The sum of the individual antioxidant capacities of vitamin C and tocopherol in the assay was very close to the total antioxidant capacity of the corresponding combination of two compounds. Using this assay system, and in the concentration ranges applied, vitamin C and tocopherols in combination displayed additive interaction.

8-hydroxyarctigenin isolated from safflower sprouts inhibits melanogenesis of melan-a cells and light quality during the sprout growth determines the compound yield

Safflower sprouts were grown under different light frequencies and conditions, including fluorescent white light, red LED or blue LED light and darkness. The sprout extracts were tested for their inhibitory effect on melanin synthesis. Two compounds from safflower sprout extract were isolated and tested for their activities. Safflower seeds were sown in growth chambers set to lights and harvested at 9 days after sowing. Methanolic extracts of safflower sprouts were subjected to melanin synthesis inhibitory effect on MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetraxolium Bromide] and melanin bioassay methods with a dose dependent manner. Two compounds were identified by using open column chromatography and LC-MS (liquid chromatography-mass spectrometry) analysis. The MTT and melanin bioassays with the identified compounds were conducted. Darkness or fluorescent white light irradiation induced extracts with inhibitory effects on melanin synthesis (in a dose dependent manner). In contrast, blue light induced extracts to slightly increase melanin synthesis. It was found that 8-hydroxyarctigenin, a compound isolated from the safflower sprouts grown under fluorescent white light for 9 days after germination, induced inhibitory effect of melanin synthesis. The compound was contained more in the darkness or fluorescent white light treatment than others. Safflower sprouts grown under dark or fluorescent white light conditions were more effective on inhibiting melanin synthesis than conditions under red or blue light. An active compound, 8-hydroxyarctigenin, may be a useful whitening agent in cosmetic resources.