Scopoletin from Cirsium setidens Increases Melanin Synthesis via CREB Phosphorylation in B16F10 Cells

In this study, we isolated scopoletin from Cirsium setidens Nakai (Compositae) and tested its effects on melanogenesis. Scopoletin was not toxic to cells at concentrations less than 50 microM and increased melanin synthesis in a dose-dependent manner. As melanin synthesis increased, scopoletin stimulated the total tyrosinase activity, the rate-limiting enzyme of melanogenesis. In a cell-free system, however, scopoletin did not increase tyrosinase activity, indicating that scopoletin is not a direct activator of tyrosinase. Furthermore, Western blot analysis showed that scopoletin stimulated the production of microphthalmia-associated transcription factor (MITF) and tyrosinase expression via cAMP response element-binding protein (CREB) phosphorylation in a dose-dependent manner. Based on these results, preclinical and clinical studies are needed to assess the use of scopoletin for the treatment of vitiligo.

Acute Toxicity and General Pharmacological Action of QGC EXT

It has been shown that QGC isolated and purified from Rumecis folium found protective effects of gastritis and esophagitis which EXT is an ethanol extract of it. We examined acute toxicity and the general pharmacological action of QGC EXT to search for any side effects of it in rats, mice, guinea pigs, and cats. In a single dose toxicity study, QGC EXT didn't show toxicological effects in rats and mice, and the LD50 was over 5 g/kg in both animals, and there were also no changes in weight, feed and water intake during these toxicological experimental periods. We examined the general pharmacological action on central controlled behavior responses, and peripheral organs including blood pressure, heart rate, respiration and gastrointestinal system, We found that there were no significant changes in body temperature, locomotors activity, stereotyped behaviors, sleeping time, and convulsion. In other studies, writhing reaction, normal body temperature, there did not appear to be any changes. The large intestine movement and electrical field stimulation-induced contraction was not changes by its EXT. In addition, the influences on blood pressure, heart rates, and respiration by QGC EXT were not found. These results indicate that QGC EXT may be very safe as a new drug, since its LD50 was very high over 5 g/kg and any side effects were not found.

The Protective Effect of Quercetin-3-O-beta-D-Glucuronopyranoside on Ethanol-induced Damage in Cultured Feline Esophageal Epithelial Cells

Quercetin-3-O-beta-D-glucuronopyranoside (QGC) is a flavonoid glucoside extracted from Rumex Aquaticus Herba. We aimed to explore its protective effect against ethanol-induced cell damage and the mechanism involved in the effect in feline esophageal epithelial cells (EEC). Cell viability was tested and 2',7'-dichlorofluorescin diacetate assay was used to detect intracellular H2O2 production. Western blotting analysis was performed to investigate MAPK activation and interleukin 6 (IL-6) expression. Exposure of cells to 10% ethanol time-dependently decreased cell viability. Notably, exposure to ethanol for 30 min decreased cell viability to 43.4%. When cells were incubated with 50 microM QGC for 12 h prior to and during ethanol treatment, cell viability was increased to 65%. QGC also inhibited the H2O2 production and activation of ERK 1/2 induced by ethanol. Pretreatment of cells with the NADPH oxidase inhibitor, diphenylene iodonium, also inhibited the ethanol-induced ERK 1/2 activation. Treatment of cells with ethanol for 30 or 60 min in the absence or presence of QGC exhibited no changes in the IL-6 expression or release compared to control. Taken together, the data indicate that the cytoprotective effect of QGC against ethanol-induced cell damage may involve inhibition of ROS generation and downstream activation of the ERK 1/2 in feline EEC.

Methyl gallate and chemicals structurally related tomethyl gallate protect human umbilical vein endothelial cells from oxidative stress

Methyl gallate (meGAL) is known as one of major antioxidants. To investigate whether meGAL protects human cells from oxidative stress, meGAL extracted from Korean medicinal plant, Cercis chinensis leaves, was primarily screened using cell viability assay against oxidative stress. Human umbilical vein endothelial cells (HUVECs) were treated with three different concentrations of meGAL for indicated time. After or during meGAL treatment, H2O2 was added and incubated. meGAL showed free radical scavenging effect at low concentration (0.02 mM) and cell protective effect against H2O2-mediated oxidative stress. meGAL recovered viability of HUVECs damaged by H2O2-treatment, reduced the lipid peroxidation (LPO) and decreased the internal reactive oxygen species (ROS) level elevated by H2O2-treatment. Free radical scavenging effect of meGAL was proven to be very high. Differential display reverse transcription-PCR analysis showed that meGAL upregulated the levels of regulator of chromatin condensation 1, type 1 sigma receptor and phosphate carrier protein expressions, respectively. Based on structural similarity compared with meGAL, 14 chemicals were chosen and viability assay was performed. Four chemicals, haematommic acid (56.2% enhancement of viability), gallic acid (35.0%), methylorsellinic acid (23.7%), and syringic acid (20.8%), enhanced more potent cell viability than meGAL, which showed only 18.1% enhancement of cell viability. These results suggest that meGAL and four meGAL-related chemicals protect HUVECs from oxidative stress.

Natural compounds, fraxin and chemicals structurally related to fraxin protect cells from oxidative stress

Coumarins comprise a group of natural phenolic compounds found in a variety of plant sources. In view of the established low toxicity, relative cheapness, presence in the diet and occurrence in various herbal remedies of coumarins, it appears prudent to evaluate their properties and applications further. The purpose of this study is to investigate cellular protective activity of coumarin compound, fraxin extracted from Weigela florida var. glabbra, under oxidative stress, to identify genes expressed differentially by fraxin and to compare antioxidative effect of fraxin with its structurally related chemicals. Of the coumarins, protective effects of fraxin against cytotoxicity induced by H2O2 were examined in human umbilical vein endothelial cells (HUVECs). Fraxin showed free radical scavenging effect at high concentration (0.5 mM) and cell protective effect against H2O2-mediated oxidative stress. Fraxin recovered viability of HUVECs damaged by H2O2- treatment and reduced the lipid peroxidation and the internal reactive oxygen species level elevated by H2O2 treatment. Differential display reverse transcription-PCR revealed that fraxin upregulated antiapoptotic genes (clusterin and apoptosis inhibitor 5) and tumor suppressor gene (ST13). Based on structural similarity comparing with fraxin, seven chemicals, fraxidin methyl ether (29.4% enhancement of viability), prenyletin (26.4%), methoxsalen (20.8 %), diffratic acid (19.9%), rutoside (19.1%), xanthyletin (18.4%), and kuhlmannin (18.2%), enhanced more potent cell viability in the order in comparison with fraxin, which showed only 9.3% enhancement of cell viability. These results suggest that fraxin and fraxin-related chemicals protect HUVECs from oxidative stress.