Inhibitory effects of Taraxacum mongolicum with phreatic water on melanin synthesis.

BACKGROUND: Recently, people have begun showing heightened interest in skin whitening. Melanin is an important factor that determines skin color. The purpose of this study is to investigate the inhibitory effect of Taraxacum mongolicum (TAM) with phreatic water (PW) from Dogo Hot Springs on melanin synthesis. METHODS: We assessed the inhibitory effects of TAM on melanin synthesis in B16F10 mouse melanoma cells. The mRNA levels of tyrosinase related protein (TRP)-1, TRP-2, tyrosinase, MITF, ERK, and PKA protein were analyzed with reverse transcription polymerase chain reaction and Western blot analysis. We also assessed the inhibitory effects of TAM with PW on melanin synthesis in HRM-2 melanin-possessing hairless mice. After UVB irradiation, differences in melanin were analyzed with an image analysis software between the left dorsal skin (untreated part) and the right dorsal skin (treated part). The mRNA levels of TRP-1, TRP-2, and matrix metalloproteinase (MMP)-9 were analyzed with real-time quantitative polymerase chain reaction. The dorsal skins were analyzed with histological test by hematoxylin and eosin staining. RESULTS: TAM inhibited the TRP-1, TRP-2, tyrosinase, MITF mRNA gene expression, and PKA protein expression on the concentration-dependent B16F10 cell. Moreover, TAM increased the ERK mRNA gene expression in the B16F10 cell. After UVB irradiation, TAM with PW increased the differences in melanin between the left dorsal skin (untreated part) and the right dorsal skin (treated part) in HRM-2 mice. TAM with PW inhibited the TRP-1, TRP-2, and MMP-9 mRNA gene expression in HRM-2 mice. TAM with PW decreased the epidermal thickness, around the cell deformation, keratinization, and infiltration in HRM-2 mice. CONCLUSION: These results indicate that TAM with PW has the inhibitory effect of decreasing the melanin synthesis.

The abuse potential of oxethazaine: effects of oxethazaine on drug-seeking behavior and analysis of its metabolites in plasma and hair in animal models.

Oxethazaine, an over-the-counter (OTC) antacid, is a precursor of phentermine, which is the most abused anorectic by methamphetamine users in Korea. However, no studies have investigated the abuse potential of oxethazaine. Therefore, we examined and compared the consequences of oxethazaine and phentermine treatment on animal models of conditioned place preference (CPP) and self-administration. Furthermore, oxethazaine and its metabolites in rat plasma were monitored using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after oxethazaine administration, and compared with phentermine itself after phentermine administration to clarify the relationship between phentermine production by oxethazaine ingestion and the possible oxethazaine dependence. Oxethazaine metabolites were also determined by LC-MS/MS in rat hair after oxethazaine administration to investigate the possibility of phentermine detection in hair from oxethazaine abusers. In the behavioral experiment, phentermine (3mg/kg) produced CPP in mice while oxethazaine (5, 10, and 15mg/kg) did not. Moreover, phentermine (0.25mg/kg/infusion) was self-administered by rats at 80% of free-feeding weight, whereas oxethazaine was not. In the analytical study, mephentermine and phentermine, both oxethazaine metabolites, were detected below the limit of quantitation or not detected in both plasma and hair from rats that had ingested oxethazaine (10mg/kg, single dose or for 2weeks). On the other hand, phentermine was detected in plasma and hair samples from rats that had ingested phentermine (10mg/kg, single dose or for 2weeks). Consequently, phentermine induced significant rewarding effects, but oxethazaine did not. Presumably, either oxethazaine does not have any abuse potential or oxethazaine metabolism to phentermine does not result in a pharmacologically active level of psychostimulant in the body. Furthermore, phentermine was not a major metabolite in hair obtained from oxethazaine abusers, which should make it possible to differentiate between chronic oxethazaine and phentermine users.

Cytoprotective effect of lignans from Forsythia suspensa against peroxynitrite-induced LLC-PK1 cell damage.

There is mounting evidence that peroxynitrite (ONOO(-)) is closely related to the pathogenesis of various diseases. As a pharmacological strategy aimed at preventing ONOO(-)-mediated toxicity, the protective activity of Forsythia suspensa (Thunb.) Vahl (Oleaceae) against ONOO(-)-induced cellular damage was investigated and its active components identified. After bioactivity-guided fractionation of its methylene chloride fraction, two tetrahydrofurofuran lignans were isolated, namely phillygenin and 8-hydroxypinoresinol. The protective effects of these lignans against ONOO(-)-induced cell death were evaluated using renal epithelial cell LLC-PK1. Phillygenin and 8-hydroxypinoresinol significantly reduced the cell injury by 3-morpholinosydnonimine (SIN-1), a ONOO(-) generator. The hydroxy substituents on the phenyl moieties may contribute to the antioxidant activities of these lignans. These results suggest that phillygenin and 8-hydroxypinoresinol may be useful for the therapeutic or preventive applications in treating ONOO(-)-related diseases.

Hydroxyl radical scavenging activities of isoquinoline alkaloids isolated from Coptis chinensis.

The hydroxyl radical (*OH) scavenging and ferrous ion chelating activities of four isoquinoline alkaloids isolated from Coptis chinensis Franch were studied for the identification of their structural characteristics to scavenge *OH. The *OH was generated via Fe(II)-catalazed Fenton reaction in this study and the reliable measurement of *OH scavenging activities of isoquinoline alkaloids were achieved using electron spin resonance (ESR) spectrometry method. At the 1 mM concentration, berberrubine (85%) showed the strongest *OH scavenging activity and the next were in the decreasing order of coptisine (79%), berberine (23%), and palmatine (22%). The ferrous ion chelating effects of the alkaloids showed similar pattern with their *OH scavenging effects. These results suggest that *OH scavenging effects of the alkaloids were closely related to their ferrous ion chelating activities. In addition, metal chelating functional groups such as hydroxy group at C-9 and methylenedioxy group at C-9 and C-10 were thought to contribute to the *OH scavenging activities of the isoquinoline alkaloids.

Characterization of increased phenolic compounds from fermented Bokbunja (Rubus coreanus Miq.) and related antioxidant activity.

This study examined the changes in the phenolic acid-content and antioxidant activity of Rubi Fructus (RF), the fruit of Rubus coreanus Miq., after fermentation with yeast (Saccharomyces cerevisiae). The phenolic acids were fractionated into three forms, free (Fr. A), ester (Fr. B), and insoluble-bound phenolic acids (Fr. C) and quantified by high performance liquid chromatography with a diode array detector (HPLC-DAD). This method was validated and allowed the successful identification of 11 phenolic acids in the RF extracts. HPLC-DAD analysis of the samples showed substantial increases in the levels of protocatechuic, vanillic and p-coumaric acid as the result of yeast fermentation. The total phenolic content (TPH) was also increased by fermentation. The total phenolics in Fr. A and Fr. B increased from 117 to 173 mg GAE/100 g and from 488 to 578 mg GAE/100 g, respectively. The total phenolics in Fr. C decreased from 264 to 175 mg GAE/100 g. The antioxidant activity of the fermented RF was measured as the 1,1-diphenoly-2-picrylhydrazyl (DPPH) radical scavenging capacity, which is expressed as the IC(50). The IC(50) for Fr. A and Fr. B decreased from 5.9 to 4.0 mg/ml (mg of dried RF equiv./ml) and from 1.2 to 0.8 mg/ml, respectively. In Fr. C, the IC(50) value increased from 2.1 to 2.8 mg/ml. In summary, the fermented RF had a higher total phenolic content and better DPPH radical-scavenging activity than the unfermented material.

Inhibition of cholinesterase and amyloid-beta aggregation by resveratrol oligomers from Vitis amurensis.

In the course of screening for acetylcholinesterase and butyrylcholinesterase inhibitors from natural products by an in vitro Ellman method, the extract of the roots of Vitis amurensis Rupr. (Vitaceae) showed significant cholinesterase inhibitory activity. Employing a bioassay-linked HPLC method, followed by a semi-preparative HPLC method, two compounds of interest were isolated and characterized as vitisin A and heyneanol A. They inhibited effectively both acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner and exhibited higher activity against butyrylcholinesterase compared with that of galantamine, a positive control. Furthermore, the aggregation of beta-amyloid was evaluated in vitro based on a thioflavine T fluorescence assay to expand their activity profile, with the result that both compounds showed the ability to block beta-amyloid aggregation.

Lignans from the fruits of Forsythia suspensa.

Bioactivity-guided fractionation of the methanol extract of the fruits of Forsythia suspensa Vahl has led to the isolation of two new monoepoxylignans, forsythialan A (1) and B (2), together with a known tetrahydrofurofuran lignan, phillyrin (3). The structures of compounds 1 and 2 were elucidated by spectroscopic methods. The antioxidant activities of these lignans have been assessed by evaluating their protective effects against peroxynitrite-induced oxidative stress. The compounds 1 and 2 showed protective effects against renal epithelial cell injury by 3-morpholinosydnonimine (SIN-1), a peroxynitrite generator. The relatively stronger antioxidant activities of compounds 1 and 2 may be associated with the presence of aromatic hydroxy function.

Cytoprotective effect of baicalein against peroxynitrite-induced toxicity in LLC-PK(1) cells.

The various reactions of peroxynitrite (ONOO(-)) with enzymes, macromolecules and lipids, have been shown to influence cellular functions and may be involved in the pathogenesis of various diseases. Therefore, targeting ONOO(-)-induced cytotoxicity is now accepted as a viable strategy to alleviate disease signs in numerous diseases. There is a growing interest in the antioxidant characteristics and use of dietary flavonoids in the management of ONOO(-)-related diseases. Baicalein, a major bioactive flavonoid constituent of Scutellaria baicalensis Georgi, possesses a multitude of pharmacological activities that have been associated with its antioxidant effects. In this study, we have investigated the ONOO(-) scavenging ability of baicalein and its protective effect on ONOO(-)-induced cell death in cultured LLC-PK(1) cells. Baicalein was able to scavenge ONOO(-) in a concentration-dependent manner, which was comparable to penicillamine. In addition, baicalein at the concentration range of 10-50 microM increased cell viability and decreased LDH leakage in 3-morpholinosydnonimine (SIN-1)-treated cells, reflecting its prevention of ONOO(-)-induced cytotoxicity. These results suggest that the protective effects of baicalein can be explained with respect to its ability to scavenge ONOO(-) and may be useful as a possible therapeutic strategy for the treatment of involved diseases.

Resveratrol oligomers from Vitis amurensis attenuate beta-amyloid-induced oxidative stress in PC12 cells.

Oxidative damage induced by beta-amyloid (Abeta) is closely associated with the hallmark pathologies of Alzheimer's disease (AD) and may play a critical role in the development of AD. In this study, the protective effects of vitisin A and heyneanol A, resveratrol oligomers isolated from Vitis amurensis Rupr. (Vitaceae), against Abeta-induced oxidative cell death were investigated using rat pheochromocytoma (PC12) cells. Exposure of PC12 cells to the Abeta (20 microM) for 24 h resulted in neuronal cell death, whereas pretreatment with vitisin A or heyneanol A at the concentration range of 5-50 microM reduced Abeta-induced cell death. In addition, Abeta-induced elevation of reactive oxygen species generation, the primary cause of Abeta-induced oxidative stress, was attenuated by treatment of vitisin A or heyneanol A (10, 25, 50 microM). Abeta-treated cells also displayed characteristic features of apoptosis such as induction of DNA fragmentation and caspase-3 activation, but vitisin A and heyneanol A (10, 50 microM) significantly suppressed these events. These results suggest that vitisin A and heyneanol A prevent Abeta-induced neurotoxicity through attenuating oxidative stress induced by Abeta, and may be useful as potential preventive or therapeutic agents for AD.