Tai-Hyun Kang

Sedative activity of two flavonol glycosides isolated from the flowers of Albizzia julibrissin durazz

The flowers of Albizzia julibrissin are used as a sedative in oriental traditional medicine. The phytochemical study of this plant allowed the isolation of two flavonol glycosides, quercitrin (1) and isoquercitrin (2). The sedative activity of these compounds was evaluated, and both compounds 1 and 2 increased pentobarbital-induced sleeping time in dose-dependent manner in mice. These results support the use of the flowers of this plant as a sedative agent.

Antiproliferative effects of alkaloids from Sedum sarmentosum on murine and human hepatoma cell lines.

The whole plant of Sedum sarmentosum (SS) has been traditionally used for the treatment of chronic viral hepatitis in China and South Korea. Certain hepatitis virus causes acute and chronic hepatitis and induces hepatocellular carcinoma (HC). In the present study, we examined whether the crude alkaloid fraction (CAF) of SS had any anticancer effects on hepatoma cell lines. Murine hepatoma (BNL CL. 2) and human hepatoma (HepG2) cell lines were cultured in the presence of CAF of SS at various doses (50-150 microg/ml) for 24 or 48 h. CAF caused a dose-dependent inhibition of cell proliferation without necrosis or apoptosis. Antiproliferative effects of CAF of SS were associated with an increase in the number of cells in the G1 phase of cell cycle. This study suggests that SS may improve survival of hepatoma patients via the inhibition of excessive growth of tumor cells.

An isocoumarin with hepatoprotective activity in Hep G2 and primary hepatocytes from Agrimonia pilosa.

Phytochemical investigation of the aqueous extract of the roots of Agrimonia pilosa Ledeb. (Rosaceae), as guided by hepatoprotective activityin vitro, furnished two isocoumarins, agrimonolide (1) and agrimonolide 6-O-β-D-glucoside (3), and (+)-catechin (2). Compound 1 showed hepatoprotective effects on both tacrine-induced cytotoxicity in human liver-derived Hep G2 cells andtert-butyl hydroperoxide-induced cytotoxicity in rat primary hepatocytes with EC50 values of 88.2 ± 2.8 and 37.7 ± 1.6 μM, respectively.

Inhibitory effects of butanol fraction of the aqueous extract of Forsythia koreana on the nitric oxide production by murine macrophage-like RAW 264.7 cells.

The aim of this study was to investigate the effect of butanol fraction of the aqueous extract of Forsythia koreana fruits on the nitric oxide (NO) production and inducible nitric oxide synthesis (iNOS) gene expression in murine macrophage-like RAW 264.7 cells. Butanol fraction alone affected neither NO production nor iNOS gene expression in macrophage-like RAW 264.7 cells. However, the butanol fraction inhibited NO production and iNOS gene expression in RAW 264. 7 cells stimulated with interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS). These findings suggest that inhibition of NO production by this butanol fraction in RAW 264.7 cells stimulated with IFN-gamma plus LPS was due to the suppression of iNOS gene expression.

Protective Effect of Jakyak-Gamcho-Tang Extract and Its Constituents Against t-BHP-Induced Oxidative Damage in HT22 Cells

The present study investigated whether Jakyak-Gamcho-Tang (JGT, Shaoyao-Gancao-tang) and its constituents have the protective effect against tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity on hippocampal HT22 cell line. JGT consists of two medicinal herbs, Paeoniae Radix (PR) and Glycyrrhizae Radix (GR). In contrast to treating with t-BHP alone, pre-treatment of HT22 cells with JGT, PR and GR (50-400 microg/ml) for 3 hours significantly increased the cell viability in a concentration-dependent manner. In addition, JGT, PR and GR exhibited the scavenging activity in both 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion assays. Among the tested extracts, PR showed the most potent protective and antioxidative activities. These results suggest that PR acts as an antioxidant and this property may contribute to the neuroprotective activity of JGT extract.

Effects of Aqueous Extract of Sophora flavescens on the Expression of Cell Cycle Regulatory Proteins in Human Oral Mucosal Fibroblasts

Sophorae Radix, the dried roots of Sophora flavescens AITON (Leguminosae), has been used in Oriental traditional medicine for treatment of skin and mucosal ulcers, sores, gastrointestinal hemorrhage, diarrhea, inflammation and arrhythmia. In the present study, we examine the effect of the aqueous extract of Sophorae Radix (AESR) on cell proliferation and cell cycle regulation in human oral mucosal fibroblasts (HOMFs). To study the molecular mechanisms of cell cycle regulation by AESR, we also measured the intracellular levels of cell cycle regulatory proteins such as cyclin D, cyclin-dependent kinases (CDK)-4, CDK-6, cyclin E, CDK-2, p53, p21WAF1/CIP1 and p16INK4A. Cell proliferation was increased in the presence of 10 approximately 500 microg/ml of AESR. Maximal growth stimulation was observed in those cells exposed to 100 microg/ml of AESR. Exposure of HOMFs to 100 microg/ml of AESR resulted in an increase of cell cycle progression. The levels of cyclin E and CDK-2 were increased in HOMFs after 100 microg/ml of AESR treatment, but the levels of cyclin D, CDK-4, and CDK-6 were unchanged. After exposure to 100 microg/ml of AESR, the protein levels of p16INK4A and p53 were decreased as compared to that of the control group, but the level of p21WAF1/CIP1 was similar in the cells treated with 100 microg/ml of AESR and untreated cells. The results suggest that AESR may increase cell proliferation and cell cycle progression in HOMFs, which is linked to increased cellular levels of cyclin E and CDK-2 and decreased cellular levels of p53 and p16INK4A. Further studies are necessary to clarify the active constituents of AESR responsible for such biomolecular activities.