Jeong Hill Park

High-performance liquid chromatographic analysis of ginseng saponins using evaporative light scattering detection

Abstract Ginseng saponins were analysed using HPLC with evaporative light scattering detection (ELSD). A LiChrosorb NH 2 column was used to separate ginseng saponins in white and red ginseng. The complete separation of ginsenoside Rb 1 , Rb 2 , Rc, Rd, Re, Rf, Rg 1 , Rg 2 , Rg 3 and Rh 1 was achieved within 35 min with an amino-bonded column using an acetonitrile-water-2-propanol gradient system. The ELSD drift tube temperature was set at 145°C and the nitrogen flow was set at 40 mm rotameter units. The detection limits ( S / N =3) of the ginsenosides ranged from 35 to 155 ng.

Aloesin and arbutin inhibit tyrosinase activity in a synergistic manner via a different action mechanism

In this study, we present evidence that cotreatment of aloesin and arbutin inhibits tyrosinase activity in a synergistic manner by acting through a different action mechanism. Aloesin or arbutin similarly inhibited enzyme activity of human- and mushroom-tyrosinases with an IC50 value of 0.1 or 0.04 mM, respectively. Lineweaver-Burk plots of the enzyme kinetics data showed that aloesin inhibited tyrosinase activity noncompetitively with a Ki value of 5.3 mM, whereas arbutin did it competitively (Maeda, 1996). We then examined whether cotreatment of these agents inhibits the tyrosinase activity in a synergistic manner. The results showed that 0.01 mM aloesin in the presence of 0.03 mM arbutin inhibited activity of mushroom by 80% of the control value and the reverse was also true. The inhibitory effects were calculated to be synergistic according to the Bürgi method. Taken together, we suggest that aloesin along with arbutin inhibits in synergy melanin production by combined mechanisms of noncompetitive and competitive inhibitions of tyrosinase activity.

Cdk2 activity is associated with depolarization of mitochondrial membrane potential during apoptosis

In this study we show that panaxadiol, a ginseng saponin with a dammarane skeleton, induces apoptotic cell death by depolarization of mitochondrial membrane potential in human hepatoma SK-HEP-1 cells. Sequential activation of caspases-9, -3, and -7, but not of caspase-8, occurs after mitochondrial membrane depolarization and cytochrome c release from the mitochondria of panaxadiol-treated cells. Moreover, Cdk2 kinase activity, but not Cdc2 kinase activity, is markedly upregulated in the early stages of apoptosis. Olomoucine or roscovitine, specific Cdks inhibitors, effectively prevent mitochondrial membrane depolarization as well as apoptotic cell death in panaxadiol-treated cells. Thus, panaxadiol-treatment induces cell death-dependent activation of Cdk2 kinase activity, which is functionally associated with depolarization of mitochondrial membrane potential and subsequent cytochrome c release.

Ginsenoside Rs(3), a genuine dammarane-glycoside from Korean red ginseng.

A genuine dammarane-glycoside, named as ginsenoside Rs3, was isolated from the MeOH extracts of Korean red ginseng (Panax ginseng C.A. Meyer) through repeated silica gel column chromatographies and its chemical structure was determined as (20S)-protopanaxadiol 3-O-[6″-O-acetyl-β-D-glucopyranosyl (1→2)-β-D-glucopyranoside on the basis of several spectral and physical evidences including HMBC and FAB-MS.

Determination of betaine in Lycium chinense fruits by liquid chromatography-electrospray ionization mass spectrometry.

A rapid and sensitive high-performance liquid chromatography-electrospray mass spectrometric method has been developed for the determination of betaine in Lycium chinense fruits. Betaine was analyzed on a system consisting of a NH2 stationary phase and a mobile phase of water-acetonitrile (25:75) by isocratic elution for 40 min. Betaine was identified and quantitated by electrospray ionization mass spectrometry with selected ion monitoring of the protonated ion [Betaine+H]+ and clustered ions [nBetaines+H]+. The limit of detection for betaine by this method was ca. 0.2 ng/ml and the relative standard deviations of the assay (intra- and inter-day) were less than 8.1%.

Sesquiterpene alkaloids from Euonymus japonica

Abstract Five new sesquiterpene alkaloids, euojaponine A, C, I, L, and M, and a known compound, mayteine, were isolated from the root bark of Euonymus japonica . The structures of these compounds were elucidated by various spectroscopic methods.

Studies on the constituents of PhilippinePiper betle leaves

Fourteen volatile components including eight allypyrocatechol analgos were isolated and identified from the essential oil and ether soluble fraction of PhilippinePiper betle leaves (Piperaceae). The major constituents of PhilippinePiper betle oil were chavibetol and chavibetol acetate. Capillary GC analysis of the oil showed chavibetol (53.1%), chavibetol acetate (15.5%), caryophyllene (3.79%), allypyroacatechol diacetate (0.71%), campene (0.48%), chavibetol methyl ether (=methyl eugenol, 0.48%), eugenol (0.32%), α-pinene (0.21%), β-pinene (0.21%), α-limonene (0,14%), safrole (0.11%), 1,8-cineol (0.04%), and allylpyrocatechol monoacetate. The major component of the ether soluble fraction was allylpyrocatechol (2.38% of the leaves).

Studies on the alkaloidal components of the fruits ofLycium chinense

N9-Formylharman, 1-carbomethoxy-β-carboline and perlolyrine with an unidentified alkaloid (C10H13NO2, M+ 179.094) have been isolated from the fruits ofLycium chinense Miller (Solanaceae) and characterized on the basis of chemical and physical evidence.

ALOESIN UP-REGULATES CYCLIN E/CDK2 KINASE ACTIVITY VIA INDUCING THE PROTEIN LEVELS OF CYCLIN E, CDK2, AND CDC25A IN SK-HEP-1 CELLS

In the present study, we show that aloesin, which is a low molecular weight ingredients present in Aloe vera, stimulates the proliferation of cultured human hepatoma SK‐HEP‐1 cells. The incorporation of [3H] thymidine into DNA in the cell cultures was significantly increased at a dose of 10 μM aloesin. The aloesin‐induced DNA synthesis appears to require newly synthesized proteins because cycloheximide treatment blocked the DNA synthesis evoked by this compound. We then examined whether this compound increases the intracellular levels of cell cycle regulators by immunoblotting. The data showed that aloesin increased the levels of cyclin E, CDK2, and CDC25A in SK‐HEP‐1 cells. In addition, immuno‐complex kinase assays showed that aloesin up‐regulated the enzyme activity of cyclin E/CDK2 kinase in a dose‐dependent manner. Collectively, these results suggest that aloesin stimulates the proliferation of SK‐HEP‐1 cells by inducing the intracellular levels of cyclin E/CDK2 kinase complex and CDC25A, which, together, result in the up‐regulation of cyclin E‐dependent kinase activity.

High performance liquid chromatographic determination of ginsenosides using photoreduction fluorescence detection

Abstract A high performance liquid chromatographic method using photoreduction fluorescence detection was described for the analysis of ginsenosides. Ginsenosides were separated on an amino column using acetonitrile and aqueous 2-tert-butylanthraquinone(t-BAQ) solution. Column effluent was passed through a 45cm-PTFE capillary tube coiled around a 10W-UV lamp to reduce t-BAQ to a highly fluorescent dihydroxy anthracene derivative which was detected by a fluorescence detector. The detection limit for the ginsenoside Rg1 by this method was found to be about 130ng. This method is less influenced by other UV-absorbing compounds compared to the conventional HPLC-UV detection method.