Biomedical subjects

Hyoung Ja Kim

Publications and source records attributed to Hyoung Ja Kim.

At least 19 recordsLinked to original sources

PubMed2006

Secondary metabolites from Opuntia ficus-indica var. saboten.

A butanol fraction, from the methanolic extract of Opuntia ficus-indica var. saboten, on purification either by preparative TLC or reversed phase HPLC, yielded three chemical components: isorhamnetin 3-O-(6''-O-E-feruloyl)neohesperidoside (1), (6R)-9,10-dihydroxy-4,7-megastigmadien-3-one-9-O-beta-D-glucopyranoside (2) and (6S)-9,10-dihydroxy-4,7-megastigmadien-3-one-9-O-beta-D-glucopyranoside (3) along with 15 known compounds. Structures of compounds (1-3) were elucidated by aid of spectroscopic analyses. The absolute stereochemistry in compounds 2 and 3 was established with the help of CD data analysis and comparison with the literature data. In a DPPH radical scavenging assay, compound 1 showed moderate inhibitory activity (IC50 = 45.58 microg/ml).

Magnetic Resonance Spectroscopy↗

PubMed2006

Synthesis of tyrosinase inhibitory kojic acid derivative.

Kojic acid derivative 2 was synthesized by joining two pyrone rings through an ethylene linkage by Horner-Emmons reaction of phosphonate 6 with aldehyde 7. The intermediates 6 and 7 were derived from kojic acid. The tyrosinase inhibitory activity of 2 was about 8 times more potent (IC(50) = 3.63 microM) than that of kojic acid (IC(50) = 30.61 microM). Compound 2 also exhibited potent melanin synthesis inhibitory activity (19.53% inhibition at 5 mug) indicating that the connection of two pyrone rings of kojic acid through a suitable linker can be an useful strategy for identification of potent tyrosinase inhibitors.

Animals↗

PubMed2006

Vanillic acid glycoside and quinic acid derivatives from Gardeniae Fructus.

Bioassay-directed chromatographic fractionation of an ethyl acetate extract of Gardenia jasminoides (Gardeniae Fructus) afforded a new vanillic acid 4-O-beta-d-(6'-sinapoyl)glucopyranoside (1) and five new quinic acid derivatives, methyl 5-O-caffeoyl-3-O-sinapoylquinate (2), ethyl 5-O-caffeoyl-3-O-sinapoylquinate (3), methyl 5-O-caffeoyl-4-O-sinapoylquinate (4), ethyl 5-O-caffeoyl-4-O-sinapoylquinate (5), and methyl 3,5-di-O-caffeoyl-4-O-(3-hydroxy-3-methyl)glutaroylquinate (6), together with three known quinic acid derivatives, two flavonoids, two iridoids, and two phenolic compounds. The structures of new compounds were elucidated by the aid of spectroscopic methods. These compounds were assessed for antioxidant activity using three different cell-free bioassay systems and for HIV-1 integrase inhibitory activity. Five new quinic acid derivatives showed potent DPPH radical scavenging, superoxide anion scavenging, and lipid peroxidation inhibition activities. These new quinic acid derivatives also exhibited HIV-1 integrase inhibitory activity.

Antioxidants↗

PubMed2005

An update on bioactive plant lignans.

Lignans are a class of secondary plant metabolites produced by oxidative dimerization of two phenylpropanoid units. Although their molecular backbone consists only of two phenylpropane (C6-C3) units, lignans show an enormous structural diversity. There is a growing interest in lignans and their synthetic derivatives due to applications in cancer chemotherapy and various other pharmacological effects. This review deals with lignans possessing anticancer, antioxidant, antimicrobial, anti-inflammatory and immunosuppressive activities, and comprises the data reported in more than 100 peer-reviewed articles, so as to highlight the recently reported bioactive lignans that could be a first step towards the development of potential new therapeutic agents.

Anti-Bacterial Agents↗

PubMed2005

Two new antioxidant stilbene dimers, parthenostilbenins A and B from Parthenocissus tricuspidata.

The ethyl acetate fraction of an aqueous alcoholic extract from the stem of Parthenocissus tricuspidata yielded 11 known compounds (1-11) and two new stilbene dimers parthenostilbenins A (12) and B (13) upon purification either by preparative TLC or reversed phase HPLC. The structures of the new isolates were identified using a combination of FAB-MS and NMR. These compounds were assessed for antioxidant activities in three different bioassay systems. Among them, piceatannol showed the strongest inhibitory activity in these assay systems. Two new compounds, parthenostilbenins A (12) and B (13) inhibited lipid peroxidation (IC (50) = 20.35 +/- 1.22 and 18.68 +/- 0.51 microg/mL, respectively) in a rat liver homogenate.

Animals↗

PubMed2005

Identification of tyrosinase inhibitors from Glycyrrhiza uralensis.

Tyrosinase is a key enzyme in the production of melanins. Phytochemical studies of a Glycyrrhiza uralensis extract were performed by measuring the tyrosinase and melanin synthesis inhibitory activity. Glycyrrhisoflavone and glyasperin C were identified as tyrosinase inhibitors for the first time. Glyasperin C showed a stronger tyrosinase inhibitory activity (IC (50) = 0.13 +/- 0.01 microg/mL) than glabridin (IC (50) = 0.25 +/- 0.01 microg/mL) and a moderate inhibition of melanin production (17.65 +/- 8.8 % at 5 microg/mL). Glycyrrhisoflavone showed a strong melanin synthesis inhibitory activity (63.73 +/- 6.8 % inhibition at 5 microg/mL). These results suggest that glyasperin C and glycyrrhisoflavone could be promising candidates in the design of skin-whitening agents.

Enzyme Inhibitors↗

PubMed2005

Identification of new dicaffeoylquinic acids from Chrysanthemum morifolium and their antioxidant activities.

Two new dicaffeoylquinic acids, 3,5-dicaffeoyl- epi-quinic acid (1) and 1,3-dicaffeoyl- epi-quinic acid (2), were isolated from Chrysanthemum morifolium Ramar together with six known dicaffeoylquinic acid derivatives and three flavonoids. The structures of the new compounds were elucidated using of spectroscopic methods. These compounds were assessed for antioxidant activities in the DPPH radical and superoxide anion radical scavenging systems. Most of the isolates showed strong antioxidant activities in these assay systems. Two new compounds showed potent superoxide anion radical scavenging activity (IC50 = 2.9 +/- 0.1 for 1 and 2.6 +/- 0.4 microg/mL for 2, respectively) in the xanthine/xanthine oxidase system as compared to quercetin and also showed potent DPPH radical scavenging activity (IC50 = 5.6 +/- 0.1 for 1 and 5.8 +/- 0.2 microg/mL for 2, respectively).

Antioxidants↗

PubMed2004

Antioxidant caffeic acid derivatives from leaves of Parthenocissus tricuspidata.

Five caffeic acid derivatives; methyl ester of caffeoylglycolic acid (1), dimethyl ester of caffeoyltartaric acid (2), dimethyl ester of caffeoyltartronic acid (3), monomethyl ester of caffeoyltartronic acid (4), methyl ester of caffeic acid (5), and some other secondary metabolites including; quercetin, quercetin 3-O-beta-D-glucuronide methyl ester, kaempferol, 3,5,7,4'-O-tetramethylkaempferol, beta-sitosterol glucoside, 2alpha-hydroxyursolic acid and 2,24-dihydroxyursolic acid, have been isolated and characterized. All the isolated compounds were characterized with the help of NMR spectroscopy and mass spectrometry. Structure of compound 3 was also confirmed by a single X-ray crystallographic technique. Isolates were evaluated for antioxidant activities and most of the tested compounds were found to be potent in DPPH free radical scavenging (IC50 = 4.56-14.17 microg/mL) and superoxide anion scavenging (IC50 = 0.58-7.39 microg/mL) assays.

Animals↗

PubMed2004

Anti-inflammatory and antinociceptive effects of sinapyl alcohol and its glucoside syringin.

In the present study, syringin, isolated by activity-guided fractionation of the ethyl acetate (EtOAc) extracts of the stem bark of Magnolia sieboldii, and sinapyl alcohol, the hydrolysate of syringin, were evaluated for anti-inflammatory and antinociceptive activities. Sinapyl alcohol (20, 30 mg/kg/day, p. o.) inhibited increased vascular permeability by acetic acid in mice and reduced acute paw edema by carrageenan in rats more so than syringin. When analgesic activity was measured using the acetic acid-induced writhing test and the hot plate test, sinapyl alcohol was much more potent than syringin in a mouse model. In addition, sinapyl alcohol more potently inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO), prostaglandin E2 (PGE2), and tumor necrosis factor (TNF)-alpha production by macrophages than syringin. Consistent with these observations, the expression levels of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 was reduced by sinapyl alcohol in a concentration-dependent manner. These results suggest that the anti-inflammatory and antinociceptive effects of syringin after oral administration may be attributed to its in vivo transformation to sinapyl alcohol.

Acetic Acid↗

PubMed2003

Neuroprotective effects of antioxidative flavonoids, quercetin, (+)-dihydroquercetin and quercetin 3-methyl ether, isolated from Opuntia ficus-indica var. saboten.

The flavonoids quercetin, (+)-dihydroquercetin, and quercetin 3-methyl ether were isolated from the ethyl acetate fractions of the fruits and stems of Opuntia ficus-indica var. saboten. In the present study, we evaluated their protective effects against oxidative neuronal injuries induced in primary cultured rat cortical cells and their antioxidant activities by using three different cell-free bioassays. Quercetin was found to inhibit H(2)O(2)- or xanthine (X)/xanthine oxidase (XO)-induced oxidative neuronal cell injury, with an estimated IC(50) of 4-5 micro g/ml. However, it was no more protective at concentrations of 30 micro g/ml and above. (+)-Dihydroquercetin concentration-dependently inhibited oxidative neuronal injuries, but it was less potent than quercetin. On the other hand, quercetin 3-methyl ether potently and dramatically inhibited H(2)O(2)- and X/XO-induced neuronal injuries, with IC(50) values of 0.6 and 0.7 micro g/ml, respectively. All three principles markedly inhibited lipid peroxidation and scavenged 1,1-diphenyl-2-picrylhydrazyl free radicals. In addition, quercetin and quercetin 3-methyl ether were shown to inhibit XO activity in vitro, with respective IC(50) values of 10.67 and 42.01 micro g/ml. These results indicate that quercetin, (+)-dihydroquercetin, and quercetin 3-methyl ether are the active antioxidant principles in the fruits and stems of Opuntia ficus-indica var. saboten exhibiting neuroprotective actions against the oxidative injuries induced in cortical cell cultures. Furthermore, quercetin 3-methyl ether appears to be the most potent neuroprotectant of the three flavonoids isolated from this plant.

Animals↗

PubMed2003

A new pterocarpan, (-)-maackiain sulfate, from the roots of Sophora subprostrata.

A new pterocarpan, (-)-maackiain 3-sulfate (1) was isolated from the methanol extract of roots of Sophora subprostarata together with (-)-maackiain (2), trifolirhizin (3), lupeol (4), ononin (5), 7,4'-dihydroxyflavone (6), and (+)-syringaresinol (7). The structure of 1 was determined by analyses of 2D NMR and HRFABMS. Compounds 5-7 were isolated from this plant for the first time.

Plant Extracts↗

PubMed2003

Constituents of the stems and fruits of Opuntia ficus-indica var. saboten.

From the stems and fruits of Opuntia ficus-indica var. saboten, eight flavonoids, kaempferol (1), quercetin (2), kaempferol 3-methyl ether (3), quercetin 3-methyl ether (4), narcissin (5), (+)-dihydrokaempferol (aromadendrin, 6), (+)-dihydroquercetin (taxifolin, 7), eriodictyol (8), and two terpenoids, (6S,9S)-3-oxo-alpha-ionol-beta-D-glucopyranoside (9) and corchoionoside C (10) were isolated and identified by means of chemical and spectroscopic. Among these isolates, compounds 3-5 and 8-10 were reported for the first time from the stems and fruits of O. ficus-indica var. saboten.

Fruit↗

PubMed2003

Angiotensin converting enzyme inhibitory phenylpropanoid glycosides from Clerodendron trichotomum.

The stems of Clerodendron trichotomum have been traditionally used for treatment of hypertension in far East Asia including China, Korea, and Japan. Bioassay-guided fractionation and purification of the EtOAc-soluble extract of Clerodendron trichotomum afforded acteoside (1), leucosceptoside A (2), martynoside (3), acteoside isomer (4), and isomartynoside (5). The angiotensin converting enzyme (ACE) activities were significantly inhibited by the addition of these phenylpropanoid glycosides (1-5) in a dose-dependent manner of which IC(50) values were 373+/-9.3 microg/ml, 423+/-18.8 microg/ml, 524+/-28.1 microg/ml, 376+/-15.6 microg/ml, 505+/-26.7 microg/ml, respectively. These results suggest that the antihypertensive effect of Clerodendron trichotomum may be, at least in part, due to ACE inhibitory effect of phenylpropanoid glycosides.

Acetates↗

PubMed2003

In vivo anti-inflammatory and antinociceptive effects of liriodendrin isolated from the stem bark of Acanthopanax senticosus.

In the present study, liriodendrin isolated by activity-guided fractionation from the ethyl acetate (EtOAc) extracts of the stem bark of Acanthopanax senticosus, was evaluated for anti-inflammatory and antinociceptive activities. Liriodendrin (5, 10 mg/kg/day, p. o.) significantly inhibited the increase of vascular permeability induced by acetic acid in mice and reduced an acute paw edema induced by carrageenan in rats. When the analgesic activity was measured by the acetic acid-induced writhing test and hot plate test, liriodendrin showed a dose-dependent inhibition in animal models. In addition, syringaresinol, the hydrolysate of liriodendrin, more potently inhibited the LPS-induced production of NO, PGE 2 and TNF-alpha production of macrophages than liriodendrin. Consistent with these observations, the expression level of iNOS and COX-2 enzyme was decreased by syringaresinol in a concentration-dependent manner. These results suggest that the anti-inflammatory and antinociceptive effects of liriodendrin after oral administration were attributable to the in vivo transformation to syringaresinol, which may function as the active constituent.

Analgesics↗

PubMed2003

A new anti-HIV flavonoid glucuronide from Chrysanthemum morifolium.

A new flavonoid glucuronide, apigenin 7-O-beta-D-(4'-caffeoyl)glucuronide (1), and the known compound, apigenin 7-O-beta-D-glucurnoide, were isolated from the flowers of Chrysanthemum morifolium, along with five known flavonoids. The structure of 1 was elucidated by the aid of spectroscopic analyses. Among isolated compounds, apigenin 7-O-beta-D-(4"-caffeoyl)glucuronide showed strong HIV-1 integrase inhibitory activity (IC (50) = 7.2 +/- 3.4 microg/ml) and anti-HIV activity in a cell culture assay (EC (50) = 41.86 +/- 1.43 microg/ml) using HIV-I (IIIB) infected MT-4 cells.

Anti-HIV Agents↗

PubMed2003

Saucernetin-7 and saucernetin-8 isolated from Saururus chinensis inhibit the LPS-induced production of nitric oxide and prostaglandin E2 in macrophage RAW264.7 cells.

In the present study, we demonstrate that saucernetin-8 ( 1) and saucernetin-7 ( 2), isolated from the underground parts of Saururus chinensis (Saururaceae), exerted potent inhibitory effects on LPS-induced nitric oxide (NO) and prostaglandin E (2) (PGE (2)) production in RAW 264.7 cells. Both compounds 1 and 2, known as dineolignans, also suppressed the expression of iNOS and COX-2 protein in a dose-dependent manner. Thus, this study suggests that compounds 1 and 2-mediated inhibition of iNOS and COX-2 expression may be one of the mechanisms responsible for the anti-inflammatory effects of the underground parts of Saururus chinensis.

Animals↗

PubMed2002

A prenylated flavonol, sophoflavescenol: a potent and selective inhibitor of cGMP phosphodiesterase 5.

During the search for naturally occurring cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5) inhibitors, it was found that the extracts from Sophora flavescens exhibit potent inhibitory activity against cGMP PDE5 prepared from rat diaphragm. Therefore, the inhibitory activities of five flavonoids, kushenol H (1), kushenol K (2), kurarinol (3), sophoflavescenol (4) and kuraridine (5), isolated from S. flavescens were measured against cGMP PDE5 to identify potent cGMP PDE5 inhibitory constituents. Among tested compounds, sophoflavescenol (4), a C-8 prenylated flavonol, showed the most potent inhibitory activity (IC(50)=0.013 microM) against cGMP PDE5 with 31.5- and 196.2-fold selectivity over PDE3 and PDE4, respectively. Kinetic analysis revealed that sophoflavescenol was a mixed inhibitor of PDE5 with a K(i) value of 0.005 microM.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2002

New iridoids from Asperula maximowiczii.

Three new dimeric iridoid glucosides, named asperuloides A (1), B (2), and C (3), were isolated from Asperula maximowiczii, along with the known compound picconioside II. The structures of the new compounds were determined by spectroscopic and chemical methods and by the single-crystal X-ray diffraction analysis of 1.

Chromatography, High Pressure Liquid↗