In-Kyoung Lee

Cytotoxic benzyl dihydroflavonols from Cudrania tricuspidata

Three new dihydroflavonols, gericudranins A-C were isolated from the stem bark of Cudrania tricuspidata. They were identified as 6,8-di-p-hydroxybenzyltaxifolin, 8-p-hydroxybenzyltaxifolin and 6-p-hydroxybenzyltaxifolin, respectively, by means of spectral studies. These compounds were cytotoxic to human tumor cell lines, such as CRL 1579 (skin), LOX-IMVI (skin), MOLT-4F (leukemia), KM12 (colon) and UO-31 (renal) in culture, with ED50 values of 2.7-31.3 micrograms ml-1.

Ellagic acid rhamnosides from the stem bark of Eucalyptus globulus

Four ellagic acid rhamnosides were isolated from the stem bark of Eucalyptus globulus. Their structures have been established on the basis of the analysis of their 1H NMR, 13C NMR, HMBC, IR and MS spectral data. The HMBC data of these compounds were most useful for their structure determinations, with these bring determined to be 3-O-methylellagic acid 3-O-alpha-rhamnopyranoside, 3-O-methylellagic acid 3-O-alpha-3-O-acetylrhamnopyranoside, 3-O-methylellagic acid 3-O-alpha-2-O-acetylrhamnopyranoside, 3-O-methylellagic acid 3-O-alpha-4-O-acetylrhamnopyranoside, respectively. Their antioxidant activities were evaluated by measuring the inhibition of lipid peroxidation using rat liver microsomes, with IC50 values of 10.0-14.0 microg/ml.

Lipid peroxidation inhibitory activity of some constituents isolated from the stem bark ofEucalyptus globulus

Twelve compounds with lipid peroxidation inhibitory activity were isolated from the stem bark ofE. globulus. Their structures were assigned as a new aromatic monoterpene (1) and eleven known compounds, pinoresinol (2), vomifoliol (3), 3,4,5-trimethoxyphenol 1-O-β-D-(6′-O-galloyl)glucopyranoside (4), methyl gallate (5), rhamnazin (6), rhamnetin (7), eriodictyol (8), quercetin (9), taxifolin (10), engelitin (11), and catechin (12) on the basis of UV, mass, and NMR spectroscopic analyses. These compounds except vomifoliol significantly inhibited lipid peroxidation in rat liver microsome.

Three naphthalenes from root bark of Hibiscus syriacus

Three new naphthalenes, designated as syriacusins A-C, were isolated from the root bark of Hibiscus syriacus. These compounds were identified as 2,7-dihydroxy-6-methyl-8-methoxy-1-naphthalenecarbaldehyde, 2-hydroxy-6-hydroxymethyl-7,8-dimethoxy-1-naphthalenecarbaldehyde, 1-carboxy-2,8-dihydroxy-6-methyl-7-methoxynaphthalenecarbolactone (1-->8), respectively, on the basis of various spectral studies. The compounds inhibited lipid peroxidation with IC50s of 0.54, 5.90 and 1.02 micrograms ml-1, respectively. The first compound also showed cytotoxicity against some human cancer cell lines with an ED50 of 1.5-2.4 micrograms ml-1.

Agrocybenine, novel class alkaloid from the Korean mushroom Agrocybe cylindracea

Abstract A new type alkaloid agrocybenine was isolated from mushroom Agrocybe cylindracea . The structure of agrocybenine was elucidated by spectroscopic methods, especially 15 N-NMR studies using pulsed field gradient(PFG)-HMBC and HMQC techniques.

Hibispeptin A, a novel cyclic peptide from Hibiscus syriacus

Abstract A new cyclic peptide, designated as hibispeptin B, has been isolated from the root bark of Hibiscus syriacus. Hibispeptin B has a unique amino acid unit assigned as 2-amino-3-(2-hydroxy-5-aminoacetylbenzyl)pentanoic acid (Ahabpa) in cyclic core. Its structure was established as cyclo[-Ahabpa(-pyro-Glu)-Pro-Leu-Leu-] on the basis of various spectroscopic analyses. Configurations of all normal amino acids were determined as L by chiral-TLC analysis.

Chemical Constituents of the Fruiting Bodies of Clitocybe nebularis and Their Antifungal Activity

During a continuing search for antimicrobial substances from Korean native wild mushroom extracts, we found that the methanolic extract of the fruiting body of Clitocybe nebularis exhibited mild antifungal activity against pathogenic fungi. Therefore we evaluated the antifungal substances and other chemical components of the fruiting body of Clitocybe nebularis, which led to the isolation of nebularine, phenylacetic acid, purine, uridine, adenine, uracil, benzoic acid, and mannitol. Nebularine showed mild antifungal activity against Magnaphorthe grisea and Trichophyton mentagrophytes, and phenylacetic acid potently inhibited the growth of Pythium ultium and displayed moderate antifungal activity against Magnaphorthe grisea, Botrytis cinerea, and Trichophyton mentagrophytes. The other isolated compounds showed no antimicrobial activity.

Diaporthin and Orthosporin from the Fruiting Body of Daldinia concentrica

In our continuing study on the chemical constituents in the fruiting bodies of Daldinia concentrica, diaporthin and orthosporin were isolated. Their chemical structures were assigned based on various spectral studies. Diaporthin and orthosporin, phytotoxins previously found in Aspergillus ocltraceus, were isolated from wood-rotting mushroom D. concentrica for the first time.

HIBISPEPTIN B, A NOVEL CYCLIC PEPTIDE FROM HIBISCUS SYRIACUS

Abstract A new cyclic peptide, designated as hibispeptin B, has been isolated from the root bark of Hibiscus syriacus . Hibispeptin B has a unique amino acid unit assigned as 2-amino-3-(2-hydroxy-5-aminoacetylbenzyl)pentanoic acid (Ahabpa) in cyclic core. Its structure was established as cyclo [-Ahabpa(-pyro-Glu)-Pro-Leu-Leu-] on the basis of various spectroscopic analyses. Configurations of all normal amino acids were determined as L by chiral-TLC analysis.

Chemical Constituents of Gymnopilus spectabilis and Their Antioxidant Activity

Gymnopilus spectabilis, a hallucinogenic mushroom belonging to the family Cortinariaceae, is found growing in dense clusters on stumps and logs of hardwoods and conifers. It contains the hallucinogenic alkaloid psilocybin and its strongly bitter taste makes it undesirable as an edible. In an effort to identify chemical constituents of Korean native wild mushrooms, 4,6-decadiyne-1,3,8-triol (1), ergosta-4,6,8(14), 22-tetraen-3-one (2), bisnoryangonin (3), and hispidin (4) were isolated from the methanolic extract of the fruiting bodies of G. spectabilis. Their structures were assigned on the basis of various spectroscopic studies. Compounds 3 and 4 displayed significant scavenging activity against the ABTS radical cation, DPPH radical, and superoxide radical anion, while 1 and 2 exhibited no antioxidant activity.