Biomedical subjects

Yong Sup Lee

Publications and source records attributed to Yong Sup Lee.

At least 19 recordsLinked to original sources

PubMed2006

Synthesis and anticancer activity of lavendustin A derivatives containing arylethenylchromone substituents.

2-Styrylchromones, which are relatively scarce in nature, have been reported to possess potent cytotoxicities on KB cell line. Lavendustin A, a metabolite of Streptomyces griseolavendus, has been shown to inhibit a growth of A431 cell line. Accordingly, a series of compounds 3a-g having structural features of styrylchromones and lavendustin A were synthesized and evaluated for cytotoxicity using SRB assay on four tumor cell lines. Compounds 3a-g were synthesized by the condensation of 2-methylchromone derivative 7 with several aromatic aldehydes. Among synthesized, compound 3e showed the significant cytotoxic activity on HCT-15 cell line with IC(50) values of 7.17 microg/ml indicating that lavendustin A derivatives containing 2-arylethenylchromone ring have a potential in anti-tumor application.

Antineoplastic Agents↗

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

Synthesis and biological evaluation of chromone carboxamides as calpain inhibitors.

Excessive calpain activations contribute to serious cellular damage and have been found in many pathological conditions. Novel chromone carboxamides derived from ketoamides were prepared and evaluated for mu-calpain inhibition. Among synthesized, compound 2i was the most potent calpain inhibitor with an IC(50) value of 0.24 +/- 0.11 microM comparable to the activity of peptide aldehyde calpain inhibitor MDL 28,170. Furthermore, compound 2i showed higher selectivity for mu-calpain over two related cysteine proteases cathepsin B and cathepsin L, suggesting the chromone ring as a good scaffold for selective mu-calpain inhibitors.

Calpain↗

PubMed2005

Synthesis and biological activity of 3,4-dihydroquinazolines for selective T-type Ca2+ channel blockers.

We have synthesized 3,4-dihydroquinazoline derivatives for the potent and selective T-type Ca(2+) channel blockers and evaluated for their inhibitory activities against two subtypes T-type Ca(2+) channels and N-type Ca(2+) channels. Among them, 5b (KYS05044, IC(50)=0.56+/-0.10 microM) was identified as potent T-type Ca(2+) channel blocker with in vitro selectivity profile at meaningful level (T/N-type, SI=>100).

Calcium Channel Blockers↗

PubMed2005

Synthesis and biological evaluation of bis(methoxy methyl)-7,8-dihydro-[1,4]dioxino[2,3-g]quinazolines as EGFR tyrosine kinase inhibitors.

A series of 7,8-bis(methoxymethyl)-7,8-dihydro-[1,4]dioxino[2,3-g]quinazolines were prepared and evaluated for their inhibition of phosphorylation of the isolated epidermal growth factor receptor (EGFR) enzyme and for their growth inhibition of the A431 cell line. Among them, compound 3c having a 3-iodophenyl ring was most potent (IC(50) = 1.66 nM) against the isolated EGFR enzyme and also showed meaningful potency (GI(50) = 1.99 microM) against the A431 cell line, although less than PD153035 (GI(50) = 1.03 microM). However, compound 3e as the exact rigidified analogue of Erlotinib (Tarceva) was inferior to the original compound when compared to its reported data.

Cell Proliferation↗

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↗

PubMed2005

Neuroprotective and antioxidant effects of the ethyl acetate fraction prepared from Tussilago farfara L.

The flower buds of Tussilago farfara L. (Compositae) have been traditionally used in Oriental medicine for the treatment of bronchitis and asthma. The extract of T. farfara was reported to exhibit antiinflammatory actions by inhibiting arachidonic acid metabolism and nitric oxide (NO) production in lipopolysaccharide-activated macrophages. In the present study, we investigated the effects of the ethyl acetate (EA) fraction on various types of neuronal cell damage induced in primary cultured rat cortical cells. Its antioxidant activities were also evaluated by cell-free bioassays. We found that the EA fraction potently inhibited the neuronal damage induced by arachidonic acid. We also found that it significantly attenuated the neuronal damage induced by spermine NONOate, a stable NO generator. In addition, it inhibited the A(beta(25-35))-induced neurotoxicity and glutamate- or N-methyl-D-aspartic acid-induced excitotoxicity. It was found that the oxidative neuronal damage induced by H2O2, xanthine/xanthine oxidase, or Fe(2+)/ascorbic acid was also inhibited by the EA fraction. Furthermore, it was shown to inhibit lipid peroxidation initiated by Fe(2+)/ascorbic acid in rat brain homogenates, and scavenge DPPH radicals. This is the first demonstration of neuroprotective and antioxidant effects of T. farfara. Although complex mechanisms may be involved in the neuroprotective actions, T. farfara may be useful for the management of neurodegenerative disorders associated with inflammation, A(beta), excitotoxicity, and/or oxidative stress.

Acetates↗

PubMed2004

Anti-inflammatory effect of caffeic acid methyl ester and its mode of action through the inhibition of prostaglandin E2, nitric oxide and tumor necrosis factor-alpha production.

The anti-inflammatory effects of caffeic acid (CA), caffeic acid methyl ester (CM) and di-O-acetylcaffeic acid (DAC) were investigated in rats using the carrageenin-induced edema model and the antinociceptive effects of these compounds were also assessed in mice by means of the acetic acid-induced abdominal constriction test and hot plate test. CM (10mg/kg, p.o.) showed the most potent anti-inflammatory and antinociceptive effects in these animal models. To investigate the mechanism of the anti-inflammatory action, we examined the effects of these compounds on the lipopolysaccharide (LPS)-induced NO and PGE2 responses in the murine macrophage cell line, RAW 264.7. Our data indicate that CM is the most potent inhibitor of NO and PGE2 production and it also significantly decreased tumor necrosis factor-alpha (TNF-alpha) release. Consistent with these observations, the protein and mRNA expression levels of iNOS and COX-2 were found to be inhibited by CM in a dose-dependent manner. Furthermore, CM inhibited the nuclear factor-kappaB (NF-kappaB) activation induced by LPS, which was associated with the prevention of the degradation of the inhibitor kappaB, and subsequently with decreased p65 protein levels in the nucleus. Taken together, our data indicate that the anti-inflammatory properties of CM might result from the inhibition of iNOS, COX-2 and TNF-alpha expression through the down-regulation of NF-kappaB binding activity.

Active Transport, Cell Nucleus↗

PubMed2004

3,4-Dihydroquinazoline derivatives as novel selective T-type Ca2+ channel blockers.

For LVA T-type Ca2+ channel blockers, 3,4-dihydroquinazoline derivatives as new scaffolds were prepared and evaluated for the inhibitory activity against two members of the recombinant T-type Ca2+ channel family. Among them, 8a (KYS05001, IC50=0.9 microM) was nearly equipotent with mibefradil (IC50=0.84 microM) and inhibited LVA T-type Ca2+ channel with greater efficacy than HVA Ca2+ channel.

Animals↗

PubMed2004

First pharmacophoric hypothesis for T-type calcium channel blockers.

A three-dimensional pharmacophore model was developed for T-type calcium channel blockers in order to map common structural features of highly active compounds by using CATALYST program. In the absence of three dimensional structure based information like binding mode and unavailability of more number of specific T-type calcium channel blockers, this hypothesis which consists of three hydrophobic regions, one hydrogen bond acceptor and one positive ionizable regions will act as a valuable tool in designing new ligands. Further more after the withdrawal of mibefradil, the first marketed T-type calcium channel blocker, due to the drug-drug interactions, there is an urgent need for more work in this interest.

Calcium Channel Blockers↗

PubMed2004

Styrylquinazolines: a new class of inhibitors on prostaglandin E2 production in lipopolysaccharide-activated macrophage cells.

A series of styrylquinazoline derivatives (2a-k) were prepared and evaluated for their inhibiton of prostaglandin E(2) (PGE(2)) production by cyclooxygenase-2 (COX-2). The latter was induced by lipopolysaccharide-stimulated macrophage cells RAW264.7. 3', 4'-Dihydroxylated styrylquinazolines (2a-c), 3'-hydroxylated styrylquinazolines (2h, 2i), and 3'-acetoxy-styrylquinazolines (2j, 2k) exhibited good inhibitory effects of PGE(2) production by COX-2 with a range of IC(50) values of 1.19 approximately 3.56 microM. The potencies were comparable or better than that of the representative stilbene resveratrol (IC(50) = 3.07 microM). These results indicate that styrylquinazolines can be considered as potential resveratrol analogues in the modulation of prostaglandin production by COX-2.

Cell Line↗

PubMed2004

Suppressive effect of inducible nitric oxide synthase (iNOS) expression by the methanol extract of Actinodaphne lancifolia.

Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) has played a crucial role in various pathophysiological processes including inflammation and carcinogenesis. Therefore, the inhibitors of NO synthesis or iNOS gene expression have been considered as potential anti-inflammatory and cancer chemopreventive agents. In our continuous search for iNOS inhibitors from natural products we have evaluated indigenous Korean plant extracts using an assay for inhibition of nitric oxide formation on lipopolysaccharide (LPS)-activated mouse macrophage RAW 264.7 cells. As a result, the methanolic stem extract of Actinodaphne lancifolia showed an inhibitory activity of NO production in a dose-dependent manner (IC50 = 2.5 microg/ml). Additional study demonstrated that the extract of Actinodaphne lancifolia significantly suppressed the iNOS protein and gene expression in a dose-dependent manner. These results suggest that Actinodaphne lancifolia could be a potential candidate for developing an iNOS inhibitor from natural products. Further elucidation of active principles for development of new cancer chemopreventive and/or anti-inflammatory agents could be warranted.

Animals↗

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↗