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Biomedical subjects

I M Chang

Publications and source records attributed to I M Chang.

At least 19 recordsLinked to original sources
PubMed2001

Studies on the possible mechanisms of protective activity against alpha-amanitin poisoning by aucubin.

Aucubin, an iridoid glucoside, was investigated to determine whether it has a stimulating effect on alpha-amanitin excretion in alpha-amanitin intoxicated rats, and whether there is binding activity to calf thymus DNA. High-performance liquid chromatography (HPLC) analysis of alpha-amanitin in rat urine allowed quantitative measurement of the alpha-amanitin concentration with a detection limit of 50 ng/ml. In this system, a group treated with both alpha-amanitin and aucubin showed that alpha-amanitin was excreted about 1.4 times faster than in the alpha-amanitin only treated group. Our previous results showed that the toxicity of alpha-amanitin is due to specific inhibition of RNA polymerase activity and the resultant blockage of the synthesis of certain RNA species in the nucleus. However, no significant activity change on RNA polymerase from Hep G2 cells was observed when aucubin was treated with alpha-amanitin at any concentration tested. Nevertheless, aucubigenin inhibited both DNA polymerase (IC50, 80.5 microg/ml) and RNA polymerase (IC50, 135.0 microg/ml) from the Hep G2 cells. The potential of both alpha-amanitin and aucubin to interact with DNA were examined by spectrophotometric analysis. Alpha-Amanitin showed no significant binding capacity to calf thymus DNA, but aucubin was found to interact with DNA, and the apparent binding constant (Kapp) and apparent number of binding sites per DNA phosphate (Bapp) were 0.45 x 10(4) M(-1) and 1.25, respectively.

Amanitins↗
PubMed2001

Effect of genistein analogs on oxygen radical production in leukocytes stimulated by unopsonized zymosan.

Effects of genistein analogs on oxygen radical production have been analyzed in human neutrophils, human monocytes or murine macrophages Raw264.7 stimulated with unopsonized zymosan by lucigenin- and luminol-enhanced chemiluminescence assays. Genistein exhibited IC50 values of 10.7-11.5 microM on the oxygen radical production in human neutrophils, 10.9-11.0 microM in human monocytes, and 14.8-27.3 microM in Raw264.7 cells. Orobol, a genistein analog with an additional hydroxy group at the 3' position, exhibited IC50 values of 3.0-3.3 microM on the oxygen radical production in human neutrophils, 2.8-3.1 microM in human monocytes, and 1.5-3.9 microM in Raw264.7 cells. Genistin and sophoricoside are genistein glycosides with a glucose moiety at 7 or 4' position, respectively. The genistein glycosides exhibited 23-37% inhibitory effects at 100 microM on the oxygen radical production.

Animals↗
PubMed2001

Anti-aging and health-promoting constituents derived from traditional oriental herbal remedies: information retrieval using the TradiMed 2000 DB.

Asia, Korea, China, and Japan have legally adopted the traditional Oriental (Chinese) medical system along with the Western system. A number of traditional herbal drugs including the polypharmacy type of prescriptions (a combination of multiple herbs) are available and are widely dispensed. Herbal therapy used in traditional Oriental medicine appears to be quite different from its counterpart Western drug therapy. The polypharmacy type of herbal therapy generally exhibits holistic effectiveness by exerting activities to multitarget organs (organ systems) according to the principles of traditional Oriental medicine. The Traditional Oriental Medicine Database (TradiMed 2000 DB) is a unique database of traditional Oriental herbal therapy containing a variety of information such as formulae, chemical information on ingredients, botanical information on herbal materials, and a dictionary of disease classification (TOM and Western classification). A formula, namely, the Sip-Jeon-Dae-Bo-Tang consisting of 10 different herbs, was selected by retrieving information from the TradiMed 2000 DB. Then its tonic effects for elderly people were shown as an example.

Aged↗
PubMed2000

Differential inhibitory effects of sophoricoside analogs on bioactivity of several cytokines.

Effects of sophoricoside and its analogs on proinflammatory cytokines have been investigated. Sophoricoside, genistein and orobol exhibited inhibitory effects on IL-5, IL-3, GM-CSF and IL-6 bioactivities. Genistin showed inhibitory effects on IL-5 and IL-3 bioactivities, but did not inhibit GM-CSF and IL-6 bioactivities. None of the sophoricoside analogs showed inhibitory effects on both IL-1beta and TNF-alpha bioactivities. Among the compounds, sophoricoside exhibited the highest inhibitory effects on IL-5, IL-3 and IL-6 bioactivities with IC50 values of 1.9 microM, 6.9 microM and 6.0 microM, respectively and orobol did show on GM-CSF bioactivity with an IC50 value of 18.0 microM. The result would provide an additional mechanism by which the compounds exert immunosuppressive and anti-inflammatory effects.

Animals↗
PubMed2000

Detection of antifungal activity in Portulaca oleracea by a single-cell bioassay system.

The antifungal activity of Portulaca oleracea extracts against hyphal growth of various fungi was evaluated in real time using an automatic single-cell bioassay system. Target organisms were the filamentous fungi Aspergillus and Trichophyton and the yeast Candida. A colony of test fungi was in contact with the assay medium, or assay medium containing plant extract, in sequence. The antifungal activity of each fraction of P. oleracea was evaluated based on the dynamic hyphal growth response curves of test fungi. A crude sample obtained by EtOAc extract showed a specific and marked activity against dermatophytes of the genera Trichophyton.

Antifungal Agents↗
PubMed1999

Purification and characterization of a serine protease with fibrinolytic activity from Tenodera sinensis (praying mantis).

Mantis egg fibrolase (MEF) was purified from the egg cases of Tenodera sinensis using ammonium sulfate fractionation, gel filtration on Bio-Gel P-60 and affinity chromatography on DEAE Affi-Gel blue gel. The protease was assessed homogeneous by SDS-polyacrylamide gel electrophoresis and has a molecular mass of 31500 Da. An isoelectric point of 6.1 was determined by isoelectric focusing. Amino acid sequencing of the N-terminal region established a primary structure composed of Ala-Asp-Val-Val-Gln-Gly-Asp-Ala-Pro-Ser. MEF readily digested the Aalpha- and Bbeta-chains of fibrinogen and more slowly the gamma-chain. The nonspecific action of the enzyme results in extensive hydrolysis of fibrinogen and fibrin releasing a variety of fibrinopeptide. The enzyme is inactivated by Cu2+ and Zn2+ and inhibited by PMSF and chymostatin, yet elastinal, aprotinin, TLCK, TPCK, EDTA, EGTA, cysteine, beta-mercaptoethanol, iodoacetate, E64, benzamidine and soybean trypsin inhibitor do not affect activity. Antiplasmin was not sensitive to MEF but antithrombin III inhibited the enzymatic activity of MEF. Among chromogenic protease substrates, the most sensitive to MEF hydrolysis was benzoyl-Phe-Val-Arg-p-nitroanilide with maximal activity at pH 7.0 and 30 degrees C. MEF preferentially cleaved the oxidized B-chain of insulin between Leu15 and Tyr16. D-Dimer concentrations increased on incubation of cross-linked fibrin with MEF, indicating the enzyme has a strong fibrinolytic activity.

Amino Acid Sequence↗
PubMed1999

Inhibitory effects of resveratrol analogs on unopsonized zymosan-induced oxygen radical production.

Resveratrol, a natural hydroxystilbene, has been reported to have anti-inflammatory and anticarcinogenic activities. Inhibitory effects of resveratrol and its analogs on reactive oxygen species (ROS) production in unopsonized zymosan-stimulated murine macrophage Raw264.7 cells, human monocytes, and neutrophils were analyzed to investigate if the anti-inflammatory and anticarcinogenic activities of resveratrol are related to the inhibition of ROS production. Resveratrol was a potent inhibitor of ROS production in both unopsonized zymosan-stimulated Raw264.7 cells and human monocytes and neutrophils. Resveratrol exhibited 50% inhibition values (IC50) of 17 microM in activated Raw264.7 cells, 18 microM in human monocytes, and 23 microM in human neutrophils. 3,5-Dihydroxy-4'-methoxystilbene or 3,4'-dimethoxy-5-hydroxystilbene exhibited IC50 values of 63 or 73 microM in Raw264.7 cells, 51 or >100 microM in human monocytes, and 10 or 37 microM in human neutrophils, respectively. Trimethylresveratrol, piceid, and 3,5-dihydroxy-4'-methoxystilbene-3-O-beta-D-glucoside were weak inhibitors of ROS production. Thus, resveratrol was identified as a potent inhibitor of ROS production, which might be one biochemical mechanism related to its anti-inflammatory and anticarcinogenic activities. The number and position of hydroxy substituents in resveratrol analogs seem to play an important role in the inhibitory potency of ROS production.

Adult↗
PubMed1999

Sophoricoside analogs as the IL-5 inhibitors from Sophora japonica.

Fruits of Sophora japonica L. (Leguminosae) exhibited an inhibitory effect in the IL-5 bioassay of mIL-5-dependent Y16 proliferation. The isoflavonoids of sophoricoside, genistein, orobol, and genistin were isolated as the IL-5 inhibitors from fresh fruits of the plant by activity-guided fractionation. Among the IL-5 inhibitors, sophoricoside exhibited the highest inhibitory effect with 89% inhibition at 12.5 microM, 82% at 6.3 microM, 72% at 3.1 microM, 59% at 1.6 microM, and 24% at 0.8 microM where the 50% inhibition (IC50) was shown at the concentration of 1.5 microM. Oxyphenylbutazone as the positive control exhibited the IC50 value at the concentration of 31.7 microM. In the order of IC50 values the inhibitory potency in the IL-5 bioassay was sophoricoside > orobol (9.8 microM) approximately equal to genistin (10.6 microM) > genistein (51.9 microM). The position of O-glycosylation and number of hydroxy groups in the isoflavonoids seem to play an important role in the inhibitory effect in the IL-5 bioassay.

Animals↗
PubMed1998

Oxyresveratrol as the potent inhibitor on dopa oxidase activity of mushroom tyrosinase.

Oxyresveratrol (2,3',4,5'-tetrahydroxystilbene), a naturally occurring compound particularly found in Morus alba L., exhibited a potent inhibitory effect on dopa oxidase activity of tyrosinase which catalyzes rate-limiting steps of melanin biosynthesis. Oxyresveratrol with 0.3 to 5 microM exhibited potent and dose-dependent inhibitions (25 to 84%) on the enzyme activity, where 50% of inhibition was shown at the concentration of about 1 microM. Oxyresveratrol seemed to inhibit the dopa oxidase activity of tyrosinase via a noncompetitive manner (Ki = 9.1 x 10(-7) M) when L-dopa was used as a substrate. Oxyresveratrol exhibited about a 150-fold more potent inhibitory effect than resveratrol (3,4',5-trihydroxystilbene). The more hydroxy groups of the hydroxystilbenes are methylated to be methoxy groups, while the less inhibitory effects on the enzyme activity were exhibited. The results indicate that both the number and positions of hydroxy groups in oxyresveratrol seem to play a critical role in exerting the inhibitory effect on dopa oxidase activity of mushroom tyrosinase.

Basidiomycota↗
PubMed1998

Genotoxicity study of bojungchisup-tang, an oriental herbal decoction-in vitro chromosome aberration assay in Chinese hamster lung cells and in vivo supravital-staining micronucleus assay with mouse peripheral reticulocytes.

The toxicity evaluation of oriental herbal drugs is of great concern at present. Bojungchisuptang (BCST, in Korean), a decocted medicine of oriental herbal mixture, is now well used in clinic at oriental hospitals for the treatment of edema of several diseases in practice. However, the toxicity of the oriental herbal decocted medicines such as genetic toxicity is not well defined until now. In this respect, to clarify the genetic toxicity of BCST, in vitro chromosome aberration assay with Chinese hamster lung (CHL) fibroblasts and in vivo supravital micronucleus assay with mouse peripheral reticulocytes were performed in this study. In the chromosome aberration assay, we used 5,000 micrograms/ml BCST as maximum concentration because no remarkable cytotoxicity in CHL cells was observed both in the presence and absence of S-9 metabolic activation system. No statistical significant differences of chromosome aberrations were observed in CHL cells treated with 5,000, 2,500 and 1,250 micrograms/ml BCST for 6 hour both in the presence and absence of S-9 metabolic activation. However, very weak positive result (6.5-8.0% aberration) of BCST was obtained in the absence of S-9 metabolic activation system at 5,000 micrograms/ml BCST when treated for 24 hour, i.e. 1.5 normal cell cycle time. And also, in vivo clastogenicity of BCST was studied by acridine orange-supravital staining micronucleus assay using mouse peripheral reticulocytes. We used 2,000 mg/kg as the highest oral dose in this micronucleus assay because no acute oral toxicity of BCST was observed in mice. The optimum induction time of micronucleated reticulocytes (MNRETs) was determined as 36 hours after oral administration of 2,000 mg/kg BCST. No significant differences of MNRETs between control and BCST treatment groups were observed in vivo micronucleus assay. From these results, BCST revealed very weak positive result in chromosome aberration assay in vitro with CHL cells and no clastogenicity in micronucleus assay in vivo.

Animals↗
PubMed1998

Screening of new bioactive materials from microbial extracts of soil microorganism (I). Antimicrobial activity from 200 samples using microdilution assay.

The microdilution assay recommended by NCCLS (National Committee for Clinical Laboratory Standards) is one of the standardized methods of antibiotic susceptibility test. This method has been widely used clinically to obtain MIC values of antibiotics on pathogenic microorganisms. It is more convenient, rapid and simple to test many samples than other test methods such as agar diffusion assay and broth macrodilution assay. The screening of antimicrobial agents from microbial extracts is too laborious in its process. Therefore, a number of screening methods having more simple procedure have been developed. In our laboratory, we applied microdilution assay for screening the antimicrobial agents. This assay showed dose-response results and was more sensitive than disc diffusion assay in our system. We tested 200 samples of microbial extracts originated from 100 microbial strains and selected several samples as potential candidates. In this report, we show that the microdilution assay is more convenient method in screening of antibiotic susceptibility than those previously reported.

Anti-Bacterial Agents↗
PubMed1998

Reynosin from Sassurea lappa as inhibitor on CINC-1 induction in LPS-stimulated NRK-52E cells.

An inhibitor on CINC-1 (cytokine-induced neutrophil chemoattractant-1) induction in LPS-stimulated rat kidney epithelioid NRK-52E cells was purified from the roots of Sassurea lappa Clarke, a herbal medicine used in Korean traditional prescriptions for gastric intestinal diseases by a variety of column chromatographic procedures. The inhibitor was identified as reynosin, a sesquiterpene lactone isolated and characterized previously from Ambrosia confertiflora DC., and Magnolia grandiflora L. Reynosin exhibited a dose-dependent inhibition on CINC-1 induction in LPS-stimulated NRK-52E cells, where 50% of inhibitory effect was shown at the concentration of about 1 microM.

Animals↗
PubMed1998

Liver-protective activities of aucubin derived from traditional oriental medicine.

The iridoid glycosides including aucubin (AU), catalpol (CA), swertimarin (SW), and gardenoside (GA) are frequently found as natural constituents of many traditional oriental medicinal plants including Chinese herbs. Among these iridoid glycosides, AU was systematically studied for its potent liver-protective activities using experimental systems of hepatic damage. AU showed high liver-protective activity against carbon tetrachloride-induced hepatic damage in mice. Also AU showed significant protective activity against alpha-amanitin-induced hepatic damage in mice, and it prevented a depression of liver RNA biosynthesis caused by alpha-amanitin administration. Potent antidotal effects on mushroom poisoning in beagle dogs ingested with aqueous extract of Amanita virosa was observed; beagle dogs completely survived, even when AU administration was withheld for half an hour after mushroom poisoning. In addition, AU was found to suppress hepatitis B viral DNA replication in vitro. Conversion of AU to its aglycone form appeared to be a prerequisite step for an exhibition of such antiviral activity.

Amanita↗
PubMed1996

A new glycosaminoglycan from the giant African snail Achatina fulica.

A new glycosaminoglycan has been isolated from the giant African snail Achatina fulica. This polysaccharide had a molecular weight of 29,000, calculated based on the viscometry, and a uniform repeating disaccharide structure of -->4)-2-acetyl,2-deoxy-alpha-D-glucopyranose (1-->4)-2-sulfo-alpha-L-idopyranosyluronic acid (1-->. This polysaccharide represents a new, previously undescribed glycosaminoglycan. It is related to the heparin and heparan sulfate families of glycosaminoglycans but is distinctly different from all known members of these classes of glycosaminoglycans. The structure of this polysaccharide, with adjacent N-acetylglucosamine and 2-sulfo-iduronic acid residues, also poses interesting questions about how it is made in light of our current understanding of the biosynthesis of heparin and heparan sulfate. This glycosaminoglycan represents 3-5% of the dry weight of this snail's soft body tissues, suggesting important biological roles for the survival of this organism, and may offer new means to control this pest. Snail glycosaminoglycan tightly binds divalent cations, such as copper(II), suggesting a primary role in metal uptake in the snail. Finally, this new polysaccharide might be applied, like the Escherichia coli K5 capsular polysaccharide, to the study of glycosaminoglycan biosynthesis and to the semisynthesis of new glycosaminoglycan analogs having important biological activities.

Animals↗
PubMed1996

Survey of natural occurrence of trichothecene mycotoxins and zearalenone in Korean cereals harvested in 1992 using gas chromatography/mass spectrometry.

For the survey of the natural occurrence of trichothecene mycotoxins, produced by species of fungi imperfecti such as Fusarium and Trichothecium, a sensitive analytical method was developed for the simultaneous detection and quantitation of the major trichothecene mycotoxins, viz. T-2 toxin (T-2), HT-2 toxin (HT-2), nivalenol (NIV), fusarenon-X (F-X), deoxynivalenol (DON), 3-acetyl deoxynivalenol (3-Ac DON), and zearalenone (ZEN), using gas chromatography/mass spectrometry-selected ion monitoring (GC/MS-SIM) mode after trimethyl silyl derivatization. The incidence of NIV and DON in 30 barley samples were 93% and 67%, respectively; the average contents of NIV and DON in positive samples were 390 ng/g (range 40-2038) and 106 ng/g (range 5-361) respectively. In 15 maize samples, the incidences of NIV and DON were 53% and 93% respectively and the average contents were 168 ng/g and 145 ng/g, respectively. These results suggest that NIV and DON were the major contaminating trichothecene mycotoxins in Korean barley and maize samples harvested in 1992.

Edible Grain↗
PubMed1996

Purification and molecular cloning of calobin, a thrombin-like enzyme from Agkistrodon caliginosus (Korean viper).

A thrombin-like enzyme, calobin, has been purified to homogeneity from the venom of Agkistrodon caliginosus by a procedure involving Bio-Gel P-100, Mono S, and Pro-RPC. The enzyme was identified as a monomer with a molecular weight of 34,000 on SDS-PAGE, and its isoelectric point was 6.2. Calobin acted on fibrinogen to form fibrin with a specific activity of 226 NIH equivalent units, and also exhibited arginine esterase activity. The enzyme predominantly cleaved the alpha-chain of fibrinogen with little degradation of the beta-chain. It contained abundant asparagine/aspartic acid residues, but very few tyrosine or methionine residues. The proteolytic activity of the enzyme with TAME as a substrate was higher than that of thrombin. However, it showed neither lysine esterase nor caseinolytic activity. The enzyme activity was strongly inhibited by PMSF, and moderately by benzamidine and soybean trypsin inhibitor, indicating it is a serine protease. On the other hand, the enzyme activity was not inhibited by hirudin or aprotinin. cDNA (1.6 kb) for calobin has been cloned from an A. caliginosus cDNA library. The cDNA sequence indicates that calobin is synthesized as a pre-zymogen of 262 amino acids, including a putative secretory signal peptide of 18 amino acids and a proposed zymogen peptide of 6 amino acid residues. The cDNA sequence encodes a 238-amino acid residue molecule exhibiting strong amino acid sequence homology to those of ancrod, batroxobin, and flavoxobin isolated from other snake venoms. Calobin contains 12 cysteine residues. As judged on alignment of the amino acid sequences of other thrombin-like enzymes (batroxobin, ancrod, and flavoxobin), calobin constitute the formation of six disulfide bridges. Amino acid residues, His43, Asp88, and Ser182, which are thought to be the catalytic active site are highly conserved. As calobin is a glycoprotein, its possible glycosylation site, Asn-X-Thr, is located at amino acid residues 81-83.

Agkistrodon↗
PubMed1995

Purification and characterization of piscivorase I and II, the fibrinolytic enzymes from eastern cottonmouth moccasin venom (Agkistrodon piscivorus piscivorus).

Fibrinolytic enzymes, piscivorase I and II, were isolated from Agkistrodon piscivorus piscivorus (eastern cottonmouth moccasin) venom using gel filtration on Bio-Gel P-100 and ion-exchange chromatography on CM-Sepharose CL-6B. The mol. wts of these proteases, piscivorase I and II, are 23,400 and 29,000 and isoelectric points are 6.6 and 8.5, respectively. These fibrinolytic enzymes were homogeneous by SDS-polyacrylamide gel electrophoresis. Piscivorase I readily cleaved the A alpha- and B beta-chain of fibrinogen, but piscivorase II cleaved readily the A alpha-chain and more slowly the B beta-chain. These fibrinolytic enzymes were activated by Ca2+, Mg2+ and Ba2+, but inhibited by Zn2+, Cu2+ and Mn2+. Both fibrinolytic enzymes were also inhibited by cysteine, beta-mercaptoethanol, and by metal chelators such as EDTA and EGTA, but not by benzamidine, phenylmethanesulfonyl fluoride (PMSF), soybean trypsin inhibitor and aprotinin. These fibrinolytic enzymes did not act like thrombin, plasmin and kallikrein, using specific chromogenic substrates. Neither fibrinolytic enzyme induced platelet aggregation, and piscivorase I showed low haemorrhagic activity at dosages of 55 micrograms.

Amino Acids↗