• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.619-626
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• 1994

The purpose of present study was to examine pharmacological effect of Artemisia Iwayomogi methanol extract(AIME) on biochemical parameters(activities of AST, ALT, LDH, and ALP, contents of total bilirubin, total protein, albumin and A/G ratio in serum and levels of hepatic microsomal lipid peroxide and glucose-6-phosphatase activities) against hepatic injury by carbon tetrachloride($CCl_4$) in rats. Increased AST, ALT and LDH activities by $CCl_4$ were decreased in AIMS treatment group at 48 or 72 hours. Together, increased ALP activity by $CCl_4$ almost returned toward normal value in AIME treatment group at 72 hours. Serum total bilirubin contents increased to 87, 79 and 31% compared with normal group by $CCl_4$ which were decreased to 64, 42 and 26% in AIME treatment group at 24, 48 and 72 hours, respectively. Decreased contents of total protein and albumin, and A/G ratio by $CCl_4$ were recovered in AIME treatment group. Hepatic microsomal lipid peroxide levels(nmol malonic dialdehyde/100mg protein) increased to 140, 95 and 78% compared with normal group by $CCl_4$ which were decreased to 107, 74 and 65% in AIME treatment group at 24, 48 and 72 hours, separately. Hepatic microsomal glucose-6-phosphatase activities decreased to 60, 50 and 53% compared with normal group by $CCl_4$ at 24, 48 and 72 hours, respectively, which were increased at 72 hours in AIME treatment group. In conclusion, AIME enhanced the amelioration process from $CCl_4$-induced lipid peroxidation, degeneration of liver cell, and impairment of protein and bilirubin metabolisms.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.610-616
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• 1997

Hepatotoxic cyanobacteria, Microcystis species, were collected from the Nakdong River and we could isolate hepatotoxins, microcystin-LR and microcystin-RR, which are also strong inhibitors of protein phosphatase 1 and 2A. From the microcystins, several microcystin derivatives were synthesized and tested on the mouse toxicity in order to establish the structure-activity relationship. Esterification od carboxyl groups of Glu and MeAsp residue produced nontoxic compounds. However, when we reduced the Mdha residue with sodium borohydride into Ala residue, toxicity was still maintained. Also, the change of guanidyl moiety of Arg residue in microcystin-LR into dimethylpyrimidyl moiety did not change the toxicity of microcystins as well. Thus the carboxyl groups seem to play important roles in binding with protein phosphatase 1 and 2A, whereas Mdha residue and the guanidyl moiety of Arg residue do not.

• BMB Reports
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• v.29 no.4
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• pp.386-392
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• 1996

A Saccharomyces cerevisiae Protein Tyrosine Phosphatase, PTP1, was expressed from an Escherichia coli expression system and milligram quantities of active PTP1 were purified chromatographically. The substrate specificity of the recombinant PTP1 was probed using synthetic phosphotyrosine-containing peptides corresponding to the regulatory phosphorylation sites of the yeast MAP kinase homologues $Fus3_{176-186}$, $Kss1_{179-189}$, and $Hog1_{170-180}$. Peptide sequences derived from the MAP kinase homologues were chosen arbitrarily as starting points for sequence variation studies even though they are not likely to be candidates for physiological substrates of PTP1. Phosphotyrosyl-$Hog1_{170-180}$ peptide showed a $K_M$ value of 877 ${\mu}M$ and phosphorylated $Kss1_{179-189}$ and $Fus3_{176-186}$ peptides showed lower $K_M$ values of 74 ${\mu}M$ and 51 ${\mu}M$ each. To study the effect of sequence variations of the peptide, amino acids of the undecapeptide $Hog1_{170-180}$ (DPQMTGpYVSTR) were sequentially substituted by an alanine residue. More extensive variations of each amino acid revealed positional importance of each amino acid residue. Based on these results, we derived a peptide sequence (DADEpYDA) that is recognized by PTP1 with an affinity ($K_M$ is 4 ${\mu}M$) significantly higher than that of the peptides derived from the phosphorylation sites of Fus3, Kss1, and Hog1.

• Biomolecules & Therapeutics
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• v.12 no.4
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• pp.228-234
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• 2004

Brazilin shows hypoglycemic effect in diabetic animals through enhancement of glucose metabolisms in insulin responsive tissues. One of the major mechanisms of brazilin to enhance glucose metabolism is stimulation of glucose transport in adipocytes. In this study, the essential molecular moiety of brazilin for the stimulation of glucose transport was investigated. We found that brazilin undergoes a structural change in physiological buffer and produces hydrogen peroxide. Methylation of hydroxyl group of brazilin or addition of catalase along with brazilin resulted in the complete inhibition of brazilin-induced glucose transport in adipocytes. Because hydrogen peroxide increases glucose transport by inhibition of phosphatases, we examined the effect of brazilin on phosphatase activity. Brazilin inhibited phosphatases in a wide range of activity, and protein phosphatase 1 and 2A were also inhibited. These results suggest that the production of hydrogen peroxide by oxidation of catechol hydroxyl group of brazilin mediates glucose transport through inhibition of phosphatases which otherwise decrease glucose transport in adipocytes.

• Journal of Korean Neurosurgical Society
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• v.46 no.4
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• pp.389-396
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• 2009

Objective : Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. Methods : MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by $^3H$-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. Results : At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. Conclusion : Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.6
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• pp.1532-1536
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• 2008

Quercetin which isolated form the roots of Houttuynia cordata. was determined on the basis of IR, ID and 2D NMR specta by direct comparison with authentic compounds. Protein tyrosine phophatase 1B (PTP1B) is thought to be a negative regulator in insulin signal-transduction pathway. Insulin-resistance by the activation of PTP1B is a hallmark of both type 2 diabetes and obesity. Thus, the compound inhibiting PTP1B can improve insulin resistance and can be effective in treating type 2 diabetes and obesity. Quercetin which measured the inhibitory activity against PTP1B was 92.1% inhibition in the 30 ${\mu}g$/mL, 83.4% inhibition in the 6 ${\mu}g$/mL and 76.5% inhibition in the 3 ${\mu}g$/mL. These results suggest that quercetin retains a potential PTP1B activity.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.237-242
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• 1992

In order to clone the gene coding for alkaline phosphatase in the yeast Kluyveromyces fragilis, a genomic library was constructed using the yeast-E. coli shuttle vector pHN114 as a cloning vector. From the genomic library, a clone carrying the gene was isolated and the plasmid was designated as pSKH101. A restriction enzyme map was made using this plasmid. Subcloning experiments and complementation studies showed that alkaline phosphatase was active only in the original 3.1 kb insert. Southern hybridization analysis confirmed that the cloned DNA fragment was derived from K. fragilis genomic DNA. Using a minicell experiment, the product of the cloned gene was identified as a protein with a molecular weight of 63 KDa. A 0.6 kb HindIII fragment, which showed promoter activity, was isolated using the E. coli promoter-probe vector pKO-1.

• Preventive Nutrition and Food Science
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• v.16 no.4
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• pp.291-298
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• 2011

Yam extracts (Dioscorea batatas) have been reported to possess a variety of functions. However, studies on its osteogenic properties are limited. In this study, we investigated the effect of ethanol and water extracts on osteoblast proliferation and bone matrix protein synthesis, type I collagen and alkaline phosphatase (ALP), using osteoblastic MC3T3-E1 cell model. MC3T3-E1 cells were cultured with yam ethanol and water extracts (0~30 mg/L) within 39 days of osteoblast differentiation period. Cell proliferation was measured by MTT assay. Bone matrix proteins were assessed by the accumulation of type I collagen and ALP activity by staining the cell layers for matrix staining. Also, the secreted (media) matrix protein concentration (type I collagen) and enzyme activity (ALP) were measured colorimetrically. Yam ethanol and water extracts stimulated cell proliferation within the range of 15~30 mg/L at 15 day treatment. The accumulation of type I collagen in the extracellular matrix, as well as secreted collagen in the media, increased with increasing doses of yam ethanol (3~15 mg/L) and water (3~30 mg/L) extracts. ALP activity was not affected by yam ethanol extracts. Our results demonstrated that yam extracts stimulated osteoblast proliferation and enhanced the accumulation of the collagenous bone matrix protein type I collagen in the extracellular matrix. These results suggest that yam extracts may be a potential activator for bone formation by increasing osteoblast proliferation and increasing bone matrix protein type I collagen. Before confirming the osteogenic action of yam, further studies for clarifying how and whereby yam extracts can stimulate this ostegenesis action are required.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.76-87
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• 1999

The effect of retrograde root-end filling materials(IRM, Super-EBA, Vitremer, MTA) on human periodontal ligament fibroblasts and osteoblasts was observed. The cell activities were evaluated by MTT assay, protein assay and alkaline phosphatase activity examination. The results as follows ; 1. After 24hrs culture, both E1 cells & PDL fibroblast adding root-end filling materials were suppressed cell activities but after 48hrs, cell activities were recovered. 2. Cell activity was lowest in Vitremer followed by IRM, MTA, Super-EBA. 3. Cell activity depression by Vitremer was not concerned with pH changes. 4. Protein synthesis by root-end filling materials were not significant difference in Both E1 cell & PDL fibroblasts but protein synthesis were a little increased by Super-EBA. 5. Alkaline phosphatase activity was increased in E1 cell by Super-EBA & MTA but was not significant differences in E1 cell by IRM & Vitremer. Alkaline phosphatase activity was a little depressed in PDL fibroblast by Vitremer. This findings suggest that these root-end filling materials may have important roles in promotion of PDL healing and consequently may be useful for clinical application in apical surgery.

• Natural Product Sciences
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• v.13 no.4
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• pp.311-316
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• 2007

In this study, the twenty-four ethyl acetate extracts of twenty-two medicinal plants, traditionally used in Vietnam as anti-diabetes agents, were investigated for ${\alpha}$-amylase and protein tyrosine phosphatase 1B (PTP1B) enzymes inhibitory activity in vitro. The results indicated that, twelve materials (50.0%) showed moderate to strong inhibitory activity in ${\alpha}$-amylase inhibitory activity with $IC_{50}$ values ranging from 2.5 to $48.8{\mu}g/mL$; meanwhile, ten extracts (41.6%) could demonstrate PTP1B activity with $IC_{50}$ values less than $30.5{\mu}g/mL$. Some plants presented interesting activities against both of ${\alpha}$-amylase and PTP1B enzymes such as Catharanthus roseus, Carthamus tinctorius, Momordica charantia, Gynostemma pentaphyllum, Glycyrrhiza glabra, Smilax glabra, Psidium guajava (leave), and Rehmannia glutinosa. The study may provide a proof, at least in a part, for the ethno-medical use in diabetes disease of these plants.