• YAKHAK HOEJI
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• v.44 no.2
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• pp.197-203
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• 2000

The enzymatic properties of $\beta$-galactosidases from Aspergillus oryzae, bovine liver and Saccharomyces pragilis have been studied using enzyme-linked lectin assay based on the RC $A_{120}$ and BS-II lectins which specifically bind to terminal galactose and GlcNAc residue, respectively. Asialofetuin, a monomeric glycoprotein with approximately 48 kDa in molecular weight, was used as a substrate. This glycoprotein contains three N-linked triantennary complex type carbohydrate chains with each of which terminating in Ga1$\beta$P1 longrightarrow4G1cNAc (74%). Their optimal pHs were 3.5 and 6.5 (A. oryzae), and 3.5~5.5 (bovine liver and S. fragilis) at 37$^{\circ}C$ during 24 hrs, and the effective concentrations were 0.9, 2.9, and 1.7 mg/ml, respectively The enzyme from A oryzae requires 100 mM N $a^{+}$ or $K^{+}$, while the enzyme from bovine liver requires $Ba^{2+}$ for activity. However all of the three $\beta$-galactosidases were inactivated by SDS and C $u^{2+}$. These results indicate that the hydrolysis of glycoprotein such as asialofetuin depends on the reaction conditions of $\beta$-galactosidases and some metal ions. ions.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.99-105
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• 1999

BamHI restriction pattern and genomic library of Herpes simplex virus type 2 (HSV-2) strain G were constructed, and locations of the glycoproteins gB and gD, and tk genes on the fragments were detected by Southern blot analysis. HSV-2 genomic DNAs were cleaved into twenty-seven fragments by BamHI enzyme in the range of 0.72 to 15.08 (total 150.44 kb), which were cloned into the BamHI site of pBluescript SK(+) to construct genome library of the HSV-2. The library was named by the order of the fragment size from smallest one to largest one. HSV-2 glycoprotein gD gene was located in pHLA2-21 and pHLA2-22 recombinant plasmids, gB gene in pHLA2-24 plasmid, and tk gene in pHLA2-11 clone by Southern blot analysis.

• Journal of Pharmaceutical Investigation
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• v.34 no.1
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• pp.15-21
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• 2004

The pharmacokinetics of orally administered verapamil (10 mg/kg) was studied in six rabbits after 20 min pretreatment with quercetin ad coadministration of quercetin (2.0 mg/kg, 1 mg/g and 20 mg/kg, respectively). Pretreatment with quercetin significantly (p < 0.01, p < 0.05) increased the plasma concentration of verapamil. However, coadministration of quercetin showed no significantly effect on the pharmacokinetic parameters of verapamil. The elimination rate constant $(K_{el})$ of verapamil pretreated with quercetin (1 mg/kg and 20 mg/kg) was significantly (p < 0.05) reduced compared with control. The area under the plasma concentration-time curve (AUC) and the peak concentration $(C_{max})$ of verapamil pretreated with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) were increased significantly (p < 0.01, p < 0.05) compared with control. Pretreatment with quercetin (2.0 mg/kg, 10 mg/kg and 20 mg/kg) significantly (p < 0.01, p < 0.05) increased the relative bioavailability of verapamil to 159 - 219%. These results suggest that quercetin alters disposition of verapamil by inhibition of P-glycoprotein efflux pump and its first-pass metabolism. The dosage of verapamil should be adjusted when it is administered chronically with quercetin in a clinical situation.

• The Journal of the Korean bone and joint tumor society
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• v.3 no.1
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• pp.9-17
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• 1997

Resistance to combination chemotherapy remains challenge in the treatment of osteosarcoma. One of the mechanisms of multiple drug resistance is an increased expression of the multidrug resistance gene(mdr1). Expression of the P-glycoprotein(mdr-1 gene product) was studied immunohistochemically and the mdr-1 gene by in situ hybridization in 33 osteosarcomas relating to various prognostic factors. Thirty cases out of 33 osteosarcomas(90.9%) showed positive cytoplasmic reactions with P-glycoprotein and nineteen instances(57.6%) were strong positive(2+). The older(>20 years) and female patients revealed more intense immunohistochemical reactions rather than those of the younger and male patients. Osteoblastic and chondroblastic osteosarcomas revealed more strong immunohistochemical reactions compared to fibroblastic types. There were no significant staining differences between the type of bony involvement, Broder's grade and the presence of necrosis. On follow-up, the mean survival rate was decreased in the strong positive group, however, this was not statistically significant. In situ hybridization for mdr-1 gene revealed positive signals in 22 cases out of 29 osteosarcomas(75.9%). Chemotherapy was done in 15 cases out of 28 patients(53.6%). The results of immunohistochemistry and in situ hybridization were not correlated with the protocols for chemotherapy. However, this result should be confirmed by a larger scale study about mdr1 mRNA expression.

• YAKHAK HOEJI
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• v.47 no.2
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• pp.98-103
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• 2003

The purpose of this study was to investigate the effect of flavone (20 mg/kg) on the pharmacokinetic parameters and the bioavailability of paclitaxel (40 mg/kg) orally coadministered in rats. The plasma concentration of paclitaxel in combination with flavone was increased significantly (coadministration p＜0.05, pretreatment p＜0.0l) compared to that of control. Area under the plasma concentration-time curve (AVC) of paclitaxel with flavone was significantly (coadministration p＜0.05, pretreatment p＜0.0l) higher than that of control. Peak concentration (Cmax) of paclitaxel with flavone were significantly increased (coadministration p＜0.05, pretreatment p＜0.01) compared to that of control. Time to peak concentration (Tmax) of paclitaxel with flavone decreased significantly (p＜0.05) than that of control. The total body clearance (CLt) and elimination rate constant ($\beta$) of paclitaxel with flavone were significantly reduced (p＜0.05) compared to those of control. Half-life (t$_{1}$2/) of paclitaxel with flavone was significantly prolonged (p＜0.05) compared to that of control. Based on these results, it might be concluded that flavone may enhance bioavailability of paclitaxel through the inhibition of cytochrome P450 and P-glycoprotein, which are engaged in paclitaxel absorption and metabolism in liver and gastrogintestinal mucosa, respectively.

• Applied Biological Chemistry
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• v.30 no.2
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• pp.169-178
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• 1987

The extracellular and intracellular inulases from Kluyveromyces marxianus were purified and characterized. The maximum production of both inulases was achieved at stationary phase in a pH-controlled medium at pH 5 with yeast nitrogen base as organic nitrogen source. Each enzyme was concentrated by tannic acid precipitation and separated into two fractions by DEAF-cellulose chromatography. Electrophoretic analysis showed that the four fractions had three glycoprotein bards each. Only main glycoprotein band, however, had both inulase and invertase activities. There were no significant differences between two enzymes in the optimum pH and temperature. But the intracellular inulases had higher heat stability and less affinity toward inulin than the extracellular enzymes do. All the purified enzymes were considered to be exo-inulases using hydrolyzate analysis with TLC.

• Archives of Pharmacal Research
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• v.28 no.7
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• pp.823-828
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• 2005

Multidrug resistance (MDR) is one of the most significant obstacles in cancer chemotherapy. One of the mechanisms involved in the development of MDR is the over-expression of P-glycoprotein (P-gp). It is widely known that natural compounds found in vegetables, fruits, plant-derived beverages and herbal dietary supplements not only have anticancer properties, but may also modulate P-gp activity. Therefore, the purpose of this investigation was to examine the effects of naturally occurring products on P-gp function in human breast cancer cell lines, MCF-7 (sensitive) and MCF-7/ADR (resistant). The accumulation of daunomycin (DNM), a P-gp substrate, was greater in the sensitive cells compared to the resistant cells, while the efflux of DNM was higher in the resistant cells compared to the sensitive cells over a period of 2h. The $IC_{50}$ value of DNM in the resistant cells was about 22 times higher than that in the sensitive cells, indicating an over-expression of P-gp in the resistant cells, MCF-7/ADR. All of the compounds tested, with the exception of fisetin, significantly decreased the $IC_{50}$ value of DNM. Biochanin A showed the greatest increase in $[^3H]-DNM$ accumulation, increasing by $454.3{\pm}19.5%$ in the resistant cells, whereas verapamil, the positive control, increased the accumulation by $229.4{\pm}17.6%$. Also, the accumulation of $[^3H]-DNM$ was increased substantially by quercetin and silymarin while it was reduced by fisetin. Moreover, biochanin A, silymarin, and naringenin significantly decreased DNM efflux from MCF-7/ADR cells compared with the control. These results suggest that some flavonoids such as biochanin A and silymarin may reverse MDR by inhibiting the P-gp function.

• Journal of Korean Neurosurgical Society
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• v.41 no.6
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• pp.397-402
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• 2007

Objective : Balloon cells and dysplastic neurons are histopathological hallmarks of the cortical tubers of tuberous sclerosis complex [TSC] and focal cortical dysplasia [FCD] of the Taylor type. They are believed to be the epileptogenic substrate and cause therapeutic drug resistant epilepsy in man. P-glycoprotein [P-gp] is the product of multidrug resistance gene [MDR1], and it maintains intracellular drug concentration at a relatively low level. The authors investigated expression of P-gp in balloon cells and dysplastic neurons of cortical tubers in patients with TSC. Methods : An immunohistochemical study using the primary antibody for P-gp, as an indicative of drug resistance, was performed in the cortical tuber tissues in two patients of surgical resection for epilepsy and six autopsy cases. Results : Balloon cells of each lesion showed different intensity and number in P-gp immunopositivity. P-gp immunopositivity in balloon cells were 28.2%, and dysplastic neurons were 22.7%. These immunoreactivities were more prominent in balloon cells distributed in the subpial region than deeper region of the cortical tubers. Capillary endothelial cells within the cortical tubers also showed P-gp immunopositivity. Conclusion : In this study, the drug resistance protein P-glycoprotein in balloon cells and dysplastic neurons might explain medically refractory epilepsy in TSC.

• Journal of Pharmaceutical Investigation
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• v.35 no.2
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• pp.101-106
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• 2005

The pharmacokinetics of oral nifedipine (5 mg/kg) was studied in rabbits given after or simultaneously with naringin (1.5, 7.5 and 15 mg/kg, respectively). The area under the plasma concentration-time curve (AUC) and the peak concentration $(C_{max})$ of nifedipine coadministered or pretreated with naringin were significantly increased (p < 0.05, coad.; p < 0.01, pret.) compared with the control group. The absolute bioavailability (AB%) of nifedipine was significantly (p < 0.05, coad.; p < 0.01, pret.) higher by 22.3 - 28.1 % compared to the control (17.9%). The relative bioavailability (RB%) of nifedipine was higher by 1.24 - 1.43 times (coad.) and 1.32 -1.57 times (pret.) than those of the control, showing that preatreatrnent of naringin was more effective than that of the coadministration of naringin. Naringin did not show significant effect on the Tmax and $t_{1/2}$ of nifedipine. It is suggested that naringin may alter pharmacokinetic paramiters of nifedipine by inhibition of P-glycoprotein efflux pump and its first-pass metabolism. The dosage of nifedipine should be adjusted when it is administered with naringin in a clinical situation.

• YAKHAK HOEJI
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• v.54 no.5
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• pp.370-376
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• 2010

The aim of this study is to investigate the effect of apigenin on the pharmacokinetics of tamoxifen in rats. Tamoxifen was administered orally (10 mg/kg) or intravenously (2 mg/kg) without or with oral administration of apigenin (0.4, 2.0 or 8.0 mg/kg) to rats. The effect of apigenin on the P-glycoprotein (P-gp) and CYP3A4 activity was also evaluated. Apigenin inhibited CYP3A4 enzyme activity with 50% inhibition concentration ($IC_{50}$) of 1.8 ${\mu}M$. In addition, apigenin significantly enhanced the cellular accumulation of rhodamine 123 in MCF-7/ADR cells overexpressing P-gp. The plasma concentrations of tamoxifen were increased significantly by apigenin compared to control. The areas under the plasma concentration-time curve (AUC) and the peak concentrations ($IC_{max}$) of tamoxifen with apigenin were significantly higher than those of the control group. Consequently, the relative bioavailability (RB%) of tamoxifen with apigenin was 2-3-fold higher than the control, and absolute bioavailability (AB%) of tamoxifen were significantly higher (p<0.05 with co-administration, p<0.01 with pretreatment) than those of the control. The increased bioavailability of tamoxifen in rats with apigenin might be associated with the inhibition of an efflux pump P-glycoprotein and CYP3A4 by apigenin. From these results, dosage regimen of tamoxifen may be need to adjust when concomitantly administered with apigenin.