• Biomolecules & Therapeutics
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• v.21 no.1
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• pp.54-59
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• 2013

In this study, we investigated the effect of (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins from green tea leaves, on activities of cyclooxygenase (COX)-1 and thromboxane synthase (TXAS), thromboxane $A_2$ ($TXA_2$) production associated microsomal enzymes. EGCG inhibited COX-1 activity to 96.9%, and TXAS activity to 20% in platelet microsomal fraction having cytochrome c reductase (an endoplasmic reticulum marker enzyme) activity and expressing COX-1 (70 kDa) and TXAS (58 kDa) proteins. The inhibitory ratio of COX-1 to TXAS by EGCG was 4.8. These results mean that EGCG has a stronger selectivity in COX-1 inhibition than TXAS inhibition. In special, a nonsteroid anti-inflammatory drug aspirin, a COX-1 inhibitor, inhibited COX-1 activity by 11.3% at the same concentration ($50{\mu}M$) as EGCG that inhibited COX-1 activity to 96.9% as compared with that of control. This suggests that EGCG has a stronger effect than that of aspirin on inhibition of COX-1 activity. Accordingly, we demonstrate that EGCG might be used as a crucial tool for a strong negative regulator of COX-1/$TXA_2$ signaling pathway to inhibit thrombotic disease-associated platelet aggregation.

• Analytical Science and Technology
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• v.33 no.2
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• pp.59-67
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• 2020

Nadolol is a β-blocker drug, which effectively manages hypertension and angina pectoris. Its chemical structure allows the formation of four possible stereoisomers. A coupled column high-performance liquid chromatographic (HPLC) system with UV and fluorescence detection was investigated for simultaneously determining four nadolol enantiomers in human plasma. The plasma samples were prepared using a convenient liquid-liquid extraction process and passed through HPLC. Nadolol was initially separated from the endogenous compounds or other impurities in human plasma on a Phenomenex silica column, and its enantiomers were resolved and determined on a Chirapak AD-H column. The developed HPLC method achieved an effective chiral separation and significantly eliminated endogenous compound interference. This optimal HPLC method was validated following FDA guidelines. The results showed good selectivity, linearity, accuracy (90.50 % - 105.27 %), and precision (RSDs < 9.52 %) for each enantiomer. This method was also successfully applied to determine nadolol enantiomers in the plasma samples of a healthy male volunteer (after orally administering 80 mg racemic nadolol), proving its suitability for nadolol stereoselective pharmacokinetic studies.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1496-1500
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• 2010

Sibutramine enantiomers were separated successfully by capillary zone electrophoresis using substituted cyclodextrins as chiral selectors. The effects of cyclodextrin concentration, pH, voltage, buffer type, and electrolyte concentration on the migration time and resolution of enantiomers were examined. Separation of sibutramine enantiomers on an unmodified fused silica capillary (total length, 54 cm; effective length, 45 cm) was achieved using a mixed buffer of 20 mM phosphate/10 mM citrate containing either 5 mM methyl-${\beta}$-cyclodextrin (pH 4.3) or 5 mM carboxymethyl-${\beta}$-cyclodextrin (pH 6.5). Samples were injected with a pressure of 50 mbar for 5 s and were detected at a wavelength of 223 nm. The established method showed good precision and accuracy, with intra- and inter-day variations of less than 2.9 and 4.7%, respectively, and recoveries of 95.7 - 103.8%. The stability constants of (R)- and (S)-sibutramine demonstrated that the resolution of sibutramine enantiomers was attributable primarily to the difference in stability constants. When this optimized method was applied to the determination of sibutramine enantiomers in commercial drug formulations, it proved to be economical and convenient, affording sufficient accuracy, precision, and reproducibility as well as sensitivity and selectivity.

• YAKHAK HOEJI
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• v.57 no.6
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• pp.420-425
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• 2013

Phentermine (PT) and phenmetrazine (PM) have been widely used as anti-obesity drugs. These drugs should be used with caution due to its close relation to amphetamine in its structure and toxicity. PT and PM, amphetamine-type anorectics, have recently been considered as alternatives for methamphetamine abuse in Korea. In addition, the misuse and abuse of PT and PM obtained by illegal sources such as the internet become a serious social problem. In the present study, a simultaneous detection and quantification method for determining PT and PM in human urine was developed and validated according to the international guidelines. The urine samples were screened using a fluorescence polarization immunooassay and analyzed by gas chromatography mass spectrometry (GC-MS) after extraction using automatic solid phase extraction (SPE) with a mixed-mode cation exchange cartridge and derivatization with pentafluoropropionic anhydride (PFPA). The validation results for selectivity, linearity, limits of detection (LOD) and quantification (LOQ), intra- and inter-assay precision and accuracy and recovery were satisfactory. The validated method was successfully applied to authentic urine samples collected from 38 drug abuse suspects. PT and/or PM were identified with or without methamphetamine in urine samples. Abuse of PT and PM have increased continuously in Korea, therefore, closer supervision of the inappropriate use of anoretics is necessary.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.2
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• pp.71-78
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• 2009

(S)-Carbamic acid 2-[4-(4-fluoro-benzoyl)-piperidin-1-yl]-1-phenyl-ethyl ester hydrochloride (YKP1447) is a novel "atypical" antipsychotic drug which selectively binds to serotonin (5-$HT_{2A}$, Ki=0.61 nM, 5-$HT_{2C}$, Ki=20.7 nM) and dopamine ($D_2$, Ki=45.9 nM, $D_3$, Ki=42.1 nM) receptors with over $10\sim100$-fold selectivity over the various receptors which exist in the brain. In the behavioral studies using mice, YKP1447 antagonized the apomorphine-induced cage climbing ($ED_{50}$=0.93 mg/kg) and DOI-induced head twitch ($ED_{50}$=0.18 mg/kg) behavior. In the dextroamphetamine-induced hyperactivity and conditioned avoidance response (CAR) paradigm in rats, YKP1447 inhibited the hyperactivity induced by amphetamine ($ED_{50}$=0.54 mg/kg) and the avoidance response ($ED_{50}$=0.48 mg/kg); however, unlike other antipsychotic drugs, catalepsy was observed only at much higher dose ($ED_{50}$=68.6 mg/kg). Based on the CAR and catalepsy results, the therapeutic index (TI) value for YKP1447 is over 100 (i.p.). These results indicate that YKP1447 has an atypical profile and less undesirable side effects than currently available drugs.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.1
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• pp.7-12
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• 2008

OLETF (Otsuka Long-Evans Tokushima Fatty) rats are characterized by obesity-related insulin resistance, which is a phenotype of type 2 diabetes. Sulfonylurea drugs or benzoic acid derivatives as inhibitors of the ATP-sensitive potassium $(K_{ATP})$ channel are commercially available to treat diabetes. The present study compared sulfonylurea drugs (glimepiride and gliclazide) with one of benzoic acid derivatives (repaglinide) in regard to their long-term effect on ameliorating insulin sensitivity in OLETF rats. Each drug was dissolved and fed with drinking water from 29 weeks of age. On high glucose loading at 45 weeks of age, response of blood glucose recovery was the greatest in the group treated with glimepiride. On immunohistochemistry analysis for the Kir6.2 subunit of $K_{ATP}$ channels, insulin receptor ${\beta}$-subunits, and glucose transporters (GLUT) type 2 and 4 in liver, fat and skeletal muscle tissues, the sulfonylurea drugs (glimepiride and gliclazide) were more effective than repaglinide in recovery from their decreased expressions in OLETF rats. From these results, it seems to be plausible that $K_{ATP}$-channel inhibitors containing sulfonylurea moiety may be much more effective in reducing insulin resistance than those with benzoic acid moiety. In contrast to gliclazide, non-tissue selectivity of glimepiride on $K_{ATP}$ channel inhibition may further strengthen an amelioration of insulin sensitivity unless considering other side effects.

• Analytical Science and Technology
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• v.34 no.2
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• pp.68-77
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• 2021

Cannabis is one of the most abused drugs in Korea. The main psychoactive component in cannabis, Δ9-tetrahydrocannabinol, is metabolized to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide (THCCOOH-glu) in the human liver, whereby the amount of THCCOOH-glu found in urine is twice as high as that of THCCOOH. The analytical process adapted by the majority of urine drug-testing programs involves a two-step method consisting of an initial immunoassay-based screening test followed by a confirmatory test if the screening test result is positive. In this study, a qualitative gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the detection of THCCOOH in human urine, where THCCOOH-glu was converted into THCCOOH by alkaline hydrolysis. For purification of the urine extract prior to instrumental analysis, high-speed centrifugation was used to minimize interference. In addition, an injection-port derivatization method using ethyl acetate and N,O-bis(trimethylsilyl)-trifluoroacetamide containing 1 % trimethylchlorosilane was employed to reduce the time required for derivatization, and an aliquot of the final solution was injected into the GC-MS. The method was validated by measuring the selectivity, limit of detection (LOD), and repeatability. The sensitivity, specificity, precision, accuracy, Kappa, F-measure, false positive, and false negative rate were determined by comparing the GC-MS results with those obtained using the immunoassay. The LOD was determined to be 0.32 ng/mL, while the repeatability was within 9.1 % for THCCOOH. Furthermore, a comparison study was carried out, whereby the screening immunoassay exhibited a sensitivity of 86.4 % and a specificity of 100 % compared to GC-MS. The applicability of the developed method was examined by analyzing spiked urine and forensic urine samples obtained from suspected cannabis abusers (n = 221).

• Biomolecules & Therapeutics
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• v.27 no.1
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• pp.117-125
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• 2019

Mebendazole (MBZ), a microtubule depolymerizing drug commonly used for the treatment of helminthic infections, has recently been noted as a repositioning candidate for angiogenesis inhibition and cancer therapy. However, the definite anti-angiogenic mechanism of MBZ remains unclear. In this study, we explored the inhibitory mechanism of MBZ in endothelial cells (ECs) and developed a novel strategy to improve its anti-angiogenic therapy. Treatment of ECs with MBZ led to inhibition of EC proliferation in a dose-dependent manner in several culture conditions in the presence of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) or FBS, without selectivity of growth factors, although MBZ is known to inhibit VEGF receptor 2 kinase. Furthermore, MBZ inhibited EC migration and tube formation induced by either VEGF or bFGF. However, unexpectedly, treatment of MBZ did not affect FAK and ERK1/2 phosphorylation induced by these factors. Treatment with MBZ induced shrinking of ECs and caused G2-M arrest and apoptosis with an increased Sub-G1 fraction. In addition, increased levels of nuclear fragmentation, p53 expression, and active form of caspase 3 were observed. The marked induction of autophagy by MBZ was also noted. Interestingly, inhibition of autophagy through knocking down of Beclin1 or ATG5/7, or treatment with autophagy inhibitors such as 3-methyladenine and chloroquine resulted in marked enhancement of anti-proliferative and pro-apoptotic effects of MBZ in ECs. Consequently, we suggest that MBZ induces autophagy in ECs and that protective autophagy can be a novel target for enhancing the anti-angiogenic efficacy of MBZ in cancer treatment.

• Advances in nano research
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• v.7 no.4
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• pp.233-240
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• 2019

The present research work reports in-vitro anti-cancer activity of biologically synthesized ZnO nanoparticles (ZnO NPs) against human carcinoma cells viz SCC-40, SK-MEL-2 and SCC-29B using Sulforhodamine-B (SRB) Assay. ZnO NPs were synthesized by a unique and novel biological route using Temperature-gradient phenomenon where the extract of combination of Catharanthus roseus (L.) G. Don (C. roseus), Azadirachta indica (A. indica), Ficus religiosa (F. religiosa) and NaOH solution were used as synthesis medium. The morphology of the ZnO NPs was characterized by Transmission Electron Microscopy (TEM). TEM images reveal that particle size of the samples reduces from 76 nm to 53 nm with the increase in reaction temperature and 68 nm to 38 nm with the increase in molar concentration of NaOH respectively. XRD study confirms the presence of elements and reduction in crystallite size with increase in reaction temperature and NaOH concentration. The diffraction peaks show broadening and a slight shift towards lower Bragg angle ($2{\theta}$) which represents the reduction in crystallite size as well as presence of uniform strain. The FTIR spectra of the extract show transmittance peak fingerprint of Zn-O bond and presence of bioactive molecules These NPs exhibit inhibition greater than 50% for SCC-40, SK-MEL-2 and SCC-29B cell lines and more than 50% cell kill for SCC-29B cells at concentrations < $80{\mu}g/ml$. Nanoparticles with smallest size have shown better anti-cancer activity and peculiar cell-selectivity. The combination of extracts of these plants with ZnO NPs can be used in targeted drug delivery as an effective anti-cancer agent, a potential application in cancer treatment.

• Parasites, Hosts and Diseases
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• v.59 no.4
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• pp.329-339
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• 2021

Ion channels are important targets of anthelmintic agents. In this study, we identified 3 types of ion channels in Ascaris suum tissue incorporated into planar lipid bilayers using an electrophysiological technique. The most frequent channel was a large-conductance cation channel (209 pS), which accounted for 64.5% of channels incorporated (n=60). Its open-state probability (P_o) was ~0.3 in the voltage range of -60~+60 mV. A substate was observed at 55% of the main-state. The permeability ratio of Cl^- to K⁺ (P_Cl/P_K) was ~0.5 and P_Na/P_K was 0.81 in both states. Another type of cation channel was recorded in 7.5% of channels incorporated (n=7) and discriminated from the large-conductance cation channel by its smaller conductance (55.3 pS). Its Po was low at all voltages tested (~0.1). The third type was an anion channel recorded in 27.9% of channels incorporated (n=26). Its conductance was 39.0 pS and P_Cl/P_K was 8.6±0.8. P_o was ~1.0 at all tested potentials. In summary, we identified 2 types of cation and 1 type of anion channels in Ascaris suum. Gating of these channels did not much vary with voltage and their ionic selectivity is rather low. Their molecular nature, functions, and potentials as anthelmintic drug targets remain to be studied further.