• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.895-898
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• 2005

In the course of searching for potent chitin synthase 1 inhibitors from natural resources, Streptomyces sp. A6705 was found to exhibit potent inhibitory activity against the chitin synthase 1 from C. albicans (CaCHS1p). As a result, the inhibitor was isolated and identified using a series of chromatographies. Through chemical analyses with UV spectrophotometry, MS spectrometry, and various NMR techniques, the inhibitor was identified as N,N-bis(2-phenylethyl)urea. The compound exhibited strong inhibitory activity against the chitin synthase 1 from C. albicans with an $IC_{50}$ of 14 ${\mu}g$/ml, representing a similar inhibitory activity to that of the well-known chitin synthase inhibitor, polyoxin D ($IC_{50}$ 15 ${\mu}g$/ml). However, the compound showed no inhibitory activity against the chitin synthase 2 of Saccharomyces cerevisiae up to 280 ${\mu}g$/ml, which is structurally and functionally analogous to CaCHS 1 p. In addition, the compound exhibited weak antifungal activities against Cryptococcus neoformans and Rhizoctonis solani.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.84-89
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• 2001

Isolation and Characterization of Cathepsin B inhibitor Produced by Streptomyces luteogriseus KT-IO. Han, Kil~Hwan and Sang~Dal Kim*. Department of Applied Microbiology, Yeungnam Universit}/t Kyongsan 712749, Korea - The cathepsin B inhibitor produced by Streptomyces luteogriseus KT-IO was very stable in heat, acidic and alkaline conditions. The cathepsin B inhibitor was isolated from the extracted fraction of culture broth with butanol, methanol and chloroform subsequently, the inhibitor was purified with following several column chromatography sLlch as DEAE-Sephadex A-25, Sephadex G-15, silica gel 60, Sephadex LH-20, and preparative HPLC. The cathepsin B inhibitor showed positively to detective reaction of ninhydrine, 5% H2S04, iodine, but negatively to the reaction of Ehrlich's reagent, DNS, aniline. The molecular formular of cathepsin B inhibitor was elucidated by JR, lH and 13C-NMR, FAB mass and elemental analyzer. Consequently, it was identified as C4HlI04N6. The cathepsin B inhibitor had the mode of competitive inhibition with the reaction of cathepsin B.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E2
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• pp.121-128
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• 2002

This study was carried out to investigate if nitric oxide synthase (NOS) inhibitors modulate airway inflammation induced by diesel exhaust particles (DEP). N$\^$G/-nitro-L-arginine methyl ester (L-NAME), a potent constitutive NOS (cNOS) inhibitor, and aminoguanidine (AG), a selective inducible NOS (iNOS) inhibitor, were administered to mice in their drinking water for 7 weeks. Airway inflammation was elicited by the repeated intratracheal administration of DEP. The results showed that macrophages, inflammatory eosinophils and neutrophils in bronchoalveolar lavage (BAL) fluids by intratracheal DEP instillation were significantly suppressed in the mice treated with two NOS inhibitors toghther with DEP. The suppression of these cells was more effective in AG treated groups than in L -NAME treated groups. NOS inhibitor treatment also reduced interleukin -5 (IL-5 in the BAL fluids and lung homogenates. Additionally, it was found that eosinophil peroxidase (EPO) activity in the BAL fluids was also decreased by NOS inhibitor treatment. These results suggest that nitric oxide (NO) is produced in airway inflammation by repeated DEP instillation, and that iNOS inhibition as well as cNOS inhibition can play a modulating role in this airway inflammation by DEP.

• Molecules and Cells
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• v.44 no.9
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• pp.688-695
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• 2021

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has become a global health concern. Various SARS-CoV-2 vaccines have been developed and are being used for vaccination worldwide. However, no therapeutic agents against coronavirus disease 2019 (COVID-19) have been developed so far; therefore, new therapeutic agents are urgently needed. In the present study, we evaluated several hepatitis C virus direct-acting antivirals as potential candidates for drug repurposing against COVID-19. Theses include asunaprevir (a protease inhibitor), daclatasvir (an NS5A inhibitor), and sofosbuvir (an RNA polymerase inhibitor). We found that asunaprevir, but not sofosbuvir and daclatasvir, markedly inhibited SARS-CoV-2-induced cytopathic effects in Vero E6 cells. Both RNA and protein levels of SARS-CoV-2 were significantly decreased by treatment with asunaprevir. Moreover, asunaprevir profoundly decreased virion release from SARS-CoV-2-infected cells. A pseudoparticle entry assay revealed that asunaprevir blocked SARS-CoV-2 infection at the binding step of the viral life cycle. Furthermore, asunaprevir inhibited SARS-CoV-2 propagation in human lung Calu-3 cells. Collectively, we found that asunaprevir displays broad-spectrum antiviral activity and therefore might be worth developing as a new drug repurposing candidate for COVID-19.

• The World Journal of Men's Health
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• v.39 no.3
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• pp.541-549
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• 2021

Purpose: To determine if chronic administration of Jun-amino terminal kinase (JNK)-inhibitors and LIM-kinase 2 (LIMK2)-inhibitors from the immediate post-injury period in a rat model of cavernous-nerve-crush-injury could normalize cavernousveno-occlusive-function, and to compare it with phosphodiesterase type 5 (PDE5)-inhibitors. Materials and Methods: A total of 75 12-week-old male Sprague-Dawley-rats were randomized into five groups: sham-surgery (S), cavernous-nerve-crush-injury (I), cavernous-nerve-crush-injury treated with 10.0 mg/kg LIMK2-inhibitor (L) or 10.0 mg/kg JNK-inhibitor and 10.0 mg/kg LIMK2-inhibitor (J+L) or 20.0 mg/kg udenafil (P) for five-weeks. Five-weeks after surgery, dynamic-infusion-cavernosometry, histological-studies, caspase-3-activity-assay, and Western-blot were investigated. Results: Group-I had lower papaverine-response, higher maintenance-rate and higher drop-rate, compared to Group-S. Group-L, Group-J+L and Group-P showed improvement in the three dynamic-infusion-cavernosometry parameters. The papaverine-response and drop-rate in Group-J+L and Group-P recovered to sham-control level, but those in Group-L did not. Regarding apoptosis, Group-I had decreased content of α-smooth-muscle-actin, increased caspase-3 activity and increased cJun-phosphorylation. The cJun-phosphorylation improved only in Group-J+L. The α-smooth-muscle-actin content and caspase-3-activity in Group-J+L and Group-P improved, but those in Group-L were not. Regarding fibrosis, Group-I had decreased smooth muscle (SM)/collagen-ratio, increased protein-expression of fibronectin, and increased Cofilin-phosphorylation. Cofilin-phosphorylation was normalized in Group-L and Group-J+L, but not in Group-P. SM/collagen-ratio and proteinexpression of fibronectin in Group-L, Group-J+L and Group-P improved. Conclusions: Our data indicate that chronic inhibition of JNK and LIMK2 can restore cavernous-veno-occlusive-function by suppressing cavernous-apoptosis and cavernous-fibrosis, comparable to the results by PDE5-inhibitors. Chronic inhibition of JNK and LIMK2 might be a potential mechanism-specific targeted therapy for cavernous-veno-occlusive-dysfunction induced by cavernous nerve-injury.

• The Korean Journal of Pain
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• v.19 no.2
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• pp.142-145
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• 2006

Background: Nitric oxide (NO) is involved in the transmission and modulation of nociceptive information at the peripheral, spinal cord and supraspinal levels. We conducted this experiment to assess the antinociceptive effects of a nonselective nitric oxide synthase (NOS) inhibitor, N-nitro-L-arginine methyl ester (L-NAME), on the modulation of pain in rats subjected to the formalin test. Methods: Formalin 5% was injected in the right hind paw after intraperitoneal (IP) injection of various doses of L-NAME (0.5 mg/kg, 1.5 mg/kg with and without L-arginine 100 mg/kg, 5.0 mg/kg). The number of flinches was measured. Results: Formalin injected into the rat hind paw induced a biphasic nociceptive behavior. IP injected L-NAME diminished the nociceptive behaviors in a dose-dependent manner during phases 1 and 2. The concomitant injection of L-arginine reversed the antinocipetive effect of L-NAME. Conclusions: The data demonstrates that a nonselective NOS inhibitor, L-NAME, possesses antinociceptive properties in rats subjected to the formalin test, and the antinociceptive effect of L-NAME is reversed by the concomitant administration of L-arginine.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.126-135
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• 2001

Quinacrine (QU), a phospholipase-A2 (PLA-2) inhibitor has been used clinically as a chemotherapeutic adjuvant. To understand the mechanisms leading to its chemotherapeutic effect, we have investigated QU-induced apoptotic signaling pathways in human cervical squamous carcinoma HeLa cells. In this study, we found that QU induced cytochrome c-dependent apoptotic signaling. The release of pro-apoptotic cytochrome c was QU concentration- and time-dependent, and preceded activation of caspase-9 and -3. Flow cytometric FACScan analysis using fluorescence intensities of $DiOC_6$/ demonstrated that QU-induced cytochrome c release was independent of mitochondrial permeability transition (MPT), since the concentrations of QU that induced cytochrome c release did not alter mitochondrial membrane potential (${\blacktriangle}{\Psi}_m$). Moreover, kinetic analysis of caspase activities showed that cytochrome c release led to the activation of caspase-9 and downstream death effector caspase-3, Caspase-3 inhibitor (Ac-DEVD-CHO) partially blocked QU-induced apoptosis, suggesting the importance of caspase-3 in this apoptotic signaling mechanism. Supplementation with arachidonic acid (AA) sustained caspase-3 activation induced by QU. Using inhibitors against cellular arachidonate metabolism of lipooxygenase (Nordihydroxyguaiaretic Acid, NDGA) and cyclooxygenase (5,8,11,14-Eicosatetraynoic Acid, ETYA) demonstrated that QU-induced apoptotic signaling may be dependent on its role as a PLA-2 inhibitor. Interestingly, NDCA attenuated QU-induced cytochrome c release, caspase activity as well as apoptotic cell death. The blockade of cytochrome c release by NDCA was much more effective than that attained with cyclosporin A (CsA), a MPT inhibitor. ETYA was not effective in blocking cytochrome c release, except under very high concentrations. Caspase inhibitor z-VAD blocked the release of cytochrome c suggesting that this signaling event is caspase dependent, and caspase-8 activation may be upstream of the mitochondrial events. In summary, we report that QU induced cytochrome c-dependent apoptotic signaling cascade, which may be dependent on its role as a PLA-2 inhibitor. This apoptotic mechanism induced by QU may contribute to its known chemotherapeutic effects.

• Preventive Nutrition and Food Science
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• v.3 no.3
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• pp.216-220
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• 1998

Lipoxygenase inhibitory acitivity of the methanolic extract of 60 different kinds of plant seeds was determined by a spectrophotometric method using a soybean lipoxigenase(SLO) and linolenic acid. Among the extracts examined, the methanolic extract of nutmeg(Myristical fragrans)seed showed the most potent SLO inhibitory activity. To isolate SLO inhibitor, hence, the defatted methanol extract was further partitioned with ether, ehtylacetate , and n-butanol , stepwise. The ether souble fraction was successively chromatographed on silica gel, Sephadex LH-20 and preparative TLC. Three phenolic compounds were isolated , and one of them showing a strong SLO inhibition activity was identified as a 2,6-dihydroxy-9-(3', 4', -dihydroxyphenyl)nonylphenone (IC50a=0.39$\mu\textrm{g}$/ml) by 1H-& 13C0NMR, IR, and MS spectroscopy.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.19-26
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• 1996

A phospholipase C (PLC) inhibitor (MT267-2B) was isolated from the culture broth of actinomycetes isolate MT2617-2 by the extraction with n-butanol and column chromatographic techniques. The molecular weight of the inhibitor was 1057, by the spectroscopic analyses of IR, $^{13}C$-and $^{1}H$-NMR and ESI-MS. The chemical structure of MT2617-2B was found to be a macrolide compound consisted of a hemiketal ring, polyhydroxyl and polymethyl groups, which had a malonate and guanidine group as its side chain. MT2617-2B produced its two isomers having the same molecular weight by standing in methanol solution at room temperature. Therefore, MT2617-2B was identified as copiamycin and niphithricin A, macrolide antibiotics. The values of $IC_{50}$ against PLC-${\gamma}$1 and PLC-${\beta}$1 were 25 and 50${\mu}$g/ml, respectively. MT2617-2B had antimicrobial activities against Staphylococcus aureus and Candida albicans, but not against Escherichia coli.

• Microbiology and Biotechnology Letters
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• v.34 no.1
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• pp.52-57
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• 2006

For the purpose of production of a novel antihyperlipemial HMG-CoA reductase inhibitor from bacteria, a bacterium which showed the highest HMG-CoA reductase inhibitory activity was isolated from traditional Doenjang. This strain was identified as Bacillus cereus (D-3) based on its microbiological characteristics and 165 rRNA sequence analysis. The maximal HMG-CoA reductase inhibitor production from Bacillus cereus D-3 was obtained by cultivation in a Glucose-CSL broth containing 2% glucose, 0.6% corn steep liquor, $0.04%\;K_{2}HPO_4$ and $0.05%\;KH_{2}PO_4$ at $30^{\circ}C$ for 36 h. The final HMG-CoA reductase inhibitory activity under the above conditions was 39.4%.