• Archives of Pharmacal Research
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• v.26 no.9
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• pp.768-772
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• 2003

Tween 80 (Polysorbate 80) is a hydrophilic nonionic surfactant commonly used as an ingredient in dosing vehicles for pre-clinical in vivo studies (e.g., pharmacokinetic studies, etc.). Tween 80 increased apical to basolateral permeability of digoxin in Caco-2 cells suggesting that Tween 80 is an in vitro inhibitor of P-gp. The overall objective of the present study was to investigate whether an inhibition of P-gp by Tween 80 can potentially influence in vivo absorption of P-gp substrates by evaluating the effect of Tween 80 on the disposition of digoxin (a model P-gp substrate with minimum metabolism) after oral administration in rats. Rats were dosed orally with digoxin (0.2 mg/kg) formulated in ethanol (40％, v/v) and saline mixture with and without Tween 80 (1 or 10％, v/v). Digoxin oral AUC increased 30 and 61％ when dosed in 1 ％ and 10％ Tween 80, respectively, compared to control (P＜0.05). To further examine whether the increase in digoxin AUC after oral administration of Tween 80 is due, in part, to a systemic inhibition of digoxin excretion in addition to an inhibition of P-gp in the GI tract, a separate group of rats received digoxin intravenously (0.2 mg/kg) and Tween 80 (10％ v/v) orally. No significant changes in digoxin IV AUC was noted when Tween 80 was administered orally. In conclusion, Tween 80 significantly increased digoxin AUC and Cmax after oral administration, and the increased AUC is likely to be due to an inhibition of P-gp in the gut (i.e., improved absorption). Therefore, Tween 80 is likely to improve systemic exposure of P-gp substrates after oral administration. Comparing AUC after oral administration with and without Tween 80 may be a viable strategy in evaluating whether oral absorption of P-gp substrates is potentially limited by P-gp in the gut.

• Journal of Electrochemical Science and Technology
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• v.13 no.2
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• pp.237-253
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• 2022

The methyl 2-(1,3-dithietan -2- ylidene)-3-oxobutanoate (MDYO) and 2-(1,3-dithietan-2-ylidene) cyclohexane -1,3-dione (DYCD) were synthesized and tested at various concentrations as corrosion inhibitors for 316L stainless steel in 1 M HCl using weight loss, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface analysis techniques (SEM / EDX and Raman spectroscopy) and Functional Density Theory (DFT) was also used to calculate quantum parameters. The obtained results indicated that the inhibition efficiency of MDYO and DYCD increases with their concentration, and the highest value of corrosion inhibition efficiency was determined in the range of concentrations investigated (0.01 × 10^-3 - 10^-3 M). Polarization curves (Tafel extrapolation) showed that both compounds act as mixed-type inhibitors in 1M HCl solutions. Electrochemical impedance spectra (Nyquist plots) are characterized by a capacitive loop observed at high frequencies, and another small inductive loop near low frequencies. The thermodynamic data of adsorption of the two compounds on the stainless steel surface and the activation energies were determined and then discussed. Analysis of experimental results shows that MDYO and DYCD inhibitors adsorb to the metal surface according to the Langmuir model and the mechanism of adsorption of both inhibitors involves physisorption. SEM-EDX results confirm the existence of an inhibitor protective film on the stainless steel surface. The results derived from theoretical calculations supported the experimental observation.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.747-754
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• 1995

E. coli growth is inhibited by organic acids produced in the broth. In order to reduce the inhibition, an electrodialysis unit was used. Model solutions (acetic acid plus distilled water or M-9 medium) were tested in the unit for investigating the optimum condition of current and voltage. Electrodialysis cultures were performed with the optimum condition where the highest current efficiency could be attained. The distilled water plus acetic acid gave us a higher current efficiency than the M-9 plus acetic acid. Electrodialysis efficiently removed acetic acid and so enhanced the specific growth rate of E. coli compared with the control experiment without clectrodialysis.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.5
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• pp.389-396
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• 2001

Neuroprotective properties of lithium were investigated by using in vivo NMDA excitotoxicity model. The appearance of TUNEL positive cells was prominent within 24 h of NMDA (70 mg/kg, i.p.) injection in the regions of the cortex, hippocampal formation, and thalamus of mouse cerebrum. NMDA treatment resulted in the extensive enhancement of Bax immunoreactivity in the cortical and hippocampal regions. NMDA also increased the immunoreactivity of caspase 8 in the similar regions of the mouse cerebrum. However, the increased immunoreactivity of Bax and caspase 8 were dramatically attenuated by chronic lithium pretreatment (lithium chloride, 300 mg/kg/d, i.p. for $7{\sim}10$ days). At the same time, lithium ion blocked the appearance of TUNEL positive cells, and the morphological assessment indicated an effective neuroprotection by lithium against NMDA excitotoxicity. Although the exact action mechanism of lithium is not straightforward at this time, we propose that the inhibition of Bax and caspase cascade is involved in the neuroprotective action of lithium.

• Journal of Electrochemical Science and Technology
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• v.6 no.1
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• pp.7-15
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• 2015

3-(4-Iodophenyl)-2-imino-2,3-dihydrobenzo[d]oxazol-5-yl 4-methylbenzenesulfonate (4-IPhOXTs) was synthesized and its inhibiting action on the corrosion of stainless steel 316L (SS) in sulfuric acid was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of the investigation show that this compound has excellent inhibiting properties for SS corrosion in sulfuric acid. Inhibition efficiency increases with increase in the concentration of the inhibitor. The adsorption of 4-IPhOXTs onto the SS surface followed the Langmuir adsorption model with the free energy of adsorption ΔG⁰_ads of −8.45 kJ mol⁻¹ . Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of 4-IPhOXTs.

• Journal of Ginseng Research
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• v.7 no.1
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• pp.80-87
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• 1983

In an endeavour to elucidate effects of ginseng on some characteristics of enzymes, malate dehydrogenase (EC 1.1.1.37) was chosen as a model enzyme and effects of ginseng saponin on the enzyme such as optimum pH, product inhibition, optimum temperature and the activity was investigated. The product inhibition by NADH-a reaction product of the enzyme-was increased 33% by 0.3% ginseng saponin. And the optimum pH of the enzyme was 8.3 but in the presence of 0.3% ginseng saponin it increased to 8.5. The enzyme activity and the optimum temperature was not affected by ginseng saponin in the concentration of 1.0% and 0.3%, respectively. In this work, the possibility of contribution of ginseng saponin to the adaptogen activity is suggested; Potentiation of the regulatory activity of an enzyme may contribute to the normalization of the physiological state and consequently may increase the nonspecific resistance of an organism.

• YAKHAK HOEJI
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• v.52 no.5
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• pp.370-375
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• 2008

In this study, the anti-allergic activity and mechanim of Salviae radix (SR) were investigated. The ethanol extract of SR showed significant inhibitory effect on degranulation from antigen-stimulated mast cells and it also inhibited the expression and secretion of TNF-${\alpha}$ and IL-4 in antigen-stimulated RBL-2H3 cells. In the mast cell-mediated local animal allergy model, it suppressed the passive cutaneous anaphylaxis in a dose-dependent manner. As its mechanism of action, SR inhibited the activating phosphorylation of Syk, a downstream signaling molecule of Src-family kinase, for the activation of mast cells. The results of the study indicate that the anti-allergic activity of SR is mediated by the inhibition of Src-family kinase in mast cells.

• Archives of Pharmacal Research
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• v.21 no.1
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• pp.30-34
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• 1998

The ethanol extracts of Opuntia ficus-indica fructus (EEOF) and Opuntia ficus-indica stem (EEOS) were prepared and used to evaluate the pharmacological effects of cactus. Both the extracts inhibited the writhing syndrome induced by acetic acid, indicating that they contains analgesic effect. The oral administrations of EEOF and EEOS suppressed carrageenan-induced rat paw edema and also showed potent inhibition in the leukocyte migration of CMC-pouch model in rats. Moreover, the extracts suppressed the release of $\beta$-glucuronidase, a lysosomal enzyme in rat neutrophils. It was also noted that the extracts showed the protective effect on gastric mucosal layers. From the results it is suggested that the cactus extracts contain anti-inflammatory action having protective effect against gastric lesions.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2365-2368
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• 2012

The $11{\beta}$-hydroxysteroid dehydrogenase type 1 ($11{\beta}$-HSD1) enzyme is involved in modulation of glucocorticoid activity within target tissues. This enzyme may contribute to obesity and/or metabolic disease through its action in adipose or liver tissue. Inhibition of $11{\beta}$-HSD1 has major therapeutic potential for glucocorticoid-associated diseases, including obesity, diabetes (wound healing), and muscle atrophy. To develop such therapeutics, we performed a pharmacophore-based virtual screening (VS) for identification of novel $11{\beta}$-HSD1 inhibitors and found that the VS hit compounds show potent inhibition of $11{\beta}$-HSD1 enzyme activity. Further, we present a binding model for active compounds. The proposed pharmacophore may serve as a useful guideline for future design of new chemical entities as $11{\beta}$-HSD1-targeted antidiabetic agents.

• Korean Journal of Pharmacognosy
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• v.45 no.3
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• pp.268-274
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• 2014

The aim of this study is to explore the potent phosphodiesterase 4 and 7 inhibitor from various herbal medicines for atopy treatment. In this study, 51 kinds of each herbal medicine, which were extracted with ethanol, was carried out the screening of PDE 4 and 7 inhibition using enzyme inhibitory assay. Of these, 8 species of herbal medicines, Rubus coreanus, Duchesnea chrysantha, Alisma orientale, Rehmannia glutinosa, Angelica dahurica, Thuja orientalis, Astragalus membranaceus and Perilla frutescens were screened as potential inhibitor against PDE 4 and 7. Among 8 species, Duchesnea chrysantha showed poteinial anti-atopic effect on DNCB-induced atopic model. Duchesnea chrysantha extract decreased serum IgE and histamine release significantly.