• Environmental Analysis Health and Toxicology
• /
• v.31
• /
• pp.10.1-10.8
• /
• 2016

Objectives Aromatase inhibitors that block estrogen synthesis are a proven first-line hormonal therapy for postmenopausal breast cancer. Although it is known that standardized extract of Ginkgo biloba (EGb761) induces anti-carcinogenic effects like the aromatase inhibitors, the effects of EGb761 on steroidogenesis have not been studied yet. Therefore, the effects of EGb761 on steroidogenesis and aromatase activity was studied using a H295R cell model, which was a good in vitro model to predict effects on human adrenal steroidogenesis. Methods Cortisol, aldosterone, testosterone, and $17{\beta}$-estradiol were evaluated in the H295R cells by competitive enzyme-linked immunospecific assay after exposure to EGb761. Real-time polymerase chain reaction were performed to evaluate effects on critical genes in steroid hormone production, specifically cytochrome P450 (CYP11/ 17/19/21) and the hydroxysteroid dehydrogenases ($3{\beta}$-HSD2 and $17{\beta}$-HSD1/4). Finally, aromatase activities were measured with a tritiated water-release assay and by western blotting analysis. Results H295R cells exposed to EGb761 (10 and $100{\mu}g/mL$) showed a significant decrease in $17{\beta}$-estradiol and testosterone, but no change in aldosterone or cortisol. Genes (CYP19 and $17{\beta}$-HSD1) related to the estrogen steroidogenesis were significantly decreased by EGb761. EGb761 treatment of H295R cells resulted in a significant decrease of aromatase activity as measured by the direct and indirect assays. The coding sequence/Exon PII of CYP19 gene transcript and protein level of CYP19 were significantly decreased by EGb761. Conclusions These results suggest that EGb761 could regulate steroidogenesis-related genes such as CYP19 and $17{\beta}$-HSD1, and lead to a decrease in $17{\beta}$-estradiol and testosterone. The present study provides good information on potential therapeutic effects of EGb761 on estrogen dependent breast cancer.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.6
• /
• pp.1256-1266
• /
• 2004

2-Bromooctanoic acid (2-BrOA) is known to block the formation of polyhydroxyalkanoic acid (PHA) in Pseudomonasfluorescens BM07 without any influence on the cell growth when grown on fructose, but it inhibits the cell growth when grown on octanoate (OA) (Lee et al., Appl. Environ. Microbiol. 67: 4963- 4974, 2001). We investigated the role of 2-BrOA in the PHA synthesis of the bacterium grown with mixtures of fructose and fatty acids. OA, 11­phenoxyundecanoic acid (1 1-POU), and 5-phenylvaleric acid (5-PV) were selected as model substrates. When supplemented with 50 mM fructose, all these carboxylic acids suppressed the formation of PHA from fructose, however, the ~-oxidation coenzyme A monomers derived from the carboxylic acids were efficiently polymerized, but the conversion yield [(mol of carboxylate substrate converted into PHA)/(mol of carboxylate substrate in the feed)] was low (e.g., maximally $\~53\%$ for 5 mM 11-POU). Addition of 2-BrOA (up to 5 mM) to the mixed carbon sources raised the conversion yield sensitively and effectively only at low levels of the acid substrates (e.g., 2 mM 1 1-POU or 5 mM OA): For instance, $100\%$ of 2 mM ll-POU were converted into PHA in the presence of 5 mM 2-BrOA, whereas only $\~10\%$ of the 1 1-POU were converted in the absence of 2-BrOA. However, at highly saturated suppressing levels (e.g., 5 mM ll-POU), 2-BrOA inhibitor showed no significant additional effect on the conversion ($60- 70\%$ conversion irrespective of 2-BrOA level). The existence of competitive and compensative relationship between 2­BrOA and all the carboxylic acid substrates used may indicate 'Present address: Section on Brain Physiology and Metabolism, Bldg. 10, Rm. 6N202, National Institute on Agmg, National Institute of Health, Bethesda, MD 20892, U.S.A. that all the acid substrate-derived inhibiting species bind to the same site as the 2-BrOA inhibiting species does. We, therefore, suggest that 2-BrOA can be used for efficiently increasing the yield of conversion of expensive substituted fatty acids into PHA and then substituted 3-hydroxyacids by hydrolyzing it.

• The Korean Journal of Physiology and Pharmacology
• /
• v.20 no.6
• /
• pp.605-611
• /
• 2016

Ketamine is an anesthetic with hypertensive effects, which make it useful for patients at risk of shock. However, previous ex vivo studies reported vasodilatory actions of ketamine in isolated arteries. In this study, we reexamined the effects of ketamine on arterial tones in the presence and absence of physiological concentrations of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) by measuring the isometric tension of endothelium-denuded rat mesenteric arterial rings. Ketamine little affected the resting tone of control mesenteric arterial rings, but, in the presence of 5-HT (100~200 nM), ketamine ($10{\sim}100{\mu}M$) markedly contracted the arterial rings. Ketamine did not contract arterial rings in the presence of NE (10 nM), indicating that the vasoconstrictive action of ketamine is 5-HT-dependent. The concentration-response curves (CRCs) of 5-HT were clearly shifted to the left in the presence of ketamine ($30{\mu}M$), whereas the CRCs of NE were little affected by ketamine. The left shift of the 5-HT CRCs caused by ketamine was reversed with ketanserin, a competitive 5-$HT_{2A}$ receptor inhibitor, indicating that ketamine facilitated the activation of 5-$HT_{2A}$ receptors. Anpirtoline and BW723C86, selective agonists of 5-$HT_{1B}$ and 5-$HT_{2B}$ receptors, respectively, did not contract arterial rings in the absence or presence of ketamine. These results indicate that ketamine specifically enhances 5-$HT_{2A}$ receptor-mediated vasoconstriction and that it is vasoconstrictive in a clinical setting. The facilitative action of ketamine on 5-$HT_{2A}$ receptors should be considered in ketamine-induced hypertension as well as in the pathogenesis of diseases such as schizophrenia, wherein experimental animal models are frequently generated using ketamine.

• The Korean Journal of Pharmacology
• /
• v.24 no.1
• /
• pp.11-16
• /
• 1988

Various Benzylacyclouridine (BAU, HM-BAU, suc-BAU, BBAU, HMBBAU, suc-BBAU, and BBBAU) developed as specifc inhibitors of uridine phosphorylase (UrdPase), inhibit transport (zero-trans influx) of ridine (Urd) in human erythrocytes. The inhibition pattern of these compounds is competitive, though suc-BBAU and BBBAU show a slight noncompetivieness. The order of potency as an inhibitor of the nucleoside transport system is BBAU ${\sim}$ HM-BBAU ${\sim}$ suc-BBAU > BBBAU > BAU ${\sim}$ suc-BAU ${\sim}$ HM-BAU ($K_1$ values of 19, 23, 38, 112, 124, 174 and 176 ${\mu}M$, respectively). These data indicate that there is a differnece in potency of Urd transport inhibition between the analogs of BAU and BBAU. Further, the potency correlates with the hydrophobicity of the compound, but it has a limit in the size of $C_5$ substitution. Abbreviation: BAU (5-benzylacyclouridine), 5-benzyl-1-(2'-hydroxyethoxymethyl) uracil; HM-BAU (3'-hydroxymethyl-BAU), 5-benzyl-1- [(1',3'-dihydroxy-2-propoxy) methyl]uracil; suc-BAU, 3'-succinyl-BAU; BBAU (benzyloxybenzylacyclouridine), 5-( m-benzyloxybenByl)-1-(2'-hydroxyethoxymethyl)uracil; HM-BBAU (3'-hydroxymethyl-BBAU), 5-(m-benzyloxybenzyl)-1- [(1'3'-dihyd.oxy-2-p.epoxy)methyll u.acil; suc-BAU, 3'-succinyl-BBAU; BBBAU, 5- f 3-(4-benzyloxyben-Eyl)benzyll -1-(2'-hydroxyethoxymethyl)uracil; Urdpase, uridine phosphorylase; Urd, Uridine; Fd-Urd, 5-fluoro-2'-deoxyuridine; AcThd, aoyclothyrnidine; AcUrd, acyclouridine; dThd, thymidine; NBMPR, nitrobenzylthioisone; FUra, 5-fluorouracil.

• Microbiology and Biotechnology Letters
• /
• v.30 no.4
• /
• pp.395-401
• /
• 2002

Methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) have been widely used as solvents in various industries. Biodegradation of MEK and MIBK by Pseudomonas putida KT-3, which could utilize MEK or MIBK as a sole carbon source, was characterized, and the cosubstrate interaction in MEK/MIBK mixture was also studied. Within the range of initial MEK concentration (from 0.5 to 5.5 mM), an increased substrate concentration increased the specific degradation rate of MEK by P putida KT-3 (from 3.15 to 10.58 mmol/g DCW$\cdot$h), but the rate sightly increased at 11.0 mM of initial MEK concentation (11.28 mmol/g DCW$\cdot$h). The similar degradation rates of MIBK (4.69-4.92 mmol/g DCW$\cdot$h) were obtained at more than 3.0 mM of initial MIBK concentation. Kinetic analysis on the degradation of MEK/MIBK mixture by P. putida KT-3 showed that MEK or MIBK acted as a competitive inhibitor. Maximum degradation rate ($V_{max}$), saturation constant ($K_{m}$) and inhibition constant ($K_{1}$) were as follows: $V_{max,MEK}$=12.94 mmol/g DCW$\cdot$h; $K_{m,MEK}$=1.72 mmol/L; $K_{l,MEK}$=1.30 mmol/L; $V_{max,MIBK}$=5.00 mmol/g-DCW$\cdot$h; $K_{m,MIBK}$=0.42 mmol/L; $K_{l,MEK}$=0.77 mmol/L.

• Journal of Life Science
• /
• v.25 no.11
• /
• pp.1298-1303
• /
• 2015

Machilus thunbergii (Lauraceae) is an evergreen tree cultivated in Korea and Japan. M. thunbergii has long been used as a traditional medicine in Korea, China, and Japan to treat various diseases, including edema, abdominal pain, and abdominal distension. In this study, dried stem bark of M. thunbergii extracted in methanol and extract was partitioned into n-hexane, CHCl₃, and BuOH. The CHCl₃-soluble extracts chromatographed on silica gel column using a CHCl₃/acetone and n-hexane/EtOAc mixture to afford Compound 1 and 2. Two dibenzylbutane lignans, macelignan (1) and meso-dihydroguaiaretic acid (2), were isolated from the CHCl₃-soluble extract of M. thunbergii stem bark. The structures of 1 and 2 were determined by ¹H- and ¹³C-NMR spectroscopic data analyses and a comparison with literature data. The tyrosinase inhibitory activity of the isolated compounds was evaluated. Among these compounds, Compound 2 strongly inhibited the monophenolase (IC₅₀=10.2 μM) activity of tyrosinase. A kinetic analysis showed that Compound 2 was a competitive inhibitor. The apparent inhibition constant (K_i) for Compound 2 binding to free enzyme was 4.8 μM. Based on these results, it can be concluded that meso-dihydroguaiaretic acid (2) is a potential candidate for the treatment of melanin biosynthesis-related skin diseases.

• Microbiology and Biotechnology Letters
• /
• v.41 no.1
• /
• pp.112-118
• /
• 2013

This study was performed to investigate the possible use of Eisenia bicyclis (EB) ethanol extract to inhibit activity against lipase. In tests, the lipase inhibitory activity of EB ethanol extract was noted as being 43, 27, and 24% at concentrations of 5, 2.5, and 1 mg/ml, respectively. Isolation was carried out by liquid and liquid extraction, silica-gel column chromatography, and HPLC. The results showed that the lipase inhibitory activity of the ethyl acetate (EA) fraction from EB ethanol extract exhibited the strongest lipase inhibitory activity with an $IC_{50}$ value of 1.31 mg/ml. The EA fraction was separated using silica-gel column chromatography and we obtained 22 sub-fractions. Amongst them, the EA1 fraction showed the highest lipase inhibitory activity with an $IC_{50}$ value of 0.54 mg/ml. Eight peaks were obtained from the EA1 fraction by HPLC. Fraction 5 also showed a strong lipase inhibitory activity with an $IC_{50}$ value of 0.37 mg/ml. The fraction 5 was identified as dieckol and the inhibition pattern analyzed from Lineweaver-Burk plots revealed a non-competitive inhibitor. These results suggest that EB has potential as a natural anti-obesity agent.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1998.11a
• /
• pp.170-170
• /
• 1998

In order to discover new types of 5-hydroxytryptamine antagonists, we have devoted our attention to investigating naturally occurring compounds having anti-5HT activity in vitro. Recently, ${\gamma}$-mangostin [1,3,6,7-tetrahydroxy-2,8-bis(3-methyl-2-bytenyl)-9H-xanthen-9-one] from the fruit hull of Garcinia mangostana Linn has been shown to be a selective antagonist for 5-hydroxytryptamine$_{2A}$ receptors in smooth muscle and platelets. It is of interesting that y-mangostin which does not have a nitrogen atom, possesses marked 5-$HT_{2A}$ receptor blocking activity. The present study was undertaken to investigate the effects of ${\gamma}$-mangostin on central 5-HT receptors by using animal behavioural models. Intracerebronventricular injection of ${\gamma}$-mangostin (10-40n mol/mouse) inhibited 5-fluoro-${\alpha}$-methyltryptamin (5-FMT) (45 mg kg$^{-1}$, i.p.)-induced head-twitch response in mice in the presence or absence of citalopram (5-HT-uptake inhibitor). Neither the 5-FMT- nor the 8-hydroxy-2-( di-n-propylamino )tetralin (5-HT$_{1A}$-agonist)-induced 5-HT syndrome (head weaving and hindlimb abduction) was affected by ${\gamma}$-mangostin. The locomotor activity stimulated by 5-FMT through the activation of at-adrenoceptors did not alter in the presence of ${\gamma}$-mangostin. 5-HT-induced inositol phosphates accumulation in mouse brain slices was abolished by ketanserin. ${\gamma}$-Mangostin caused a concentration-dependent inhibition of the inositol phosphates accumulation and the binding of [$^3H$]-spiperone, a specific 5-$HT_{2A}$ receptor antagonist, to mouse brain membranes. Kinetic analysis of the [$^H3$]-spiperone binding revealed that ${\gamma}$-mangostin increased the $_{d}$ value without affecting the $B_{max}$ value, indicating the mode of the competitive nature of the inhibition by ${\gamma}$-mangostin. These results suggest that ${\gamma}$-mangostin inhibits 5-FMT-induced head-twitch response in mice by blocking 5-$HT_{2A}$ receptors not by blocking the release of 5-HT from the central neurone. ${\gamma}$-Mangostin is a promising 5-$HT_{2A}$ receptors antagonist in the central nervous system.m.

• Korean Journal of Food Science and Technology
• /
• v.40 no.5
• /
• pp.558-561
• /
• 2008

Culture broth of Bacillus subtilis Y3-7 in tryptic soy broth (TSB) isolated from Korean traditional fermented food was evaluated for the inhibition of $\alpha$-glucosidase. The results of in vitro studies using the yeast $\alpha$-glucosidase demonstrated that the culture broth exerted inhibitory effects on $\alpha$-glucosidase with $IC_{50}$ value of 1.62 mg/mL, and functioned as a competitive inhibitor. Furthermore, the culture broth of B. subtilis Y3-7 significantly improved glucose tolerance in normal and streptozotocin-induced diabetic mice. The blood glucose levels in the mice receiving sucrose supplementation in the culture broth (1 g/kg, 2 g/kg) were measured at 48.7%, which corresponded to 22.2% of the levels measured in the control mice. These results indicated that the culture broth of B. subtilis Y3-7 in TSB might be considered as a useful compound for the preparation of functional foods for diabetic patients.

• Journal of Life Science
• /
• v.20 no.6
• /
• pp.831-837
• /
• 2010

KR-31125 (2-butyl-5-dimethoxymethyl-6-phenyl-7-methyl-3-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-3H-imidazo[4,5-b]pyridine) is a potent inhibitor of angiotensin II type 1 ($AT_1$) receptors in human recombinant $AT_1$ receptors and rabbit aorta. These in vitro studies revealed that KR-31125 inhibited specific [$^{125}I$] [$Sar^1$, $Ile^8$]-angiotensin II binding to human recombinant $AT_1$ receptors in a concentration dependent manner with an $IC_{50}$ value of $19.72{\pm}2.65$ nM. However, no interaction with $AT_2$ receptors was detected as displayed by the competition binding of [$^{125}I$] CGP 42112A to human recombinant $AT_2$ receptor. The binding action was also confirmed as a competitive mode that was identical to the previously studied compound, losartan. In addition, KR-31125 caused a nonparallel shift to the right in the concentration response curves to angiotensin II with a 30-80% decrease in the maximum contractile responses ($pK_B$: 7.63). Compared to the previous studies with losartan that showed a parallel right shift in the maximum contractile responses to AII ($pA_2$: 7.59), KR-31125 presented a different mode of action with a similar potency to losartan. These results demonstrate that KR-31125 is a highly potent and $AT_1$ selective angiotensin II receptor antagonist that can be applied to the fields of new diagnostic and research tools with upcoming in vivo study results.