• Journal of Microbiology and Biotechnology
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• 제30권12호
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• pp.1835-1842
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• 2020

Ergosterol, an essential constituent of membrane lipids of yeast, is distributed in both the cell membrane and intracellular endomembrane components such as vacuoles. Honokiol, a major polyphenol isolated from Magnolia officinalis, has been shown to inhibit the growth of Candida albicans. Here, we assessed the effect of honokiol on ergosterol biosynthesis and vacuole function in C. albicans. Honokiol could decrease the ergosterol content and upregulate the expression of genes related with the ergosterol biosynthesis pathway. The exogenous supply of ergosterol attenuated the toxicity of honokiol against C. albicans. Honokiol treatment could induce cytosolic acidification by blocking the activity of the plasma membrane Pma1p H+-ATPase. Furthermore, honokiol caused abnormalities in vacuole morphology and function. Concomitant ergosterol feeding to some extent restored the vacuolar morphology and the function of acidification in cells treated by honokiol. Honokiol also disrupted the intracellular calcium homeostasis. Amiodarone attenuated the antifungal effects of honokiol against C. albicans, probably due to the activation of the calcineurin signaling pathway which is involved in honokiol tolerance. In conclusion, this study demonstrated that honokiol could inhibit ergosterol biosynthesis and decrease Pma 1p H+-ATPase activity, which resulted in the abnormal pH in vacuole and cytosol.

• Mycobiology
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• 제38권3호
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• pp.215-218
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• 2010

Azoles are currently the most widely used class of antifungal drugs clinically, and are effective for treating fungal infections. Target site of azoles is ergosterol biosynthesis in fungal cell membrane, which is absent in the mammalian host. However, the development of resistance to azole treatments in the fungal pathogen has become a significant challenge. Here, we report the identification and functional characterization of a UPC2 homolog in the human pathogen Cryptococcus neoformans. UPC2 plays roles in ergosterol biosynthesis, which is also affected by the availability of iron in Saccharomyces cerevisiae and Candida albicans. C. neoformans mutants lacking UPC2 were constructed, and a number of phenotypic characteristics, including antifungal susceptibility and iron utilization, were analyzed. No differences were found between the mutant phenotypes and wild type, suggesting that the role of C. neoformans UPC2 homolog may be different from those in S. cerevisiae and C. albicans, and that the gene may have a yet unknown function.

• Natural Product Sciences
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• 제9권4호
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• pp.299-303
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• 2003

For the screening of inhibitors of sterol biosynthesis from natural products, a simple and rapid assay method was developed using recombinant yeast carrying human lanosterol synthase, main target of this assay method. Sterol biosynthesis inhibition activity was monitored only by the inhibition of growth of the recombinant yeast. By changing the substrate, this assay method can figure out which step is inhibited in the sterol biosynthesis by the test material. With this assay method total 102 plant samples were screened for their inhibitory activity of sterol biosynthesis. Among plant water extracts screened, 11 plant samples showed inhibitory activity on sterol biosynthesis in ergosterol (-) medium. For selection of the specific inhibitory materials, 11 plant samples were reassayed in ergosterol (+) medium. After all 5 plant samples, Abutilon avicennae Gaertn. (stem), Alnus japonica Steud. (stem), Amaranthus mangostanus L. (aerial part), Philadelphus schrenckii Pupr. (leaf) and Pimpinelia brachycarpa Nakai (aerial part), showed specific inhibitory activity.

• The Plant Pathology Journal
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• 제17권6호
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• pp.366.3-366
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• 2001

• BMB Reports
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• 제30권5호
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• pp.370-377
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• 1997

A novel assay method is described for rapid quantitation of reaction rate of sterol ${\Delta}^7$-reductase (${\Delta}^7$-SR) which catalyzes reduction of the ${\Delta}^7$-double bond of sterols. Of six different organ tissues-liver, small intestine, brain, lung, kidney, and testis-. ${\Delta}^7$-SR activity was detected only in liver (2.30 nmol/min/mg protein) and testis (0.11 nmol/min/mg protein). Using a newly developed method which employs diet-induced enzyme proteins and ergosterol as substrate, we assessed both kinetics ($K_m=210\;{\mu}M$, $V_{max}=1.93\;nmol/min/mg$) and inhibition of the rat hepatic ${\Delta}^7$-SR against well-studied cholesterol lowering agents such as triparanol ($IC_{50}=16\;{\mu}M$). 3-$\beta$-[2-(diethylamino)ethoxy]androst-5-en-17-one (U18666A) ($IC_{50}=5.2\;{\mu}M$), and trans-1.4-bis(2-chlorobenzylaminomethyl)cyclohexane dihydrochloride (AY-9944) ($IC_{50}=0.25\;{\mu}M$). Of the three well-known AY-9944-sensitive cholesterogenic enzymes (i.e., ${\Delta}^7$-SR, sterol ${\Delta}^8$-isomerase, and sterol ${\Delta}^14$-reductase). ${\Delta}^7$-SR was found to be the most sensitive enzyme with a noncompetitive inhibition of this compound ($K_i=0.109\;{\mu}M$). Substrate specificity studies of the microsomal ${\Delta}^7$-SR indicate that the relative reaction rate for 7-dehydrocholesterol and ergosterol are 5.6-fold and 1.6-fold higher than that for lathosterol. ${\Delta}^7$-SR activity was also modulated by feeding rats a diet supplemented with 0.5% ergosterol (>2.6-fold) in addition to 5.0% cholestyramine plus 0.1% lovastatin ($\simeq$5.0-fold). Finally, microsomal ${\Delta}^7$-SR was solubilized by 1.5% 3-[3-(cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and enriched on PEG (0~10%) precipitation, which should be suitable for further purification of the enzyme.

• 식물병연구
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• 제11권2호
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• pp.185-192
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• 2005

전국의 고추 재배지에서 1999년과 2002년에 채집한 병든 고추로부터 각각 130개와 258개의 고추 탄저병균을 분리한 후, 4종의 보호용 살균제와 3종의 ergosterol생합성 저해 살균제에 대한 균사 생장 저해 정도를 측정함으로서 살균제들에 대한 저항성 모니터링을 실시하였다. 1999년에 분리한 균주는 세 가지 보호용 살균제, 즉 dithianon, chlorothalonil 및 propineb에 대해서는 2002년의 균주보다 더 저항성을 보였다. 이에 반하여 다른 보호용 살균제인 iminoctadine에 대해서는 오히려 2002년의 균주가 더 저항성인 것으로 나타났다. 세 개의 ergosterol 생합성 저해(EBI) 살균제, 즉 tebuconazole, hexaconazole 및 prochloraz에 대해서는 2002년의 균주가 1999년의 균주보다 더 저항성이 컸으며, 2002년도의 균주들의 $EC_{50}$ 값은 1999년 균주들보다 1.2배 내지 4.4배가 높았다 위의 살균제들에 대한 탄저병균의 반응을 보면, 채집한 지역 간에 저항성을 차이가 크게 나타나고 있었다. 단기간내에 충북에서 분리한 균주들은 채집한 시기가 늦어질수록, 고추의 생육 초기에 주로 많이 사용되는 보호용 살균제들에 대한 $EC_{50}$값은 감소하였다. 그러나 ergosterol 생합성 저해 살균제에 대한 균주들의 반응은 정해진 생육 기간 중에는 변화가 거의 없었다.

• Journal of Microbiology and Biotechnology
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• 제14권4호
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• pp.693-697
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• 2004

YH-1715R, (2R,3R)-2-(2,4-difluorophenyl)-3-(3-methoxy-1,2,4-isothiazol-3-yl-thio)-1-( 1H-1,2,4-triazol-l-yl)-2-butanol, a new triazole derivative obtained by the structural modification of fluconazole, was found to exhibit potent anti-Candida activity against a wide variety of Candida albicans (C. albicans) (MIC: 0.4-12.5 mg/l). To investigate the mode of action of YH-1715R, its effect on ergosterol biosynthesis in cell-free extracts and whole cells of C. albicans was examined. The inhibitory activity of YH-1715R was approximately ten-fold higher than that of fluconazole. To determine the primary action mechanism of YH-1715R, its inhibitory activity against lanosterol $14\alpha$-demethylase (14$\alpha$-DM), a major target for azole, was measured using gas-liquid chromatography. YH-1715R and fluconazole were found to inhibit 14a-DM with an $IC_{50}$ of 0.015 $\mu$M and 0.01$8\mu$M, respectively, plus the mode of inhibition of YH-1715R and fluconozole was noncompetitive with a $K_i$ of 0.0533$\mu$M and 0.0975$\mu$M.

• Applied Biological Chemistry
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• 제32권3호
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• pp.270-277
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• 1989

사과나무 부란병균(腐爛病菌)(Valsa ceratosperma)에 대(對)한 항균력(抗菌力)이 인정된 prochloraz 및 triadimefon의 ergosterol 생합성(生合成) 과정(過程)에 미치는 영향(影響)은 다음과 같다. Triadimefon 및 prochloraz를 처리(處理)하지 않은 무처리구(無處理區)에서는 시간(時間)이 경과함에 따라 ergosterol의 생합성(生合成)이 계속되어 약제처리(藥劑處理) 후(後) 19시간(時間) 후(後)에 각각(各各) 65.0 및 66.0%이던 것이 168시간(時間) 후(後)에는 각각(各各) 70.3, 70.2%로 증가(增加)되었고, 24-methylenedihydrolanosterol의 경우는 10.1 및 11.6%에서 6.4 및 8.0%로 시간(時間)이 경과(經過)함에 따라 감소(減少)하였다. 반면(反面)에 triadimefon 10ppm 처리시(處理時)는 ergosterol의 함량(含量)은 60.8%에서 40.0%로 시간(時間)이 경과(經過)함에 따라 감소(減少)되었고 24-methylenedihydrolanosterol은 17.5%에서 37.6%로 증가(增加)하였다. 또한 prochloraz 5ppm 처리시(處理時)는 ergosterol은 56.5%에서 37%로 감소(減少)되었고 24-methylenedihydrolanosterol은 19.6%에서 41.0%로 증가(增加)되었다. Ergosterol의 함량(含量)은 약제(藥劑)의 농도(濃度)가 높을수록, 그리고 처리(處理) 후(後) 경과시간(經過時間)이 길수록 감소(減少)되였고 상대적(相對的)으로 24-methylenedihydrolanosterol은 증가(增加)되었다. 따라서 Valsa ceratosperma에서 이들 두 약제(藥劑)는 C-14의 demethylation을 저해(沮害)하여 ergosterol의 생합성과정(生合成過程)을 저해(沮害)하는 것으로 추측(推測)된다.

• Journal of Applied Biological Chemistry
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• 제56권2호
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• pp.109-112
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• 2013

Azole fungicides are one of the most wide-spread antifungal compounds in agriculture and pharmaceutical applications. Their major mode of action is the inhibition of ergosterol biosynthesis, giving depletion of ergosterol, precursors and abnormal steroids. However, metabolic consequences of such inhibition, other than steroidal metabolitesare not well established. Comprehensive metabolic profiles of Saccharomyces cerevisiae has been presented in this study. Wild type yeast was treated either with glucose as control or azole fungicide (ketoconazole). Both polar metabolites and lipids were analyzed with gas chromatography-mass spectrometry. Approximately over 180 metabolites were characterized, among which 18 of them were accumulated or depleted by fungicide treatment. Steroid profile gives the most prominent differences, including the accumulation of lanosterol and the depletion of zymosterol and ergosterol. However, the polar metabolite profile was also highly different in pesticide treatment. The concentration of proline and its precursors, glutamate and ornithine were markedly reduced by ketoconazole. Lysine and glycine level was also decreased while the concentrations of serine and homoserine were increased. The overall metabolic profile indicates that azole fungicide treatment induces the depletion of many polar metabolites, which are important in stress response.

• 한국식품영양과학회지
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• 제38권12호
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• pp.1779-1784
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• 2009

우리 국민의 주식이 되는 쌀(백미)과 콩류, 감귤류, 열대과 일류, 엽채류, 엽경채류, 근채류, 과채류, 버섯류에 속하는 농산물(989건)에 대해 8종의 EBI계 농약의 잔류 여부를 분석하였다. 그 결과 8건의 검체에서 농약이 검출되었고 농약 수는 5종이 검출되었다. 기준 미설정 농약은 2종이었으며, 곡류 134건 중 4건 검출로 3.0%, 채소류 471건 중 4건 검출로 0.8%의 검출율을 나타내었다. 그 외 콩류(48건), 견과종실류(72건), 과실류(197건), 버섯류(67건)에서는 전혀 검출되지 않았으며 부적합율은 0.1%로 나타났다. 국내 미등록농약인 paclobutrazole이 근대에서 잠정허용기준을 초과하는 것으로 확인되었다. 그리고 EBI계의 검출율은 0.8%로 매우 낮았으며 검출된 농약의 경우도 기준규격 이하로 안전한 수준이었다.