• 분석과학
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• 제14권1호
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• pp.1001-1010
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• 2001

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.32-35
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• 1999

Addition of ${\beta}$-cyclodextrin (${\beta}$-CD) polymer during the biotransformation of digitoxin into digoxin using cell suspension cultures of Digitalis lanata enhanced the conversion yield. Digitoxin showed better adsorption to CD polymer compared to digoxin, so that the optimization of addition time was found to be necessary. In the case of adding CD polymer 24 hours after the feeding of substrate digitoxin, the highest digoxin production could be achieved. At this period, digitoxin was almost consumed by cells and productivity was proportionally enhanced according as the amount of substrate was increased. Immobilization of CD polymer did not promote the biotransformation. When 3.33 g/L of CD selective inclusion complex formation could be expected. Adsorption rate was found to be rapid and saturation was obtained within 10 hours of contact.

• Journal of Microbiology and Biotechnology
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• 제8권5호
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• pp.478-483
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• 1998

For the enhanced production of a cardiac glycoside, digoxin, using in situ adsorption by biotransformation from digitoxin in plant cell suspension cultures, selection of proper resins was attempted and the culture conditions were optimized. Among various kinds of resins tested, Amberlite XAD-8 was found to be the best for digoxin production in considering adsorption characteristics as well as the effect on cell growth. Adequate time for resin addition was determined to be 36 h from the beginning of biotransformation and the presence of resins should be as short as possible to increase the productivity. In addition, to prevent the cells from direct contact with resin particles, immobilized systems were designed and examined. Immobilization further improved the advantages of in situ adsorption. It was confirmed that the increase of the contact area for mass transfer was an important factor in utilizing an immobilized system to enhance digoxin production.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.809-816
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• 2010

Microbial biotransformations can be used to predict mammalian drug metabolism. The present investigation deals with microbial biotransformation of valdecoxib using microbial cultures. Thirty-nine bacterial, fungal, and yeast cultures were used to elucidate the biotransformation pathway of valdecoxib. A number of microorganisms metabolized valdecoxib to various levels to yield nine metabolites, which were identified by HPLC-DAD and LC-MS-MS analyses. HPLC analysis of biotransformed products indicated that a majority of the metabolites are more polar than the substrate valdecoxib. Basing on LC-MS-MS analysis, the major metabolite was identified as a hydroxymethyl metabolite of valdecoxib, whereas the remaining metabolites were produced by carboxylation, demethylation, ring hydroxylation, N-acetylation, or a combination of these reactions. The hydroxymethyl and carboxylic acid metabolites were known to be produced in metabolism by mammals. From the results, it can be concluded that microbial cultures, particularly fungi, can be used to predict mammalian drug metabolism.

• Food Science and Biotechnology
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• 제18권4호
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• pp.833-841
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• 2009

Monoterpenes, in special limonene and its derivatives, are well studied in the literature due to their several properties. They are well recognized as major components of essential oils; some of them, are important industry residues, and others present some important biological activities. In this review, the biotransformation of the inexpensive limonene into flavor compounds was briefly reviewed and the main pathways for limonene biotransformation are presented. Furthermore, some important biological properties of these compounds were also considered, like bactericidal activity, induction of immune response, and role in disease prevention, with a little emphasis on some possibilities related to the mechanisms of anticancer action.

• Journal of Microbiology and Biotechnology
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• 제9권2호
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• pp.147-149
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• 1999

Biotransformation of exogenous (-)-(4R)-isopiperitenone in cell suspension cultures of Mentha piperita resulted in oxidized products, with (-)-7-hydroxyisopiperitenone being the major compound. The mass of products obtained $unde^{18}O_2$, atmosphere was two units higher than that under normal atmosphere. The biotransformation was inhibited by several cytochrome P450-specific inhibitors as well as by carbon monoxide. Carbon monooxide inhibition was substantially overcome by irradiation of cells with blue light including light at 450nm wavelength. These results suggested that a cytochrome P450-type monooxygenase was involved in the biotransformation.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.566-570
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• 2018

Because glycosylation of aesculetin and its 6-glucoside, aesculin, enhances their biological activities and physicochemical properties, whole-cell biotransformation and enzymatic synthesis methodologies using Neisseria polysaccharea amylosucrase were compared to determine the optimal production method for glycoside derivatives. High-performance liquid chromatography analysis of reaction products revealed two glycosylated products (AGG1 and AGG2) when aesculin was used as an acceptor, and three products (AG1, AG2, and AG3) when using aesculetin. The whole-cell biotransformation production yields of the major transfer products for each acceptor (AGG1 and AG1) were 85% and 25%, respectively, compared with 68% and 14% for enzymatic synthesis. These results indicate that whole-cell biotransformation is more efficient than enzymatic synthesis for the production of glycoside derivatives.

• 한국미생물·생명공학회지
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• 제22권6호
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• pp.651-658
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• 1994

For the production of digoxin by using biotransformation in suspension-cultured Digita- lis lanata cells, a two-stage culture process was optimized. Modified Murashige and Skoog medium was used for growth in the first stage and the cells were transferred to glucose solution for the production of digoxin from digitoxin via biotransformation in the second stage. When the cells were cultivated for 10 days in the growth period, 12$\beta$-hydroxylation capacity was the best. It was found that the optimum amount of digitoxin as substrate was 400 mg/l with initial cell density of 21%. Maximum productivity was achieved 5 days after transfer of cells to production medium. Sucrose and fructose provided similar digoxin yield as that in glucose, and 6% was proved to be the best glucose solution. Most of the components of modified MS medium except phosphate reduced the efficiency of digoxin formation. Besides, peptone and beef extracts inhibited 12$\beta$-hydroxylation, while promoting glucosylation. Finally, it was apparent that light enhanced the formation of digoxin significantly.

• KSBB Journal
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• 제13권4호
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• pp.352-356
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• 1998

Addition of cyclodextrin in the biotransformation of digitoxin into digoxin by Digitalis lanata cell suspension cultures enhanced the conversion yield. Presence of cyclodextrin also supported good stability of the intermediate product, digoxin, for long time. Among several kinds of cyclodextrins, ${\beta}$-cyclodextrin provided the best results. It was found that the optimum form of cyclodextrin utilization was the external addition of iclusion complexes between digitoxin and ${\beta}$-cyclodextrin at 1: 2 molar ratio from the beginning of biotransformation. With the optimized conditions, addition of ${\beta}$-cyclodextrin enhanced the production of digoxin up to 1.55 fold. In this case, not only digitoxin consumption was increased, but also the production of by-product was reduced.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.172.3-173
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• 2002