• 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.

• 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.

• 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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• 제9권5호
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• pp.589-592
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• 1999

Suspension cultures of Digitalis lanata were successfully performed in an aqueous two-phase system (ATPS) of 4.5％ polyethylene glycol (PEG) 20,000 and 2.8％ crude dextran. Cell growth in the medium containing an individual ATPS-forming polymer was inhibited due to the toxicity of PEG and a high viscosity of dextran. Formation of ATPS supported cell growth by showing a considerably decrease in viscosity and partitioning of cells into a PEG-lean dextran phase. It was found that an aqueous two-phase cultivation of plant cells in a stirred tank bioreactor could be successfully applied.

• Journal of Microbiology and Biotechnology
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• 제14권6호
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• pp.1129-1133
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• 2004

The effects of Pluronic F-68, a non-ionic surfactant, on the growth and physical characteristics of Digitalis lanata suspension cultures were investigated in aqueous two-phase systems (ATPSs) composed of $4.5\%$ polyethylene glycol (PEG) 20,000 and $2.8\%$ crude dextran. In the range of 0.1-10.0 g $1^{-1}$, Pluronic F-68 enhanced the maximum cell density in a medium with ATPSs, even though Pluronic F-68 did not affect cell growth in a normal growth medium. In terms of physical properties of ATPSs with cell suspension cultures, 0.2 g $1^{-1}$ of Pluronic F-68 reduced viscosity by up to $40\%$, while 0.1 g $1^{-1}$ of Pluronic F-68 significantly enhanced the oxygen transfer rate. In addition, we successfully performed aqueous two-phase cultivation in a 5-1 stirred tank bioreactor with 0.5 g $1^{-1}$ of Pluronic F-68, and discovered that cell growth in ATPSs was similar to that in normal growth medium.

• 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.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1995년도 식물학심포지움 식물로부터 유용 2차대사산물의 생산 PRODUCTION OF USEFUL SECONDARY METABOLITES FROM PLANTS
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• pp.79-90
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• 1995

Production of a cardiac glycoside, digoxin, by 12$\beta$-hydroxylation from digitoxin was studied in plant cell suspension cultures of Digitalis lanata. In order to increase the conversion yield, various culture conditions including immobilization were investigated and optimized. Since digoxin was released in the medium temporarily and converted further into a glucosylated product, deacetyllanatoside C, in situ adsorption of digoxin was employed to recover the product continuously. Amberlite resin XAD-8 showed the best adsorption characteristics for digoxin among the examined resins, and an integrated process was developed to increase the productivity. In addition, it was found that the utilization of $\beta$-cyclodextrin to entrap digoxin during the culture enhanced the biotransformation yield significantly.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2003년도 춘계 학술대회지
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• pp.10-16
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• 2003

Natural resource plants have been useful and helpful materials for human to against diseases and Prevention since ancient Egyptian and Roman times. However, according to recent survey, its habitat and indigenous are continuously decreased and almost extinct some valuable species, as Adonis vernalis, Digitalis lanata etc., especially in Eastern Europe and east Asian countries due to radical political and social reforms. ESCOP and FAO have already initiated to protect the endangered species for conservation, protection and propagation technology but it is not easy tasks without global concerning. Most natural resource plants have volatile components in essential oils and its consumption and demanding is increased every year, which contained certain compounds have no side effects and good properties for biological activities. Essential oils of natural resource plants are also well known for medical purposes, such as Central Nervous System (CNS, linalool), anticancer (d-limonene, perillyl alcohol, etc.), microbial and fungicidal activities (menthol, borneol, etc). Essential oil also used for natural therapy to prevent and increase immune systems instead of chemical synthesis drugs. With this, researchers of natural resource plants are ultimately faced to develop and optimal technology for increasing the Korean farmer's income by high added-value herbal products in present and future.