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리팜피신에 내성인 Bifidobacterium bifidum 균주개발
최응칠(Eung Chil Choi),고성열(Sung Youl Ko),김희선(Hee Sun Kim),최성숙(Sung Sook Choi),김숙경(Sook Kyung Kim),김병각(Byoung Kak Kim) 대한약학회 1993 약학회지 Vol.37 No.5
Bifidobacterium bifidum, one strain of medical preparations being on the market for human intestinal disorder, is very sensitive to rifampicin. If this preparation is taken with rifampicin, its therapeutic effect can't be expected. To develope rifampicin resistant mutants, B. bifidum was treated with N-methyl-N''-nitro-N-nitrosoguanidine(MNNG). All of thirty strains grown on the plates containing 10 mcg/ml rifampicin were over 1,000 times more resistant to rifampicin than parental strain and they were identified as B. bifidum by fructose-6-phosphoate phosphoketolase test. Three strains out of thirty, which produced almost same amount of organic acid as parental strain, were selected for further studies. They showed identical growth inhibition activity aganist E. coli compared with that of parental strain. And rifampicin was not inactivated.
한국산 고등균류의 성분 연구(Ⅳ) : Lactarius Piperatus (Fr.) S.F. Gray로 부터 Gultorin 의 분리
최응칠(Eung Chil Choi),김병각(Byong Kak Kim) 한국생약학회 1975 생약학회지 Vol.6 No.1
In order to isolate constituents of Lactarius piperatus(FR.) S.F. GRAY, the fresh carpophore was homogenized with ethanol in a blendor, stored for three years and subsequently extracted with ethanol. From the concentrated ethanol solution, a mixture of compounds was precipitated, from which a white needle crystal, named gultorin, (mp.160∼162°) was obtained. The physical and chemical characteristics of gultorin were determined.
최응칠(Eung Chil Choi),김병각(Byong Kak Kim),정경수(Kyeong Soo Chung) 대한약학회 1988 약학회지 Vol.32 No.5
394 strains of soil microorganism were isolated from the Korean soil samples. The isolated strains were shake-cultured in oat-meal medium. The filtrates of the cultures were screened for the production of alpha-amylase inhibitors. Five strains were identified to produce alpha-amylase inhibitors. And these strains were identified as Actinomycetes.
Bacillus licheniformis EMR 균주에서 린코사마이드계 항생물질에 의한 유도내성
최응칠(Eung Chil Choi),우정원(Jung Won Woo),B. 와이스브럼(Bernard Weisblum) 대한약학회 1986 약학회지 Vol.30 No.6
To clarify resistance mechanisms of lincosamide antibiotics, it was examined whether lincosamide antibiotics was able to induce high resistance to macrolide and lincosamide antibiotics against EMR-1 strain of Bacillus species. And it was also examined whether the inducible resistance was plasmid-mediated or chromosome-mediated. This strain was identified as Bacillus licheniformis by its morphological and physiological characteristics. The subinhibitory concentrations of lincomycin and clindamycin induced high resistance in the strain to lincosamide antibiotics, but not to macrolide antibiotics. The inducible resistance was not eliminated by treating the strain with ethidium bromide, and plasmid was not identified by the alkaline lysis method of plasmid preparation. These results indicate, therefore, that the inducible resistance to macrolide and lincosamide antibiotics in the strain may be chromosome-mediated, not plasmid-mediated.
리팜피신에 내성인 Streptococcus faecalis 균주의 개발
최응칠(Eung Chil Choi),김승호(Seung Ho Kim),권애란(Ae Ran Kwon),이미정(Mi Jeong Lee),오정자(Jeong Ja Oh),김병각(Byong Kak Kim) 대한약학회 1993 약학회지 Vol.37 No.4
The preparation of Streptococcus faecalis RSI is used as a medicinal preparation for human intestinal disorders. But the microbe in this preparation is very sensitive to rifampicin. If this preparation is taken with rifampicin, its therapeutic effect can not be expected. To develope rifampicin resistant mutants, the rifampicin sensitive strain S. faecalis RSI was treated with N-methyl-N''-nitro-N-nitrosoguanidine(MNNG). Twelve strains of the MNNG-induced mutants showed distinct resistance to rifampicin and five mutants were selected for further studies. They also exhibited identical characteristics with the parent S. faecalis RSI when they were tested for lactic acid formation and growth inhibition of E. coli. From in vitro test, it was identified that rifampicin is not inactivated by certain factors of the rifampicin resistant mutants. Conclusively, the rifampicin resistant mutants are efficient strains that have insensitivity against rifampicin and original biochemical characteristics of the parent strain.
한국산 생약자원 개발연구 (제2보) : prunus tomentosa의 약효성분에 관하여
최응칠(Eung-Chil Choi),한대석(Dae-Suk Han),김영호(Young-Ho Kim),홍인혁(In-Hyuk Hong) 한국생약학회 1983 생약학회지 Vol.14 No.2
HPLC is a useful method for identifying amygdalin which has been the subject of considering controversy for cancer remedy. The resolution of amygalin was satisfactory and the separation of amygdalin was accomplished using carbohydrate analysis column, mobile phase of acetonitrile: H₂O (90 : 10), and UV detector. Quantitative analysis showed that amygdalin contents of Prunus tomentosa, P. serrulata, and P. ishidoyana(Amygdalaceae) were 2.18, 2.41, and 2.26%, respectively. It was suggested that the seed of Prunus species was worth useful resource of amygdalin.
Resistance Mechanism of Acinetobacter spp. Strains Resistant to DW-116, a New Quinolone
Choi, Keum-Hwa,Baek, Moon-Chang,Kim, Byong-Kak,Choi, Eung-Chil The Pharmaceutical Society of Korea 1998 Archives of Pharmacal Research Vol.21 No.3
DW-116 is a new fluoroquinolone antimicrobial agent with a broad spectrum. In order to elucidate the resistance mechanism to DW-116 in Acinetobacter spp. bacteria, total chromosomal DNA was isolated from 10 strains of Acinetobacter spp. resistant to DW-116. Quinolone resistance determinant region (QRDR) of DNA gyrase gene was amplified by PCR. The 345 bp nucleotide fragment yielded was inserted into pKF 3 which was used as the vector. Comparisons of the DNA sequences of 8 strains with that of the wild type strain revealed a Ser-83 to Leu mutation in mutants and all ten strains contained one silent mutation$(T{\rightarrow}G)$in QRDR. From Acinetobacter MB4-8 strain, DNA gyrase was isolated and purified, through novobiocin-sepharose, heparin-sepharose affinity column chromatography. The enzyme was composed of two subunits and the molecular mass of subunits A and B were 75.6 and 51.9 kDa, respectively. The supercoiling activity of the reconstituted DNA gyrase composed of subunit A from Acinetobacter MB4-8 and subunit B from E. coli was not inhibited by $128{\mu}\textrm{g}$ml of ciprofloxacin. It might be said that one of the resistance mechanisms to DW-116 in Acinetohacter MB4-8 was subunit A alteration of DNA gyrase.
Studies on Protoplast Formation and Regeneration of Ganoderma lucidum
Choi, Seung-Hee,Kim, Byong-Kak,Kim, Ha-Won,Kwak, Jin-Hwan,Park, Eung-Chil,Kim, Young-Choong,Yoo, Young-Bok,Park, Yong-Hwan The Pharmaceutical Society of Korea 1987 Archives of Pharmacal Research Vol.10 No.3
To obtain a new strain of Ganoderma lucidum by protoplast fusion technique, its protoplast formation and regeneration were studied. Several factors affecting the protoplast formation and regeneration were investigated to find their optimum conditions. The mycelium was grown for four days on the cellophane membrane placed on G. Incidum complete medium (GCM). When various commercial lytic enzymes were examined for protoplast isolation, the combination of Novozym 234 and $\beta$glucuronidase was found to be effective. An osmotic stabilizer, 0.6 M sucrose in 20 mM phosphate buffer pH 5.8, gave the highest yield of protoplasts. Three-hour incubation in shaking incubator was most suitable for releasing protoplasts. To increase the protoplast yield, pretreatment with 2-mercaptoethanol was carried out. The regeneration frequency in GCM containing 0.6M MgSO$_4$ 7$H_2O$ was shown to be 0.66%.