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임계농도 응고욕을 이용한 아크릴 섬유의 현성과 물성에 관한 연구(I)
이승락,문규열,조현혹,이장우,죽전홍 한국섬유공학회 1992 한국섬유공학회지 Vol.29 No.5
In order to elucidate the coagulation mechanism for the polyacrylonitrile/HNO₃ (solvent)/H₂0(nonsolvent) wet-spinning system, the effects of the coagulation bath temperature and composition (content of solvent m the bath) on the coagulation behavior, and hence structure and properties of the resulting(proto and drawn) fibers have been investigated prior to finding out the optimum(critical) bath composition. Apparent diffusion coefficients of solvent at different coagulation conditions have been estimated from diffusing-out experiments during the coagulation step using Takeda's simplified model based on quasi-binary, equimolar diffusion. The changes in structure and properties of the fibers caused by the variation of the diffusion coefficient at different coagulation conditions have been confirmed from the experiments on mechanical properties, dye sorption, and morphological structure of the fibers.
이승락,Jin Hee Choi,류림,김진철,팽창현,김선희,김기현 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.11
As part of our current work to discover structurally and/or biologically novel compounds from Korean wild mushrooms, we isolated five ergostane-type steroids (1-5) from the fruiting bodies of Xerula furfuracea via repeated column chromatographic separations and HPLC purification. The chemical structures of the isolated steroids were shown to be (22E,24R)-24-methylcholesta-4,22- diene-3,6-dione (1), ergosta-7,22-diene-3β,5α,6β-triol (2), ergosta-7,22-diene-3β,5α,6β,9α-tetraol (3), (22E,24R)-5α,8α-epidioxyergosta-6,22-diene-3β-ol-3-O-β-D-glucopyranoside (4), and (22E,24R)-5α,8α-epidioxyergosta-6,9,22-triene-3β-ol-3-O-β-D-glucopyranoside (5) based on comparison of the data regarding their spectroscopic and physical properties with those of previous studies. Notably, this is the first report on the presence of the identified steroids (1-5) in this mushroom. We tested compounds 1–5 to determine their effects on adipogenesis and osteogenesis in the mouse mesenchymal stem cell line C3H10T1/2 and found that compounds 4 and 5 suppressed the differentiation of stem cells into adipocytes. Notably, in addition to its suppressive effect on adipogenesis, compound 5 was also shown to promote the osteogenic differentiation of stem cells. These findings demonstrate that the bioactive compounds isolated might be effective for the treatment of menopause-associated syndromes, such as osteoporosis and obesity, as the isolated compounds were shown to suppress adipogenesis and/or promote osteogenesis of stem cells.
이승락,강희선,유민정,유재식,이슬아,이상아,Christine Beemelmanns,이재철,김기현 한국생약학회 2020 Natural Product Sciences Vol.26 No.3
A pregnane steroid, 3α-hydroxy-pregn-7-ene-6,20-dione (1), was isolated from a Hydractinia-associated Cladosporium sphaerospermum SW67 by repetitive column chromatographic separation and high-performance liquid chromatography (HPLC) purification. The planar structure of 1 was elucidated from the analysis of the spectroscopic data (1D and 2D NMR spectra) and LC-MS data. The absolute configuration of 1 was determined by interpretation of ROESY spectrum of 1, together with the comparison of reported spectroscopic values in previous studies. To the best of our knowledge, this is the first report of the identification of the pregnane scaffold from C. sphaerospermum, a natural source. Compound 1 was evaluated for its effects on lipid metabolism and adipogenesis during adipocyte maturation and showed that compound 1 substantially inhibited lipid accumulation compared to the control. Consistently, the expression of the adipocyte marker gene (Adipsin) was reduced upon incubation with 1. Further, we evaluated the effects of 1 on lipid metabolism by measuring the transcription of lipolytic and lipogenic genes. The expression of the lipolytic gene ATGL was significantly elevated upon exposure to 1 during adipogenesis, whereas the expression of lipogenic genes FASN and SREBP1 was significantly reduced upon treatment with 1. Thus, our findings provide experimental evidence that the steroid derived from Hydractinia-associated C. sphaerospermum SW67 is a potential therapeutic agent for obesity.