1184-05-0Relevant articles and documents
Steryl and stanyl esters of fatty acids by solvent-free esterification and transesterification in vacuo using lipases from Rhizomucor miehei, Candida antarctica, and Carica papaya
Weber,Weitkamp,Mukherjee
, p. 5210 - 5216 (2001)
Sitostanol has been converted in high to near-quantitative extent to the corresponding long-chain acyl esters via esterification with oleic acid or transesterification with methyl oleate or trioleoylglycerol using immobilized lipases from Rhizomucor miehei (Lipozyme IM) and Candida antarctica (lipase B, Novozym 435) as biocatalysts in vacuo (20-40 mbar) at 80 °C, whereas the conversion was markedly lower at 60 and 40 °C. Corresponding conversions observed with papaya (Carica papaya) latex lipase were generally lower. High conversion rates observed in transesterification of sitostanol with methyl oleate at 80 °C using Lipozyme IM were retained even after 10 repeated uses of the biocatalyst. Saturated sterols such as sitostanol and 5α-cholestan-3β-ol were the preferred substrates as compared to Δ5-unsaturated cholesterol in transesterification reactions with methyl oleate using Lipozyme IM. Transesterification of cholesterol with diethyl 1,8-octanedioate using Lipozyme IM in vacuo yielded methylcholesteryl 1,8-octanedioate (75%) and dicholesteryl 1,8-octanedioate (5%). However, transesterification of cholesterol with diethyl carbonate and that of oleyl alcohol with ethylcholesteryl carbonate, both catalyzed by Lipozyme IM, gave ethylcholesteryl carbonate and oleylcholesteryl carbonate, respectively, in low yield (20%). Moreover, cholesterol was transesterified with ethyl dihydrocinnamate using Lipozyme IM to give cholesteryl dihydrocinnamate in moderate yield (56%), whereas the corresponding reaction of lanosterol gave lanosteryl oleate in low yield (14%).
Purification of recombinant acyl-coenzyme a:cholesterol acyltransferase 1 (ACAT1) from H293 cells and binding studies between the enzyme and substrates using difference intrinsic fluorescence spectroscopy
Chang, Catherine C. Y.,Miyazaki, Akira,Dong, Ruhong,Kheirollah, Alireza,Yu, Chunjiang,Geng, Yong,Higgs, Henry N.,Chang, Ta-Yuan
, p. 9957 - 9963 (2010)
Acyl-coenzyme A:cholesterol acyltransferase 1 (ACAT1) is a membrane-bound enzyme utilizing long-chain fatty acyl-coenzyme A and cholesterol to form cholesteryl esters and coenzyme A. Previously, we had expressed tagged human ACAT1 (hACAT1) in CHO cells and purified it to homogeneity; however, only a sparse amount of purified protein could be obtained. Here we report that the hACAT1 expression level in H293 cells is 18-fold higher than that in CHO cells. We have developed a milder purification procedure to purify the enzyme to homogeneity. The abundance of the purified protein enabled us to conduct difference intrinsic fluorescence spectroscopy to study the binding between the enzyme and its substrates in CHAPS/phospholipid mixed micelles. The results show that oleoyl-CoA binds to ACAT1 with Kd = 1.9 μM and elicits significant structural changes of the protein as manifested by the significantly positive changes in its fluorescence spectrum; stearoyl-CoA elicits a similar spectrum change but much lower in magnitude. Previously, kinetic studies had shown that cholesterol is an efficient substrate and an allosteric activator of ACAT1, while its diastereomer epicholesterol is neither a substrate nor an activator. Here we show that both cholesterol and epicholesterol induce positive changes in the ACAT1 fluorescence spectrum; however, the magnitude of spectrum changes induced by cholesterol is much larger than epicholesterol. These results show that stereospecificity, governed by the 3β-OH moiety in steroid ring A, plays an important role in the binding of cholesterol to ACAT1.
COMPOSITION FOR PREVENTING HAIR LOSS AND ACCELERATING HAIR GROWTH
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Paragraph 0017, (2015/10/05)
Disclosed is a composition for prevention of hair loss and promotion of hair growth. The composition includes a compound represented by Formula 1, wherein A is derived from polycyclic compounds, and R is a hydroxyl group, or a saturated or unsaturated straight or branched alkyloxy or acyloxy group having 1 to 20 carbon atoms.
FeCl3·6H2O as a versatile catalyst for the esterification of steroid alcohols with fatty acids
Komura, Kenichi,Ozaki, Akiyoshi,Ieda, Noboru,Sugi, Yoshihiro
experimental part, p. 3407 - 3410 (2009/05/09)
FeCl3·6H2O is an active catalyst for the esterification of some steroid alcohols with fatty acids under azeotropic reflux in mesitylene as solvent. Georg Thieme Verlag Stuttgart.
A simple and efficient method for direct acylation of acetals with long alkyl-chain carboxylic acid anhydrides
Stamatov, Stephan D.,Stawinski, Jacek
, p. 9697 - 9703 (2007/10/03)
We have developed an efficient and simple method for direct transformation of acetals to carboxylic acid esters. The method consists of treatment of acetals with carboxylic anhydrides in the presence of boron trifluoride etherate as a catalyst and affords the corresponding ester derivatives in high yields with retention of configuration in the alcohol moiety. Some mechanistic aspects of this synthetically useful transformation are also discussed. (C) 2000 Elsevier Science Ltd.
