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- Title
Efficiently enhancing regioselective acylation of 5-azacytidine catalysed by Candida antarctica lipase B with co-solvent mixtures as the reaction media.
- Authors
Hong Wu; Minhua Zong; Xiyu Chen
- Abstract
A comparative study of regioselective acylation of 5-azacytidine catalysed by CAL-B (Candida antarctica lipase B) in co-solvent mixtures and in pure organic solvents was performed, to our knowledge for the first time, and it was shown that a remarkable enhancement in the initial rate and substrate conversion in the reaction could be achieved with co-solvents as the reaction medium instead of pure organic solvents. For the CAL-B-catalysed regioselective synthesis of 5′-O-butyryl-5-azacytidine in co-solvent mixtures, the optimal conditions were as follows: optimal co-solvent mixture, hexane/pyridine (40/60, v/v); initial aw (water activity), 0.07; enzyme dosage, 50 units/ml; vinyl butyrate/5-azacytidine molar ratio, 15:1; temperature, 60 °C. Under the optimal conditions, v0 (the initial reaction rate), C (the substrate conversion) and the regioselectivity of the reaction were 0.75 mM/min, 99.0% and above 99% respectively. Similar phenomena were observed in the CAL-B-catalysed regioselective acylation of 5-azacytidine with an extensive range of fatty acid vinyl esters (from C2 to C18). Compared with pure pyridine, the reactions were greatly accelerated in a hexane/pyridine (40/60, v/v) co-solvent mixture and 5-azacytidine could be biotransformed into its derivative 5′-O-acyl-5-azacytidine at a much higher conversion rate (91.4–99.0% as against 40.2–43.5%). Meanwhile, adoption of a co-solvent mixture as the reaction medium could also greatly lower the enzyme dosage and the molar ratio of acyl donor to 5-azacytidine.
- Subjects
ACYLATION; CATALYSIS; CANDIDA; LIPASES; NUCLEOSIDES; ORGANIC solvents; CHEMICAL reactions; FATTY acids; ESTERS; PYRIDINE
- Publication
Biotechnology & Applied Biochemistry, 2009, Vol 53, Issue 3, p201
- ISSN
0885-4513
- Publication type
Article
- DOI
10.1042/ba20080178