The Study On Enzymatic Synthesis Of Cephaloaporins

With the rapid development of bioengineering technology and immobilized enzyme technology,enzymatic synthesis of β-lactam antibiotics has made a great breakthrough in many aspects,such as the reaction of enzyme condensation,the separation of product.Currently,large-scale industrial production of enzymatic synthesis already has formed a mature process.Compared with the traditional chemical synthesis method,enzymatic synthesis has the advantages of mild reaction,less steps and clean.In the 21 st century,enzymatic synthesis of β-lactam antibiotics will be the inevitable trend of development.In this paper,7-amino-3-[(Z)-allyl-1-yl]-3-cephem-4-carboxylic acid(7-APCA)is synthesized through enzymatic synthesis in this paper,and it is the nucleus of cefprozil.The synthesis route was carried with 7-phenylacetamido-3-chloromethylcephalosporanic acid p-methoxybenzyl ester(GCLE)as the starting material.7-phenylacetamido-3-(propen-1-yl)-3-cephem-4-carboxylic acid 4-methoxybenzyl ester(GPRE)was synthesized from GCLE by "one pot" reaction,in which the iodine substitution,the quaternary phosphorylation and the Wittig reactions were carried out simultaneously.The GPRE removed the carboxyl protecting group under the action of aluminum trichloride to give 7-phenylacetamido-3-(propen-1-yl)-3-cephem-4-carboxylic acid.7-phenylacetamido-3-(propen-1-yl)-3-cephem-4-carboxylic acid was hydrolyzed to remove the amino protecting group by the penicillin acylase(PGA),and 7-APCA was obtained.The total yield was 64.45% and the purity of the product was higher than 95%.The focus of this paper is to optimize the enzymatic synthesis and the crystallization process of cefprozil,cefradine,cefaclor.Effects of various factor such as the activity of enzyme,reaction p H,temperature,the amount of enzyme,feed ratio,substrate concentration,on the synthetic hydrolysis ratio were investigated systematically,and it was also studied that the influence on yield and purity from the temperature of acidification,seed,the temperature of crystallization,the time of crystallization.After the optimization of the process,the S/H of enzymatic synthesis of cefprozil was more than 8,and the yield was about 88%,the purity was above 95%.The S/H of enzymatic synthesis of cefradine was more than 10,and the yield was about 81.33%,the purity was above 95%.The S/H of enzymatic synthesis of cefaclor was more than 5,and the yield was about91.8%,the purity was above 95%.The chemical structures of 7-APCA,cefprozil,cefradine and cefaclor were confirmed by infrared spectroscopy and nuclear magnetic resonance spectroscopy.The quality of product meet the requirements of national pharmacopoeia.