Efficient Enzymatic Synthesis Of Amoxicillin In Fully Organic Media And One-pot Enzymatic Synthesis Of Amoxicillin

Amoxicillin is one of the most widely usedβ-lactam antibiotics and suitable for a broad spectrum of bacterial infections. It is usually produced via traditional chemical procedures, which need unhydrous organic solvents, very low temperature, multi-step protection and unprotection, with heavy pollution. Enzymatic synthesis, which markedly reduces the production of waste and the dependence on organic solvents, is an efficient alternative to the chemical synthesis for the production ofβ-lactam antibiotics.This thesis focuses on the enzymatic synthesis of amoxicillin in fully organic medium. We also researched the cyclohexanol-cosolvenl K system and one-pot enzymatic synthesis of amoxicillin.The efficient enzymatic synthesis of amoxicillin in fully organic medium was successfully achieved with D-HPGM as the activated acyl donor. A series of organic solvents with different polarity were screened and it was shown that remarkable catalytic activity of the IPA was retained in relatively apolar organic solvents, among which cyclohexanol was the best. The influence fators including the reaction time, initial substrate concentration, molar ratio of substrates, IPA concentration and temperature on the enzymatic synthesis of amoxicillin in pure cyclohexanol were systematically examined. As a result, high yield (83.5%) and S/H ratio (1.0) were successfully achieved with 100 mM 6-APA and 200 mM D-HPGM under the optimum conditions.The cyclohexanol-organic solvent system was studied. Media composed with different organic solvents were screened and cyclohexanol-cosolvent K system (50/50. v/v) was found to be able to remarkably improve the enzyme activity. The conversion of 6-APA and D-HPGM was greatly improved, and the reaction was fast. After 6 h reaction, the conversion of 6-APA was nearly 100% and S/H ratio of 1.1 were achieved in reaction carried out at 25℃. Water content in reaction media was also investigated and high S/H ratio of 2.2 was achieved without reducing the synthesis vield. The method of one-pot enzymatic synthesis of amoxicillin was developed. 6-APA was obtained from the hydrolysis of penicillin G potassium salt (PGK) catalyzed by IPA, and subsequently acylated by D-HPGM with IPA. Amoxicillin was directly produced from PGK without the separation and purification of 6-APA. The amoxicillin yield of one-pot enzymatic synthesis in water-glycol system was much higher than that in fully aqueous medium, while the hydrolysis of D-HPGM was restrained. As a result, the yield of 55.2% and S/H ratio of 0.60 were achieved.