Controllable Selective Enzymatic Synthesis Of Amino Acid-drug Conjugates

Enzymatic methods play an important role in the synthesis of pharmaceutical compounds and their derivatives due to their high selectivity and mild reaction conditions. In this thesis, selective enzymatic synthesis of some drug derivatives, such as 1,2-diol drugs and nucleoside drugs, were developed.In this paper, we synthesized six Boc-protected amino acid vinyl esters (vinyl-N-Boc-L-Phe, vinyl-N-Boc-L-Ala, vinyl-N-Boc-L-Val, vinyl-N-Boc-L-Leu, divinyl-N-Boc-L-Asp, divinyl-N-Boc-L-Glu). These vinyl esters with high activity could be used as acyl donors in the enzymatic transesterification. Polymerizable aminoacyl vinyl ester derivatives of drug could be achieved via enzymatic transesterification drug with divinyl esters of amino acids. The obtained drug containing monomers with functionalized amino acid could be further utilized as precursors for biodegradable polymeric prodrugs.The selective enzymatic synthesis of some drugs derivatives containing multi-hydroxyl in non-aqueous media was developed. Three 1,2-diol drugs, Guaifenesin, Chlorphenesin and Mephenesin, were chosen as substrates. Divinyl-N-Boc-L-Asp and divinyl-N-Boc-L-Glu were used as donor agents. Six kinds of polymerizable aminoacyl vinyl ester derivatives of drug were selectively prepared through enzymatic reaction. It was a facial and quick method. Moreover, the influence factors of enzymatic synthesis including enzyme sources, reaction media, reaction time, water content, enzyme concentration, reaction temperature and the effect of enzyme reused were investigated. Furthermore, the initial reaction rate and the optimal reaction time were researched by the study of reaction kinetics.Selective enzymatic synthesis of nucleoside drugs aminoacyl derivatives in non-aqueous media was also developed. Enzymatic aminoacylation of Azacitidine, Cytarabin and Ribavirin with two divinyl aminocarboxylates and four vinyl aminocarboxylates with different side chain were developed to six kinds of polymerizable aminoacyl vinyl esters derivatives and twenty kinds of aminoacyl derivatives of drugs in good yields.The controllable selective synthesis of azacitidne aminoacyl derivatives could be achieved. Catalysis by Alkaline protease from Bacillus subtilis (Subtilinsin) in pyridine could facilitated the single step synthesis of 5'-O-aminoacyl Azacitidine derivatives in high yields. The application of Amano Lipase PS from Aspergllus mellcus (Lipase PS) in DMF afforded the mixture products of 2'-O-aminoacyl and 3'-O-aminoacyl azacitidine derivatives. The controllable selectivity of different position of azacitidine was achieved by changing the reaction conditions.Four kinds of novel amino acid ester prodrugs of azacitidine were obtained after deprotection process. The water-solubility and in-vitro release of amino acid ester prodrugs were also investigated, and the results suggested that prodrug can be considered as a promising prodrug form. Moreover, the relationship between chemical stability results and the structures of prodrugs was discussed.