Synthesis and biodegradability of new polyesteramides containing peptide linkages

Monomers having amino acid residues at the both ends were synthesized from amino acids, adipoyl chloride, and 1,4-butanediol. Polyesteramides containing peptide linkages (Phe-Phe, Phe-Leu, Phe-Val, and Phe-Ala) were synthesized from these monomers by using 1-ethyl-3-(3-dimethylaminopropyl) carbadiimide hydrochloride as the coupling agent. Polymers with moderate molecular weight (5600-7700) were obtained. These polymers were soluble in organic acids and polar aprotic solvents such as dimethyl sulfoxide (DMSO) and N,N-dimethyl formamide (DMF), as well as in chloroform. The results of biodegradation studies indicated that all of these polyesteramides were hydrolyzed by enzymes, such as alpha -chymotrypsin, subtilisin Carlsberg, and lipase. The rate of degradation depended strongly on the nature of amino acid residues in the polymer chains reflecting the enzyme specificity. The polymers obtained are anticipated to find agricultural or biomedical applications.