Synthesis and Development of Some Biodegradable Polypeptides as Antimicrobial Agents

Biodegradable and bioactive polymers are gaining considerable attention in the field of biomedical research to achieve therapeutic effects, drug-targeting and as drug carriers. Two acidic amino acid (glutamic and aspartic acids) monomer units were converted into polyanionic long chain polypeptidespoly-glutamic acid (PGA) and poly-aspartic acids (PAA). The synthesized derivatives were characterized by various physicochemical and spectral methods. The approximate molecular weight of the synthesized polypeptides were determined by Sorenson’s method, and further confirmed by gel electrophoresis and MALDITOF techniques. The in vitro hydrolysis studies of the synthesized polypeptides was performed in simulated conditions outside the body, which mimic truly the in vivo scenario, and was used to study biodegradation. Results of the study clearly demonstrated that PGA and PAA are less prone towards hydrolytic degradation under acidic conditions in comparison to that in slight alkaline medium. Finally, the synthesized polypeptides were subjected to biological screening for antibacterial activity, at 10 and 50 μg/mL concentrations, against P. morganii and S. aureus bacterial strains using agar diffusion (filter paper disc) method. The antibacterial activity was exhibited by both PGA and PAA against both the selected strains, with the potency of PGA being slightly more than that of PAA. This could be attributed to the selective uptake of the compound by the particular strains of microorganisms. Thus, it can be concluded that polyanionic polypeptides can exert broad spectrum antimicrobial activity, and shall be biodegradable by physiological enzymes into smaller non toxic fragments/monomeric units having essential dietary value.