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Abstract

ABSTRACT:Acinetobacter baumanniiis typically coccobacillus GramNegative bacterium, resists almost all antibiotics in use. Synthetic antimicrobial peptides (AMPs) against this bacterium were designed with the aid of computational software and databases to be with the accepted models. Antimicrobial peptides (AMPs) might be the candidate solution for the this problems. Four peptides designated MY1, MY2, MY3 and MY4 were synthesized with length 11-14 amino acids, they were rich in Arginine and Tryptophan. The MICs of the peptides against colistin sensitive A. baumannii were 2.4, 6.2, 6.9, 6.6 µg/ml (mean for 10 strains) respectively vs Mastoparan as control was 10.4 µg/ml, whereas the MICs of peptides against colistin resistant A. baumannii were 3.8, 6.2, 6.8, 6.4 µg/ml (mean for 10 strains) respectively vs Mastoparan 13.6 µg/ml. The designed peptides showed no hemolytic activity at effective MICs. The practical calculated Therapeutic Index were 141.7, 67.7, 60.9, 77.3 vs 7.7 for Mastoparan (Colistin sensitive strains) and for resistant strains were 89.5, 67.7, 61.8, 79.7 vs Mastoparan 5.9.