Antimicrobial activity of N-phthaloylamino acid hydroxamates.

Antibacterial and antifungal activity of N-phthaloylamino acid hydroxamates [C6H4(CO)2N-X-CONHOH, X=amino acid residues of glycine, beta-alanine or D-phenylglycine], was examined against 44 strains of Gram-positive and Gram-negative bacteria, and 10 species of yeasts. The level of antimicrobial activity was established using the in vitro agar assay and the standard broth dilution susceptibility test. N-phthaloyl-D-phenylglycine-hydroxa- mic acid , the substance with the highest lipophilicity (log P), showed the best antibacterial activity, especially against Gram-negative bacteria. Minimum inhibitory concentration of was 0.008 mg mL-1 in the activity against Yersinia enterocolitica O3, confirmed by a large inhibition zone (30 mm) by the diffusion test. Hydroxamates inhibit growth by chelation of the PDF enzyme metal in both Gram-positive and Gram-negative bacteria, and LpxC enzyme in Gram-negative enzyme. Phthalimides appear to contribute to inhibition by destabilizing m-RNA. Antifungal activity of substances is not very expressed.