Synthesis, characterization and biological evaluation of cyclomontanin D

In present study, it was of interest to synthesize a natural proline-rich cyclooligopeptide - cyclomontanin D 8 by coupling of tripeptide Boc-L-Asn(bzh)-L-Pro-Gly-OH and tetrapeptide L-Leu-L-Pro-L-Tyr-L-Ala-OMe followed by cyclization of linear polypeptide fragment. Structure of synthesized cyclopeptide was confirmed by detailed spectral analysis including FTIR, (1)H NMR, (13)C NMR, ESIMS/MS and elemental analysis. From the results of biological evaluation, it was concluded that newly synthesized cyclooligopeptide possessed good bioactivity against Gram-negative bacteria Klebsiella pneumonia, Pseudomonas aeruginosa as well as potent antidermatophyte activity against Microsporum audouinii and Trichophyton mentagrophytes, in comparison to reference drugs - ciprofloxacin and griseofulvin. Moreover, 8 exhibited moderate antifungal activity against pathogenic Candida albicans with minimum inhibitory concentration (MIC) value of 6 mu g/ml.