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, 1H NMR, 13C 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 bacteriaKlebsiella 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 mg/ml.   Key words: Annona montana, cyclomontanin D, cyclic heptapeptide, peptide synthesis, antibacterial activity, antidermatophyte activity.