Synthesis and biological evaluation of cyclic tripeptide and its analog isolated from young leaves of azadirachta Indica

Abstract

In present research, two naturally occurring cyclic tripeptides have been synthesized which are present in Azadirachta indica A. Juss and earlier were isolated. Solution phase peptide synthesis technique was used to obtain the desired cyclic tripeptides. The compounds were synthesized in presence of coupling agent i.e dicyclohexylcarbodiimide along with base N-methylmorpholine with continuous stirring. The linear precursors were obtained by joining of deprotected dipeptide units with methyl ester hydrochlorides of amino acid. Cyclization was carried out by keeping linear tripeptide units at 0-5�celcius for a week in the presence of triethylamine or N-methylmorpholine to get final cyclic tripeptides. The structures were elucidated with spectral techniques viz. infrared and nuclear magnetic resonance. The synthesized compounds were evaluated for antibacterial and antifungal activity at different concentrations and compared with Ciprofloxacin (50�g/ml) and Amphotericin B (50�g/ml) was taken as positive control for both bacterial and fungal strains respectively. It was concluded that compound 8 showed maximum activity against all bacterial strains and compound 9 showed maximum activity against all fungal strains.