Gramicidin

A group of peptide antibiotics from bacillus brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of tyrothricin. (In Vitro) :Gramicidin is an antimicrobial peptide assembling as channels in membranes and increasing their permeability towards cations. There is poor Gramicidin activity against E. coli and S. cerevisae as shown from the survival of microbes (%) over a range of Gramicidin concentrations, in contrast with the action of Gramicidin on S. aureus. The microbicidal activity occurs over a range of low Gramicidin and DODAB concentrations which are not toxic to S. cerevisae.