Retro-indolicidin is a biological active peptide. (Reverse peptide of indolicidin (Rev4) is a 13-amino acid residue peptide based on the sequence of indolicidin. Indolicidin, a member of the cathelicidin protein family, is a 13-amino acid residue cationic, antimicrobial peptide-amide isolated from the cytoplasmic granules of bovine neutrophils. The synthetic peptide Rev4 has been shown to possess strong antimicrobial as well as protease inhibitory activities in vitro.)