A novel anti-HIV macrocyclic peptide from Palicourea condensata

A 37 amino acid cyclic polypeptide has been isolated from the organic extract of the tropical tree Palicourea condensata. Palicourein (1) is the largest of a growing family of plant peptides that contain a cyclized amino acid backbone cross-linked via three internal disulfide bridges. Palicourein inhibits the in vitro cytopathic effects of HIV-1(RF) infection of CEM-SS cells with an EC50 value of 0.1 muM and an IC50 value of 1.5 muM.