Antimalarial activity of ultra-short peptides.

Ultra-short peptides 1-9 were designed and synthesized with phenylalanine, ornithine and proline amino acid residues and their effect on antimalarial activity was analyzed. On the basis of the IC(50) data for these compounds, the effects of nature, polarity, and amino acid sequence on Plasmodium berghei schizont cultures were analyzed too. Tetrapeptides Phe-Orn-Phe-Orn (4) and Lys-Phe-Phe-Orn (5) showed a very important activity with IC(50) values of 3.31 and 2.57 microM, respectively. These two tetrapeptides are candidates for subsequent in vivo assays and SARS investigations.