Synthesis and cytotoxic activity of new peptides containing basic amino acid residues

In search of more potent compounds endowed with a cytotoxic activity, a new series of basic peptides was synthesized using solid-phase methods. All peptides were purified by preparative reverse-phase HPLC and characterized by electrospray mass spectrometry. The cytotoxic activity was determined in cultured HeLa cells. The hexadecapeptides 5 and 6 showed a 50% inhibition at the concentration of 30 micrograms/ml. The salmina and the polyamino acids of L-arginine, L-histidine and L-lysine, containing sixteen residues, were virtually inactive. This demonstrates that a specific peptide sequence is necessary to obtain a positive response in HeLa test.