This family consists of Bombinin and Maximin proteins from Bombina maxima (Chinese red belly toad). Two groups of antimicrobial peptides have been isolated from skin secretions of Bombina maxima. Peptides in the first group, named maximins 1, 2, 3, 4 and 5, are structurally related to bombinin-like peptides (BLPs). Unlike BLPs, sequence variations in maximins occurred all through the molecules. In addition to the potent antimicrobial activity, cytotoxicity against tumor cells and spermicidal action of maximins, maximin 3 possessed a significant anti-HIV activity. Maximins 1 and 3 have been found to be toxic to mice. Peptides in the second group, termed maximins H1, H2, H3 and H4, are homologous with bombinin H peptides.