Two peptides with antimicrobial and cytolytic properties were purified from an extract of the skin of Tago's brown frog Rana tagoi. The primary structure of one peptide (FLPILGKLLS(10)GIL . NH2) identifies it as a member of the temporin family, whereas the second peptide (AIGSILGALA(10)KGLPTLISWI(20)KNR . NH2) displays 78% sequence identity to melittin from the venom of the honeybee Apis florea. Compared with melittin, the melittin-related peptide (MRP) was equipotent in inhibiting the growth of the Gram-positive bacterium Staphylococcus aureus, 5-fold less potent against the Gram-negative bacterium Escherichia coli and against the fungal pathogen, Candida albicans. MRP was 13-fold less hemolytic than melittin against human erythrocytes and 4- and 5-fold less cytolytic against mouse EL4 T-lymphoma-derived cells and L929 fibroblasts, respectively. However, at non-cytotoxic concentrations (less than or equal to8 muM), MRP did not protect HeLa cells from cell death produced by human rhinovirus type 2 infection. (C) 2003 Elsevier Science (USA). All rights reserved.