An antimalarial tetrapeptide from the entomopathogenic fungus Hirsutella sp. BCC 1528.

Hirsutellic acid A (1), a new linear tetrapeptide possessing an anthranilic acid residue at the C-terminus, was isolated from a fermentation broth of the entomopathogenic fungus Hirsutella sp. BCC 1528. The structure of this compound was elucidated by NMR and MS analyses, and its absolute configuration was deduced by HPLC analysis of the acid hydrolysate using a chiral column. Hirsutellic acid A exhibits activity against the malarial parasite Plasmodium falciparum K1 with an IC(50) value of 8.0 microM, while it was noncytotoxic to Vero cells at a concentration of 95 microM.