LL-F28249 antibiotic complex: a new family of antiparasitic macrocyclic lactones. Isolation, characterization and structures of LL-F28249 alpha, beta, gamma, lambda.

A new family of antiparasitic macrolides has been isolated from Streptomyces cyaneogriseus sp. noncyanogenus. The compounds, designated LL-F28249 alpha, beta, gamma and lambda, possess potent antiparasitic activity. The isolation, purification and structure determination by spectroscopic methods are presented.