Saprolmycins A-E, new angucycline antibiotics active against Saprolegnia parasitica.

Saprolmycins A-E, five new anti-Saprolegnia parasitica antibiotics were isolated from the culture broth of Streptomyces sp. strain TK08046. As determined using a combination of NMR and spectroscopic analyses, the structures of these compounds were elucidated as a new group of angucycline compounds closely related to saquayamycin. Saprolmycin A and E exhibited potent anti-S. parasitica selective activities, with MIC values of 3.9 and 7.8 ng ml(-1), respectively, but weak or no activity against fungi, gram-positive or -negative bacteria, and microalgae or zooplankton. Our results suggest these two compounds as highly effective and environmentally safe anti-saprolegniasis candidates.