Abstract: Three compounds, β-rubromycin (1),γ-rubromycin (2) and griseorhodin F (3),were separated and purified by medium-pressure MCI column and semipreparative HPLC from the fermentation broth of Streptomyces sp.KIB-717,which was isolated from soil samples collected in Gaoligongshan in Tengchong from Yunnan Province,China.The structures of three isolates were characterized through extensive analysis of NMR and mass spectrometry data and by comparison the NMR data with that reported in literatures.The antifungal experiments demonstrated that compounds 1 and 2 possessed significant antifungal activity against most of the tested plant pathogenic fungi,such as Botrytis cinerea and Magnaporthe grisea (Hebert) Barr.

Key words: Streptomyces, secondary metabolites, isolation and identification, plant pathogenic fungi, antifungal activity