Abstract: Objective To explore the bioactivities of Kanglemycin A,a novel ansamycin group antibiotic against M.tuberculosis(TB)in vitro. Methods Kanglemycin A was purified by silica gel chromatography and sephadex LH-20 chromatography,and its MICs to 20 strains including M.smegmatis,M.tuberculosis H₃₇Rv,M.tuberculosis H₃₇Ra,ofloxacin(OFLX)-sensitive M.tuberculosis clinical isolates and OFLX-resistant M.tuberculosis isolates were determined by equivalent serial dilution method. Results Kanglemycin A MIC to M.smegmatis was 64ug/ml,to M.tuberculosis H₃₇Rv and H₃₇Ra was 8ug/ml,to OFLX-sensitive M.tuberculosis isolates were 1-8?ug/ml,to OFLX-resistant M.tuberculosis isolates were 1-16ug/ml. Conclusion Kanglemycin A had strong inhibitory activity against M.tuberculosis,and might be a potential anti-TB drug candidate or leading compound.

Key words: Kanglemycin A, Mycobacterium tuberculosis, MIC