Bk. Hwang et al., PRODUCTION, PURIFICATION, AND ANTIFUNGAL ACTIVITY OF THE ANTIBIOTIC NUCLEOSIDE, TUBERCIDIN, PRODUCED BY STREPTOMYCES-VIOLACEONIGER, Canadian journal of botany, 72(4), 1994, pp. 480-485
Three antibiotic substances strongly inhibitory to Phytophthora capsic
i or Magnaporthe grisea were isolated from the broth culture of Strept
omyces violaceoniger strain A50. A butanol-solubIe mixture of antibiot
ics from the broth were partially purified by XAD-2 column chromatogra
phy. The XAD-2 eluates inhibited the mycelial growth of P. capsici and
M. grisea and the development of Phytophthora blight on pepper (Capsi
cum annuum L.) plants. The antibiotics were separated by silica gel co
lumn chromatography and then purified on a Sephadex LH-20 column to yi
eld three peaks of antifungal activity: SF1A, SF1B, and SF2A. The pure
antibiotic SF2A was further purified by preparative HPLC and identifi
ed as the pyrrolo[2,3-d]pyrimidine nucleoside tubercidin based on the
UV, H-1, and C-13 NMR spectral data and other chemical evidence. The a
ntibiotic SF2A and authentic tubercidin showed a high antifungal activ
ity against the plant pathogenic fungi P. capsici, Botryosphaeria doth
idea, and Rhizoctonia solani.