Description
Nucleoside antibiotic produced by Streptomyces griseochromogenes
(1). Biosynthesized from cytosine, glucose, arginine,
and methionine (2).
Uses
Blasticidin-S is used for the control of rice blast (PyricuZuria oryzae)
by foliar application.
Uses
Blasticidin S is a nucleoside produced by several species of Streptomyces, first reported in the late 1950s. Blasticidin S is an antifungal agent with particularly potent activity against the rice pathogen, Piricularia oryzae, for which it was used commercially for some time in Japan. Blasticidin S inhibits protein synthesis and is active against bacteria, tumour cell lines and nematodes. More recently, blasticidin S has been used as a marker for strain manipulations. Blasticidin S provided by BioAustralis is presented as the free base to avoid problems associated with the use of the hydrochloride.
Definition
ChEBI: A blasticidin that is an antibiotic obtained from Streptomyces griseochromogene.
Production Methods
Blasticidin S is produced by Streptomyces griseochromogenes,
and has a wide range of antimicrobial activity (4).
This antibiotic was utilized in the Far East beginning in
1961 against the rice blast pathogen Pyricularia oryzae,
with effective control achieved at rates of 10–40 ppm (4).
General Description
Blasticidin S was found in the culture broth of Streptomyces griseochromogenes by Yonehara et al. of the University of Tokyo in 1958. It has a nucleoside-analogue structure and shows strong activity against phytopathogenic fungi, especially Pericularia oryzae, the pathogen causing rice blast. Blasticidin S has been used to protect rice plants.
Pharmacology
Inhibits protein synthesis both in eukaryotes and in
prokaryotes (5,6). Interacts with ribosomal RNA in large
subunit, interfering with the transpeptidation step.
Inhibits cell-free protein synthesis in P. oryzae and
Escherichia coli.
Metabolic pathway
Several blasticidin S-resistant microorganisms are
found to produce blasticidin S deaminase which
catalyzes the hydrolytic deamination of the cytosine
moiety in blasticidin S to give a non-toxic
deaminohydroxy derivative.
Metabolism
3H-blasticidin S administered to mice was excreted in
the urine and feces within 24 h. Cytomycin and cytosin
were identified as the main metabolites in and on rice
plants, respectively (7). In soil, DT
50 < 5 d. Metabolized to
nontoxic deaminohydroxy blasticidin S by Aspergillus sp.
and resistant Bacillus cereus. Novel deaminase and coding
genes, BSD and bsr, were isolated as selectable marker
genes for genetic engineering (8).
Toxicity evaluation
Acute oral LD
50 for male rats: 56.8, female rats: 55.9,
male mice: 51.9, and female mice: 60.1 mg/kg. Acute
percutaneous LD
50 for rats >500 mg/kg. Eye: severe irritation.
Degradation
Blasticidin-S is obtained as white needle crystals which are very soluble in
water. The compound is stable in the pH range 5-7 but it is unstable under
alkaline conditions. It is readily degraded by sunlight when on the surface
of rice plants with the main degradation product being cytosine (2)
(Yamaguchi et al., 1972) as shown in Scheme 1.
