BIALAPHOS

Description

Bilanofos is a natural product formed during the fermentation of Streptomyces hygroscopicus. It is readily soluble in water and insoluble in organic solvents such as acetone, ethanol, benzene, and hexane (9).
Bilanophos is a GS inhibitor. In the plant, bilanofos is metabolized to L-glufosinate, which inhibits the enzyme GS. Ammonium ions rapidly accumulate in the plant, and photosynthesis is inhibited, leading to rapid death of the plant. It is inactivated in soil.

History

Bialaphos[peptide derivative of PPT (PPT linked to two L-alanine moieties)] was originally isolated from cultures of Streptomyces viridochromogenes (87) and Streptomyces hygroscopicus (88). L-PPT is the natural isomer, and it was the first natural amino acid found to contain a phosphinic group. PPT strongly inhibited glutamine synthetase activity in E. coli (87), and Hoechst Ag patented it as a herbicide after its phytotoxicity was discovered (89). Bialaphos was patented as a herbicide (90) and is marketed in Japan (91). Glufosinate (ammonium salt of PPT) is the synthesized commercial product. Bialaphos is hydrolyzed by plant and soil microbial peptidases to yield the active herbicide (PPT) (92–94). PPT is also rapidly degraded, with half-life of 4 to 7 days in soils (95). In a test of 300 bacterial isolates from soil, all strains degraded L-PPT to the 2-oxo analog of PPT via transamination (96).

Definition

ChEBI: A tripeptide comprising one L-phosphinothricyl and two L-alanyl units joined in sequence.

Origin

The compound was launched as a nonselective contact herbicide in 1984.

Metabolic pathway

When 14C-bialaphos [L-2-amino-4- [(hydroxy)(methyl)phosphinoyl]butyryl-L-alanyl-L- alanine] is administered in an aqueous solution to mice, the metabolite of bialaphos which is identified as 2-amino-4-[(hydroxy)(methyl)phosphinoyl]butyric acid is excreted in the feces and urine.

Metabolism

The major metabolite following oral administration in the mouse was 2-amino-4- (hydroxy)(methyl)phosphinyl)butyric acid, which was eliminated in feces.