The mechanism of action of bacimethrin, a naturally occurring thiamin antimetabolite

The mechanism of bacimethrin (2) toxicity has been determined. This compound is converted to 2′-methoxy-thiamin pyrophosphate (10) by the thiamin biosynthetic enzymes. Of the seven thiamin pyrophosphate utilizing enzymes in Escherichia coli, 2′-methoxy-thiamin pyrophosphate inhibits α-ketoglutarate dehydrogenase, transketolase, and deoxy- -xylulose-5-phosphate synthase. Bacimethrin does not cause repression of the genes coding for the thiamin biosynthetic enzymes.