Detoxification of L-canavanine by the tobacco budworm, Heliothis virescens [Noctuidae

Abstract

The detoxification of L-canavanine and the ability of this natural product to induce a protein able to detoxify it were investigated in the tobacco budworm, Heliothis virescens. The available evidence indicates that this detoxification mechanism is part of larval constitutive metabolism and not induced in response to canavanine. H. virescens larvae, administered 5 mg/g L-canavanine supplemented with 37.7 kBq L-(guanidinooxy-{sup 14}C)canavanine, were sacrificied 0, 1, 2, 4, 6, and 12 h postinjection. The principle products of L-canavanine degradation were ({sup 14}C)guanidine and ({sup 14}C)urea. Homoserine formation was confirmed by automated amino acid analysis. This study demonstrates that the principal detoxification pathway for L-canavanine in H. virescens larvae is by reductive cleavage to guanidine and L-homoserine.