INSECTICIDAL PROPERTIES OF SOME DERIVATIVES OF L-CANAVANINE

The canavanine derivatives D-canavanine and L-homocanavanine as well as the 1-methyl and 1-ethyl esters of L-canavanine were synthesized and evaluated for biological activity in fifth instar larvae of the tobacco hornworm, Manduca sexta [Sphingidae]. While L-homocanavanine did not increase intrinsic toxicity, it was as deleterious as L-canavanine. D-Canavanine was biologically active, as demonstrated by its ability to cause larval edema, but the D-enantiomer had little ability to elicit the larval growth inhibition and pupal deformity which are hallmarks of canavanine toxicosis and was postulated to be linked to aberrant protein production. The 1-methyl and 1-ethyl esters of L-canavanine were synthesized to determine if enhancing canavanine's hydrophobicity might increase its bioavailability. Our experiments revealed that these esters are less toxic than canavanine; the ethyl ester disrupted larval growth more than did the methyl analogue.