Insecticidal activity of various 3-acyl and other derivatives of veracevine relative to the Veratrum alkaloids veratridine and cevadine
1991
Ujvary, I. | Eya, B.K. | Grendell, R.L. | Toia, R.F. | Casida, J.E.
Sixty-five 3-acyl derivatives of veracevine, including 44 aromatic and 21 aliphatic esters or related derivatives, were isolated or prepared and their insecticidal activities determined by topical application to adult houseflies and milkweed bugs. Of these the naturally occurring veratridine [3-(3,4-dimethoxybenzoyl)veracevine] and cevadine [3-[(Z)-2-methylbut-2-enoyl]veracevine] are near optimal in potency. Piperonyl butoxide synergism indicates that oxidative detoxification limits the toxicity of all the compounds to houseflies. Five other veratridine and cevadine derivatives examined are inactive, but the related protoveratrine A has high insecticidal potency. The most active of the synthetic aliphatic esters, 3-pivaloylveracevine, is equally potent to or less potent than cevadine. In the aromatic ester series, the 2,5- and 3,5-dimethoxy analogues are more potent than veratridine and the 3,5-dimethoxy compound is also improved in selective toxicity, i.e., LD50 ratio for mice vs the insects tested. These findings lay the background for determining the relative importance of metabolism and receptor site sensitivity in species specificity.
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