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29–Fluorophytosterols: Novel Pro–Insecticides which Cause Death by Dealkylation

Bio/Technologyvolume 1pages6265 (1983) | Download Citation



The 29–fluorophytosterols, members of a new class of selective pro–insecticides, have been synthesized and examined in vivo in tobacco hornworms. Dealkylation at C–24 of the steroid side chain by insects releases the latent poison fluoroacetate. Vertebrates lack this dealkylation pathway and should be incapable of the lethal synthesis. The 29–fluorophytosterols cause dose–dependent reductions in growth rate, maximum weight, and survival when fed at 1 to 100 ppm to Manduca sexta. Larval steroid composition is unaffected. Similar biological effects were observed when fluorocitrate and its metabolic precursors were fed to horn worms. The effects of five related 29–monofluorosterols show that the 22,23– double bond increases toxicity dramatically, making 29–fluorostigmasterol 100 fold more active than 29–fluorositosterol.

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  1. Glenn D. Prestwich: Fellow of the Alfred P. Sloan Foundation (1981–85) and Camille and Henry Dreyfus Teacher-Scholar (1981–86), to whom correspondence should be addressed.


  1. Department of Chemistry, State University of New York, Stony Brook, NY, 11794

    • Glenn D. Prestwich
    • , Apurba K. Gayen
    • , Seloka Phirwa
    •  & Toni B. Kline


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