Synthesis and Antifeedant Activity of Podophyllotoxin Analogues with 4β Sulfur Substituted Groups

Three 4β-thioester-4-deoxypodophyllotoxins,two 4β-thioether-4-deoxypodophyllotoxins and one 4β-thiol-4-deoxypodophyllotoxin were synthesized,and their structures were confirmed by IR,MS,1H NMR and elemental analysis.The 24 h and 48 h antifeedant activities against the 3rd larvae of Mythimna separate were assayed with leaf-disk method.The bioassay results showed that 4β-thiol-4-deoxypodophyllotoxin had the highest activity among synthesized compounds.Its 24 h and 48 h AFC50(concentration for 50% antifeedant activity) were 164.6 and 248.1 mg/L,5.8 and 3.0 times of that of podophyllotoxin,respectively.4β-thioester and 4β-thioether derivatives had relative lower activities than the others.