Microbial Hydrolysis of Racemic β-Aryl-γ-ethylidene-γ-lactones and Antifeedant Activity of the Products against Panzer.

Hydrolysis of (±)-β-aryl-γ-ethylidene-γ-lactones by fungal strain AM370 afforded (−)-()-γ-ethylidene-γ-lactones ⁻ and (+)-()-γ-ketoacids ⁻. Enantiomeric purity of the unreacted lactones was strictly related to a size of an aryl substituent at C-4 of γ-lactone ring, with the highest (77%) obtained for the (−)-()-γ-ethylidene-γ-lactone possessing unsubstituted benzene ring () and the lowest one (15%) determined for the (−)-()-γ-ethylidene-γ-lactone with bulky 1,3-benzodioxole system (). Lactones ⁻, both racemic and enantiomerically enriched, as well as products of their hydrolysis showed varying degrees of feeding deterrent activity against lesser mealworm, Panzer, which depended on the structure of the compound and the developmental stage of the lesser mealworm. In the case of adults, more active were γ-lactones ⁻, compared with ketoacids ⁻. Only in the case of lactone was the effect of configuration of stereogenic center on the activity found. Particularly strong deterrents against this stage (T > 180) were racemic and (−)-()-γ-ethylidene-γ-lactone with -methoxysubstituted phenyl ring ().