Studio in vitro sull’inibizione di alcuni sistemi enzimatici di Apis mellifera L. ad opera di nuovi derivati del PBO

[Autom. eng. transl.] Synergistic products (such as piperonyl-butoxide - PBO) are molecules without or with negligible insecticidal activity but which when applied in combination with various plant protection products enhance their effectiveness by inhibiting the metabolic detoxification systems of the target insect. Within the European project "Ecosyn" (EcoSyn -Ecofriendly synergists for insecticide formulations, funded by the Seventh Framework Program of the European Union - Contract No. 605740) new synergists have been developed and synthesized, starting from the molecular structure of the PBO. In addition to the evaluation of the ability of these new molecules to inhibit the metabolic resistance mechanisms of various species of agricultural and veterinary interest, it was decided to verify if their use could have negative repercussions on the pollinators and in particular on Apis mellifera L. The classic PBO, a series of benzodioxol derivatives, indicated respectively as EN1-213, EN1-216, EN1-218, and two derivatives of 2,3-dihydrobenzofuran, indicated as EN16-55 and EN16-41. The ability of these compounds to inhibit the activity of enzymes of which it is widely known, in many arthropod species, the ability to intervene in the detoxification and sequestration processes of various classes of insecticides has been investigated. In this phase, still preliminary, esterases and glutathione S-transferases were considered. The possibility that these synergists may affect the activity of acetylcholinesterases has also been investigated. The enzymatic activity was measured by spectrophotometric analysis in absorbance both in the presence and absence of synergists to calculate the residual activity, after pre-incubation of the homogenate with acetone or with the synergist. The preliminary results indicate that in vitro the activity of the enzymes studied is only partially inhibited by the derivatives of 2,3-dihydrobenzofuran (EN16-41 and EN16-55) and that it is not inhibited by synergists derived from benzodioxol (EN1-213, EN1 -216 and EN1-218). The use of the latter in the field, against harmful insects resistant to insecticides, could therefore be considered safe against bees. Further investigations are underway to evaluate the "in vitro" effect of different concentrations and exposure times of the synergist, also on other enzymatic systems such as mono-oxygenases.