Produtos naturais inibidores da enzima glutationa S-transferase como estratégia biotecnológica para o controle de Rhipicephalus microplus e R. decoloratus

Abstract

Ticks of the genus Rhipicephalus constitute one of the main limitations to livestock production in tropical and subtropical regions, due to the significant economic losses associated with infestations and the increasing resistance to currently available synthetic acaricides. In this scenario, glutathione S-transferase (GST) stands out as a strategic molecular target, since it plays a central role in detoxification processes and resistance mechanisms of these ectoparasites. Thus, this study aimed to identify, characterize, and evaluate the potential of natural compounds as inhibitors of GSTs from R. microplus and R. decoloratus, employing integrated in silico and in vitro approaches. Initially, structural modeling and molecular docking analyses were conducted to investigate the interaction of different natural compounds with tick GSTs, including the alkaloid anonaine, the brachydins G, I, J, and K, as well as the compounds -stearyoxy-olean-12-ene, diosgenin, quercitrin, naringenin, ellagic acid, rutin, and quercetin, allowing the prediction of the affinity and binding mode of these molecules to the enzyme sites. In parallel, pharmacokinetic and toxicological properties were evaluated in silico to support the selection of the most promising candidates. Subsequently, the selected compounds were evaluated for their ability to inhibit recombinant GSTs, as well as for associated biological effects, including carrapaticidal activity, association with commercial acaricides, and cytotoxicity on bovine erythrocytes. The results showed that anonaine, an alkaloid isolated from Annona crassiflora, exhibited higher affinity, in silico, for R. microplus GST compared with human GST, used as a three-dimensional structural model for mammals. Furthermore, this alkaloid inhibited recombinant GST activity by up to 37.5% in a dose-dependent manner. Anonaine significantly enhanced the efficacy of cypermethrin, resulting in a reduction of the Additionally, the brachydins G, I, J, and K exhibited potent inhibitory activity on R. microplus ranging from 0.058 to 0.079 mg/mL, associated with stable molecular interactions in docking analyses and low hemolytic effect. Additionally, natural compounds belonging to the triterpene, flavonoid, and polyphenol classes demonstrated inhibitory activity against the GSTs of R. microplus and R. decoloratus. Among -stearyloxy-olean-12-ene and the flavonoid naringenin exhibited activity showed inhibitory activity against the GST of R. decoloratus These results indicate that natural compounds can act as selective inhibitors of the GSTs of R. microplus and R. decoloratus, suggesting the potential of this biotechnological approach in the development of sustainable and more effective acaricides.