The cattle tick Rhipicephalus (Boophilus) microplus (Canestrini, 1887) poses a severe economic threat to livestock producers through physical effects on infested animals and diseases caused by the transmission of parasitic protists (Kumar et al., 2013). It is estimated that R. microplus causes annual losses in the Brazilian cattle herd of up to US$ 3.2 billion (Grisi et al., 2014).

Tick control is usually carried out through the repeated use of chemical acaricides, such as synthetic pyrethroids (Kumar et al., 2013), which has led to increased selection of acaricide resistance among tick populations, in addition to promoting contamination of the environment and food products (Kaewmongkol et al., 2015).

Plants defend themselves against pests by producing several phytochemicals that have been considered potential alternatives for tick control (Guneidy et al., 2014). For instance, anonaine, an alkaloid present in the plant Annona crassiflora (Martius, 1841) (Annonaceae), a tree native to the Brazilian Cerrado popularly known as “araticum”, is a bioactive compound displaying several biological properties, including antiparasitic activity (Li et al., 2013).

Various enzyme inhibitors have been studied to develop control methods against parasites (Olivares-Illana et al., 2006; Braz et al., 2019; Cuevas-Hernándes et al., 2020), based on the identification of molecules that induce selective inhibition of parasite over host enzymes (Ahmad et al., 2008; Moraes et al., 2011; Ozelame et al., 2022). Based on these previous results, the enzyme glutathione S-transferase (GST) can be considered a target for developing antiparasitic drugs. Each of the GST subunits has its active site that is composed of a glutathione (GSH) binding site (G site) and an electrophilic substrate binding site (H site) (Prade et al., 1997). GSTs play an essential role in detoxifying xenobiotics (Mannervik, 1985; Mannervik et al., 1988; Hamza and Dailey, 2012). Compounds capable of inhibiting the tick's GST activity to interrupt its detoxification system, could provide an alternative form of control (Guneidy et al., 2014; Ozelame et al., 2022). As alkaloids are among the natural products capable of inhibiting GST (Mangoyi et al., 2010; Azeez et al., 2012; Divya et al., 2014; Behera and Bhatnagar, 2019), anonaine is a potential candidate for the control of R. microplus through the inhibition of this enzyme.

Recently, in silico techniques have facilitated the discovery of new drug candidates (Alvarez, 2004; Choubey and Jeyaraman, 2016; Ganesan, 2016; Roche and Bertrand, 2016; Saramago et al., 2018). For instance, through molecular docking, drug candidates can be recognized, and the potential for their optimization can be explored as molecular interactions between ligands and target molecules can be analyzed and modelled (Wadood et al., 2013).

Given the scientific and economic importance of the development of new acaricide products against ticks and considering that GST is a target enzyme essential in the physiology of the ticks, this study used in silico and in vitro assessments to analyze the potential use of anonaine as a specific tick GST inhibitor. By decreasing the activity of this enzyme one can interfere with the detoxification of cypermethrin, thereby increasing the effectiveness of this synthetic pyrethroid.