Toxoplasma gondii is a protozoan parasite capable of infecting many warm-blooded vertebrates causing toxoplasmosis (Dubey et al., 2012, 2021; Montoya and Liesenfeld, 2004). T. gondii infection during pregnancy may result in the vertical transmission (Montoya and Remington, 2008; Peyron et al., 2017), which is a drastic public health problem worldwide, especially in Brazil (Dubey et al., 2012, 2021).

Once the diagnosis is confirmed, the use of antiparasitic drugs is indicated to treat T. gondii-infected pregnant [e.g., spiramycin, or the combination of sulfadiazine and pyrimethamine (SDZ + PYR)](Doliwa et al., 2013; Fallahi et al., 2018; Montoya and Remington, 2008). However, these classical treatments are associated with serious side effects that available drugs cause both to the mother and to the child, including teratogenicity. Congenital toxoplasmosis is still a potential threat to public health (Dubey et al., 2021). In this concerning scenario, the development of novel potent candidates that would be well-tolerated in both pregnant women and newborns is mandatory.

The copaiba trees belong to the genus Copaifera and the Fabaceae family is one of the most important plant families in ethnopharmacology. This genus is represented by many species on the American and African continents (Arruda et al., 2019). Copaifera trees produce an oleoresin known as copaiba oil, which is currently used by the popular traditional medicine as a healing agent, as well as to treat skin and urinary tract infections, respiratory diseases, ulcers, rheumatism, among others (Churqui et al., 2018; Veiga Junior and Pinto, 2002; Veiga et al., 2007).

Since its approval by the Food and Drug Administration in 1972, the copaiba oil has been indicated for traditional use (Veiga Junior and Pinto, 2002). These oleoresins are related to a wide variety of pharmacological properties, such as anti-inflammatory (Furtado et al., 2015; Símaro et al., 2021; Veiga et al., 2007), antinociceptive (Gomes et al., 2007), antitumoral (Lima et al., 2003), gastroprotective (Lemos et al., 2015), antimicrobial (Pfeifer Barbosa et al., 2019) and antiparasitic (de Souza et al., 2017; Santos et al., 2008).

The Copaifera oleoresin is a liquid composed by a volatile oil part consisting of a mixture of sesquiterpenes, and a solid phase or resin with a non-volatile portion comprising mainly diterpenes acid (e.g., kaurenoic, copalic and polyalthic acid, among other compounds) (Arruda et al., 2019; Leandro et al., 2012). Although it is one of the most common diterpenes found in the Copaifera genus, including CTO, the literature findings on ent-polyalthic acid (ent-15,16-epoxy-8(17),13(16),14-labdatrien-19-oic acid) (here referred as PA) are scarce; however, this biological molecule has been associated with clinically important activities, such as the antitumor (Chibas et al., 2019), antimuscarinic (Sánchez-Mendoza et al., 2009), antinociceptive, antiallodynic, antihyperalgesic and anti-inflammatory (Rodríguez-Silverio et al., 2021), and antiparasitic (Mizuno et al., 2015). In this scenario, it was reported that PA reduced the viability of parasite protozoans, such as Leishmania donovani and Trypanosoma brucei (Mizuno et al., 2015).

In this context, our research group has worked to discover therapeutic alternatives to combat congenital toxoplasmosis (Barbosa et al., 2012; da Silva et al., 2017b). Recently, we have reported the anti-T. gondii activity of four oleoresins from C. duckei, C. paupera, C. reticulata and C. pubiflora. This pioneering study demonstrated that these oleoresins were able to control efficiently the parasite infection in different experimental models of maternal-fetal interface (Teixeira et al., 2020).

Copaifera is known in the folk medicine as copaiba oil or pau d'óleo, and its use by the indigenous people is mainly associated with the oleoresin obtained from the trunk of the tree. Several studies have highlighted the natural products obtained from the genus Copaifera as promising sources of agents to combat infectious diseases, as well as for the treatment of neglected parasitic diseases, such as Chagas disease, leishmaniasis, malaria and toxoplasmosis with an anti-inflammatory profile and low toxicity to the hosts (Arruda et al., 2019; Leandro et al., 2012).

The current literature has reported the Copaifera trapezifolia Hayne oleoresin (CTO) as a new source of anti-infective agents (Alves et al., 2020; Leandro et al., 2016) with low or no genotoxic risk (Furtado et al., 2018). Taken together, all described medicinal properties of the oleoresins and their isolated molecules offer reasonable scientific evidences for their use in the fight against the congenital toxoplasmosis, a parasitic disease that still affects a large number of pregnant women and children worldwide. Although several studies have reported the use of the oleoresin from many species of the Copaifera genus to treat infectious diseases, the knowledge about this action of CTO and its isolated substances is still scarce. To gain insights into the underlying mechanisms involved in this effect, the present study aimed to investigate the activity of CTO and its isolated compound, PA, against T. gondii infection using human villi explants as an ex vivo model of congenital toxoplasmosis.