Parasitosis in ruminants represents an economic and health problem of global importance. Latin America comprises 25% of the world´s area for livestock production (Molento et al., 2011; Roeber et al., 2013). Several studies have evaluated the economic impact of the main parasites (nematodes, trematodes and cestodes) that infect ruminants, reporting economic losses due to low productivity and deaths (Arsenopoulos et al., 2021; Starling et al., 2019). Haemonchus contortus is the most pathogenic parasite nematode, due to its hematophagous behaviour, which causes severe health and productivity problems in sheep and goat production systems (Arsenopoulos et al., 2021; Besier et al., 2016; Oliveira Santos et al., 2019). The control of gastrointestinal parasitosis in small ruminants has been using anthelmintic drugs like ivermectin, albendazole and febendazole. However, a consequence of the frequent treatment is the development of resistance to these products (Kaplan and Vidyashankar, 2012). The drugs decrease their effectiveness and contribute to the spread of anthelmintic resistance around the world (Roeber et al., 2013). The techniques focused on non-chemical control, known as integrated parasite control, have been developed to reduce dependence on conventional anthelmintics, increasing their application interval and thus delaying the appearance of resistance (Torres-Acosta et al., 2012a; Waller and Thamsborg, 2004). One of the integrated parasite control methods is the use of plants with secondary metabolites, which can have a direct effect on parasites in the animal (Torres-Acosta et al., 2012b). Plants belonging the Malvaceae family like Hibiscus rosa-sinensis, Malva sylvestris, Althaea officinalis and Guazuma ulmifolia, have been evaluated in feeding small ruminants, due to their nutritional potential and antiparasitic properties (Mayren-Mendoza et al., 2018; Reséndiz-González et al., 2022; Váradyová et al., 2018; Velázquez-Antunez et al., 2022).

Guazuma ulmifolia Lam, commonly named as "Guacimo" or "Cuaulote" in Mexico, is a tree species with some biological properties such as antioxidant, antimicrobial, antiprotozoal and anthelmintic activities (Morais et al., 2017; Pereira et al., 2019). The G. ulmifolia leaves have been proposed as an alternative source of protein for the diets of sheep (Castrejón-Pineda et al., 2016). In Mexico, the leaves and fruits of this arboreal plant have been employed as an additional dietary supplement for lambs (Sosa-Rubio et al., 2004). There are studies with hydroalcoholic extracts and their fractions among them ethyl acetate fraction (EtoAc-F) from G. ulmifolia leaves that have evidenced ovicidal and larvicidal effect against H. contortus (Velázquez-Antunez et al., 2022). The bioactive fraction used in the present study has been reported with anthelmintic activity on this parasite. The EtoAc-F was evaluated in vitro with larvae and eggs (CL90: 30.48 and 0.138 mg/mL respectively) (Reséndiz-González et al., 2022). The author’s ideintified some secondary compounds in EtOAc-F like kaempferol, ethyl ferulate, ethyl coumarate, ferulic acid, coumaric acid derivative, and quercetin glucoside. On the other hand, there are reports about the toxicological test on the plants extracts using different biological models. A preliminary oral toxicity test of the secondary metabolites can performed by histopathological analysis in target organs such as the liver and kidney using gerbils (Valderas-García et al., 2022).

Gastrointestinal nematodes (GIN) like H. contortus have developed defense mechanisms when are exposed to anthelmintic products and they produce some antioxidant enzymes that cleave to reactive oxygen species. The Glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) are enzymes that play a crucial role in parasites as defense mechanism (Sun et al., 2012). The plant secondary compounds could act on these enzymes. The Hc29 is a selenium-independent GPx enzyme in parasites like H. contortus, which is involved in functions as a backup system against reactive oxygen species (Sun et al., 2012). A study by Higuera-Piedrahita et al. (2021) associated relative expression of Hc29 on H. contortus larvae after exposure to an n-hexanic extract from Artemisia cina and found upregulation of this gene in comparison to negative control.

The nematocidal activity of plant extracts or fractions of utmost importance looking for new tools for control of parasites. This assessment offers essential insights for research endeavours aimed at investigating their possible effectiveness within living organisms, as part of the search for alternative methods to manage haemonchosis (Torres-Acosta et al., 2012). The organic fraction (EtOAc-F) used in the present study was previously assessed against eggs and infective larvae of H. contortus and this fraction was obtained from a bipartition of a Hydroalcoholic extract from G. ulmifolia leaves (González-Reséndiz et al., 2022). Thus, the purposes of this study were first, assess the anthelmintic effect of EtOAc-F against gerbil’s (Meriones unguiculatus) artificially infected with H. contortus infective larvae (L3). Second, evaluate the preliminary toxicity after oral administration of EtOAc-F in gerbils. Third, determine the relative expression of biomarkers as glutathione, catalase, and superoxide dismutase against H. contortus L3 post-exposition to EtOAc-F.