Antioxidant, anticoccidial, and toxicological evaluation of Ocimum gratissimum and Vernonia amygdalina leaf extracts against Eimeria spp

The plants Ocimum gratissimum and Vernonia amygdalina are widely used in traditional medicine for their biological properties, but their antioxidant and anticoccidial activities and toxicological profile remain poorly documented. This study aims to evaluate the antioxidant potential, anticoccidial efficacy against Eimeria magna and Eimeria media, phytochemical composition, and toxicity of aqueous and hydroacetonic extracts from their leaf. Aqueous and hydroacetonic leaf extracts of both plants were prepared and quantified for their polyphenol, flavonoid, and tannin contents. Antioxidant activity was determined using the DPPH radical scavenging assay. The anticoccidial activity of graded extract concentrations was evaluated against Eimeria oocysts and sporozoites. Toxicity was assessed through lethality tests on Artemia salina larvae and clinical evaluations in rats. The extracts of V. amygdalina leaf exhibited stronger antioxidant and anticoccidial activities than those of O. gratissimum. hydroacetonic extracts of both plants showed lower EC₅₀ values (O. gratissimum: 51.2 ± 5.59 µg/mL; V. amygdalina: 67.15 ± 3.29 µg/mL) compared with the aqueous extracts. In anti-oocyst assays, hydroacetonic extracts of V. amygdalina inhibited the sporulation of E. magna oocysts by up to 91% at 40 mg/mL (p < 0.05). Toxicity assays indicated no lethality in A. salina and no major histopathological alterations in rats. Collectively, these findings demonstrate that O. gratissimum and V. amygdalina extracts possess significant antioxidant and anticoccidial activities while exhibiting low toxicity, supporting their potential application in natural antioxidant and anticoccidial therapies. These results suggest that extracts of O. gratissimum and V. amygdalina have strong potential as natural antioxidants and anticoccidials with good biocompatibility, paving the way for their use in sustainable coccidiosis control strategies in livestock farming.