In vitro larvicidal and in vivo anthelmintic effects of Oxalis tetraphylla (Oxalidaceae) hydroalcoholic extract against Haemonchus contortus in lambs

Oxalis tetraphylla (Class: Magnoliopsidae) Possess Flavonoid Phytoconstituents with Nematocidal Activity against Haemonchus contortus

The nematocidal activity of an Oxalis tetraphylla hydroalcoholic extract against the nematode Haemonchus contortus (Hc) was assessed in vitro and the major compounds associated with nematocidal activity were identified. One hydroalcoholic extract was obtained from O. tetraphylla stems and leaves (Ot HE-SLE). The in vitro lethal concentrations (LC50 and LC90) against both eggs and exsheathed Hc infective larvae (L3) were assessed. Ot HE-SLE showed a potent ovicidal activity (LC50 = 0.213 mg/mL; LC90 = 0.71 mg/mL) and larvicidal effect (LC50 = 28.01 mg/mL; LC90 = 69.3 mg/mL). Later on, the extract was bipartitioned to obtain an ethyl acetate phase (EtOAc-Ph) and an aqueous phase (Aq-Ph). Both phases were assessed against Hc eggs at 0.25 and 1.0 mg/mL concentrations. The results with EtOAc-Ph showed 93.6% ovicidal activity, while 96.6% was recorded with Aq-Ph at 48 h post-confrontation (PC). In the case of larvicidal activity, both phases were assessed at 28 mg/mL; Aq-Ph showed >80% larvicidal activity 24 and 72 h PC, while EtOAc-Ph did not show important activity. HPLC analysis showed the presence of coumaric acid and flavonols. Flavonol compounds were the major compounds and were associated with the nematocidal activity. Additionally, the Aq-Ph that showed the highest activity was purified, and the fraction F3 showed the highest nematocidal activity.

Insecticidal and Nematicidal Contributions of Mexican Flora in the Search for Safer Biopesticides

Plant metabolites have been used for many years to control pests in animals and to protect crops. Here, we reviewed the available literature, looking for the species of Mexican flora for which extracts and metabolites have shown activity against pest insects and parasitic nematodes of agricultural importance, as well as against nematodes that parasitize domestic cattle. From 1996 to 2018, the search for novel and eco-friendly biopesticides has resulted in the identification of 114 species belonging to 36 botanical families of Mexican plants with reported biological effects on 20 insect species and seven nematode species. Most plant species with detected pesticide properties belong to the families Asteraceae, Fabaceae, and Lamiaceae. Eighty-six metabolites have been identified as pesticidal active principles, and most have been terpenoids. Therefore, the continuation and intensification of this area of research is very important to contribute to the generation of new products that will provide alternatives to conventional pesticide agents. In addition, future studies will contribute to the recognition and dissemination of the importance of propagating plant species for their conservation and sustainable use.