In vitro anthelmintic effects of crude aqueous extracts of Tephrosia vogelii, Tephrosia villosa and Carica papaya leaves and seeds

Abstract

The prevalence of anthelmintic resistance and the consumer demand for alternative farming systems that limit the use of chemical anthelmintics has made the search for alternative gastrointestinal nematode parasites control methods crucial. Traditional medicinal/herbal plants can offer an alternative to the reliance on chemical anthelmintic drugs. This study evaluates the efficacy of crude aqueous extracts of Tephrosia vogelii Hook., Tephrosia villosa Pers., and Carica papaya Linn. leaves and Carica papaya Linn. seeds against gastrointestinal nematodes using in vitro egg hatch and larval development inhibition assays. Rectal faecal samples from sheep were subjected to parasitological examination for faecal egg counts (FEC) using the McMaster counting technique. 100 g of dried and poultice aqueous leaf extract of T. vogelii, T. villosa, C. papaya leaves and seeds was blended into liquefaction in 200 ml of distilled water then boiled at 90-100°C for 1 h and cooled. Levamisol and distilled water were used as positive and negative control in the bioassay. Egg hatch assay revealed more than 95.8% reduction in egg hatch at concentration of 500 mg/ml for dried and poultice paste of T. vogelii leaves and C. papaya seeds. Larval development inhibition assay results showed that both dried and poultice paste of T. vogelii leaves and C. papaya seeds extract yielded more than 98% inhibition at a concentration of 500 mg/ml. Based on the LD50 dried extract of C. papaya seeds was most potent extracts for the inhibition of both egg hatching (49.94 mg/ml) and larval development (49.32 mg/ml). Both poultice and dried extract for all the plants showed significant and dose dependent egg and larval development inhibition. These findings indicate that the evaluated plants have potential anthelmintic effect and could provide viable alternatives for the control of gastrointestinal helminthes in ruminants.