This study was conducted to comparatively assess the anthelminthic activity of leaves, stem bark, and seeds of Carica papaya, in order to identify which of the plant parts possess the highest anthelminthic activity. Three concentrations of ethanolic and hydroethanolic extracts of the plant parts (1 mg/ml, 2.5 mg/ml, and 5 mg/ml) were prepared and tested against Pheretima posthuma using albendazole as the positive control and 0.9% normal saline solution as the negative control. Preliminary phytochemical investigation showed the presence of alkaloids, saponins, and reducing sugars of glycosides present in all the crude extracts of Carica papaya. Tannins were observed only in extracts of the leaves, while fixed oils were only present in the extracts of the seeds. The results of the anthelminthic activity testing indicated that all crude extracts prepared were more effective than albendazole in reducing paralysis time (p<0.0001) and death time (p<0.0001). It was further shown that the extracts from the seeds (SE and SHE) were more effective than the extracts from the stem bark and leaves both in reducing paralysis and death times. Fractionation of SE provided a fraction, SEB, which was more effective than SE both in reducing paralysis and death times (p<0.0001) and was established to contain fixed oils. The outcome of the current study has provided a scientific justification for the preference of the seeds of Carica papaya for the treatment of helminth infections and has shown that the fixed oils present in the seeds could be responsible for such activity.
