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Effects of the methanolic seeds extract of Carica Papaya on plasmodium Berghei infected mice
Authors: Amazu LU, Ebong OO, Azikiwe CCA, Unekwe PC, Siminialayi MI, Nwosu PJC, Ezeani MC, Obidiya OS, Ajugwo AO
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Objective: The leaves extract of Carica Papaya (C. Papaya)papaya has been shown to possess antimalarial activity, thus this work aims at finding out if the plants antimalarial activity is present in or extended to the seeds. %100,0,100,0〗Methods: The seeds of C. papaya were collected from its fruit, air dried for 5 days and ground into fine powder. 80.65 g of the powder was then soaked for 48hours in 300 mL of methanol. Filtration was carried out using Whatman No.1 filter paper. The filtrate was evaporated to dryness by a three-day continuous heating on a hot plate of 30℃. The dry extract yield was scraped out of the Petri dish weighed and refrigerated until required. The percentage extract yield was calculated out from the initial powder weight. A preliminary phytochemical study was done by re-dissolving the appropriate amount of the dry extract in distilled water and appropriate test reagent added. The LD50 of the seeds of C. papaya was carried out using arithmetic method. Swiss albino Mice of both sexes and of average weight of 18-25 g were used as animals for antimalarial activity. They were housed in standard animal house, fed on Rats/Mice pellets and had non restricted excess to both feed and water throughout the 60day study period. While the non pregnant female Mice were used as test animals, the male animals were used as malaria parasite donors. Precautions were taken to ensure that all animals in the study groups were free from infection with Eperythrozoon coocoides. The female animals were then divided into three main groups (A-C) of 25 animals per group. Group A was used for malaria suppressive study (early infection day 0-3) and was further subdivided to 5subgroups (a-e) of 5animals per group. Group B was used for malaria curative study (established malaria infection day 3-7) and was further subdivided to 5subgroups (a-e) of 5animals per group. Group C was used for malaria prophylactic study (repository4days treatment prior to malaria parasite infection) and was also further subdivided into 5subgroups (a-e) of 5animals per group. At the appropriate time, 50 mg/kg/day, 100 mg/kg/day and 200 mg/kg/day of crude extract of C. papaya were administered orally to the different subgroups(b-d) within the three main groups. One subgroup(a) in each main group also received orally, 5 mg/kg/day of chloroquine phosphate as positive control while one subgroup (e) in each main group also received orally, 0.2 mL/kg/day of distilled water as negative control. Malaria parasites infected red blood cells numbering 1×107 and suspended in 0.2 mL of physiological saline was inoculated intraperitoneally, to each animal of the subgroups (a-d) in each of the three main groups at the appropriate time. Blood smears were made from animals' tail, stained with Lieshman and examined microscopically at 100× for the presence of malaria parasite. Percentage malaria parastaemia was calculated as well as average percentage malaria parasitaemia suppression. %100,0,100,0 Results: Extraction yield of 25.29% was obtained while the LD50 was 620 mg/kg. The phytochemistry showed the richly presence of alkaloids, as well as glycosides, carbohydrates, resins, fats and fixed oils. The suppressive study at doses of 200,100 and 50mg/kg/day showed 53.02%, 43.43% and 19.83 % suppressive activity against Plasmodium berghei respectively. This activity compared to that of chloroquine, a standard antimalaria drug that gave 95.95% suppressive anti-parasitaemia. The prophylactic study at doses of 200, 100 and 50 mg/kg/day showed 63.85%, 61.12% and 48.08% prevention to malaria parasitaemia respectively as against 94.78% showed by chloroquine. The curative study however, at doses of 200, 100 and 50 mg/kg/day failed to suppress malaria parasitaemia with a mean survival range of 6-8 days as against 27.2 days showed by chloroquine. The seeds extract of C. papaya showed a significant malaria parasitaemia suppressive activity (P≤0.05). These activities are dose dependent and comparable to those of Chloroquine phosphate. 100,0,100,0〗Conclusion: The results above suggest that the seeds extracts of C. papaya possess antimalarial activity like the leaf extracts. The antimalarial activity may be attributable to the richly presence of alkaloids and or the presence of its proteolytic enzyme (Papain). The present finding justifies the inclusion of the seeds of C. papaya in the treatment of malaria by local herbalists. The seeds extracts therefore, if well purified and characterized may be used in treatment of very early plasmodiasis as well as a good prophylactic drug in human. This work at the moment is limited to animals, thus clinical trials in humans is be recommended particularly, when C. papaya seeds are non harmful/non toxic.