Evaluation of the Schistosomicidal Potentials of Carica papaya (Pawpaw) Extracts on the Control of Schistosomiasis: A Neglected Tropical Disease

Abstract

The study was conducted to evaluate the Schistosomicidal potential of Carica papaya, which is known for its broad spectrum therapeutic properties. The herb came from Sokun village, where it is traditionally used to heal diseases. The stem bark was peeled; air dried at room temperature, crushed and sieved into standardized particles, then extracted with ethanol and distilled water. Phenols were the most abundant phytochemicals in all extracts except the seeds ethanol extracts, which were undetectable. Cardiac glycosides were detected in all of the extracts, albeit in negligible levels. The seeds extracts contained a significant concentration of alkaloids, however the stem lacked them. The stem ethanol extract was the most effective, killing all ten snails (100%) at the lowest and highest doses (50mg/l and 150mg/l, respectively). Other extracts that resulted in 100% mortality include seed ethanol extract (150 mg/l) and stem water extract (150 mg/l). The stem water extract killed a maximum of 104.65% of snails. LD₅₀ is the lowest dose required to kill 50% of the snails. The stem ethanol extract had the lowest calculated LD₅₀, 2.437mg/l, followed by the stem water extract (104.65mg/l). The aqueous extract of seed ethanol had the highest LD₅₀ at 127.71mg/l. The stem ethanol extract killed a maximum of three miracidia at a dosage of 10mg/l. The stem ethanol extract at concentrations of 15mg/l and 5mg/l both killed one miracidium. The lowest LT₅₀ was 70.77 minutes recorded for 10mg/l of the stem ethanol extract. LT values for 5mg/l and 10mg/l of seeds water extracts could not be computed because they did not kill miracidia. The results indicated that miracidia exhibited a high level of tolerance to all extracts from this plant. At low concentrations of 50,100 and 150µg/l no deaths were recorded for all plant extracts. When the concentrations were increased to 50, 100, and 150mg/l cercariae exhibited intolerance which was dose and time dependent. The ethanol extract of the seeds was the most lethal to cercariae.  At doses of 100mg/l and 150mg/l, all ten (100%) cercariae treated to this extract died within 15 minutes and 45 minutes, respectively. The highest quantity of seed water extract killed up to 5 cercariae. The findings were subjected to Finney Probit analysis with Biostat 2009 to calculate the (LT₅₀) of the plant extracts. This study provides baseline data that can be used by pharmaceutical companies, researchers, and the Ministry of Health to create new schistosomicides.