Cercaricidal efficacy of plant extract: evidence from the methanolic leaves and bark extracts of Anacardium ocidentale (Linnaeus)

Abstract

Schistosomiasis continues to be a public health problem causing in unsatisfactorily high level of morbidity. Praziquantel is a recent medicine for treatment but unable to kill emerging schistosomes. It does not prevent re-infection and its constant application may lead to the advent of drug-resistant parasites. Qualitative phytochemical screening of the methanol crude extract of A. occidentale revealed the presence of Tannins, Flavonoids and Saponins. Cercaricidal activity on Gymnocephalous cercaria, after 120 minutes of contact in a concentration of 0.10 mg/mL, showed that there was 92 and 34% death when exposed to the methanol leave and bark extracts of A. occidentale leaves, and A. occidentale bark respectively. There was 99% and 98.5% mortality between the methanol bark extract of A. occidentale and the leaf of A. occidentale plant respectively in a concentration of 0.60mg/mL. Lethal concentration on Gymnocephalous cercariae showed that A. occidentale methanolic bark extract had the highest LC50 and LC84 of 0.151 and 0.204 mg/mL respectively while A. occidentale methanol leaf extract had the lowest LC50 and LC84 of 0.123 and 0.162 respectively. A. occidentale methanol bark extract had the lowest LC50 of 0.237 and A. occidentale methanol leaf extract had the lowest LC 84 of 0.316 mg/ml. The correlation coefficient of the plant parts showed a strong positive correlation between the log concentrations and probit mortality. The extracts had an effect on the cercariae tested. A. occidentale leaves extract showed highest cercaricidal activity. Gymnocephalous cercariae was more susceptible to the plant parts than the Brevifurcate cercaria