Evaluation of schistosomacidal activity of lannea schimperi and searsia longipes stem bark extracts

Abstract

Schistosomiasis is one of the chronic threatening but neglected parasitic disease caused by trematode worms under genus schistosoma. Praziquantel is the only drug recommended by WHO for the treatment of all forms of human schistosomiasis. Praziquantel is currently facing challenges, among which selective efficacy and resistance, making it of high imperative searching for new anti-schistosomal drugs. This study aimed to evaluate schistosomacidal activity of Lannea schimperi and Searsia longipes extracts against cercariae, schistosomula and adult stage of Schistosoma mansoni. Bioassays were conducted in vitro in 24 well plates for cercariae and schistosomula and 6 well plates for adult worms. Lannea schimperi and Searsia longipes expressed highest activity against schistosomula at 1 to 2 mg/ml and 2 mg/ml respectively with the mortality rate of 100% after one hour. Searsia longipes and Lannea schimperi exhibited 100% activity against adult worms at the dose range of 0.5 to 2 mg/ml and 1 to 2 mg/ml respectively after 48 hours of exposure. One hundred percent mortality of the cercariae was observed at the concentration range of 1 to 2 mg/ml and 2 mg/ml for Searsia longipes and Lannea schimperi respectively. Both extracts exhibited good margin of safety on Swiss albino mice with LD50 above 2000 mg/kg bwt. Lannea schimperi and Searsia longipes expressed significant cytotoxicity on brine shrimp larvae with IC50 of 150.0478 and 280.7875 μg/ml respectively. Extracts have revealed to contain flavonoids, saponnins, tannins and glycosides. To the best of my knowledge, schistosomacidal activities of Lannea schimperi and Searsia longipes are reported for the first time.