In vitro Antischistosomal Activity of Clerodendrum umbellatum Poir (Labiateae) Leaves Aqueous Extract and Derived Fractions against Schistosoma mansoni Adult Worms

Aims: Treatment against schistosomiasis relies on praziquantel. Its treatment failure and the possible development of resistant schistosomes strains have been reported in the literature. Clerodendrum umbellatum leaves are used in Africa for the treatment of intestinal helminthiasis. The aim of this study was to evaluate the in vitro activity of C. umbellatum leaves aqueous extract and derived fractions on Schistosoma mansoni adult worms. Methodology: Five male and five female Schistosoma mansoni adult worms were incubated in each well for 48 h in a GMEM culture medium with C. umbellatum aqueous extract (125 to 4000 µg/mL) or its n-hexane, ethyl acetate and methanol fractions or the aqueous residue (62.5 to 2000 µg/mL). The main parameters assessed were the worm’s mortality and the reduction of motor activity. Phytochemical screening of all our tested substances was also performed. The cytotoxicity assay using mouse melanoma liver cells line was performed on the aqueous extract and on the most active fraction. Results: Our study shown that C. umbellatum leaves aqueous extract and its derived fractions promoted worm mortality. The aqueous extract disclosed a LC50 of 805.21 µg/mL while the LC50 of the methanol fraction was 343.10 µg/mL. With this lowest LC50, the methanol fraction from C. umbellatum aqueous extract was therefore the most active. Moreover, it showed low level of toxicity on hepatocytes. Incubation of worms with C. umbellatum aqueous extract and fractions also resulted in a significant reduction of the motor activity of survival worms with a 39.54 to 100% reduction after 48h. The phytochemical screening of C. umbellatum aqueous extract and fractions revealed the presence of alkaloids, phenols, flavonoids, tannins, saponins and terpenoids. Conclusion: The present study demonstrated the in vitro activity of C. umbellatum aqueous extract and derived fractions on S. mansoni adult worms and could then justify its empirical use to combat schistosomiasis.