In Vitro Evaluation of Sida pilosa Retz (Malvaceae) Aqueous Extract and Derived Fractions on Schistosoma mansoni

Sida pilosa Retz. (Malvaceae) is a medicinal plant used in Africa for the treatment of dysmenorrhea, lower abdominal pains and intestinal helminthiasis. S. pilosa aqueous extract and derived fractions were investigated for their bioactivity against Schistosoma mansoni. The aqueous extract from S. pilosa aerial parts (1.25 - 40 mg/mL) and derived fractions (n-hexane, DCM, EtOAc and n-BuOH: 0.25 - 8 mg/mL) were tested on adult S. mansoni maintained in a GMEN culture medium. Praziquantel was used as the reference drug. After 24 h of incubation, worms were monitored for their viability and egg output. The antioxidant activity of S. pilosa was evaluated by the ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl free radicals. The chemical composition of the n-BuOH fraction was investigated by HPLC-MS analysis. S. pilosa aqueous extract and fractions significantly increased worm mortality in a concentration-dependent manner. The n-BuOH fraction was the most active with a LC50 of 1.25 mg/mL. Significant reduction of motor activity (25% to 100%) was recorded for surviving worms incubated in different concentrations of the extract and fractions. Incubation of S. mansoni in different concentrations of S. pilosa extract and fractions led to significant reduction of egg laying (52% to 100%). The aqueous extract and derived fractions exhibited antioxidant activity in a concentration-dependent manner. The highest antioxidant activity was found with the EtOAc fraction, followed by the DCM and n-BuOH fractions. HPLC-MS analysis of the n-butanol fraction revealed the presence of two indoloquinoline alkaloids. This study disclosed the schistosomicidal activity of the n-butanol fraction from S. pilosa aqueous extract. This activity is probably related to the indoloquinoline alkaloids identified in the fraction.