In vitro screening of selected medicinal plants against Schistosoma mansoni larvae

Schistosomiasis, caused by various members of the trematode flatworms (Schistosoma species) is the second most important parasitic disease next to malaria. Resistance and low susceptibility towards praziquantel, the only available schistosomicidal drug, urge the search for new drugs. This study aimed at assessing the in vitro schistosomicidal effects of several medicinal plants traditionally used for the treatment of schistosomiasis or other helminths [1]. The crude MeOH extracts of selected plants Artemisia absinthium L. and A. abrotanum L. (aerial parts) Phytolacca dodecandra L. (roots), Curcuma longa L. (roots), Zingiber officinale Roscoe (roots), Punica granatum L. (peels, fruits and the aqueous extract of the fruits) and Citrus reticulata Blanco (peels) were tested against juvenile worms (schistosomulae) of S. mansoni by using the standard visual larval assay. All crude extracts, except P. granatum and C. reticulata exhibited significant antischistosomal effect. The highest activity was displayed by C. longa (IC₅₀ 4.06µg/ml), followed by A. abrotanum and Z. officinalis extracts with IC₅₀ values of 11.1µg/ml and 11.73µg/ml, respectively. In the next step, the crude MeOH extracts were subjected to a liquid-liquid partitioning scheme between aqueous MeOH, hexane and CHCl₃ and the subextracts were retested in the same assay. Generally, the lipohilic subextracts retained the initial schistosomicidal potential, whereas the aq. MeOH subextracts were mostly inactive at 100µg/ml concentration. The current study highlights the potential of plants against Schistosoma infections and confirms their use in traditional medicine. It also warrants phytochemical studies on the active plants to identify their active principles.

References: 1. Sanaa AA (2011) Res J Med Plant 5: 1–20.