Effect of ferulic acid from Hibiscus mutabilis on filarial parasite Setaria cervi: Molecular and biochemical approaches

In the reported work the in vitro activity of a methanolic extract of leaves of Hibiscus mutabilis (Malvaceae) against bovine Setaria cervi worms has been investigated. Bioassay-guided fractionation led to isolation of ferulic acid from ethyl acetate fraction. The crude extract and ferulic acid, the active molecule, showed significant microfilaricidal as well as macrofilaricidal activities against the microfilaria (L1) and adult of S. cervi by both a worm motility and MTT reduction assay. The findings thus provide a new lead for development of a filaricidal drug from natural products. To examine the possible mechanism of action of ferulic acid, the involvement of apoptosis in adult worms of S. cervi was investigated. We found extreme cellular disturbances in ferulic acid-treated adult worms characterized by chromatin condensation, in situ DNA fragmentation and nucleosomal DNA laddering. In this work we are reporting for the first time that ferulic acid exerts its antifilarial effect through induction of apoptosis and by downregulating and altering the level of some key antioxidants (GSH, GST and SOD) of the filarial nematode S. cervi. Our results have provided experimental evidence supporting that ferulic acid causes an increased proapoptotic gene expression and decreased expression of anti-apoptotic genes simultaneously with an elevated level of ROS and gradual dose dependent decline of parasitic GSH level. We also observed a gradual dose dependent elevation of GST and SOD activity in the ferulic acid treated worms.

Highlights► Bioassay-guided isolation and purification of ferulic acid from H. mutabilis. ► Ferulic acid caused lowering in parasitic GSH and elevation in GST, SOD level. ► RT-PCR, Western blotting confirmed decreased Ced-9 and increased Ced-4, Ced-3 level. ► Hoechst, TUNEL, PI staining, DNA fragmentation showed apoptosis in treated worm. ► We report antifilarial activity of ferulic acid on S. cervi through apoptosis.