Effect of (-)-epicatechin, a flavonoid on the NO and NOS activity of Raillietina echinobothrida.

(-)-Epicatechin, a natural flavonoid reportedly has huge pharmacological properties. In this study the cestocide effect of (-)-epicatechin is demonstrated in Raillietina echinobothrida. Although the antiparasitic activity of (-)-epicatechin has been demonstrated against protozoa, helminths and ectoparasites, in the present study the cestocide activity of (-)-epicatechin is shown to be related to a decrease in nitric oxide synthase (NOS) activity and nitric oxide (NO) production. On exposure to 0.53mg/ml each of epicatechin, reference drug praziquantel and Ѡ Nitro-l- Arginine Methyl Ester (NOS inhibitor), the parasites attained paralysis at 10.15, 0.27 and 11.21h followed by death at 30.15, 1.21 and 35.18h respectively. Biochemical analysis showed a significant decrease in activity of NOS (57.360, 36.040 and 44.615%) and NO (41.579, 19.078 and 24.826%) in comparison to the controls. NADPH-diaphorase histochemical staining (a selective marker for NOS in neuronal tissue) demonstrated a pronounced decline in the visible staining activity in the tegument, subtegument and the peripheral nerve regions following exposure to the treatments. Strong binding affinity of (-)-epicatechin with NOS protein was also revealed through docking studies. The results strongly define the probable anthelmintic activity of our compound through its influence on the NOS activity.