In Silico to in Vivo Development of a Polyherbal Against Haemonchus Contortus

Abstract

Haemonchus contortus is a major constraint in the development of the small ruminant subsector due to significant production losses. The present study explores the antiparasitic potential of three anthelmintic plants ( Butea monosperma, Vitex negundo and Catharanthus roseus (L.) G.Don ) against H . contortus taking albendazole as the standard.In silico molecular docking and pharmacokinetic prediction studies were conducted with known bioactive molecules of these plants (palasonin, vinblastine, vincristine, betulinic acid and ursolic acid) against GDH and tubulin. Methanolic extracts of herbs were fractionated (hexane, ethyl acetate, chloroform and methanol) and used in in vitro larvicidal studies. Based on the in vitro data, two prototypes were developed and clinically tested.All the 5 ligand molecules showed better binding affinity compared with albendazole for GDH and tubulin protein and had similar binding site in the core of the GDH hexamer with slight variations. Albendazole approximately stacked against GLY190A residue, showing hydrophobic interactions with PRO157A and a Pi-cation electrostatic interaction with ARG390 along with four hydrogen bonds. Vincristine forms 2 pi-anionic electrostatic bonds with ASP158 of B and C subunits alongwith hydrogen bonding and hydrophobic interaction with an additional pi-anion electrostatic interaction at ASP158A for vinblastine. Albendazole bound to α-tubulin near colchicine site, whereas vinblastine is bound at the laulimalide/peloruside site. Betulinic acid showed lateral interactions between the H2–H3 loop of one alpha subunit and H10 of the adjacent alpha subunit of two tubulin dimers. Ursolic acid and palasonin are bound at the intradimer N site of microtubulin involving the H1–H7 and H1–H2 zones, respectively.The in vitro studies demonstrated good dose-dependent anthelmintic potential. Both the prototypes were quite efficacious in clearing the infection and keeping it at a minimum for more than 5 months, probably through direct anthelmintic effect through GDH, tubulin depolymerization and uncoupling as well as indirectly through immunomodulation along with antioxidant and anti-inflammatory properties.