Immunomodulatory and Antimicrobial potential of ethanolic extract of Himalayan Myrica esculanta in Oncorhynchus mykiss: Molecular modelling with Aeromonas hydrophila functional proteins

Abstract

The present study was carried out to investigate the antimicrobial and immunomodulatory activity of Myrica esculenta ethanolic leaf extract (MeALE) in rainbow trout. The juvenile fish were immersed in 20 mg/l (T1) and 40 mg/l (T2) MeALE for 2 and 6 h and then challenged with pathogenic bacteria, A. hydrophila (ATCC 7966, USA) after 6 h post immersion in MeALE. The immuno-haematological parameters and relative percentage survival were recorded over 7 days post-exposure. The amino acid interaction of functional proteins of bacteria with myricetin, the active ingredient of M. esculenta was performed by AutoDock Vina software. FTIR detected the characteristic peak values and revealed the presence of various functional groups, viz. alkenes, amines, alcohols, phenols and aromatic compounds. The MIC of MeALE was found to be 2 mg/ml while MBC was recorded to be 25 mg/ml. Molecular docking revealed a strong affinity between myricetin and functional proteins of the pathogen. The fish immersed in 40 mg/l MeALE showed a significant increase in haematological indices and non-specific immunological parameters. The current study reports the successful use of MeALE as an antimicrobial and immunostimulatory agent in rainbow trout and recommends the dosage of 40 mg/l MeALE for preventing Aeromonas infection.