Antifungal Activity of Magnolia officinalis Derived Magnolol and Honokiol on Membrane Disruption of Saprolegnia parasitica

Saprolegniosis is an infectious disease caused by Saprolegnia sp. It may cause serious losses in fish farms and hatcheries in many countries. In previous research, Magnolia officinalis has been found to initiate the death of Saprolegnia sp. Magnolol and honokiol, two active substances in M. officinalis, may be responsible for the antifungal effects on Saprolegnia sp. The present study centered on the anti-fungal activity and mechanism of magnolol and honokiol on Saprolegnia parasitica. Results revealed that magnolol and honokiol displayed effective anti-fungal activity on S. parasitica, which caused their mass mortality. More intuitive research has shown that magnolol and honokiol have evolved mechanisms that can destroy the cell membranes of S. parasitica, and cause exosmosis of their cytoplasmic saccharides and proteins, and cause mortality. Magnolol and honokiol exhibited minimum inhibitory concentration values of 976.6 ug/mL and 587.4 ug/mL concentrations, respectively, and the minimum inhibitory time of both was 2 hours. This study provides a clearer understanding of the function of M. officinalis against Saprolegnia sp