Synergistic antifungal activity of Melaleuca alternifolia oil and terpinen-4-ol in stored rice

Abstract

The present investigation aimed to evaluate synergistic antifungal activity of Melaleuca alternifolia essential oil (MAEO) and terpinen-4-ol (MAEO-ter) against Aspergillus flavus and Fusarium proliferatum infestation along with aflatoxin B₁ (AFB₁), fumonisin B₁ (FB₁), and fumonisin B₂ (FB₂) production in stored rice (Oryza sativa L.) samples. The mechanism of antifungal activity of synergistic formulation was based on the assessment of plasma membrane. Results showed that the MAEO-ter synergistic formulation improved the anti-aflatoxigenic and anti-fumonisin efficacy at lower doses than individual application of MAEO and terpinen-4-ol. The impairment in ergosterol production along with enhanced release of cell contents and high propidium iodide fluorescence intensity suggested plasma membrane as possible target site of action. Moreover, the retardation in methylglyoxal biosynthesis and in silico modeling of terpinen-4-ol with Omt-A, Ver-1, Fum-1, and Fum-6 proteins unveiled the biochemical and molecular mechanism of anti-aflatoxigenic and anti-fumonisin activity. The in situ results exhibited promising efficacy of MAEO-ter synergistic formulation towards the inhibition of AFB₁, FB₁, and FB₂ production along with the suppression of lipid peroxidation, and loss of carbohydrate and protein content (p < 0.05) in rice samples. The acceptable scores of organoleptic properties and favorable safety profile in mice suggested the efficacy of MAEO-ter synergistic formulation as an effective antifungal and anti-mycotoxigenic agent in managing the loss of stored rice samples.