Unveiling the cellular and molecular mode of action of Melaleuca cajuputi Powell. essential oil against aflatoxigenic strains of Aspergillus flavus isolated from stored maize samples
2022
Chaudhari, Anand Kumar | Singh, Vipin Kumar | Das, Somenath | Kujur, Anupam | Deepika, | Dubey, N. K.
This study aimed to reveal the bio-efficacy of Melaleuca cajuputi essential oil (McEO) against aflatoxigenic fungi and lipid peroxidation causing deterioration of stored maize samples. Three different toxigenic strains of Aspergillus flavus, namely AF-LHP-M2, AF-LHP-SP2, and AF-LHP-VS8 were investigated. Gas chromatography-mass spectrometry (GC-MS) analysis of EO revealed the presence of α-pinene (49.24%) as major compound. Investigation on efficacy showed that McEO exhibited remarkable inhibitory activity against growth and AFB₁ production by AF-LHP-M2 (2.0 and 1.4 μL mL⁻¹, respectively), AF-LHP-SP2 (1.2 and 1.0 μL mL⁻¹, respectively), and AF-LHP-VS8 (0.8 μL mL⁻¹) (p < 0.05). The McEO inhibited fungal growth via inhibition of ergosterol biosynthesis, cellular constituents' leakage, and damage of mitochondrial membrane potential, while AFB₁ production by inhibition of intracellular methylglyoxal. Further, molecular docking study was carried out to unveil the binding affinities of major compounds with the target protein Nor-1 (primarily catalyze an important step in AFB₁ biosynthesis), and the results revealed good correlation with the experimental findings. In addition, McEO showed significantly (p < 0.05) higher DPPH• and ABTS•⁺ scavenging activity with IC₅₀ values 3.16 and 4.29 μL mL⁻¹, respectively. Interestingly, McEO inhibited AFB₁ production, and malondialdehyde content in fumigated maize samples without significantly (p < 0.05) changing their sensory attributes, ascertaining its efficacy in food system with high safety profile (LD₅₀ = 1800 mg kg⁻¹ body weight) on mice model. The overall results proved McEO's potential as natural food preservative of stored food products.
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