Improvement of in vitro and in situ antifungal, AFB ₁ inhibitory and antioxidant activity of Origanum majorana L. essential oil through nanoemulsion and recommending as novel food preservative

Origanum majorana essential oil (OmEO) encapsulated into chitosan nanoemulsion is being reported as a novel preservative of stored food items against fungi, aflatoxin B₁ (AFB₁) contamination and lipid peroxidation. The major component of OmEO identified through GC-MS was terpinen-4-ol (28.92%). HR-SEM, FTIR and XRD analyses confirmed successful encapsulation of OmEO into chitosan nanoemulsion (OmEO-CsNe). The results showed remarkable improvement in efficacy after nanoencapsulation, since OmEO-CsNe completely inhibited the growth and AFB₁ production by Aspergillus flavus at 1.0 μL/mL, which was 2.5 and 1.5 μL/mL, respectively for OmEO. The inhibition of ergosterol followed by release of cellular ions and 260 and 280 nm absorbing materials demonstrated plasma membrane as possible antifungal target. Inhibition of methylglyoxal confirmed antiaflatoxigenic mode of action. OmEO-CsNe showed enhanced antioxidant activity (IC₅₀ = 14.94 and 5.53 μL/mL for DPPH and ABTS, respectively) and caused in situ inhibition of lipid peroxidation and AFB₁ production in maize (third most important staple crop after wheat and rice) without altering their sensory attributes and presented safety profile (LD₅₀ = 11,889 μL/kg) when tested on mice. The findings indicate that the encapsulation considerably enhances the performance of OmEO, therefore can be recommended as a promising antifungal agent to extend the shelf-life of food items.

Keywords: Aflatoxin B(1); Chitosan nanoemulsion; Lipid peroxidation; Origanum majorana essential Oil.