A chitosan-based biopolymer as an encapsulating nanomaterial for enhancing the antifungal and aflatoxin B1 inhibitory efficacy of Zanthoxylum alatum (Roxb) essential oil and elucidation of the mode of action

Abstract

The study reports the green synthesis of nanoencapsulated Zanthoxylum alatum (Roxb) essential oil (Ne-ZAEO) using chitosan biopolymer and its assessment as an antifungal agent against food-borne molds and aflatoxin B₁ (AFB₁) contamination. Phytochemical analysis of essential oil (ZA-EO) was conducted by gas chromatography-mass spectroscopy (GC-MS). The fabricated Ne-ZAEO was analysed for average size (30–50 nm by scanning electron microscopy and atomic force microscopy), functional group interaction (Fourier transform infrared spectroscopy), and nature of crystallinity (X-ray diffraction). The Ne-ZAEO exhibited considerable encapsulation efficiency (37.33%) and loading capacity (6%). The in vitro minimum inhibitory concentration (MIC) of free ZAEO and Ne-ZAEO against Aspergillus flavus was found to be 1.20 μL mL⁻¹ and 1.0 μL mL⁻¹ respectively. The antifungal mechanism was linked to cellular dysfunction including ergosterol content, ion leakage, and carbon source utilization. In addition, the antioxidant activity (IC₅₀ value 59.93 μL mL⁻¹) of Ne-ZAEO was explored using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Ne-ZAEO at 1.0 μL mL⁻¹ significantly protects the Vigna unguiculata legume seed samples from A. flavus growth and AFB₁ contamination and preserves its sensory characteristics. The study reports that Ne-ZAEO could be used as a green antifungal agent to protect food-grains from molds and AFB₁ contamination and extend their shelf-life.