Antifungal Activity of Chitosan Nano-Encapsulated Cinnamomum zeylanicum Bark Essential Oil Against Mycotoxigenic Fungi from maize and Sorghum.

Abstract

Grain contamination by mycotoxins-producing fungi threatens food safety and quality, decreasing agricultural productivity and increasing economic losses. This study evaluated the antifungal efficacies of both free Cinnamon Bark Essential Oil (CBEO) and its Nano formulation with chitosan nanoparticles (CBEO-NP), against five Mycotoxigenic fungi isolated from maize and sorghum, collected across various locations within Niger State, Nigeria. The CBEO was extracted using soxhlet extraction method with n-hexane as extracting solvent and characterized by GC-MS analysis. Chitosan nanoparticles were synthesized via ionic gelation method and the characterization of the nanoparticles was done using Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), Ultraviolet-visible Spectrophotometry (UV-Vis), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. The antifungal bioassay was carried out at varying concentrations of 25, 50, 75, and 100 % (v/v) for CBEO and 40, 80, 120, 160 and 200 mg/ml for CBEO-NP using agar well diffusion method. The GC–MS profiling of CBEO revealed 22 bioactive constituents, with cinnamaldehyde (36.56 %) as the dominant compound. Chitosan nanoparticles synthesized, exhibited an average size of 45.61 nm. The results for the antifungal bioassays showed susceptibility of all the tested fungi at the highest concentrations of 100% (v/v) for CBEO and 200 mg/ml for CBEO-NP with Aspergillus niger (21.0 ± 1.0 and 25.0 ± 1.0) mm, Aspergillus fumigatus (18.33 ± 1.53 and 21.0 ± 1.0) mm, Aspergillus flavus (18.0 ± 1.00 and 21.67 ± 0.58) mm, Penicillium spp. (22.68 ± 1.53 and 24.0 ± 1.00) mm and Fusarium spp. (21.68 ± 0.58 and 22.33 ± 2.08) mm respectively. Both CBEO and CBEO-NPs showed significant inhibitory properties against the mycotoxigenic fungi with an enhanced efficacy observed in its nano-formulation. These findings thus, underscore the importance of CBEO-based nano-formulation as a promising natural alternative for combating fungal contamination in grains and improving