Elucidation of antifungal and aflatoxin B1 inhibitory mode of action of Eugenia caryophyllata L. essential oil loaded chitosan nanomatrix against Aspergillus flavus.

The present study investigated the novel antifungal, and anti-aflatoxin B1 mechanism of Eugenia caryophyllata L. essential oil (ECEO) loaded chitosan nanomatrix against the toxigenic strain of A. flavus (AFLV-DK-02). Phytochemical profiling of ECEO was done by GC-MS which revealed eugenol (73.6%) as the primary bioactive compound. ECEO was encapsulated inside the chitosan nanomatrix (ECEO-Np) and characterized using SEM, AFM, FTIR and XRD analysis. The ECEO-Np exhibited enhance antifungal (0.25 µL/mL) and anti-aflatoxin B1 inhibitory activity (0.15 µL/mL) than ECEO. Antifungal and antiaflatoxin B1 inhibitory activity was found to be related with impairment in the biological functioning of the plasma membrane (ergosterol synthesis, leakage of membrane ions, UV light (260, 280 nm) absorbing material, dead cell by propidium iodide assay, mitochondrial membrane potential (MMP), methylglyoxal and inhibition in essential carbon substrate utilization). ECEO-Np exhibited remarkable free radical scavenging activity with IC50 value of 0.002 µL/mL. ECEO-Np effectively preserves the sensory characteristics of exposed maize crop seed up to six months of storage and shows considerable safety profile (non-toxic, non-mutagenic, non-hepatotoxic, non-carcinogenic, non-tumorigenic and biodegradable) using computational ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis.

Fabrication of volatile compounds loaded-chitosan biopolymer nanoparticles: Optimization, characterization and assessment against Aspergillus flavus and aflatoxin B1 contamination.

The study demonstrates the use of chitosan as a carrier agent of designed antifungal formulation (CME 4:1:1) based on a combination of plant compounds such as trans- cinnamaldehyde (C), methyl eugenol (M), and estragole (E). The formulation was encapsulated inside the chitosan biopolymer nanomatrix (Ne-CME) and characterized by SEM, FTIR, and XRD. The Ne-CME exhibited enhanced antifungal and aflatoxin B1 inhibitory effect compared to the individual compounds and unencapsulated form. Ne-CME (0.04 µl/ml) caused significant protection of Piper longum fruit from fungal (90.05%) and aflatoxin B1 (100%) contamination and had no significant negative effects on its nutritional properties. In addition, the probable antifungal mechanism of Ne-CME was investigated using in-silico (effect on Omt-1 and Vbs structural genes of AFB1 biosynthesis) and biochemical (perturbances in the cell membrane, carbohydrate catabolism, methyl-glyoxal, mitochondrial membrane potential, and antioxidant defense system) assay.

Encapsulation of Bunium persicum essential oil using chitosan nanopolymer: Preparation, characterization, antifungal assessment, and thermal stability.

The present study reports the antifungal, aflatoxin B1 inhibitory, and free radical scavenging activity of chitosan-based nanoencapsulatedBunium persicum Boiss. essential oil (Ne-BPEO). The chemical profile ofBPEO was identified through Gas chromatography mass spectrometry analysis where cuminaldehyde (21.23%), sabinene (14.66%), and γ-terpinen (12.49%) were identified as the major compounds. Ne-BPEO was prepared using chitosan and characterised by Scanning electron microscope (SEM), Atomic force microscope (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) assay. Ne-BPEO completely inhibited the growth and aflatoxin B1 production at a concentration of 0.3 µL/mL. The antifungal and aflatoxin B1 inhibitory effects were related to decreasing in ergosterol content, leakage of membrane ions (Ca2+, K+, and Mg2+), impairment in carbohydrate catabolism, and functioning of ver-1 gene of A. flavus exposed to Ne-BPEO over the control. In addition, Ne-BPEO exhibited promising free radical scavenging activity through DPPH assay (IC50 12.64 µL/mL) with high thermo-stability. Therefore, chitosan could be used as a carrier agent of plant-based preservative to enhance the shelf-life of food products against A. flavus and aflatoxin B1 contamination.

Nanoencapsulated methyl salicylate as a biorational alternative of synthetic antifungal and aflatoxin B1 suppressive agents.

In view of the suspected negative impact of synthetic fungicides to the human health, nutritional quality, and non-targeted organisms, the use of plant-based antifungal agents has gained considerable interest to the agri-food industries. The aim of this study was to explore the antifungal and aflatoxin B1 (AFB1) inhibitory activity of chitosan (low molecular weight) encapsulated methyl salicylate. The nanoencapsulation of methyl salicylate (Ne-MS) has been characterized by SEM, FTIR, and XRD analysis. The encapsulation efficiency and loading capacity of Ne-MS ranged between 32-34% and 5-7% respectively. The minimum inhibitory concentration of Ne-MS (1.00 µL/mL) against the growth and aflatoxin B1 production by Aspergillus flavus was found to be lower than the free MS (1.50 µL/mL). Mode of action studies demonstrated that the Ne-MS cause a significant decrease in the ergosterol content, leakage of vital ions (Ca2+, Mg2+, and K+), utilization of different carbon source by the A. flavus. Further, the docking result showed ver1 and omt A gene of AFB1 biosynthesis are the possible molecular site of action of methyl salicylate. The in situ study revealed that Ne-MS had no significant negative impact on the organoleptic properties of the food system (maize) which strengthen its potential as a biorational alternative of synthetic fungicides.

Nanoencapsulated plant-based bioactive formulation against food-borne molds and aflatoxin B1 contamination: Preparation, characterization and stability evaluation in the food system.

A novel synergistic formulation (TML) based on the combination of thymol (T), methyl cinnamate (M), and linalool (L) has been prepared using the mixture design assay. Nanoencapsulation of developed formulation TML (Ne-TML) was prepared and characterised by SEM, XRD and FTIR. The Ne-TML was assessed for its antifungal and anti-aflatoxin B1 potential in vitro and in the food systems (Pennisetum glaucum L.), and also examined its effects on organoleptic properties. The Ne-TML cause complete inhibition of growth and AFB1 production at 0.3 µl/ml and 0.2 µl/ml. In-situ results revealed that Ne-TML exhibited maximum protection from fungal (75.40%) and aflatoxin B1 contamination (100%) at 0.3 µl/ml during six months of storage. The speculated antifungal mode of action of Ne-TML was related to the decrease in ergosterol content, membrane ions leakage, impairment in carbon-source utilization, mitochondrial functioning, anti-oxidative defence system (SOD, CAT, and GR) and Ver-1 gene of aflatoxin B1 biosynthesis.

Assessment of toxicity and biochemical mechanisms underlying the insecticidal activity of chemically characterized Boswellia carterii essential oil against insect pest of legume seeds.

The present study was undertaken to investigate the insecticidal activity of chemically characterized Boswellia carterii essential oil (EO) and its mode of action against the pulse beetle Callosobruchus chinensis and C. maculatus. GC-MS analysis depicted α-thujene (69.16%), α-Pinene (7.20) and α-Phellandrene (6.78%) as the major components of test EO. EO exhibited absolute toxicity at 0.10µl/ml air against both C. chinensis and C. maculatus following 24h exposure. EO caused a significant reduction in oviposition and further reproductive development at LC50 doses (0.050µl/ml to 0.066µl/ml in air). Compared to control, a significant elevation in ROS level accompanied with impairment in enzymatic (SOD and CAT) and non-enzymatic (GSH/GSSH) antioxidant defense system has been observed in EO exposed insect pest. However, EO has no significant effect on in vivo AChE activity. An absolute protection of Vigna radiata seeds samples exposed to EO at LC90 doses was observed without affecting seed germination. The findings revealed that the B. carterii EO has strong insecticidal potential, hence, it could be recommended as a biorational alternative to synthetic insecticides.