Chitosan nanoencapsulation of garlic and turmeric essential oils for its insecticidal and antifungal activities against stored groundnut
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Date
2024-08
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Avinashilingam
Abstract
Agriculture and food processing are crucial industries in any country, especially in emerging economies. Stored grain insect pests and microbes control mainly depend on synthetic pesticides, recent scientific research is vital in developing new sustainable and eco-friendly approaches. In this study, garlic essential oil (GEO) and turmeric essential oil (TEO) were nanoencapsulated within chitosan nanoparticles (CSNPs) to create an
innovative preservative aimed to protect stored food from insect pests and fungal infection. The GC-MS analysis of GEO identified allyl methyl trisulfide-23.10% and diallyl sulfide-19.47% as the predominant components, while TEO primarily contained α- turmerone-42.0% and β-turmerone-14.0%. The encapsulated of GEO and TEO into chitosan nanoparticles (GEO-CSNPs and TEO-CSNPs) was achieved using the ionic-gelation method and confirmed through TEM micrograph, DLS, XRD, and FT-IR analyses. The in vitro DPPH free radical activity of GEO-CSNPs and TEO-CSNPs showed a significant increase compared to non-encapsulated GEO and TEO. Additionally, GEO-CSNPs and TEO-CSNPs exhibited stronger insecticidal, repellent, and antifeedant activities against adults C. serratus, and T. castaneum, compared to GEO/TEO. Growth regulated gene expression levels of InR and Cyclin E were found to be reduced in the LC20 and LC50 treatment in comparsion to the control group, conversely, LC20 and LC50 treatments exhibited high expression levels of 4EBP and FOXO in T. castaneum. In vitro experiments demonstrated that GEO-CSNPs (1.0 μL/mL) and TEO-CSNPs (0.75μL/mL) effectively inhibited the growth of A. flavus at low doses, while also preventing AFB1 synthesis at concentrations of 0.75 μL/mL and 0.50 μL/mL, compared to the pure GEO and TEO. The biochemical analysis revealed that exposure to GEO-CSNPs and TEO- CSNPs significantly altered the ergosterol level, ions leakage, mitochondrial membrane potential (MMP), and antioxidant system of A. flavus. Similarly, in-situ tests on A .hypogea showed that GEO-CSNPs and TEO-CSNPs at MIC and 2 MIC concentration inhibited fungal growth, AFB1 production, and lipid peroxidation without affecting the seeds. Overall, these experiments suggest that EO-based nanoformulations could enhance insecticidal efficacy against pests, improve antimicrobial activity against stored foodborne pathogens, and serve as innovative preservation agents to extend the shelf life of deposited food products.
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Zoology