Assessment of preservative potential of Cinnamomum zeylanicum Blume essential oil against food borne molds, aflatoxin B 1 synthesis, its functional properties and mode of action

Inhibition Mechanism of Cinnamomum burmannii Leaf Essential Oil Against Aspergillus flavus and Aflatoxins

This investigation evaluates the comparative efficacy of Cinnamomum burmannii leaf essential oil (YXYO) and its main active ingredients as a novel preservative to protect stored food commodities from fungal infestations, aflatoxin B1 (AFB1) contamination caused by Aspergillus flavus. Morphological observations utilizing SEM and TEM revealed significant alterations in treated samples, alongside a decrease in ergosterol content and a dose-dependent disruption of the antioxidant system and energy system. Transcriptomic analysis suggested that differentially expressed genes were predominantly associated with spore growth, the cell wall, the cell membrane, oxidative stress, energy metabolism, and aflatoxin biosynthesis. Solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) identified ten active ingredients in YXYO, including borneol, α-terpineol, terpinen-4-ol, etc. Moreover, an effective inhibition of A. flavus infection in peanuts was observed with the application of 30 μL/disc of YXYO and a blend of its active compounds.

The mechanistic insights of essential oil of Mentha piperita to control Botrytis cinerea and the prospection of lipid nanoparticles to its application

Botrytis cinerea is the phytopathogenic fungus responsible for the gray mold disease that affects crops worldwide. Essential oils (EOs) have emerged as a sustainable tool to reduce the adverse impact of synthetic fungicides. Nevertheless, the scarce information about the physiological mechanism action and the limitations to applying EOs has restricted its use. This study focused on elucidating the physiological action mechanisms and prospection of lipid nanoparticles to apply EO of Mentha piperita. The results showed that the EO of M. piperita at 500, 700, and 900 μL L-1 inhibited the mycelial growth at 100 %. The inhibition of spore germination of B. cinerea reached 31.43 % at 900 μL L-1. The EO of M. piperita decreased the dry weight and increased pH, electrical conductivity, and cellular material absorbing OD260 nm of cultures of B. cinerea. The fluorescence technique revealed that EO reduced hyphae width, mitochondrial activity, and viability, and increased ROS production. The formulation of EO of M. piperita loaded- solid lipid nanoparticles (SLN) at 500, 700, and 900 μL L-1 had particle size ∼ 200 nm, polydispersity index < 0.2, and stability. Also, the thermogravimetric analysis indicated that the EO of M. piperita-loaded SLN has great thermal stability at 50 °C. EO of M. piperita-loaded SLN reduced the mycelial growth of B. cinerea by 70 %, while SLN formulation (without EO) reached 42 % inhibition. These results supported that EO of M. piperita-loaded SLN is a sustainable tool for reducing the disease produced by B. cinerea.

The Temporal Dynamics of Sensitivity, Aflatoxin Production, and Oxidative Stress of Aspergillus flavus in Response to Cinnamaldehyde Vapor

Cinnamaldehyde (CA), a natural plant extract, possesses notable antimicrobial properties and the ability to inhibit mycotoxin synthesis. This study investigated the effects of different concentrations of gaseous CA on A. flavus and found that higher concentrations exhibited fungicidal effects, while lower concentrations exerted fungistatic effects. Although all A. flavus strains exhibited similar responses to CA vapor, the degree of response varied among them. Notably, A. flavus strains HN-1, JX-3, JX-4, and HN-8 displayed higher sensitivity. Exposure to CA vapor led to slight damage to A. flavus, induced oxidative stress, and inhibited aflatoxin B1 (AFB1) production. Upon removal of the CA vapor, the damaged A. flavus resumed growth, the oxidative stress weakened, and AFB1 production sharply increased in aflatoxin-producing strains. In the whole process, no aflatoxin was detected in aflatoxin-non-producing A. flavus. Moreover, the qRT-PCR results suggest that the recovery of A. flavus and the subsequent surge of AFB1 content following CA removal were regulated by a drug efflux pump and velvet complex proteins. In summary, these findings emphasize the significance of optimizing the targeted concentrations of antifungal EOs and provide valuable insight for their accurate application.

The significance of essential oils and their antifungal properties in the food industry: A systematic review

Essential oils (EOs) are natural products called volatile oils or aromatic and ethereal oils derived from various parts of plants. They possess antioxidant and antimicrobial properties, which offer natural protection against a variety of pathogens and spoilage microorganisms. Studies conducted in the last decade have demonstrated the unique applications of these compounds in the fields of the food industry, agriculture, and skin health. This systematic article provides a summary of recent data pertaining to the effectiveness of EOs and their constituents in combating fungal pathogens through diverse mechanisms. Antifungal investigations involving EOs were conducted on multiple academic platforms, including Google Scholar, Science Direct, Elsevier, Springer, Scopus, and PubMed, spanning from April 2000 to October 2023. Various combinations of keywords, such as "essential oil," "volatile oils," "antifungal," and "Aspergillus species," were used in the search. Numerous essential oils have demonstrated both in vitro and in vivo antifungal activity against different species of Aspergillus, including A. niger, A. flavus, A. parasiticus, A. fumigatus, and A. ochraceus. They have also exhibited efficacy against other fungal species, such as Penicillium species, Cladosporium, and Alternaria. The findings of this study offer novel insights into inhibitory pathways and suggest the potential of essential oils as promising agents with antifungal and anti-mycotoxigenic properties. These properties could make them viable alternatives to conventional preservatives, thereby enhancing the shelf life of various food products.

Synthesis, characterization, and assessment of chitosan-nanomatrix enriched with antifungal formulation against biodeterioration of active ingredients of selected herbal raw materials

Aflatoxin B₁ (AFB₁), a potent natural group 1 carcinogen produced by Aspergillus flavus is considered an unavoidable toxic contaminant of herbal raw materials, which often deteriorates their active ingredients making them less effective and hazardous during their formulation in herbal drugs. The present investigation reports the antifungal (0.5 μl/ml) and AFB₁ inhibitory (0.4 μl/ml) effects of the developed formulation CIM based on a mixture of essential oils (Carum carvi, and Illicium verum), and methyl anthranilate using mathematical modeling. The insight into the mechanism of action has also been explored using biochemical, molecular docking, and RT-PCR. Further, the nanoencapsulation of CIM (Ne-CIM) was prepared using a green facile synthesis of chitosan-based nanomatrix and characterized by Dynamic light scattering (DLS), Fourier transform-infrared, (FTIR), and X-ray diffraction analysis (XRD). The in-situ results showed that at MIC doses Ne-CIM effectively controls the A. flavus (81.25-89.57 %), AFB₁ contamination (100 %), and protects the active ingredients deterioration of Piper nigrum, P. longum, Andrographis paniculata, Silybum marianum, and Withania somnifera caused by toxigenic species of A. flavus without affecting their sensory properties. Hence, Ne-CIM could be used as a green chemical agent to protect the biodeterioration of active ingredients of herbal raw materials caused by toxigenic species of A. flavus.

New insights into the persistent effect of transient cinnamaldehyde vapor treatment on the growth and aflatoxin synthesis of Aspergillus flavus

The antimicrobial effects of continuous treatment with essential oils (EOs) in both liquid and gaseous phases have been intensively studied. Due to their rapid volatility, the effects of EOs on microorganisms after transient treatment are also worth exploring. In this work, the persistent effects of cinnamaldehyde (CA) vapor on Aspergillus flavus were detected by a series of biochemical analyses. Transcriptome analysis was also conducted to study the gene expression changes between recovered and normal A. flavus. When CA vapor was removed, biochemical analyses showed that the oxidative stress induced by the antimicrobial atmosphere was alleviated, and almost all the damaged functions were restored apart from mitochondrial function. Remarkably, the suppressed aflatoxin production intensified, which was confirmed by the up-regulation of most genes in the aflatoxin synthetic gene cluster, the velvet-related gene FluG and the aflatoxin precursor acetyl-CoA. Transcriptomic analysis also demonstrated significant changes in secondary metabolism, energy metabolism, oxidative stress, and amino acid metabolism in the recovery group. Taken together, these findings provide new insights into the mechanisms underlying the response of A. flavus to CA vapor treatment and will guide the rational application of EOs.

Antifungal Activity of Essential Oil and Plant-Derived Natural Compounds against Aspergillus flavus

Aspergillus flavus is a facultative parasite that contaminates several important food crops at both the pre- and post-harvest stages. Moreover, it is an opportunistic animal and human pathogen that causes aspergillosis diseases. A. flavus also produces the polyketide-derived carcinogenic and mutagenic secondary metabolite aflatoxin, which negatively impacts global food security and threatens human and livestock health. Recently, plant-derived natural compounds and essential oils (EOs) have shown great potential in combatting A. flavus spoilage and aflatoxin contamination. In this review, the in situ antifungal and antiaflatoxigenic properties of EOs are discussed. The mechanisms through which EOs affect A. flavus growth and aflatoxin biosynthesis are then reviewed. Indeed, several involve physical, chemical, or biochemical changes to the cell wall, cell membrane, mitochondria, and related metabolic enzymes and genes. Finally, the future perspectives towards the application of plant-derived natural compounds and EOs in food protection and novel antifungal agent development are discussed. The present review highlights the great potential of plant-derived natural compounds and EOs to protect agricultural commodities and food items from A. flavus spoilage and aflatoxin contamination, along with reducing the threat of aspergillosis diseases.

Essential oils of Bursera morelensis and Lippia graveolens for the development of a new biopesticides in postharvest control

Fruit and vegetable crops that are not consumed immediately, unlike other agricultural products, require economic and time investments until they reach the final consumers. Synthetic agrochemicals are used to maintain and prolong the storage life of crops and avoid losses caused by phytopathogenic microorganisms. However, the excessive use of synthetic agrochemicals creates health problems and contributes to environmental pollution. To avoid these problems, less toxic and environment-friendly alternatives are sought. One of these alternatives is the application of biopesticides. However, few biopesticides are currently used. In this study, the biopesticide activity of Bursera morelensis and Lippia graveolens essential oils was evaluated. Their antifungal activity has been verified in an in vitro model, and chemical composition has been determined using gas chromatography-mass spectrometry. Their antifungal activity was corroborated in vitro, and their activity as biopesticides was subsequently evaluated in a plant model. In addition, the persistence of these essential oils on the surface of the plant model was determined. Results suggest that both essential oils are promising candidates for producing biopesticides. This is the first study showing that B. morelensis and L. graveolens essential oils work by inhibiting mycelial growth and spore germination and are environment-friendly biopesticides.

Antibiofilm Potential of Medicinal Plants against Candida spp. Oral Biofilms: A Review

The use of natural products to promote health is as old as human civilization. In recent years, the perception of natural products derived from plants as abundant sources of biologically active compounds has driven their exploitation towards the search for new chemical products that can lead to further pharmaceutical formulations. Candida fungi, being opportunistic pathogens, increase their virulence by acquiring resistance to conventional antimicrobials, triggering diseases, especially in immunosuppressed hosts. They are also pointed to as the main pathogens responsible for most fungal infections of the oral cavity. This increased resistance to conventional synthetic antimicrobials has driven the search for new molecules present in plant extracts, which have been widely explored as alternative agents in the prevention and treatment of infections. This review aims to provide a critical view and scope of the in vitro antimicrobial and antibiofilm activity of several medicinal plants, revealing species with inhibition/reduction effects on the biofilm formed by Candida spp. in the oral cavity. The most promising plant extracts in fighting oral biofilm, given their high capacity to reduce it to low concentrations were the essential oils extracted from Allium sativum L., Cinnamomum zeylanicum Blume. and Cymbopogon citratus (DC) Stapf.

Essential Oils and Their Application in Food Safety

Food industries are facing a great challenge due to contamination of food products with different microbes such as bacteria, fungi, viruses, parasites, etc. These microbes deteriorate food items by producing different toxins during pre- and postharvest processing. Mycotoxins are one of the most potent and well-studied toxic food contaminants of fungal origin, causing a severe health hazard to humans. The application of synthetic chemicals as food preservatives poses a real scourge in the present scenario due to their bio-incompatibility, non-biodegradability, and environmental non-sustainability. Therefore, plant-based antimicrobials, including essential oils, have developed cumulative interest as a potential alternative to synthetic preservatives because of their ecofriendly nature and generally recognized as safe status. However, the practical utilization of essential oils as an efficient antimicrobial in the food industry is challenging due to their volatile nature, less solubility, and high instability. The recent application of different delivery strategies viz. nanoencapsulation, active packaging, and polymer-based coating effectively addressed these challenges and improved the bioefficacy and controlled release of essential oils. This article provides an overview of essential oils for the preservation of stored foods against bacteria, fungi, and mycotoxins, along with the specialized mechanism of action and technological advancement by using different delivery systems for their effective application in food and agricultural industries smart green preservative.

Nanoencapsulation of essential oils and their bioactive constituents: A novel strategy to control mycotoxin contamination in food system

Spoilage of food by mycotoxigenic fungi poses a serious risk to food security throughout the world. In view of the negative effects of synthetic preservatives, essential oils (EOs) and their bioactive constituents are gaining momentum as suitable substitute to ensure food safety by controlling mycotoxins. However, despite their proven preservative potential against mycotoxins, the use of EOs/bioactive constituents in real food system is still restricted due to instability caused by abiotic factors and negative impact on organoleptic attributes after direct application. Nanoencapsulation in this regard could be a promising approach to address these problems, since the process can increase the stability of EOs/bioactive constituents, barricades their loss and considerably prevent their interaction with food matrices, thus preserving their original organoleptic qualities. The aim of this review is to provide wider and up-to-date overview on recent advances in nanoencapsulation of EOs/bioactive constituents with the objective to control mycotoxin contamination in food system. Further, the information on polymer characteristics, nanoencapsulation techniques, factors affecting the nanoencapsulation, applications of nanoencapsulated formulations, and characterization along with the study on their release kinetics and impacts on organoleptic attributes of food are discussed. Finally, the safety aspects of nanoencapsulated formulations for their safe utilization are also explored.

Plant Bioactive Compounds in Pre- and Postharvest Management for Aflatoxins Reduction

Aflatoxins (AFs) are secondary metabolites produced by Aspergillus spp., known for their hepatotoxic, carcinogenic, and mutagenic activity in humans and animals. AF contamination of staple food commodities is a global concern due to their toxicity and the economic losses they cause. Different strategies have been applied to reduce fungal contamination and AF production. Among them, the use of natural, plant-derived compounds is emerging as a promising strategy to be applied to control both Aspergillus spoilage and AF contamination in food and feed commodities in an integrated pre- and postharvest management. In particular, phenols, aldehydes, and terpenes extracted from medicinal plants, spices, or fruits have been studied in depth. They can be easily extracted, they are generally recognized as safe (GRAS), and they are food-grade and act through a wide variety of mechanisms. This review investigated the main compounds with antifungal and anti-aflatoxigenic activity, also elucidating their physiological role and the different modes of action and synergies. Plant bioactive compounds are shown to be effective in modulating Aspergillus spp. contamination and AF production both in vitro and in vivo. Therefore, their application in pre- and postharvest management could represent an important tool to control aflatoxigenic fungi and to reduce AF 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.

Assessment of Melissa officinalis L. essential oil as an eco-friendly approach against biodeterioration of wheat flour caused by Tribolium castaneum Herbst

The study reports efficacy of Melissa officinalis L. essential oil (MOEO) as a safe plant-based insecticide against Tribolium castaneum Herbst (TC) by induction of oxidative stress. MOEO nanoencapsulation in chitosan matrix was performed to enhance its bioefficacy. GC-MS analysis of MOEO depicted geranial (31.54%), neral (31.08%), and β-caryophyllene (12.42%) as the major components. MOEO showed excellent insecticidal potential in contact (100% mortality at 0.157 μL/cm²) and fumigant bioassays (LC₅₀ = 0.071 μL/mL air) and 100% repellency at concentration ≤ 0.028 μL/cm². Increased reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), and decreased ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) at the LC₅₀ dose suggested significant oxidative stress on TC in MOEO treatment sets. The encapsulated MOEO exhibited enhanced activity as fumigant (LC₅₀ = 0.048 μL/mL air) and showed significant antifeedant activity in situ (EC₅₀ = 0.043 μL/mL). High LD₅₀ value (13,956.87 μL/kg body weight of mice) confirmed favorable toxicological profile for non-target mammals. The findings depict potential of nanoencapsulated MOEO as an eco-friendly green pesticide against infestation of stored food by TC.

Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa Essential Oils: Chemical Composition, Antimicrobial and Antileishmanial Activity

The resistance mechanisms of bacteria and protozoans have evidenced the need of discover new compounds with potential pharmaceutical activity against pathogenic microorganisms. Medicinal plants have been for centuries a promising alternative as sources of new drugs. The objective of this work was to evaluate the chemical composition, antimicrobial and antileishmanial activities of Cinnamomum zeylanicum, Origanum vulgare, and Curcuma longa essential oils. Chemical analysis was performed by gas chromatography-mass spectrometry. Antimicrobial activity was performed by disk diffusion and minimum inhibitory concentration (MIC) test. Antileishmanial activity was performed against antipromastigote and intracellular amastigote of Leishmania amazonensis. Cytotoxic and nitrite production were realized in BALB/c peritoneal macrophages. The major compounds of the essential oils were cinnamic aldehyde (46.30%) in C. zeylanicum, cis-p-menth-2-en-1-ol (33.88%) and linalyl acetate (13.90%) in O. vulgare, and turmerone (55.43%) in C. longa. The MIC showed significant antimicrobial activity of C. longa essential oil against S. aureus (83.3 ± 14.43 µg/mL). Antipromastigote activity showed IC₅₀ values >500 µg/mL to C. zeylanicum, 308.4 ± 1.402 µg/mL to O. vulgare, and 405.5 ± 1.119 µg/mL to C. longa essential oil. Activity against intracellular amastigote of L. amazonensis showed IC₅₀ of 63.3 ± 1.369 µg/mL and cytotoxic was not observed, resulting in selectivity index higher than 15.79 to parasite. C. longa essential oil decreased nitrite production in peritoneal macrophages, but not in Leishmania-infected cells. The chemical composition of the three essential oils is directly associated to its potential biological action, as the antimicrobial activity. C. longa presented a potent antileishmanial activity against promastigote and intracellular amastigote of L. amazonensis, although this activity is not linked to nitric oxide, since C. longa essential oil inhibits its production.

A review on antifungal activity and mode of action of essential oils and their delivery as nano-sized oil droplets in food system

An escalated demand of minimally processed food and increased negative perception for synthetic preservative has led to a lookout for a natural preservative. Essential oils (EOs) are volatile and aromatic secondary metabolites of plants that have been tapped mainly for its flavour and fragrances and various biological properties such as antimicrobial and antioxidant. The constituents and antifungal potential of EOs have been reported widely in the present scientific literature. Moreover, the current scientific research dealing with the mode of action of EOs on fungal spores and mycelial cells are very scarce, unlike bacteria. The antimicrobial efficacy of EO in real food system may alter due to interaction with food matrix components. Besides, minimum alteration in sensory qualities while retaining its maximum activity is the most sought-after criteria for food preservation with EOs. If the oil is applied in excess to have better antimicrobial activity, it may end up having an unacceptable organoleptic impact on the food. Appropriate edible delivery systems of EOs as an emulsion is a probable approach to retain the maximum efficacy of EOs in the food system. Nano-emulsification of EO could increase its bioactivity due to increased bioavailability in the food matrix. The basis of this review is to provide an overview of current knowledge about the antifungal properties and antifungal mode of action of EOs, and to recognize the application of EO as nano-sized oil droplets in the food system.