Green synthesis of garlic oil nanoemulsion using ultrasonication technique and its mechanism of antifungal action against Penicillium italicum

Synergistic stabilization of garlic essential oil nanoemulsions by carboxymethyl chitosan/Tween 80 and application for coating preservation of chilled fresh pork

Garlic essential oil (GEO) is a potential natural antioxidant and antimicrobial agent for food preservation, but its intrinsic low water-solubility, high volatility and poor stability severely limit its application and promotion. In this work, we investigated the synergistic stabilization of the GEO-in-water nanoemulsion using carboxymethyl chitosan (CCS) and Tween 80 (TW 80). Additionally, the nanoemulsion was fabricated through high-pressure microfluidization and utilized for the coating-mediated preservation of chilled pork. The garlic essential oil nanoemulsion (GEON) with 3.0 % CCS and 3.0 % TW 80 exhibited more homogeneous droplet size (around 150 nm) and narrower size distribution, while maintained long-term stability with no significant change in size during 30 d storage. Compared with free GEO, the GEONs exhibited a higher scavenging capacity to DPPH and ABTS free radicals as well as higher inhibitory effects against Escherichia coli and Staphylococcus aureus, suggesting that the encapsulation of GEO in nanoemulsion considerably improved its antioxidant and antibacterial activities. Furthermore, the results of coating preservation experiments showed that the GEON coating effectively expanded the shelf-life of chilled fresh pork for approximately one week. Altogether, this study would guide the development of GEO-loaded nanoemulsions, and promote GEON as a promising alternative for coating preservation of chilled fresh meat.

Green Preparation and Antibacterial Activity Evaluation of AgNPs-Blumea balsamifera Oil Nanoemulsion

Bacterial infection is a thorny problem, and it is of great significance to developing green and efficient biological antibacterial agents that can replace antibiotics. This study aimed to rapidly prepare a new type of green antibacterial nanoemulsion containing silver nanoparticles in one step by using Blumea balsamifera oil (BBO) as an oil phase and tea saponin (TS) as a natural emulsifier and reducing agent. The optimum preparation conditions of the AgNPs@BBO-TS NE were determined, as well as its physicochemical properties and antibacterial activity in vitro being investigated. The results showed that the average particle size of the AgNPs@BBO-TS NE was 249.47 ± 6.23 nm, the PDI was 0.239 ± 0.003, and the zeta potential was -35.82 ± 4.26 mV. The produced AgNPs@BBO-TS NE showed good stability after centrifugation and 30-day storage. Moreover, the AgNPs@BBO-TS NE had an excellent antimicrobial effect on Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. These results demonstrated that the AgNPs@BBO-TS NE produced in this study can be used as an efficient and green antibacterial agent in the biomedical field.

Surface-Enhanced Raman Spectroscopy for Monitoring the Biochemical Changes Due to DNA Mutations Induced by CRISPR-Cas9 Genome Editing in the Aspergillus niger Fungus

In this study, surface-enhanced Raman spectroscopy (SERS) technique, along with principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA), is used as a simple, quick, and cost-effective analysis method for identifying biochemical changes occurring due to induced mutations in the Aspergillus niger fungus strain. The goal of this study is to identify the biochemical changes in the mutated fungal cells (cell mass) as compared to the control/nonmutated cells. Furthermore, multivariate data analysis tools, including PCA and PLS-DA, are used to further confirm the differentiating SERS spectral features among fungal samples. The mutations are caused in A. niger by the clustered regularly interspaced palindromic repeat CRISPR-Cas9 genomic editing method to improve their biotechnological potential for the production of cellulase enzyme. SERS was employed to detect the changes in the cells of mutated A. niger fungal strains, including one mutant producing low levels of an enzyme and another mutant producing high levels of the enzyme as a result of mutation as compared with an unmutated fungal strain as a control sample. The distinctive features of SERS corresponding to nucleic acids and proteins appear at 546, 622, 655, 738, 802, 835, 959, 1025, 1157, 1245, 1331, 1398, and 1469 cm-1. Furthermore, PLS-DA is used to confirm the 89% accuracy, 87.7% precision, 87% sensitivity, and 88.9% specificity of this method, and the value of the area under the curve (AUROC) is 0.67. It has been shown that surface-enhanced Raman spectroscopy is an effective method for identifying and differentiating biochemical changes in genome-modified fungal samples.

Foeniculum vulgare essential oil nanoemulsion inhibits Fusarium oxysporum causing Panax notoginseng root-rot disease

Background

Fusarium oxysporum (F. oxysporum) is the primary pathogenic fungus that causes Panax notoginseng (P. notoginseng) root rot disease. To control the disease, safe and efficient antifungal pesticides must currently be developed.

Methods

In this study, we prepared and characterized a nanoemulsion of Foeniculum vulgare essential oil (Ne-FvEO) using ultrasonic technology and evaluated its stability. Traditional Foeniculum vulgare essential oil (T-FvEO) was prepared simultaneously with 1/1000 Tween-80 and 20/1000 dimethyl sulfoxide (DMSO). The effects and inhibitory mechanism of Ne-FvEO and T-FvEO in F. oxysporum were investigated through combined transcriptome and metabolome analyses.

Results

Results showed that the minimum inhibitory concentration (MIC) of Ne-FvEO decreased from 3.65 mg/mL to 0.35 mg/mL, and its bioavailability increased by 10-fold. The results of gas chromatography/mass spectrometry (GC/MS) showed that T-FvEO did not contain a high content of estragole compared to Foeniculum vulgare essential oil (FvEO) and Ne-FvEO. Combined metabolome and transcriptome analysis showed that both emulsions inhibited the growth and development of F. oxysporum through the synthesis of the cell wall and cell membrane, energy metabolism, and genetic information of F. oxysporum mycelium. Ne-FvEO also inhibited the expression of 2-oxoglutarate dehydrogenase and isocitrate dehydrogenase and reduced the content of 2-oxoglutarate, which inhibited the germination of spores.

Conclusion

Our findings suggest that Ne-FvEO effectively inhibited the growth of F. oxysporum in P. notoginseng in vivo. The findings contribute to our comprehension of the antifungal mechanism of essential oils (EOs) and lay the groundwork for the creation of plant-derived antifungal medicines.

Plant-based essential oil encapsulated in nanoemulsions and their enhanced therapeutic applications: An overview

In recent years, studies on the formulation of nanoemulsions have been the focus of attention due to their potential applicability in food, pharmaceuticals, cosmetics, and agricultural industries. Nanoemulsions can be formulated using ingredients approved by the Food and Drug Administration (FDA), which assures their safety profiles to a great extent. Bioactive compounds such as essential oils although have strong biological properties and antimicrobial compounds, their usage is restricted due to their high volatility, instability, and hydrophobic nature. Therefore, nanoemulsion as carrier vehicle can be used to encapsulate essential oils to obtain stable and enhanced physicochemical characteristics of the essential oils. This review details the structure, formulation, and characterization techniques used for nanoemulsions, with a focus on the essential oil-based nanoemulsions which have the potential to be used as antimicrobial and anticancer therapeutics.

Ultrasonic-assisted supercritical fluid separation removing plasticizers from ganoderma lucidum spores' oil

Ultrasonic-assisted supercritical fluid separation (USFS) was firstly applied to regulate solubility and remove plasticizers from ganoderma lucidum spores' oil to improve product safety. Separation efficiency was related with four variables, including temperature, pressure and ultrasonic power. The QD-T6A ultrasonic generator probe, which provided for the study with adjustable ultrasonic power 0 W to 800 W and the ultrasonic frequency was 40 kHz, was fixed at the entrance of the primary separation kettle. The optimal separation conditions were determined to be temperature as 15.0 °C, pressure as 18.0 MPa, and ultrasonic power as 360 W of ultrasonic power on the basis of response surface methodology (RSM). Experimental Di-n-butylphthalate (DBP) and Diethyl phthalate (DEP) content were 0.09 mg and 0.04 mg, respectively, which were below the limits for plasticizers. Meanwhile, the total triterpene and ganoderic acid A contents were 6.89 g and 1.10 g, respectively, comparable to conventional supercritical fluid extraction. The experiments with USFS at different power intensities revealed that ultrasonic at a power intensity of 36 W/L and the power density of 0.20 W/cm2 could resolve the separation contradiction between ganoderma lucidum spores' oil and plasticizers. This study revealed that USFS could be an innovation in the field of ultrasonic separation, with numerous potentials uses in pharmaceutical manufacturing.

Actinomycins produced by endophyte Streptomyces sp. GLL-9 from navel orange plant exhibit high antimicrobial effect against Xanthomonas citri susp. citri and Penicillium italicum

BACKGROUND

Citrus canker and citrus blue mold are two severe diseases in citrus plants, which are mainly caused by Xanthomonas citri susp. citri (Xcc) and Penicillium italicum, respectively. The currently widely used pesticides for these two diseases are harmful to human health and the environment. Therefore, searching for novel antimicrobial agents, especially from natural resources, is getting increasing interest.

RESULTS

In this study, the crude extract of Streptomyces sp. GLL-9, an endophyte from a navel orange tree, was found to exhibit excellent antimicrobial effects against Xcc and P. italicum. Bioassay-guided isolation led to the discovery of three actinomycins (Acts), actinomycin X2 (Act-X2 ), actinomycin D (ActD), and actinomycin XOβ (Act-XOβ ). The MIC (minimum inhibitory concentration) values of Act-X2 , ActD, and Act-XOβ were 31.25, 62.50, and 62.50 μg mL-1 against Xcc, respectively, while 62.50 (Act-X2 ) and 125.00 μg mL-1 (ActD) against P. italicum, being better or comparable to the positive controls. The highest yield of Acts was obtained by solid-state fermentation with rice containing 1% L-tryptophan as a culture medium, being 6.03, 3.07, and 1.02 mg g-1 , for Act-X2 , ActD, and Act-XOβ , respectively. The ethyl acetate extract of Streptomyces sp. GLL-9 cultivated under the optimal fermentation conditions (EAE-1) can efficiently control these two citrus diseases by excessively producing reactive oxygen species (ROS) in both pathogens, damaging the cell membranes of P. italicum, and inhibiting the growth of Xcc. In addition, Act-X2 , ActD, and EAE-1 displayed broad-spectrum antifungal activity.

CONCLUSION

EAE-1 and Acts produced by Streptomyces sp. GLL-9 have high potential as novel antimicrobial agents against plant pathogens. © 2023 Society of Chemical Industry.

Exploring dynamic changes of fungal cellular components during nanoemulsion treatment by multivariate microRaman imaging

Recently, essential oils (EO) have gained a lot of interest for use as antifungal agent in food and agricultural industry and extensive research is ongoing to understand their mode of action. However, the exact mechanism is not yet elucidated. Here, we integrated spectral unmixing and Raman microspectroscopy imaging to unveil the antifungal mechanism of green tea EO based nanoemulsion (NE) against Magnaporthe oryzae. The dramatic change in protein, lipid, adenine, and guanine bands indicate that NE has a significant impact on the protein, lipid and metabolic processes of purine. The results also demonstrated that the NE treatment caused damage to fungal hyphae by inducing a physical injury leading to cell wall damage and loss of integrity. Our study shows that MCR-ALS (Multivariate Curve Resolution-Alternating Least Squares) and N-FINDR (N-finder algorithm) Raman imaging could serve as a suitable complementary package to the traditional methods, for revealing the antifungal mechanism of action of EO/NE.

Polymethoxylated flavonoids (PMFs)-loaded citral nanoemulsion controls green mold in citrus by damaging the cell membrane of Penicillium digitatum

Citrus is susceptible to Penicillium digitatum (P. digitatum) infection in post-harvest storage, resulting in enormous economic losses. This study aimed to investigate the antifungal activity and potential mechanism of the combination of Polymethoxylated flavones (PMFs) and citral (two natural antifungal components derived from citrus) against P. digitatum in vitro and citrus fruit. The results show that PMFs can enhance the antifungal activity of citral nanoemulsion, and PMFs-loaded citral nanoemulsion (PCT) has significant antifungal activity in a concentration-dependent manner. PCT can evidently inhibit spore germination and mycelial growth in vitro, and effectively control the growth of green mold on postharvest citrus fruit. Furthermore, PCT treatment resulted in the alteration of mycelia morphology, accumulation of reactive oxygen species, and membrane lipid peroxidation. These changes can disrupt the normal structure and function of the cell membrane, as evidenced by the reduction of total lipid and ergosterol content in the mycelia and the stronger red fluorescence of the cells emitted after PI staining. Based on the above results, we infer that PCT has a strong inhibitory effect on P. digitatum, and its potential mechanism is related to the destruction of the cell membrane. Therefore, PCT can be considered as a botanical fungicide for citrus preservation.

Nanoencapsulation application to prolong postharvest shelf life

This review offers our opinion on current and future trends regarding nanoencapsulation interventions to extend postharvest shelf life of stored grains, fruits, and vegetables. Herein, we considered two major factors influencing postharvest shelf life for comments: aerobic food spoilage microorganisms and stored pests. Nanoemulsions, edible/active coatings, and nanopackaging loading essential oils as antimicrobial, antioxidant, or pesticide showed promising results in prolonged shelf life at room/cold storage without compromising quality, organoleptic properties, and postharvest physiology. Trends with nanoencapsulation using plant-based pesticides as agrochemical-free methods to keep produce fresh longer were commented as potential candidates for prolonging the shelf life of stored grains and fruits at the postharvest stage. Research with potential large-scale feasibility is intensive, but safety assessment is required and remains little explored.

Garlic essential oil in water nanoemulsion prepared by high-power ultrasound: Properties, stability and its antibacterial mechanism against MRSA isolated from pork

Food-borne methicillin-resistance Staphylococcus aureus (MRSA) has caused significant health threats and economic loss in livestock and poultry products. Garlic essential oil (GEO) is an effective antibacterial agent but presents strong instability and hydrophobicity. In this study, GEO in water nanoemulsion (GEON) with good stability was produced by emulsification technique of high-power ultrasound. Its antibacterial activity and underlying mechanism against MRSA isolated from retailed pork were investigated. Results showed that ultrasonic treatment significantly reduced the particle size of GENO from 820.3 to 215.0 nm as time increased from 0 to 10 min. Comparatively, GEON of 10 min ultrasound was more stable than other GEONs (0, 1, 5 min) during 30 d storage. It also displayed good thermal stability and relatively good ion stability (NaCl, MgCl₂, and glucose). Antibacterial analysis showed that GEON (10 min) exhibited the best anti-MRSA activity among all GEONs, and the minimum inhibitory concentration of GEO in this nanoemulsion was 0.125 % (1.25 mg/mL). Treatment of GEON (10 min) significantly suppressed the cell proliferation of MRSA, which was mainly achieved by damaging the cell membrane as evidenced by membrane depolarization and considerable leakage of intracellular nucleic acids and protein. Laser scanning confocal microscope and scanning electron microscopy showed that treatment of GEON (10 min) significantly altered the membrane integrity and severely damaged the cellular membrane and structure. The present work illustrated that GEON produced by ultrasonic emulsification is a promising alternative to inhibit the contamination and spread of MRSA in livestock and poultry products.

Synergistic antibacterial mechanism of different essential oils and their effect on quality attributes of ready-to-eat pakchoi (Brassica campestris L. ssp. chinensis)

The mixture of garlic essential oil (GEO), ginger essential oil (GIEO) and litsea cubeba essential oil (LCEO) was prepared and its effect on the antibacterial activity of E. coli, S. aureus and P. aeruginosa, as well as properties of ready-to-eat pakchoi during storage were assessed. GEO, GIEO or LCEO treatment significantly enhanced the accumulation of reactive oxygen species (ROS) levels, resulting in disruption of the permeability of cell membrane, the leakage of cytoplasmic contents, and the alteration of the secondary structure of bacterial proteins. Meanwhile, GEO, GIEO or LCEO treatment repressed the key enzyme in tricarboxylic acid (TCA) and Hexose monophosphate pathway (HMP) cycle of E. coli, S. aureus and P. aeruginosa. Essential oil treatments (p < 0.05) could significantly prolong the shelf life of pakchoi, total bacterial count (TBC) values and chlorophyll content of GEO/GIEO/LCEO sample were 3.47 log cfu/g and 0.82 mg/g, respectively, after storage for 7 days. E. coli, S. aureus and P. aeruginosa counts in GEO/GIEO/LCEO samples decreased by 56.76 %, 70.10 %, 73.95 % compared to CK (no essential oil) samples. The comprehensive results from the sensory (flavor and color) and microbial analysis (especially TBC) showed that GEO/GIEO/LCEO could extend the shelf life of ready-to-eat pakchoi from 4 d to 7 d. As compared with GEO, GIEO or LCEO individually, the combination of GEO, GIEO and LCEO exhibited synergistic effect and more pronouncedly antibacterial activity to improve quality of ready-to-eat pakchoi.

Inhibitory Effect and Mechanism of Dill Seed Essential Oil on Neofusicoccum parvum in Chinese Chestnut

The chestnut postharvest pathogen Neofusicoccum parvum (N. parvum) is an important postharvest pathogen that causes chestnut rot. Chestnut rot in postharvest reduces food quality and causes huge economic losses. This study aimed to evaluate the inhibitory effect of dill seed essential oil (DSEO) on N. parvum and its mechanism of action. The chemical characterization of DSEO by gas chromatography/mass spectrometry (GC/MS) showed that the main components of DSEO were apiole, carvone, dihydrocarvone, and limonene. DSEO inhibited the growth of mycelium in a dose-dependent manner. The antifungal effects are associated with destroying the fungal cell wall (cytoskeleton) and cell membrane. In addition, DSEO can induce oxidative damage and intracellular redox imbalance to damage cell function. Transcriptomics analysis showed DSEO treatment induced differently expressed genes most related to replication, transcription, translation, and lipid, DNA metabolic process. Furthermore, in vivo experiments showed that DSEO and DSEO emulsion can inhibit the growth of fungi and prolong the storage period of chestnuts. These results suggest that DSEO can be used as a potential antifungal preservative in food storage.

Antifungal Activity of Polymethoxylated Flavonoids (PMFs)-Loaded Citral Nanoemulsion against Penicillium italicum by Causing Cell Membrane Damage

A major citrus postharvest pathogen, Penicillium italicum (P. italicum), causes substantial economic losses in citrus. In this study, a citral nanoemulsion containing polymethoxylated flavonoids (PMFs), the antimicrobial compounds from citrus, was prepared. The antifungal activity and potential antifungal mechanisms of the nanoemulsion against P. italicum were evaluated. The results showed that the growth of P. italicum was effectively inhibited by the nanoemulsion, with a minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 62.5 and 250 mg L−1, respectively. The nanoemulsion significantly inhibited spore germination and mycelial growth, and it altered the morphology of P. italicum. In addition, the permeability of the cell membrane increased with increasing nanoemulsion concentrations, as evidenced by a rapid rise in extracellular electric conductivity and stronger red fluorescence from mycelia (propidium iodide staining). Compared with the control, the nanoemulsion treatment induced a decrease in total lipid and ergosterol contents in P. italicum cells by 64.61% and 60.58%, respectively, demonstrating that membrane integrity had been disrupted. The results indicated that the PMFs-loaded nanoemulsion exerted antifungal activity against P. italicum by disrupting cell membrane integrity and permeability; such a nanoemulsion may be used as a potential fungicide substitute for preservation in citrus fruits.

Three-Dimensional Nanoscale Morphological Surface Analysis of Polymeric Particles Containing Allium sativum Essential Oil

Biodegradable particles were developed using poly-ε-caprolactone and gelatin carriers containing different concentrations of Allium sativum essential oil (EO) (360 µg/mL, 420 µg/mL, and 460 µg/mL). Atomic force microscopy was useful to evaluate the particles' surface based on morphological parameters. The particles' size varied from 150 nm to 300 nm. The diameter was related to the increase of the particles' height as a function of the EO concentration, influencing the roughness of the surface core values (from 20 to 30 nm) and surface irregularity. The spatial parameters Str (texture aspect ratio) and Std (texture direction) revealed low spatial frequency components. The hybrid parameters Sdq (root mean square gradient) and Sdr (interfacial area ratio) also increased as a function of the EO concentration, revealing fewer flat particles. On the other hand, the functional parameters (inverse areal material ratio and peak extreme height) suggested differences in surface irregularities. Higher concentrations of EO resulted in greater microtexture asperity on the particles' surface, as well as sharper peaks. The nanoscale morphological surface analysis allowed the determination of the most appropriate concentration of encapsulated EO, influencing statistical surface parameters.

Green Nanoemulsion Stabilized by In Situ Self-Assembled Natural Oil/Native Cyclodextrin Complexes: An Eco-Friendly Approach for Enhancing Anticancer Activity of Costunolide against Lung Cancer Cells

Lung cancer is the second-most deadly malignancy worldwide, of which smoking is considered a major risk factor and causes 75–80% of lung cancer-related deaths. Costunolide (CTD) extracted from plant species Saussurea, Aucklandia, and Inula exhibits potent anticancer properties, specifically in lung cancer and leukemia. Several nanoemulsions were prepared and optimized using a three-factor Box–Behnken experimental design. The optimized green nanoemulsion (GNE) showed a vesicle size of 199.56 nm. The IC₅₀ values revealed that A549 cells were significantly more sensitive to the optimized CTD formula than the plain formula and raw CTD. A cell cycle analysis revealed that the optimized CTD formula treatment resulted in significant cell cycle arrest at the S phase. The results also indicated that treatment with the CTD formula significantly increased caspase-3, Bax, Bcl-2, and p53 mRNA expression compared to the plain formula and CTD raw. In terms of the inflammatory markers, the optimized formula significantly reduced the activity of TNF-α and NF-κB in comparison with the plain formula and raw drug only. Overall, the findings from the study proved that a CTD GNE formulation could be a promising therapeutic approach for the treatment of lung cancer.

Development of Phosphatidylcholine/Tween 80 based biocompatible clove oil-in-water nanoemulsion as a green nanocarrier for controlled herbicide delivery

Recently, the development of ecofriendly and biocompatible agrochemical delivery systems has garnered widespread attention because of their great potential in sustainable agri-food applications. Atrazine (ATZ) is a globally used herbicide used to control weeds, but it suffers from poor aqueous solubility, poor efficacy, and environmental loss. Herein, we report a novel, eco-friendly and biocompatible clove oil-based nanoemulsion as a green nanocarrier to enhance the solubility, bioavailability, and control release of ATZ. Food grade surfactants, Tween 80 and Phosphatidylcholine (PC) were used to formulate clove oil nanoemulsion with size <200 nm using ultrasonic emulsification technique, without any use of organic solvent. The ATZ encapsulation efficiency in NEm was greater than 95%. DLS confirms the nanosize (106 nm) and monodispersity of NEm. HRTEM reveals the spherical morphology of the nanodroplets. FTIR and DSC confirm the successful incorporation of ATZ inside the NEm oil droplet core. ATZ loaded NEm showed excellent thermal and storage stability, low Ostwald ripening rate, slow and sustained herbicide release behavior, which is of vital importance for an herbicide formulation. The release rate was better than commercial ATZ and free ATZ formulations. Results from herbicidal activity assays demonstrate that ATZ NEm exhibited excellent herbicidal activity even at low concentrations as compared to commercial ATZ analogs. In consideration of biocompatible excipients, free of organic solvent, and a simple fabrication process, ATZ loaded clove oil NEm can hold great potential in weed control and sustainable agri-food applications.

Ultrasonic-assisted preparation of eucalyptus oil nanoemulsion: Process optimization, in vitro digestive stability, and anti-Escherichia coli activity

Eucalyptus oil (EO) is a natural and effective antimicrobial agent; however, it has disadvantages such as poor water solubility and instability. The aim of this study was to investigate the effect of process vessels and preparation process parameters on the particle size of the emulsion droplets using ultrasonic technique and response surface methodology to prepare eucalyptus oil nanoemulsion (EONE). The optimal sonication process parameters in conical centrifuge tubes were confirmed: sonication distance of 0.9 cm, sonication amplitude of 18%, and sonication time of 2 min. Under these conditions, the particle size of EONE was 18.96 ± 4.66 nm, the polydispersity index was 0.39 ± 0.09, and the zeta potential was -31.17 ± 2.15 mV. In addition, the changes in particle size, potential, micromorphology, and anti-Escherichia coli activity of EONE during digestion were investigated by in vitro simulated digestion. The emulsion was stable in simulated salivary fluid, tended to aggregate in simulated gastric fluid, and increased in particle size and potential value in simulated intestinal fluid. EONE showed higher anti-E. coli activity than EO by simulated digestion. These results provide a useful reference for the in vivo antimicrobial application of the essential oil.

Essential Oil Nanoemulsion as Eco-Friendly and Safe Preservative: Bioefficacy Against Microbial Food Deterioration and Toxin Secretion, Mode of Action, and Future Opportunities

Microbes are the biggest shareholder for the quantitative and qualitative deterioration of food commodities at different stages of production, transportation, and storage, along with the secretion of toxic secondary metabolites. Indiscriminate application of synthetic preservatives may develop resistance in microbial strains and associated complications in human health with broad-spectrum environmental non-sustainability. The application of essential oils (EOs) as a natural antimicrobial and their efficacy for the preservation of foods has been of present interest and growing consumer demand in the current generation. However, the loss in bioactivity of EOs from fluctuating environmental conditions is a major limitation during their practical application, which could be overcome by encapsulating them in a suitable biodegradable and biocompatible polymer matrix with enhancement to their efficacy and stability. Among different nanoencapsulated systems, nanoemulsions effectively contribute to the practical applications of EOs by expanding their dispersibility and foster their controlled delivery in food systems. In line with the above background, this review aims to present the practical application of nanoemulsions (a) by addressing their direct and indirect (EO nanoemulsion coating leading to active packaging) consistent support in a real food system, (b) biochemical actions related to antimicrobial mechanisms, (c) effectiveness of nanoemulsion as bio-nanosensor with large scale practical applicability, (d) critical evaluation of toxicity, safety, and regulatory issues, and (e) market demand of nanoemulsion in pharmaceuticals and nutraceuticals along with the current challenges and future opportunities.

Preparation and Optimization of Garlic Oil/Apple Cider Vinegar Nanoemulsion Loaded with Minoxidil to Treat Alopecia

Alopecia areata is a scarless, localized hair loss disorder that is typically treated with topical formulations that ultimately only further irritate the condition. Hence, the goal of this study was to develop a nanoemulsion with a base of garlic oil (GO) and apple cider vinegar (APCV) and loaded with minoxidil (MX) in order to enhance drug solubilization and permeation through skin. A distance coordinate exchange quadratic mixture design was used to optimize the proposed nanoemulsion. Span 20 and Tween 20 mixtures were used as the surfactant, and Transcutol was used as the co-surfactant. The developed formulations were characterized for their droplet size, minoxidil steady-state flux (MX Jss) and minimum inhibitory concentration (MIC) against Propionibacterium acnes. The optimized MX-GO-APCV nanoemulsion had a droplet size of 110 nm, MX Jss of 3 μg/cm² h, and MIC of 0.275 μg/mL. The optimized formulation acquired the highest ex vivo skin permeation parameters compared to MX aqueous dispersion, and varying formulations lacked one or more components of the proposed nanoemulsion. GO and APCV in the optimized formulation had a synergistic, enhancing activity on the MX permeation across the skin membrane, and the percent permeated increased from 12.7% to 41.6%. Finally, the MX-GO-APCV nanoemulsion followed the Korsmeyer–Peppas model of diffusion, and the value of the release exponent (n) obtained for the formulations was found to be 1.0124, implying that the MX permeation followed Super case II transport. These results demonstrate that the MX-GO-APCV nanoemulsion formulation could be useful in promoting MX activity in treating alopecia areata.

Nanoencapsulation-Based Edible Coating of Essential Oils as a Novel Green Strategy Against Fungal Spoilage, Mycotoxin Contamination, and Quality Deterioration of Stored Fruits: An Overview

Currently, applications of essential oils for protection of postharvest fruits against fungal infestation and mycotoxin contamination are of immense interest and research hot spot in view of their natural origin and possibly being an alternative to hazardous synthetic preservatives. However, the practical applications of essential oils in broad-scale industrial sectors have some limitations due to their volatility, less solubility, hydrophobic nature, and easy oxidation in environmental conditions. Implementation of nanotechnology for efficient incorporation of essential oils into polymeric matrices is an emerging and novel strategy to extend its applicability by controlled release and to overcome its major limitations. Moreover, different nano-engineered structures (nanoemulsion, suspension, colloidal dispersion, and nanoparticles) developed by applying a variety of nanoencapsulation processes improved essential oil efficacy along with targeted delivery, maintaining the characteristics of food ingredients. Nanoemulsion-based edible coating of essential oils in fruits poses an innovative green alternative against fungal infestation and mycotoxin contamination. Encapsulation-based coating of essential oils also improves antifungal, antimycotoxigenic, and antioxidant properties, a prerequisite for long-term enhancement of fruit shelf life. Furthermore, emulsion-based coating of essential oil is also efficient in the protection of physicochemical characteristics, viz., firmness, titrable acidity, pH, weight loss, respiration rate, and total phenolic contents, along with maintenance of organoleptic attributes and nutritional qualities of stored fruits. Based on this scenario, the present article deals with the advancement in nanoencapsulation-based edible coating of essential oil with efficient utilization as a novel safe green preservative and develops a green insight into sustainable protection of fruits against fungal- and mycotoxin-mediated quality deterioration.

Recent advances in nanotherapeutics for the treatment of burn wounds

Moderate or severe burns are potentially devastating injuries that can even cause death, and many of them occur every year. Infection prevention, anti-inflammation, pain management and administration of growth factors play key roles in the treatment of burn wounds. Novel therapeutic strategies under development, such as nanotherapeutics, are promising prospects for burn wound treatment. Nanotherapeutics, including metallic and polymeric nanoformulations, have been extensively developed to manage various types of burns. Both human and animal studies have demonstrated that nanotherapeutics are biocompatible and effective in this application. Herein, we provide comprehensive knowledge of and an update on the progress of various nanoformulations for the treatment of burn wounds.

Preparation and characterization of a novel green tea essential oil nanoemulsion and its antifungal mechanism of action against Magnaporthae oryzae

Blast is one of the most devastating fungal diseases of rice caused by Magnaporthe oryzae. Plant essential oil (EO) can function as antifungal agents and are regarded as a safe and acceptable method for plant disease control. However, EOs are unstable and hydrophobic, which limits its use. In the present study, we aimed for the preparation and characterization of a nanoemulsion (NE) from green tea essential oil (GTO) by ultrasonication method and determined the antifungal activity of NE onM. oryzae. The particle size and zeta potential of the NE were 86.98 nm and -15.1 mV, respectively. The chemical composition and functional groups of GTO and NE were studied by using GC-MS analysis, portable Raman spectroscopy, and FTIR coupled with chemometric analysis. GC-MS analysis showed the major components in GTO and NE were n-Hexyl cinnamaldehyde and L-α-Terpineol. Both GTO and NE showed good antioxidant activity and total phenol content. Moreover, the NE showed good antifungal activity againstM. oryzae which was further confirmed by scanning electron microscopy (SEM) examination. Also, confocal Raman micro-spectroscopy (CRM) revealed the antifungal mechanism of GTO and NE on M. oryzae which proves the cell damage. To the best of our knowledge, this is the first study on the antifungal activity of GTO and NE against M. oryzae and also the use of CRM for the evaluation of the chemical changes in single fungal hyphae in a holistic approach. This study suggests that the prepared NE could be a potential candidate for use as a substitute for synthetic fungicides.

Antibacterial and Antiviral Functional Materials: Chemistry and Biological Activity toward Tackling COVID-19-like Pandemics

The ongoing worldwide pandemic due to COVID-19 has created awareness toward ensuring best practices to avoid the spread of microorganisms. In this regard, the research on creating a surface which destroys or inhibits the adherence of microbial/viral entities has gained renewed interest. Although many research reports are available on the antibacterial materials or coatings, there is a relatively small amount of data available on the use of antiviral materials. However, with more research geared toward this area, new information is being added to the literature every day. The combination of antibacterial and antiviral chemical entities represents a potentially path-breaking intervention to mitigate the spread of disease-causing agents. In this review, we have surveyed antibacterial and antiviral materials of various classes such as small-molecule organics, synthetic and biodegradable polymers, silver, TiO2, and copper-derived chemicals. The surface protection mechanisms of the materials against the pathogen colonies are discussed in detail, which highlights the key differences that could determine the parameters that would govern the future development of advanced antibacterial and antiviral materials and surfaces.

Penicillium italicum: An Underexplored Postharvest Pathogen

In the agricultural sector, citrus is one of the most important fruit genus in the world. In this scenario, Brazil is the largest producer of oranges; 34% of the global production, and exporter of concentrated orange juice; 76% of the juice consumed in the planet, summing up US$ 6.5 billion to Brazilian GDP. However, the orange production has been considerable decreasing due to unfavorable weather conditions in recent years and the increasing number of pathogen infections. One of the main citrus post-harvest phytopathogen is Penicillium italicum, responsible for the blue mold disease, which is currently controlled by pesticides, such as Imazalil, Pyrimethanil, Fludioxonil, and Tiabendazole, which are toxic chemicals harmful to the environment and also to human health. In addition, P. italicum has developed considerable resistance to these chemicals as a result of widespread applications. To address this growing problem, the search for new control methods of citrus post-harvest phytopathogens is being extensively explored, resulting in promising new approaches such as biocontrol methods as “killer” yeasts, application of essential oils, and antimicrobial volatile substances. The alternative methodologies to control P. italicum are reviewed here, as well as the fungal virulence factors and infection strategies. Therefore, this review will focus on a general overview of recent research carried out regarding the phytopathological interaction of P. italicum and its citrus host.

Towards Green Nanoscience: From extraction to nanoformulation

The use of nanotechnology has revolutionized many biotechnological sectors, from bioengineering to medicine, passing through food and cosmetic fields. However, their clinic and industrial application has been into the spotlight due to their safety risk and related side effects. As a result, Green Nanoscience/Nanotechnology emerged as a strategy to prevent any associated nanotoxicity, via implementation of sustainable processes across the whole lifecycle of nanoformulation. Notwithstanding its success across inorganic nanoparticles, the green concept for organic nanoparticle elaboration is still at its infancy. This, coupled with the organic nanoparticles being the most commonly used in biomedicine, highlights the need to implement specific green principles for their elaboration. In this review, we will discuss the possible green routes for the proper design of organic nanoparticles under the umbrella of Green Nanoscience: from the extraction of nanomaterials and active compounds to their final nanoformulation.

β-Cyclodextrin Inclusion Complex Containing Litsea cubeba Essential Oil: Preparation, Optimization, Physicochemical, and Antifungal Characterization

Litsea cubeba essential oil (LCEO), as naturally plant-derived products, possess good antimicrobial activities against many pathogens, but their high volatility and poor water solubility limit greatly the application in food industry. In this research, inclusion complex based on β-cyclodextrin (β-CD) and LCEO, was prepared by saturated aqueous solution method. An optimum condition using the response surface methodology (RSM) based on Box–Behnken design (BBD) was obtained with the inclusion time of 2 h and β-CD/LCEO ratio of 4.2 at 44 °C. Under the condition, the greatest yield of 71.71% with entrapment efficiency of 33.60% and loading capacity of 9.07% was achieved. In addition, the structure and characteristic of LCEO/β-CD inclusion complex (LCEO/βCD-IC) were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR), which indicated that LCEO/βCD-IC was successfully formed. The particle size of LCEO/βCD-IC was determined to be 17.852 μm. Thermal properties of LCEO/βCD-IC evaluated by thermogravimetric-differential scanning calorimetry (TG-DTA) illustrated better thermal stability of the aimed product compared with the physical mixture. Furthermore, the tests of antifungal activity showed that LCEO/βCD-IC was able to control the growth of Penicillium italicum, Penicillium digitatum, and Geotrichum citri-aurantii isolated from postharvest citrus. Our present study confirmed that LCEO/βCD-IC might be further applied as an alternative to chemical fungicides for protecting citrus fruit from postharvest disease.

Synthesis and Technology of Nanoemulsion-Based Pesticide Formulation

Declines in crop yield due to pests and diseases require the development of safe, green and eco-friendly pesticide formulations. A major problem faced by the agricultural industry is the use of conventional agrochemicals that contribute broad-spectrum effects towards the environment and organisms. As a result of this issue, researchers are currently developing various pesticide formulations using different nanotechnology approaches. The progress and opportunities in developing nanoemulsions as carriers for plant protection or nanodelivery systems for agrochemicals in agricultural practice have been the subject of intense research. New unique chemical and biologic properties have resulted in a promising pesticide nanoformulations for crop protection. These innovations-particularly the nanoemulsion-based agrochemicals-are capable of enhancing the solubility of active ingredients, improving agrochemical bioavailability, and improving stability and wettability properties during the application, thus resulting in better efficacy for pest control and treatment. All of these-together with various preparation methods towards a greener and environmentally friendly agrochemicals-are also discussed and summarized in this review.