Essential Oil Nanoemulsion Research Articles

Preparation, characterization and in-vitro bioassays of nanoemulsions from palmarosa (Cymbopogon martinii) essential oil

Cymbopogon martinii essential oil (Palmarosa essential oil, PRO) has a wide range of applications in food, medicine, and cosmetics. Because of its hydrophobicity, instability, and volatility, the best option to safeguard this oil is to encapsulate it using nanoemulsion technology. In this work, we synthesize O/W (oil/water) nanoemulsions from C. martini essential oil and analyze their biological activity. The study uses co-surfactants like ethanol and surfactants like tween 80 and sodium dodecyl sulfate to create O/W nanoemulsions. The nanoemulsions were investigated using UV, fluorescence, and FT-IR fingerprinting techniques in addition to parameters such as pH and conductivity. Additionally, the study explored the biological effects of the nanoemulsions, including their antibacterial, anti-inflammatory, anticancer, and anti-diabetic capabilities. The pharmacokinetics of drug release was also examined. By using GC-FID analysis, it has been determined that geraniol is the primary component of PRO. The concentrations of total phenolic, total flavonoid, and total condensed tannin were found to be 2.91 mg/g GAE, 9.29 mg/g RE, and 3.78 mg/g VAE, respectively. Palmarosa essential oil nanoemulsions (PNE) were discovered to have 93.24% encapsulation efficiency. The nanoemulsions remained stable and spherical even after 50 days of storage. PNE was synthesized with a mean diameter of 460.55 ± 98.65 nm, a polydispersity index (PDI) value of 0.45 ± 0.04, and a zeta potential measurement of 0.1711 ± 0.05 mV. According to a drug kinetic analysis, PNE displayed a first-order model with an R 2 value of 0.930. PNE revealed a dose-dependent 92% inhibition of α-amylase. Additionally, PNE demonstrated potent anti-bacterial activity against the investigated pathogens that varied from 38% to 94%. In the same way, PNE demonstrated potent anti-fungal efficacy against the studied fungal infections, with a range of 50–95%. Anticancer research showed that the PNE-containing cells had a percent viability of 21.29% after 24 hours and 14.92% after 48 hours, respectively. The article explores the possible applications of nanoemulsions made from palmarosa essential oil in the cosmetic, food, and medicinal sectors.

Nanoencapsulation of Zataria multiflora Essential Oil Containing Linalool Reduced Antibiofilm Resistance against Multidrug-resistant Clinical Strains

Background: The rise in antimicrobial resistance, caused by the production of biofilms by bacteria, is a significant concern in the field of healthcare. Nanoemulsion technology presents itself as a viable alternative in the quest to circumvent antibiotic resistance in pathogenic bacteria. Objective: The aim of this research was to form a sustainable nanoemulsion from Z. multiflora, and evaluate its antibacterial and anti-biofilm activities against the clinical isolates of Pseudomonas aeruginosa, Proteus mirabilis, and Staphylococcus aureus. Materials and Methods: Bioactive compounds of the oil were identified using GC-MS. Zataria multiflora essential oil (ZMEO) nanoemulsion was formulated as a water-dispersible nanoemulsion with a diameter of 184.88 ± 1.18 nm. The antibacterial and antibiofilm activities of the essential oil in both pure and nanoemulsion forms were assessed against pathogenic bacteria causing hospital-acquired infections using minimal inhibitory concentrations (MICs) and the microtiter method, respectively. Results: The main constituents were found to be linalool (78.66 %), carvacrol (14.25 %), and α- pinene (4.53%). Neither ZMEO nor the emulsified ZMEO showed any antimicrobial activity. However, ZMEO exhibited a low inhibition of biofilm formation by P. mirabilis, S. aureus, and P. aeruginosa. The most promising finding was that when the emulsified ZMEO was present at a concentration of 750 μg/mL, it significantly reduced biofilm formation by the aforementioned bacteria to 39.68% ± 2.62, 56.54% ± 3.35, and 59.60% ± 2.88, respectively. This result suggests that ZMEO nanoemulsion has the potential to effectively disrupt persistent biofilms and enhance the penetration of antimicrobial agents into the biofilm matrix. Conclusion: In conclusion, the study provides evidence supporting the use of ZMEO nanoemulsion as a potential treatment option for combating biofilm-related infections caused by Pseudomonas aeruginosa, Proteus mirabilis, and Staphylococcus aureus. Further research is warranted to explore the practical application of the proposed essential oil in clinical settings.

Application of carboxymethylcellulose in combination with essential oils nano-emulsions edible coating for the preservation of kiwifruit

The present research investigates the effectiveness of nano-emulsified coatings (C-1, C-2, and C-3) in preserving the kiwifruit at a temperature of 10 ± 2 °C with 90–95 % relative humidity (RH) for 30 days. The nano-emulsions were prepared from varied carboxymethyl cellulose (CMC) concentrations with different combinations of essential oils such as thyme, clove, and cardamom. Dynamic light scattering investigation with Zeta Sizer revealed that C-1, C-2, and C-3 nano-emulsions have nano sizes of 81.3 ± 2.3, 115.3 ± 4.2, and 63.2 ± 3.2 nm, respectively. The scanning electron microscopy images showed that the nanoemulsion of C-1 had homogenous spherical globules, C-2 had voids, and C-3 showed a non-porous structure with uniform dispersion. The X-ray diffraction analysis indicated that C-1, C-2, and C-3 nano-emulsion exhibited distinct crystallinity and peaks. The nano-emulsion C-1 had reduced crystallinity, while C-2 had lower intensity peaks, and C-3 had increased crystallinity. The results documented that compared to control kiwifruit samples, the samples coated with C-3 nano-emulsion have decreased weight loss, decay incidence, soluble solids, maturity index activity, ethylene production, total bacterial count, and increased titratable acid, and firmness attributes. The results of current research are promising and would be applicable in utilization in industrial applications.

Characterization, release profile, and antibacterial properties of oregano essential oil nanoemulsions stabilized by soy protein isolate/tea saponin nanoparticles

This study successfully synthesized soy protein isolate (SPI)/tea saponin (TS)-based nanoparticles (STNPs) using the pH-driven method. The characteristics of the STNPs were investigated as a function of the SPI-to-TS mass ratio (1:0, 4:1, 2:1, 1:1, 1:2, 1:4, and 0:1). The findings demonstrated that the smallest particle size and highest surface charge appeared when the SPI-to-TS mass ratio was 2:1. Additionally, hydrogen bonding, hydrophobic interactions, and electrostatic interactions were found to contribute to the formation of STNPs. Subsequently, the synthesized STNPs were used to create oregano essential oil (OEO) nanoemulsions for further investigation of the effects of SPI-to-TS ratios on the characteristics and functional properties of nanoemulsion systems. The results revealed improved adsorption of STNPs at the oil−water interface with the increase in the proportion of TS, and, consequently, the droplet size and zeta potential of the nanoemulsion reduced significantly. Moreover, the nanoemulsions exhibited excellent rheological behaviors, high physical stability, sustained OEO release, and strong antibacterial activity when the SPI-to-TS ratio was increased from 1:0 to 2:1. However, when the SPI-to-TS mass ratio was less than 1:1, the nanoemulsion became unstable due to the formation of TS micelles in the aqueous phase, exhibiting nonuniform droplets, low stability, and rapid release of OEO. Furthermore, antibacterial analysis results indicated that the primary mechanism of antibacterial activity for nanoemulsions containing OEO involved disruption of the bacterial cytoderm, leading to leakage of intracellular contents.

The inactivation of Shigella flexneri by synergistic effect of ultrasound combined with basil essential oil nanoemulsion and application in cabbage cleaning

The inactivation of Shigella flexneri by synergistic effect of ultrasound combined with basil essential oil nanoemulsion and application in cabbage cleaning

Retracted: Nanoemulsion and Encapsulation Strategy of Hydrophobic Oregano Essential Oil Increased Human Prostate Cancer Cell Death via Apoptosis by Attenuating Lipid Metabolism.

[This retracts the article DOI: 10.1155/2022/9569226.].

Fabrication the emulsion-based edible film containing Dracocephalum kotschyi Boiss essential oil using chitosan–gelatin composite for grape preservation

The purpose of this study was to investigate the effects of novel edible films produced by incorporating Dracocephalum kotschyi (D. kotschyi) essential oil nanoemulsion into a polymeric matrix (chitosan-gelatin) with grape preservative potential during room temperature storage. To achieve this goal, the edible films' mechanical, microstructural, and physical characteristics were examined. Next, an antimicrobial analysis was conducted on five food-borne pathogens, and the results indicated that edible films with 5 % essential oil (ChG4) might be efficiently produced to have antibacterial action against particular pathogens. Additionally, the integration of the nanoemulsion resulted in the creation of microporous structures in edible films, as demonstrated by SEM studies. A positive impact of ChG4 edible film on grape preservation during 15 days’ storage was observed. The findings afford an innovative approach for the expansion of effective herbal antimicrobial formulation for food preservation.

Carboxymethyl cellulose/Tween 80/Litsea cubeba essential oil nanoemulsion inhibits the growth of Penicillium digitatum and extends the shelf-life of ‘Shatangju’ mandarin

Penicillium digitatum (P. digitatum) is the primary pathogenic fungus responsible for postharvest citrus green mold, leading to a deterioration in fruit quality and significant economic losses. Litsea cubeba essential oil (LCEO) has gained widespread attention as a natural antifungal substance due to its high safety profile, non-resistance traits, and broad-spectrum antifungal activity. In this study, we prepared Litsea cubeba essential oil nanoemulsion (LCEO-NE) using Tween 80 and carboxymethyl cellulose (CMC) as emulsifiers through ultrasonic emulsification. The investigation delved into their stability, rheology, inhibitory activity against P. digitatum, and efficacy in preserving ‘Shatangju’ mandarin during storage. The results showed that the droplet size, polydispersity index, and zeta potential were 18.69 nm, 0.116, and −29.72 mV, respectively. LCEO-NE added with CMC and Tween 80 synergistically (LCEO-NE-CMC) have exhibited higher pH stability, ionic strength stability, thermal stability, storage stability, and centrifugal stability compared to LCEO-NE with Tween 80. In vitro fungistatic tests revealed that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of LCEO-NE-CMC against P. digitatum were 1 μL mL−1 and 2 μL mL−1, respectively. LCEO-NE-CMC effectively inhibited mycelium growth, spore germination, and elongation of germ tubes. Scanning electron microscopy results demonstrated that LCEO-NE-CMC caused wrinkling and twisting of P. digitatum mycelium. Transmission electron microscopy results further revealed severe damage to the cell membrane, cytoplasm, and organelles, hindering mycelial growth. Furthermore, LCEO-NE-CMC treatment of ‘Shatangju’ mandarin significantly reduced weight loss and decay rate and delayed the decline in hardness and total soluble solids. In summary, LCEO-NE-CMC has been validated as a potent antifungal agent capable of extending the shelf life of ‘Shatangju’ mandarin.

Chitosan Coating Incorporated with Carvacrol Improves Postharvest Guava (Psidium guajava) Quality

Guava (Psidium guajava L.) is an important economic crop grown widely in tropical and subtropical regions. Guava exhibits fast ripening and senescence as a climacteric fruit, causing a short shelf life and quality deterioration. Chitosan–essential oil nanoemulsions can be an edible coating used to improve postharvest quality attributes. In this study, chitosan was mixed with carvacrol to generate a nano-emulsoid solution containing 0.1 and 0.2% (v/v) carvacrol, using a sonic dismembrator. Guava fruit were coated with the above emulsion and postharvest quality parameters were measured during storage at 20 ± 1 °C and RH = 80 ± 5% for 8 days. The result illustrated that the particle size of the chitosan–carvacrol emulsions was nanoscale, and their high stability was demonstrated by the zeta potential and polydispersity index. Chitosan coating (2%, w/v, 310–375 kDa) containing 0.2% (v/v) carvacrol maintained postharvest quality compared to chitosan alone, with higher firmness, soluble solid content, total acid, and total phenol content, and lower weight loss and pericarp browning. The collective data were further verified by principal component analysis. A chitosan coating containing carvacrol can reduce postharvest losses. It can be applied as an effective strategy to improve postharvest fruit quality.

Long-Term Stability of Lavandula x intermedia Essential Oil Nanoemulsions: Can the Addition of the Ripening Inhibitor Impact the Biocidal Activity of the Nanoformulations?

In this work, Lavandula x intermedia essential oil (LEO) was encapsulated in lipid-based nanoemulsions (NanoLEO) using the solvent-displacement technique. In order to preserve the colloidal stability of the formulation, LEO was appropriately doped with the incorporation of different levels of a water-insoluble oil used as a ripening inhibitor. All the nanoemulsion samples were evaluated in terms of the impact of the water-insoluble oil on the nanoemulsion formation, physical-chemical properties, and antibacterial effectiveness against E. coli (Gram-negative) and B. cereus (Gram-positive). The presence of the inert oil added benefits to the formulations in terms of appearance, colloidal stability, and loss of volatile components. However, the antimicrobial activity of the nanoemulsions dramatically decreased with the ripening inhibitor addition, probably because it hampered the internalization of the antimicrobial components of LEO within the bacterial cell membranes, thus nullifying the delivery ability of the nanoemulsion formulation. On the contrary, the undoped NanoLEO formulation showed unaltered antibacterial activity in both E. coli and B. cereus up to 40 weeks from the preparation.

Clove essential oil nanoemulsions: development, physical characterization, and anticancer activity evaluation

Nanoemulsions are thermodynamically unstable colloidal systems that encapsulate bioactive substances. In this study, we aimed to produce stable clove essential oil (CEO) nanoemulsions by spontaneous emulsification and compare their cytotoxic activity in vitro. Nanoemulsions were formed by mixing the CEO with medium-chain triglyceride oil (MCT) and nonionic surfactants (Tween 80 or Kolliphor HS 15) into an aqueous solution. The stability of the nanoemulsions was evaluated during storage at different temperatures (4, 20, and 37 °C). Smaller (d < 30 nm) and more stable nanoemulsions were formed with a 6% CEO concentration. The anticancer activity of nanoemulsions was evaluated against three cancer cell lines (Caco-2, HT-29, and HeLa). The nanoemulsions showed a cytotoxic activity four times higher than the free CEO against the Caco-2 cell line. Our findings show that nanoemulsions improved the cytotoxic activity against cancer lines, which could have applications in the food, pharmaceutical, and cosmetic industries.

Inhibitory effect of some probiotic strains and essential oils on the growth of some foodborne pathogens.

Bacillus cereus and Yersinia enterocolitica are implicated in foodborne diseases that have major effects on human health; therefore, it is considered universal public health disorders. Essential oils and essential oils nano emulsions have a sufficient antibacterial performance against a variety of bacteria, especially multi-drug resistant bacteria. Probiotics showed several health benefits via moderating the GIT microbiota and their metabolites. The study was designed to evaluate the biocontrol ability of cinnamon essential oil (CEO) nano emulsion and probiotics as natural antibacterial additives and reveal their bactericidal mechanism. 250 random samples (50 raw milk, 50 rice pudding, 50 kariesh cheese, 50 yogurt, and 50 ice cream) were purchased separately from different areas in Mansoura city, Egypt, and exposed to bacteriological analysis. Bacillus cereus was found with the highest mean value of 66 × 107 ± 1.3 × 108 CFU/g in raw milk and the lowest mean value of 28 × 107 ± 2.6 × 107 CFU/g in kariesh cheese while Y. enterocolitica was found in 64% of the total inspected samples with the highest incidence (84%) in yogurt. The toxinogenic potential of the tested pathogens has been evaluated by multiplex PCR pointing nhe A and ces genes for B. cereus isolates while targeting in Y. enterocolitica 16s rRNA, and YST gene. Different concentrations (0.17%, 0.25%, 0.5%, 0.8%, 1%, 1.5%, and 2%) of cinnamon oil nano emulsion were employed in this study. CEO nano emulsion had the highest reduction rate at a concentration of 1.5% in the case of B. cereus and 2% in the case of Y. enterocolitica. Among different types of probiotics, the best one which showed inhibitory potential against B. cereus and Y. enterocolitica was L. plantarum. Lactobacillus plantarum and CEO nano emulsion at a concentration of 2% have the highest reduction rate against Y. enterocolitica, while L. plantarum and CEO nano emulsion at a concentration of 1.5% has the best antibacterial effect against B. cereus. In conclusion, more attention is required for both safety and quality in dairy products through the application of natural additives such as essential oils and probiotics.

Development of carboxymethyl cellulose–chitosan based antibacterial films incorporating a Persicaria minor Huds. essential oil nanoemulsion

As plastic waste has continued to increase over the years, there is an appeal for environmental-friendly packaging containing bioactive components such as essential oil for food packaging.

Supercritical Fluid-extracted Citrus aurantium L. var. amara Engl. Essential Oil Nanoemulsion: Preparation, Characterization, and Its Sleep-promoting Effect.

To overcome the defects of Citrus aurantium L. var. amara Engl. essential oil (CAEO), such as high volatility and poor stability, supercritical fluid-extracted CAEO nanoemulsion (SFE-CAEO-NE) was prepared by the microemulsification method. Emulsifiers comprising Tween 80, polyoxyethylenated castor oil (EL-40), and 1,2-hexanediol, and an oil phase containing SFE-CAEO were used for microemulsification. We examined the physicochemical properties of SFE-CAEO-NE and steam distillation-extracted CAEO nanoemulsion (SDE-CAEO-NE), which were prepared using different concentrations of the emulsifiers. The mean particle size and zeta potential were 21.52 nm and -9.82 mV, respectively, for SFE-CAEO-NE, and 30.58 nm and -6.28 mV, respectively, for SDE-CAEO-NE, at an emulsifier concentration of 15% (w/w). SFE-CAEO-NE displayed better physicochemical properties compared with SDE-CAEO-NE. Moreover, its physicochemical properties were generally stable at different temperatures (-20-60℃), pH (3-8), and ionic strengths (0-400 mM). No obvious variations in particle size, zeta potential, and Ke were observed after storing this nanoemulsion for 30 days at 4℃, 25℃, and 40℃, suggesting that it had good stability. The sleep-promoting effect of SFE-CAEO-NE was evaluated using a mouse model of insomnia. The results of behavioral tests indicated that SFE-CAEO-NE ameliorated insomnia-like behavior. Moreover, SFE-CAEO- NE administration increased the serum concentrations of neurotransmitters such as 5-hydroxytryptamine and γ-aminobutyric acid, and decreased that of noradrenaline in mice. It also exerted a reparative effect on the function of damaged neurons. Overall, SFE-CAEO-NE displayed a good sleep-promoting effect.

Effects of hydrophilic and lipophilic emulsifier concentrations on the characteristics of Germander essential oil nanoemulsions prepared using the nanoprecipitation technique

The Germanders (Teucrium polium L.) essential oil exhibits antioxidant and bactericidal activities against a wide range of microorganisms; however, its water insolubility, susceptibility to environmental stresses, and intense flavors limit its uses in food formulations. As a solution, in the present study, nanoemulsions of Germanders (Mentha pulegium) essential oil were prepared using a bottom-up nanoprecipitation technique. A central composite design based on the response surface methodology was implemented to investigate the effects of selected lipophilic and hydrophilic emulsifier concentrations. The proposed second-order polynomial models, with relatively high coefficients of determination, could efficiently predict alterations in response parameters due to emulsifier concentrations. The results revealed that both lipophilic and hydrophilic emulsifiers had significantly affected all characteristics of the synthesized essential oil nanoemulsions. Multi-goal optimization analysis suggested that 7.8% and 4.8% concentrations of Span 80 and Tween 80, respectively, could yield the most desirable Germanders essential oil nanoemulsions, with a mean particle size of 78.56 nm, PDI of 0.1722, DPPH radical scavenging of 83.69%, Staphylococcus aureus and Salmonella enterica growth inhibition zones of 10.5 mm and 12.7 mm, respectively. The validity of the models was confirmed by the absence of substantial variations between experimental data and modeling results. While the prepared Germander essential oil nanoemulsions demonstrated acceptable physical properties, they exhibited relatively limited chemical stability during storage at 5°C for 30 days.

Lemon essential oil nanoemulsions: Potential natural inhibitors against Escherichia coli

Lemon essential oil (LEO) is a common natural antibacterial substance, and encapsulating LEO into nanoemulsions (NEs) can improve their stability and broaden its application. Our study aimed to investigate the bacterial inhibitory effect of LEO-NEs against Escherichia coli (E. coli). Results showed that the minimum inhibitory concentration (MIC) of LEO-NEs was 6.25 mg/mL, and the time-kill curve showed that E. coli were significantly killed by LEO-NEs after 5 h of treatment at 1MIC. Flow-cytometry analysis showed that LEO-NEs adversely affected the cell-membrane depolarisation, cell-membrane integrity, and efflux pump function of E. coli. Confocal laser scanning microscopy demonstrated that 8MIC of LEO-NEs induced changes in the cell-membrane permeability and cell-wall integrity of E. coli. Proteomic results suggested that the mode of action LEO-NEs against E. coli was to enhance bacterial chemotaxis and significantly inhibit ribosomal assembly. They may also affect butyric acid, ascorbic acid and aldehyde metabolism, and sulphur-relay system pathways. In conclusion, LEO-NEs had potential application as a natural antibacterial agent for the control of E. coli in the food industry.

Nanoencapsulated Thymus daenensis and Mentha piperita essential oil for bacterial and biofilm eradication using microfluidic technology

The use of essential oil (EO) nanoemulsions is expanding to meet customer demand for all-natural antibacterial agents. Thymus daenensis (T) and Mentha piperita (M) EOs were employed to make nanoemulsions (TEO and MEO NE), using Tween 80/Span 80 as surfactant/cosurfactant and a high-speed homogenizer. The TEO and MEO NEs were then characterized in terms of particle size (121, 113 nm), surface charge (-11.2 and −12.6 mV), morphology, and stability over time. Then, the antibacterial activity of EOs and their nanoformulations against Escherichia coli (E. coli) were evaluated based on various residence times, and concentrations on a microfluidic chip. The release of cytoplasmic constituents was used to compare the antibacterial activity of bulk EOs and nanoformulations. After completing MIC, MBC, and time-killing assays, the inhibitory effect of nanoformulations on E. coli biofilm formation was examined. Remarkable intensification was observed by employing a microfluidic chip owing to high-contact surface area provision between nanoemulsions and bacteria. Once compared to the conventional method for 3 h operation, the bacterial activity was nearly completely inhibited in a 24-min residence time using nanoemulsions. After 6 min of treatment, the cell membrane began to rupture, indicating that nanoemulsions could improve the antibacterial activity of bulk essential oils.

Coated composite paper with nano-chitosan/cinnamon essential oil-nanoemulsion containing grafted CNC@ZnO nanohybrid; synthesis, characterization and inhibitory activity on Escherichia coli biofilm developed on grey zucchini

This investigation aims to highlight the applicability of a potent eco-friendly developed composite film to combat the Escherichia coli biofilm formed in a model food system. ZnO nanoparticles (NPs) synthesized using green methods were anchored on the surface of cellulose nanocrystals (CNCs). Subsequently, nano-chitosan (NCh) solutions were used to disperse the synthesized nanoparticles and cinnamon essential oil (CEO). These solutions, containing various concentrations of CNC@ZnO NPs and CEO, were sequentially coated onto cellulosic papers to inhibit Escherichia coli biofilms on grey zucchini slices. Six films were developed, and Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, biodegradation, and mechanical properties were assessed. The film containing 5 % nano-emulsified CEO + 3 % dispersed CNC@ZnO nano-hybrid in an NCh solution was selected for further testing since it exhibited the largest zone of inhibition (34.32 mm) against E. coli and the highest anti-biofilm activity on biofilms developed on glass surfaces. The efficacy of the film against biofilms on zucchini surfaces was temperature-dependent. During 60 h, the selected film resulted in log reductions of approximately 4.5 logs, 2.85 logs, and 1.57 logs at 10 °C, 25 °C, and 37 °C, respectively. Applying the selected film onto zucchini surfaces containing biofilm structures leads to the disappearance of the distinctive three-dimensional biofilm framework. This innovative anti-biofilm film offers considerable potential in combatting biofilm issues on food surfaces. The film also preserved the sensory quality of zucchini evaluated for up to 60 days.

Effect of Different Hydrophilic-lipophilic Balance (HLB) on Droplet Size, Polydispersity Index and Stability of Lemon Myrtle Nanoemulsion

Using mixed non-ionic surfactants Tween/Span, we determined the required hydrophilic-lipophilic balance (HLB) value on the oil in water nanoemulsion of lemon myrtle essential oil. In this study, Span 80 mixed with Tween 80, and Span 20 mixed with Tween 20 were used as mixed non-ionic surfactant. The droplet size, polydispersity index and stability of the lemon myrtle nanoemulsion at different HLB values were obtained over a period of 28 days. Both mixed surfactants have similar required HLB value at HLB 14 due to their smallest droplet size and lowest polydispersity index during the early nanoemulsion preparation. However, after a period of 28 days, nanoemulsion with Span 80-Tween 80 surfactant mixture was more stable compared to Span 20-Tween 20 surfactant mixture. Therefore, HLB 14 using Span 80-Tween 80 surfactant mixture has been selected as the required HLB for lemon myrtle nanoemulsion due to its stability and consistency of droplet size in 28 days.

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

BackgroundFusarium 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. MethodsIn 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. ResultsResults 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. ConclusionOur 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.