Essential oils in nanostructured systems: Challenges in preparation and analytical methods

Unlocking the Therapeutic Potential of Patchouli Leaves: A Comprehensive Review of Phytochemical and Pharmacological Insights

Plant-based products play an increasingly vital role in the pharmaceutical industry, including Pogostemon cablin (Blanco) Benth. (patchouli), which is notable for its rich history and extensive use in traditional medicine. Patchouli has a longstanding historical use as a remedy for a wide range of health conditions, including colds, fevers, headaches, inflammation, digestive disorders, and insect and snake bites. Comprehensive phytochemical studies have revealed that patchouli leaves contain diverse valuable bioactive compounds, notably patchouli alcohol, β-patchoulene, pogostone, α-bulnesene, and β-caryophyllene. Recent studies have demonstrated that patchouli leaves exhibit various pharmacological properties, including anti-oxidant, anti-inflammatory, antimicrobial, antidepressant, and anticancer effects. Despite robust traditional knowledge, specific therapeutic applications of patchouli leaves require scientific validation and standardization of their bioactive compounds. This review provides a comprehensive overview of the existing literature on the phytochemical composition, pharmacological properties, and underlying mechanisms of action of patchouli essential oil (PEO) and plant extracts obtained from patchouli leaves. It offers detailed insights into potential therapeutic applications, aiming to inform and guide future research across multiple medical disciplines. Ultimately, this review underscores the need for further research to validate and develop the medicinal applications of patchouli leaves, providing a foundation for future healthcare advancements.

Preparation and characterization of a novel green cinnamon essential oil nanoemulsion for the enhancement of safety and shelf-life of strawberries

This study aimed to optimize a novel green CEO nanoemulsions (CEO NEs) and explore its physicochemical properties and the effect on the shelf-life of strawberries during storage at environmental temperature (20-25 °C). We used CEO as oil phase and tea saponin (TS) as a natural surfactant to formulate the novel green CEO NEs, and its potential as an antimicrobial agent was also investigated. The results showed that CEO NEs had a droplet size about 170 nm with uniform distribution and regularly spherical. These CEO NEs exhibited excellent storage stability, thermal stability, pH stability and centrifugal stability. The antimicrobial test indicated that the minimal inhibitory concentration and the minimal bactericidal (fungicidal) concentration of CEO NEs against Escherichia coli, Botrytis cinerea and Aspergillus flavus were 17.81 μg/mL and 35.62 μg/mL, 35.62 μg/mL and 71.25 μg/mL, 2.23 μg/mL and 4.45 μg/mL, respectively, which were significantly lower than those of pure CEO (333.75 μg/mL and 667.5 μg/mL, 667.5 μg/mL and 1335 μg/mL, 41.72 μg/mL and 83.44 μg/mL). More interestingly, after soaking strawberries in CEO NEs for 2 min, the shelf-life of strawberries can be extended to 7 days at environmental temperature, and a lower rate of weight loss and mildew were showed in the group of CEO NEs than other control groups, especially the strawberries in ultrapure water group went bad first, obviously shranked, and contaminated by molds after 3 days. The above results indicate that CEO NEs prepared in this study has great potential as a new green antimicrobial agent in fruit preservation.

Clove Essential Oil: Chemical Profile, Biological Activities, Encapsulation Strategies, and Food Applications

Plants have proven to be important sources for discovering new compounds that are useful in the treatment of various diseases due to their phytoconstituents. Clove (Syzygium aromaticum L.), an aromatic plant widely cultivated around the world, has been traditionally used for food preservation and medicinal purposes. In particular, clove essential oil (CEO) has attracted attention for containing various bioactive compounds, such as phenolics (eugenol and eugenol acetate), terpenes (β-caryophyllene and α-humulene), and hydrocarbons. These constituents have found applications in cosmetics, food, and medicine industries due to their bioactivity. Pharmacologically, CEO has been tested against a variety of parasites and pathogenic microorganisms, demonstrating antibacterial and antifungal properties. Additionally, many studies have also demonstrated the analgesic, antioxidant, anticancer, antiseptic, and anti-inflammatory effects of this essential oil. However, CEO could degrade for different reasons, impacting its quality and bioactivity. To address this challenge, encapsulation is viewed as a promising strategy that could prolong the shelf life of CEO, improving its physicochemical stability and application in various areas. This review examines the phytochemical composition and biological activities of CEO and its constituents, as well as extraction methods to obtain it. Moreover, encapsulation strategies for CEO and numerous applications in different food fields are also highlighted.

Antioxidant and antimicrobial effect of sodium alginate nanoemulsion coating enriched with oregano essential oil (Origanum vulgare L.) and Trachyspermum ammi oil (Carum cupticum) on food pathogenic bacteria

Today, microbial contamination in food is one of the major problems of the food industry and public health in general around the world. Foodborne illnesses, such as diarrheal diseases, kill many people around the world each year. The general objective of this study was to evaluate the antioxidant and antibacterial activity of sodium alginate nanoemulsion coating incorporated with oregano essential oil (Origanum vulgare L.) and Trachyspermum ammi oil (Carum cupticum) on Escherichia coli, and Listeria monocytogenes. To achieve this study, fresh chicken meat was used for this experiment. Listeria monocytogenes ATCC 19111 and Escherichia coli ATCC 35218 were obtained from the American Type Culture Collection (Manassas, VA, USA). After the preparation of the essential oil, the chemical composition of this essential oil was determined by using (GC-MS). The physicochemical properties of the nanoemulsion essential oil prepared were characterized and their antimicrobial activity was evaluated. The results showed that the GC-MS analysis of the volatile constituents of the Origanum vulgare essential oil compounds allowed the identification of 19 compounds representing 93.72% of the total oil. The major components detected in Origanum vulgare essential oil were pulegone (49.25%), eucalyptol (18.23%), and menthone (12.37%). About the Carum cupticum essential oil, 21 compounds representing 98.5% of the total oil were identified. The major components detected in Origanum vulgare essential oil were thymol (23.3%), p-cymene (17.5%), and γ-terpinene (16.8%). The best z-average (d.nm) is 483.4 nm (Carum cupticum essential oil + nano) followed by 470.1 nm (nanochitosan). The results of the antimicrobial test showed that the different preparations have a good inhibitory activity for the in vitro growth of Escherichia coli and Listeria monocytogenes. According to the MIC and MBC results of this study, the nanoemulsion also presented a good bacteriostatic activity against the two pathogenic bacteria tested in this study.

Essential oils and their nanoformulations for breast cancer therapy

Breast Cancer (BC) is the most prevalent type of cancer in the world. Current treatments include surgery, radiation, and chemotherapy but often are associated with high toxicity to normal tissues, chemoresistance, and relapse. Thus, developing novel therapies which could combat these limitations is essential for effective treatment. In this context, phytochemicals are increasingly getting popular due to their safety profile, ability to efficiently target tumors, and circumvent limitations of existing treatments. Essential Oils (EOs) are mixtures of various phytochemicals which have shown potential anticancer activity in preclinical BC models. However, their clinical translation is limited by factors such as high volatility, low stability, and poor solubility. Nanotechnology has facilitated their encapsulation in a variety of nanostructures and proven to overcome these limitations. In this review, we have efficiently summarized the current knowledge on the anticancer effect of EOs and constituents in both in in vitro and in in vivo BC models. Further, we also provide a descriptive account on the potential of nanotechnology in enhancing the anti-BC activity of EOs and their constituents. The papers discussed in this review were selected using the keywords "antiproliferative Essential Oils in breast cancer," "anticancer activity of Essential Oil in breast cancer," and "cytotoxicity of Essential Oils in breast cancer" performed in PubMed and ScienceDirect databases.

Progress of nanopreparation technology applied to volatile oil drug delivery systems

Traditional Chinese medicine volatile oil has a long history and possesses extensive pharmacological activity. However, volatile oils have characteristics such as strong volatility, poor water solubility, low bioavailability, and poor targeting, which limit their application. The use of volatile oil nano drug delivery systems can effectively improve the drawbacks of volatile oils, enhance their bioavailability and chemical stability, and reduce their volatility and toxicity. This article first introduces the limitations of the components of traditional Chinese medicine volatile oils, discusses the main classifications and latest developments of volatile oil nano formulations, and briefly describes the preparation methods of traditional Chinese medicine volatile oil nano formulations. Secondly, the limitations of nano formulation technology are discussed, along with future challenges and prospects. A deeper understanding of the role of nanotechnology in traditional Chinese medicine volatile oils will contribute to the modernization of volatile oils and broaden their application value.

Rechargeable films for protection of dry foods: A sustainable method for covalent grafting of β-cyclodextrin-thymol complex on PET/viscose platform

Rechargeable materials for the effective protection of dry food products were developed. β-cyclodextrin-thymol inclusion complex was covalently grafted on a solid platform of polyethylene terephthalate-viscose using either traditional cross-linker of epichlorohydrin, or natural cross-linker of citric acid. A correlation between the grafting method and physicochemical properties, loading capacity and release capabilities of the resulted materials was studied. The developed materials demonstrated antimicrobial properties preventing mold propagation in wheat grains. The treated grains showed normal germination abilities verifying that the prepared materials can protect dry food products without using harmful chemicals. The suggested approach can be extended to other applications and active agents. A combination of rechargeable films with natural volatiles can serve as an effective platform for sustainable active materials for food protection and in other fields such as agriculture, cosmetics, and medicine.

Nanoemulsion and Nanogel Containing Cuminum cyminum L Essential Oil: Antioxidant, Anticancer, Antibacterial, and Antilarval Properties

Cuminum cyminum L. is a widespread medicinal plant with a broad spectrum of biological activity. In the present study, the chemical structure of its essential oil was examined utilizing GC-MS analysis (gas chromatography-mass spectrometry). Then, a nanoemulsion dosage form was prepared with a droplet size and droplet size distribution (SPAN) of 121 ± 3 nm and 0.96. After that, the dosage form of the nanogel was prepared; the nanoemulsion was gelified by the addition of 3.0% carboxymethyl cellulose. In addition, the successful loading of the essential oil into the nanoemulsion and nanogel was approved by ATR-FTIR (attenuated total reflection Fourier transform infrared) analysis. The IC50 values (half maximum inhibitory concentration) of the nanoemulsion and nanogel against A-375 human melanoma cells were 369.6 (497-335) and 127.2 (77-210) μg/mL. In addition, they indicated some degrees of an antioxidant activity. Interestingly, after treatment of Pseudomonas aeruginosa with 5000 µg/mL nanogel, bacterial growth was completely (∼100%) inhibited. In addition, the growth of Staphylococcus aureus after treatment with the 5000 μg/ml nanoemulsion was decreased by 80%. In addition, nanoemulsion and nanogel LC50 values for Anopheles stephensi larvae were attained as 43.91 (31-62) and 123.9 (111-137) µg/mL. Given the natural ingredients and promising efficacy, these nanodrugs can be regarded for further research against other pathogens or mosquito larvae.

Nano-Encapsulation of Citrus Essential Oils: Methods and Applications of Interest for the Food Sector

Citrus essential oils possess many health-promoting benefits and properties of high interest in the food and agri-food sector. However, their large-scale application is limited by their sensitivity to environmental factors. Nanostructures containing citrus essential oils have been developed to overcome the high volatility and instability of essential oils with respect to temperature, pH, UV light, etc. Nanostructures could provide protection for essential oils and enhancement of their bioavailability and biocompatibility, as well as their biological properties. Nano-encapsulation is a promising method. The present review is mainly focused on methods developed so far for the nano-encapsulation of citrus essential oils, with emphasis on lipid-based (including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano- and micro-emulsions) and polymer-based nanostructures. The physico-chemical characteristics of the obtained structures, as well as promising properties reported, with relevance for the food sector are also discussed.

Antioxidative, anticancer, and antibacterial activities of a nanogel containing Mentha spicata L. essential oil and electrospun nanofibers of polycaprolactone-hydroxypropyl methylcellulose

BACKGROUND

As the largest organ, the skin has been frequently affected by trauma, chemical materials, toxins, bacterial pathogens, and free radicals. Recently, many attempts have been made to develop natural nanogels that, besides hydrating the skin, could also be used as antioxidant or antibacterial agents.

METHODS

In this study, the chemical composition of the Mentha spicata essential oil was first investigated using GC-MS analysis. Its nanoemulsion-based nanogel was then investigated; successful loading of the essential oil in the nanogel was confirmed using FTIR analysis. Besides, nanogel's antioxidative, anticancer, and antibacterial activities were investigated.

RESULTS

Carvone (37.1%), limonene (28.5%), borneol (3.9%), β-pinene (3.3%), and pulegone (3.3%) were identified as five major compounds in the essential oil. By adding carboxymethylcellulose (3.5% w/v) to the optimal nanoemulsion containing the essential oil (droplet size of 196 ± 8 nm), it was gelified. The viscosity was fully fitted with a common non-Newtonian viscosity regression, the Carreau-Yasuda model. The antioxidant effect of the nanogel was significantly more potent than the essential oil (P < 0.001) at all examined concentrations (62.5-1000 µg/mL). Furthermore, the potency of the nanogel with an IC50 value of 55.0 µg/mL was substantially more (P < 0.001) than the essential oil (997.4 µg/mL). Also, the growth of Staphylococcus aureus and Escherichia coli after treatment with 1000 µg/mL nanogel was about 50% decreased compared to the control group. Besides, the prepared electrospun polycaprolactone-hydroxypropyl methylcellulose nanofibers mat with no cytotoxic, antioxidant, or antibacterial effects was proposed as lesion dressing after treatment with the nanogel. High potency, natural ingredients, and straightforward preparation are advantages of the prepared nanogel. Therefore, it could be considered for further consideration in vivo studies.

Nano-Size Characterization and Antifungal Evaluation of Essential Oil Molecules-Loaded Nanoliposomes

Nanoliposomes, bilayer vesicles at the nanoscale, are becoming popular because of their safety, patient compliance, high entrapment efficiency, and prompt action. Several notable biological activities of natural essential oils (EOs), including fungal inhibition, are of supreme interest. As developed, multi-compositional nanoliposomes loaded with various concentrations of clove essential oil (CEO) and tea tree oil (TTO) were thoroughly characterized to gain insight into their nano-size distribution. The present work also aimed to reconnoiter the sustainable synthesis conditions to estimate the efficacy of EOs in bulk and EO-loaded nanoliposomes with multi-functional entities. Following a detailed nano-size characterization of in-house fabricated EO-loaded nanoliposomes, the antifungal efficacy was tested by executing the mycelial growth inhibition (MGI) test using Trichophyton rubrum fungi as a test model. The dynamic light scattering (DLS) profile of as-fabricated EO-loaded nanoliposomes revealed the mean size, polydispersity index (PdI), and zeta potential values as 37.12 ± 1.23 nm, 0.377 ± 0.007, and -36.94 ± 0.36 mV, respectively. The sphere-shaped morphology of CEO and TTO-loaded nanoliposomes was confirmed by a scanning electron microscope (SEM). The existence of characteristic functional bands in all tested counterparts was demonstrated by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Compared to TTO-loaded nanoliposomes, the CEO-loaded nanoliposomes exhibited a maximum entrapment efficacy of 91.57 ± 2.5%. The CEO-loaded nanoliposome fraction, prepared using 1.5 µL/mL concentration, showed the highest MGI of 98.4 ± 0.87% tested against T. rubrum strains compared to the rest of the formulations.

Spray drying encapsulation of essential oils; process efficiency, formulation strategies, and applications

Essential oils (EOs) have many beneficial qualities, including antimicrobial, antioxidant, antiviral, and antifungal activities, along with good aroma, which have played a significant role in pharmaceutical, textile, and food industries. However, their high volatility and sensibility to external factors, as well as susceptibility to deterioration caused by environmental and storage conditions, or even common processing, and consequently limited water solubility, makes it difficult to incorporate them into aqueous food matrices and limits their industrial application. Spray-drying encapsulation has been proposed as a solution and a challenging research field to retard oil oxidation, extend EO's shelf life, improve their physicochemical stability, achieve controlled release, suggest novel uses, and therefore boost their added value. The objective of this review is to discuss various used wall materials, infeed emulsion properties, the main formulation and process variables affecting the physicochemical properties and release characteristics of the EOs-loaded particles obtained by spray-drying, the stability of EOs during storage, and the applications of encapsulated EOs powders in foods and nutrition, pharmaceuticals, and textile industries. The current review also summarizes recent advances in spray drying approaches for improving encapsulation efficiency, flavor retention, controlled release, and applicability of encapsulated EOs, thereby expanding their use and functionalities.

Nanomedicine as an Emerging Technology to Foster Application of Essential Oils to Fight Cancer

Natural prodrugs extracted from plants are increasingly used in many sectors, including the pharmaceutical, cosmetic, and food industries. Among these prodrugs, essential oils (EOs) are of particular importance. These biologically active volatile oily liquids are produced by medicinal and aromatic plants and characterized by a distinctive odor. EOs possess high anticancer, antibacterial, antiviral, and antioxidant potential but often are associated with low stability; high volatility; and a high risk of deterioration with exposure to heat, humidity, light, or oxygen. Furthermore, their bioavailability is limited because they are not soluble in water, and enhancements are needed to increase their potential to target specific cells or tissues, as well as for controlled release. Nanomedicine, the application of nanotechnology in medicine, may offer efficient solutions to these problems. The technology is based on creating nanostructures in which the natural prodrug is connected to or encapsulated in nanoparticles or submicron-sized capsules that ensure their solubility in water and their targeting properties, as well as controlled delivery. The potential of EOs as anticancer prodrugs is considerable but not fully exploited. This review focusses on the recent progress towards the practical application of EOs in cancer therapy based on nanotechnology applications.

Antimicrobial effect of laurel essential oil nanoemulsion on food-borne pathogens and fish spoilage bacteria

This research aimed to apply nanotechnology for nanoformulation of Laurus nobilis essential oil (EO) by ultrasonic emulsification method and characterization of nano-form: particle size, viscosity, polydispersity index, thermodynamic stability, and surface tension. The antimicrobial activity of laurel EO nanoemulsion (LEON) and laurel EO was also investigated against a panel of ten food-borne pathogens and fish spoilage bacteria. The GC-MS analysis of EO revealed that 1,8-Cineole was the main volatile compound. According to disc-diffusion results, LEON was more effective against Gram-positive pathogen bacteria of Staphylococcus aureus and Enterococcus faecalis than EO. Laurel oil demonstrated a higher inhibitory effect against fish spoilage bacteria (6.19 to 18.5 mm). The MICs values of LEON and laurel EO ranged from 6.25 to >25 mg/mL and from 1.56 to >25 mg/mL, respectively. Nanoemulsion and oil exhibited the best bactericidal activity against Pseudomonas luteola. Therefore, LEON can be developed as a natural antimicrobial agent in food industry.

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.

Comprehensive study of α-terpineol-loaded oil-in-water (O/W) nanoemulsion: interfacial property, formulation, physical and chemical stability

In this study, the interfacial ability of α-terpineol (α-TOH) was reported, followed by its trapping into oil-in-water (O/W) nanoemulsion as active-ingredient and the long-term observation of this nanosystem influenced by the storage-time (410-days) and temperature (5, 25, 50 °C). The results indicated that the α-TOH can reduce the interfacial tension on the liquid-liquid interface (ΔG°m = -1.81 KJ mol-1; surface density = 8.19 × 10-6 mol m-2; polar head group area = 20.29 Å2), in the absence or presence of surfactant. The O/W nanoemulsion loaded with a high amount of α-TOH (90 mg mL-1; 9α-TOH-NE) into the oil phase was successfully formulated. Among the physical parameters, the mean droplet diameter (MDD) showed a great thermal dependence influenced by the storage-temperature, where the Ostwald ripening (OR) was identified as the main destabilizing phenomena that was taking place on 9α-TOH-NE at 5 and 25 °C along with time. Despite of the physical instability, the integrity of both nanoemulsion at 5 °C and 25 °C was fully preserved up to 410th day, displaying a homogeneous and comparable appearance by visual observation. On contrary, a non-thermal dependence was found for chemical stability, where over 88% of the initial amount of the α-TOH nanoemulsified remained in both 9α-TOH-NE at 5 and 25 °C, up to 410th day. Beyond the key data reported for α-TOH, the importance of this research relies on the long-term tracking of a nanostructured system which can be useful for scientific community as a model for a robust evaluation of nanoemulsion loaded with flavor oils.

Sequential loading of inclusion complex/nanoparticles improves the gastric retention of Vladimiriae Radix essential oil to promote the protection of acute gastric mucosal injury

The essential oil from Vladimiriae Radix (VEO) is a medicinal natural product with anti-ulcer activity. A novel gastroretentive drug delivery system was developed by preparing the hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex incorporated into chitosan nanoparticles (V-CD/NPs), to improve the bioavailability of VEO and its protective effect on gastric mucosa. The optimum preparation process of V-CD/NPs was obtained by Plackett-Burman and Box-Behnken response surface methodology. The resulting V-CD/NPs gained a suitable positive potential and small particle size, and showed stability in simulated gastric fluid, whose morphology and in vitro drug release profiles had a pH-sensitivity. Besides, V-CD/NPs was proved to strongly bind with mucin, and in vivo imaging revealed that it could be retained in the stomach for more than 8 h. The results of drug concentration in gastric tissues showed that the sequential loading of inclusion complex/nanoparticles promoted the local absorption of VEO in gastric tissues, which was favorable to reach the effective therapeutic concentration in the lesioned mucosa area. In comparison to VEO and V-CD, the callback effect of V-CD/NPs on 1L-1β, 1L-6, TNF-α, NF-κB, MDA and SOD was comparable to cimetidine, and V-CD/NPs outperformed in gastric mucosal protection. Therefore, the gastroretentive drug delivery system developed in our study effectively enhanced the anti-ulcer activity of VEO, which could be a promising strategy for the prevention and treatment of the acute gastric mucosal injury.

The incorporation of lemongrass oil into chitosan-nanocellulose composite for bioaerosol reduction in indoor air

The bioaerosols present in indoor air play a major role in the transmission of infectious diseases to humans, therefore concern about their exposure is increased recently. In this regard, the present investigation described the preparation of lemongrass essential oil (LGEO) loaded chitosan and cellulose nanofibers composites (CH/CNF) for controlling the indoor air bioaerosol. The evaluation of the inhibitory effect of the composite system on culturable bacteria of the indoor air was done at different sites (air volume from 30 m³ to 80 m³) and in different size fractions of aerosol (<0.25 μm-2.5 μm). The composite system had high encapsulation efficiency (88-91%) and citrals content. A significant reduction in culturable bacteria of aerosol (from 6.23 log CFUm^-3 to 2.33 log CFUm^-3) was observed in presence of cellulose nanofibers and chitosan composites. The bacterial strains such as Staphylococcus sp., Bacillus cereus, Bacillus pseudomycoides sp., Pseudomonas otitidis, and Pseudomonas sp. Cf0-3 in bioaerosols were inhibited dominantly due to the diffusion of aroma molecules in indoor air. The results indicate that the interaction of diffused aroma molecule from the composite system with bacterial strains enhanced the production of ROS, resulting in loss of membrane integrity of bacterial cells. Among different size fractions of aerosol, the composite system was more effective in finer size fractions (<0.25 μm) of aerosol due to the interaction of smaller aroma compounds with bacterial cells. The study revealed that LGEO loaded chitosan and cellulose nanofibers composites could be a good option for controlling the culturable bacteria even in small-sized respirable bioaerosol.

Essential oils and their nanoformulations as green preservatives to boost food safety against mycotoxin contamination of food commodities: a review

Postharvest food spoilage due to fungal and mycotoxin contamination is a major challenge in tropical countries, leading to severe adverse effects on human health. Because of the negative effects of synthetic preservatives on both human health and the environment, it has been recommended that chemicals that have a botanical origin, with an eco-friendly nature and a favorable safety profile, should be used as green preservatives. Recently, the food industry and consumers have been shifting drastically towards green consumerism because of their increased concerns about health and the environment. Among different plant-based products, essential oils (EOs) and their bioactive components are strongly preferred as antimicrobial food preservatives. Despite having potent antimicrobial efficacy and preservation potential against fungal and mycotoxin contamination, essential oils and their bioactive components have limited practical applicability caused by their high volatility and their instability, implying the development of techniques to overcome the challenges associated with EO application. Essential oils and their bioactive components are promising alternatives to synthetic preservatives. To overcome challenges associated with EOs, nanotechnology has emerged as a novel technology in the food industries. Nanoencapsulation may boost the preservative potential of different essential oils by improving their solubility, stability, and targeted sustainable release. Nanoencapsulation of EOs is therefore currently being practiced to improve the stability and bioactivity of natural products. The present review has dealt extensively with the application of EOs and their nanoformulated products encapsulated in suitable polymeric matrices, so as to recommend them as novel green preservatives against foodborne molds and mycotoxin-induced deterioration of stored food commodities. © 2021 Society of Chemical Industry.

Cineole-containing nanoemulsion: Development, stability, and antibacterial activity

1,8-cineole is a monoterpene commonly used by the food, cosmetic, and pharmaceutical industries owing to its flavor and fragrances properties. In addition, this bioactive monoterpene has demonstrated bactericidal and fungicidal activities. However, such activities are limited due to its low aqueous solubility and stability. This study aimed to develop nanoemulsion containing cineole and assess its stability and antibacterial activity in this context. The spontaneous emulsification method was used to prepare nanoemulsion (NE) formulations (F1, F2, F3, F4, and F5). Following the development of NE formulations, we chose the F1 formulation that presented an average droplet size (in diameter) of about 100 nm with narrow size distribution (PdI <0.2) and negative zeta potential (∼ - 35 mV). According to the analytical centrifugation method with photometric detection, F1 and F5 formulations were considered the most stable NE with lower droplet migration velocities. In addition, F1 formulation showed high incorporation efficiency (> 80 %) and TEM analyses demonstrated nanosized oil droplets with irregular spherical shapes and without any aggregation tendency. Antibacterial activity assessment showed that F1 NE was able to enhance the cineole action against Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pyogenes. Therefore, using a simple and reproducible method of low energy emulsification we designed a stable nanoemulsion containing 1,8-cineole with improved antibacterial activity against Gram-positive strains.

Plant oils: From chemical composition to encapsulated form use

The last decade has witnessed a burgeoning global movement towards essential and vegetable oils in the food, agriculture, pharmaceutical, cosmetic, and textile industries thanks to their natural and safe status, broad acceptance by consumers, and versatile functional properties. However, efforts to develop new therapy or functional agents based on plant oils have met with challenges of limited stability and/or reduced efficacy. As a result, there has been increased research interest in the encapsulation of plant oils, whereby the nanocarriers serve as barrier between plant oils and the environment and control oil release leading to improved efficacy, reduced toxicity and enhanced patient compliance and convenience. In this review, special concern has been addressed to the encapsulation of essential and vegetable oils in three types of nanocarriers: polymeric nanoparticles, liposomes and solid lipid nanoparticles. First, the chemical composition of essential and vegetable oils was handled. Moreover, we gather together the research findings reported by the literature regarding the different techniques used to generate these nanocarriers with their significant findings. Finally, differences and similarities between these nanocarriers are discussed, along with current and future applications that are warranted by their structures and properties.

Nanoencapsulation of Plant Volatile Organic Compounds to Improve Their Biological Activities

Plant volatile organic compounds (volatiles) are secondary plant metabolites that play crucial roles in the reproduction, defence, and interactions with other vegetation. They have been shown to exhibit a broad range of biological properties and have been investigated for antimicrobial and anticancer activities. In addition, they are thought be more environmentally friendly than many other synthetic chemicals 1. Despite these facts, their applications in the medical, food, and agricultural fields are considerably restricted due to their volatilities, instabilities, and aqueous insolubilities. Nanoparticle encapsulation of plant volatile organic compounds is regarded as one of the best strategies that could lead to the enhancement of the bioavailability and biological activity of the volatile compounds by overcoming their physical limitations and promoting their controlled release and cellular absorption. In this review, we will discuss the biosynthesis and analysis of plant volatile organic compounds, their biological activities, and limitations. Furthermore, different types of nanoparticle platforms used to encapsulate the volatiles and the biological efficacies of nanoencapsulated volatile organic compounds will be covered.

Insight Into Nanoliposomes as Smart Nanocarriers for Greening the Twenty-First Century Biomedical Settings

The necessity to develop more efficient, biocompatible, patient compliance, and safer treatments in biomedical settings is receiving special attention using nanotechnology as a potential platform to design new drug delivery systems (DDS). Despite the broad range of nanocarrier systems in drug delivery, lack of biocompatibility, poor penetration, low entrapment efficiency, and toxicity are significant challenges that remain to address. Such practices are even more demanding when bioactive agents are intended to be loaded on a nanocarrier system, especially for topical treatment purposes. For the aforesaid reasons, the search for more efficient nano-vesicular systems, such as nanoliposomes, with a high biocompatibility index and controlled releases has increased considerably in the past few decades. Owing to the stratum corneum layer barrier of the skin, the in-practice conventional/conformist drug delivery methods are inefficient, and the effect of the administered therapeutic cues is limited. The current advancement at the nanoscale has transformed the drug delivery sector. Nanoliposomes, as robust nanocarriers, are becoming popular for biomedical applications because of safety, patient compliance, and quick action. Herein, we reviewed state-of-the-art nanoliposomes as a smart and sophisticated drug delivery approach. Following a brief introduction, the drug delivery mechanism of nanoliposomes is discussed with suitable examples for the treatment of numerous diseases with a brief emphasis on fungal infections. The latter half of the work is focused on the applied perspective and clinical translation of nanoliposomes. Furthermore, a detailed overview of clinical applications and future perspectives has been included in this review.

Topical Administration of Terpenes Encapsulated in Nanostructured Lipid-Based Systems

Terpenes are a group of phytocompounds that have been used in medicine for decades owing to their significant role in human health. So far, they have been examined for therapeutic purposes as antibacterial, anti-inflammatory, antitumoral agents, and the clinical potential of this class of compounds has been increasing continuously as a source of pharmacologically interesting agents also in relation to topical administration. Major difficulties in achieving sustained delivery of terpenes to the skin are connected with their low solubility and stability, as well as poor cell penetration. In order to overcome these disadvantages, new delivery technologies based on nanostructures are proposed to improve bioavailability and allow controlled release. This review highlights the potential properties of terpenes loaded in several types of lipid-based nanocarriers (liposomes, solid lipid nanoparticles, and nanostructured lipid carriers) used to overcome free terpenes' form limitations and potentiate their therapeutic properties for topical administration.

Effectiveness and mechanisms of essential oils for biofilm control on food-contact surfaces: An updated review

Microbial biofilms represent a constant source of contamination in the food industry, being also a real threat for human health. In fact, most of biofilm-producing bacteria are becoming resistant to sanitizers, thus arousing the interest in natural alternatives to prevent biofilm formation on foods and food-contact surfaces. In particular, studies on biofilm control by essential oils (EOs) application are increasing, being EOs characterized by unique mixtures of compounds able to impair the mechanisms of biofilm development. This review reports the anti-biofilm properties of EOs in bacterial biofilm control (inhibition, removal and prevention of biofilm dispersion) on food-contact surfaces. The relationship between EOs effect and composition, concentration, involved bacteria, and surfaces is discussed, and the possible sites of action are also elucidated. The findings prove the high biofilm controlling capability of EOs through the regulation of genes and proteins implicated in motility, Quorum Sensing and exopolysaccharides (EPS) matrix. Moreover, incorporation in nanosized delivery systems, formulation of blends and combination of EOs with other strategies can increase their anti-biofilm activity. This review provides an overview of the current knowledge of the EOs effectiveness in controlling bacterial biofilm on food-contact surfaces, providing valuable information for improving EOs use as sanitizers in food industries.

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

A huge variety of plants are harvested worldwide and their different constituents can be converted into a broad range of bionanomaterials. In parallel, much research effort in materials science and engineering is focused on the formation of nanoparticles and nanostructured materials originating from agricultural residues. Cellulose (40-50%), hemicellulose (20-40%), and lignin (20-30%) represent major plant ingredients and many techniques have been described that separate the main plant components for the synthesis of nanocelluloses, nano-hemicelluloses, and nanolignins with divergent and controllable properties. The minor components, such as essential oils, could also be used to produce non-toxic metal and metal oxide nanoparticles with high bioavailability, biocompatibility, and/or bioactivity. This review describes the chemical structure, the physical and chemical properties of plant cell constituents, different techniques for the synthesis of nanocelluloses, nanohemicelluloses, and nanolignins from various lignocellulose sources and agricultural residues, and the extraction of volatile oils from plants as well as their use in metal and metal oxide nanoparticle production and emulsion preparation. Furthermore, details about the formation of activated carbon nanomaterials by thermal treatment of lignocellulose materials, a few examples of mineral extraction from agriculture waste for nanoparticle fabrication, and the emerging applications of plant-based nanomaterials in different fields, such as biotechnology and medicine, environment protection, environmental remediation, or energy production and storage, are also included. This review also briefly discusses the recent developments and challenges of obtaining nanomaterials from plant residues, and the issues surrounding toxicity and regulation.

The influence of PBAT content in the nanocapsules preparation and its effect in essential oils release

Nanoencapsulation provides new alternatives for the food industry, enabling a controlled and slow release of active antimicrobial agents, such as essential oils (EO). Poly (butylene adipate-co-terephthalate) (PBAT) nanocapsules loaded with linalool EO were prepared using an extrusion method with 1, 3, and 5% w/v (PBAT to chloroform). Nanocapsules' sizes ranged from 100 to 250 nm and were spherical. The release profile was studied using an ethanoic medium over 24 h, and according to the Korsmeyer-Peppas model, a Fick diffusion mechanism was involved. FT-IR and thermogravimetric analyses confirmed EO encapsulation with an encapsulation efficiency of 55%, 71%, and 74% for 1, 3, and 5%, respectively. The results indicated that encapsulation depended on organic phase concentration, with higher PBAT contents achieving better results. The resulting nanocapsules had antimicrobial activity against E. coli, which could be extended to develop active packaging systems.

Magnetite Nanoparticles and Essential Oils Systems for Advanced Antibacterial Therapies

Essential oils (EOs) have attracted considerable interest in the past few years, with increasing evidence of their antibacterial, antiviral, antifungal, and insecticidal effects. However, as they are highly volatile, the administration of EOs to achieve the desired effects is challenging. Therefore, nanotechnology-based strategies for developing nanoscaled carriers for their efficient delivery might offer potential solutions. Owing to their biocompatibility, biodegradability, low toxicity, ability to target a tissue specifically, and primary structures that allow for the attachment of various therapeutics, magnetite nanoparticles (MNPs) are an example of such nanocarriers that could be used for the efficient delivery of EOs for antimicrobial therapies. The aim of this paper is to provide an overview of the use of EOs as antibacterial agents when coupled with magnetite nanoparticles (NPs), emphasizing the synthesis, properties and functionalization of such NPs to enhance their efficiency. In this manner, systems comprising EOs and MNPs could offer potential solutions that could overcome the challenges associated with biofilm formation on prosthetic devices and antibiotic-resistant bacteria by ensuring a controlled and sustained release of the antibacterial agents.

Sage Species Case Study on a Spontaneous Mediterranean Plant to Control Phytopathogenic Fungi and Bacteria

Sage species belong to the family of Labiatae/Lamiaceae and are diffused worldwide. More than 900 species of sage have been identified, and many of them are used for different purposes, i.e., culinary uses, traditional medicines and natural remedies and cosmetic applications. Another use of sage is the application of non-distilled sage extracts and essential oils to control phytopathogenic bacteria and fungi, for a sustainable, environmentally friendly agriculture. Biocidal propriety of non-distilled extracts and essential oils of sage are w documented. Antimicrobial effects of these sage extracts/essential oils depend on both sage species and bacteria and fungi species to control. In general, it is possible to choose some specific extracts/essential oils to control specific phytopathogenic bacteria or fungi. In this context, the use of nanotechnology techniques applied to essential oil from salvia could represent a future direction for improving the performance of eco-compatible and sustainable plant defence and represents a great challenge for the future.

Evaluation of Physical and Chemical Properties of Pomelo (Citrus grandis L.) Essential Oil using Steam Distillation Process

This study attempted the extraction of essential oils from the peels of pomelo (Citrus grandis L.) grown in Ben Tre province, Vietnam through hydrodistillation method. In addition, the chemical composition and physio-chemical properties of the essential oils were reported. The results showed that the extraction yield of the extraction process achieved about 1.67%. The physico-chemical index of essential oils is determined by specific gravity (0.8572 g/cm3), acid index (0.3556 mg KOH/g), ester index (2.4216 mg KOH/g), and refractive index (1.476). The GC-MS analyses of the oil indicated the component with highest content in the oil was α-limonene (96.491%), followed by α-pinene (0.686%), β-pinene (0.248%), β-myrcene (1.644%), α-phellandrene (0.793%) and β-cis-ocimene (0.138%). These results suggested that wastes from fruit peeling process can be converted into a new material source with great potential for industrial use.

Essential Oils and Isolated Terpenes in Nanosystems Designed for Topical Administration: A Review

Essential oils are natural products with a complex composition. Terpenes are the most common class of chemical compounds present in essential oils. Terpenes and the essential oils containing them are widely used and investigated by their pharmacological properties and permeation-enhancing ability. However, many terpenes and essential oils are sensitive to environmental conditions, undergoing volatilization and chemical degradation. In order to overcome the chemical instability of some isolated terpenes and essential oils, the encapsulation of these compounds in nanostructured systems (polymeric, lipidic, or molecular complexes) has been employed. In addition, nanoencapsulation can be of interest for pharmaceutical applications due to its capacity to improve the bioavailability and allow the controlled release of drugs. Topical drug administration is a convenient and non-invasive administration route for both local and systemic drug delivery. The present review focuses on describing the current status of research concerning nanostructured delivery systems containing isolated terpenes and/or essential oils designed for topical administration and on discussing the use of terpenes and essential oils either for their biological activities or as permeation enhancers in pharmaceutic formulations.