An updated and comprehensive review of the antiviral potential of essential oils and their chemical constituents with special focus on their mechanism of action against various influenza and coronaviruses

Insights into chemistry, extraction and industrial application of lemon grass essential oil -A review of recent advances

Lemongrass essential oil (LEO), extracted from high-oil lemongrass, gains prominence as a versatile natural product due to growing demand for safe health solutions. LEO comprises beneficial compounds like citral, isoneral, geraniol, and citronellal, offering diverse pharmacological benefits such as antioxidant, antifungal, antibacterial, antiviral, and anticancer effects. LEO finds applications in food preservation, cosmetics, and pharmaceuticals, enhancing profitability across these sectors. The review focuses on the extraction of LEO, emphasizing the need for cost-effective methods. Ultrasound and supercritical fluid extraction are effective in reducing extraction time, increasing yields, and enhancing oil quality. LEO shows promise as a valuable natural resource across industries, with applications in packaging, coating, and film development. LEO's ability to extend the shelf life of food items and impart natural flavors positions it as a valuable asset. Overall, the review emphasizes LEO's therapeutic, antimicrobial, and antioxidant properties, strengthening its potential in the food, pharmaceutical, and cosmetic sectors.

Antiviral, Antibacterial, Antifungal, and Anticancer Activity of Plant Materials Derived from Cymbopogon citratus (DC.) Stapf Species

The importance of natural plant materials in modern medicine is considerable, and raw materials with antiviral, antibacterial, antifungal, and anticancer properties are still sought because of microbe resistance and difficulties in anticancer therapy. This review focuses on the lemongrass Cymbopogon citratus (DC.) Stapf. and on the lemongrass oil properties and applications. Multiple applications of this plant were described in different latitudes and cultures, including cases of digestive disorders and anti-inflammatory, antipyretic, diaphoretic, stimulating, and antispasmodic conditions. Data from the literature on the composition of essential oil and extracts from C. citratus were analyzed, and the results of research on the antifungal, antibacterial, and antiviral effects were quoted. Essential oil inhibits the growth of fungi (Aspergillus niger, A. fumigatus, Candida spp.) and has an antibacterial effect (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa). It also shows antiviral activity and deters insects. Lemongrass contains active substances with potential anticancer effects. This plant has apoptosis-stimulating properties, mainly through the activity of apigenin, which is the main active flavonoid in this plant. This active substance helps inhibit cell proliferation by stopping the cell cycle and directing cancer cells toward apoptosis.

Assessing the virucidal activity of essential oils against feline calicivirus, a non-enveloped virus used as surrogate of norovirus

Norovirus (NoV) causes serious gastrointestinal disease worldwide and is regarded as an important foodborne pathogen. Due the difficulties of in vitro cultivation for human NoV, alternative caliciviruses (i.e., feline calicivirus, FCV, or murine NoV) have long been used as surrogates for in vitro assessment of the efficacy of antivirals. Essential oils (EOs) are natural compounds that have displayed antimicrobial and antioxidant properties. We report in vitro the virucidal efficacy of four EOs, Melissa officinalis L. EO (MEO), Thymus vulgaris L. EO (TEO), Rosmarinus officinalis L. EO (REO), and Salvia officinalis L. EO (SEO) against FCV at different time contacts (10, 30 min, 1, 4 and 8 h). At the maximum non-cytotoxic concentration and at 10- and 100- fold concentrations over the cytotoxic threshold, the EOs did not decrease significantly FCV viral titers. However, MEO at 12,302.70 μg/mL exhibited a significant efficacy decreasing the viral titer by 0.75 log10 Tissue Culture Infectious Dose (TCID50)/50 μl after 10 min as compared to virus control. In this study, virucidal activity of four EOs against FCV, was investigated. A lack of virucidal efficacy of TEO, REO and SEO at different compound concentrations and time contacts against FCV was observed whilst MEO was able to significantly decrease FCV titer.

Identification and variation analysis of the composition and content of essential oil and fragrance compounds in Phoebe zhennan wood at different tree ages

Wood essential oil and wood products with special fragrances are high value-added forest products. Despite the availability of essential oil and volatile organic compounds (VOCs) from Phoebe zhennan wood, their variation and dependence on tree age have not been examined. After essential oil extraction and wood processing, the yields and compositions of essential oils and VOCs in wood from P. zhennan trees of different ages (10a, 30a, and 80a) were determined. The yield of essential oil from 30a wood was significantly greater than that from 10a and 80a wood. Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) revealed 672 and 41 volatile compounds, respectively, in the essential oil and wood, the majority of which exhibited large fluctuations in relative content and composition depending on tree age. Sesquiterpenoids, fatty acids and conjugates may greatly contribute to the main components of essential oil from wood. Almost all major sesquiterpenoid compounds, such as caryophyllene α-oxide, eudesmo, and cubebene, were identified in the essential oils from the 30a and 80a wood, and their relative contents were much greater than those in the 10a wood. The main components of the wood fragrance were sesquiterpenoids. The types and relative contents of sesquiterpenoids from wood increased with tree age. These results suggest that choosing wood from trees of a suitable age will significantly improve the efficiency of wood utilization.

Mesoporous silica nanoparticles: A versatile platform for encapsulation and delivery of essential oils for food applications

Essential oils (EOs) are biologically active and volatile substances that have found widespread applications in the food, cosmetics, and pharmaceutical industries. However, there are some challenges to their commercial utilization due to their high volatility, susceptibility to degradation, and hydrophobicity. In their free form, EOs can quickly evaporate, as well as undergo degradation reactions like oxidation, isomerization, dehydrogenation, or polymerization when exposed to light, heat, or air. Encapsulating EOs within mesoporous silica nanoparticles (MSNPs) could overcome these limitations and thereby broaden their usage. MSNPs may endow protection and slow-release properties to EOs, thereby extending their stability, enhancing their efficacy, and improving their dispersion in aqueous environments. This review explores and compares the design and development of different MSNP-based nanoplatforms to encapsulate, protect, and release EOs. Initially, a brief overview of the various types of available MSNPs, their properties, and their synthesis methods is given to better understand their roles as carriers for EOs. Several encapsulation technologies are then examined, including solvent-based and solvent-free methods. The suitability of each technology for EO encapsulation, as well as its impact on their stability and release, is discussed in detail. Opportunities and challenges for using EO-loaded MSNPs as preservatives, flavor enhancers, and antimicrobial agents in the food industry are then highlighted. Overall, this review aims to bridge a knowledge gap by providing a thorough understanding of EO encapsulation within MSNPs, which should facilitate the application of this technology in the food industry.

Chemical composition, anticancer, antimicrobial activity of Aloysia citriodora Palau essential oils from four different locations in Palestine

The primary aim of this investigation was to determine the anticancer and antimicrobial properties of essential oils (EOs) extracted from the leaves of Aloysia citriodora Palau, which were procured from four separate locations in Palestine, in addition to analyzing their chemical composition. These areas include Jericho, which has the distinction of being the lowest location on Earth, at 260 m below sea level. The EOs were acquired by hydrodistillation, and their chemical composition was examined utilizing gas chromatography-mass spectrometry (GC-MS). The minimum inhibitory concentration (MIC) of EOs was assessed against six bacterial strains and one fungal species using 96-well microtiter plates. The primary components found in these oils are geranial (26.32-37.22%), neral (18.38-29.00%), and α-curcumene (7.76-16.91%) in three regions. α-Curcumene (26.94%), spathulenol (13.69%), geranial (10.79%), caryophyllene oxide (8.66%), and neral (7.59%) were found to be the most common of the 32 chemical components in the EO from Jericho. The EOs exhibited bactericidal properties, particularly against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and showed highly effective fungicidal activity. Nevertheless, the antifungal efficacy of the EO was found to surpass its antibacterial activity when administered at lower dosages. The EOs exhibited anticancer activities against melanoma cancer cells, as indicated by their IC50 values, which ranged from 4.65 to 7.96 μg/mL. A. citriodora EO possesses substantial antifungal and anticancer characteristics, rendering it appropriate for utilization in food-related contexts, hence potentially enhancing the sustainability of the food sector.

Chitosan-Based Nanoencapsulated Essential Oils: Potential Leads against Breast Cancer Cells in Preclinical Studies

Since ancient times, essential oils (EOs) derived from aromatic plants have played a significant role in promoting human health. EOs are widely used in biomedical applications due to their medicinal properties. EOs and their constituents have been extensively studied for treating various health-related disorders, including cancer. Nonetheless, their biomedical applications are limited due to several drawbacks. Recent advances in nanotechnology offer the potential for utilising EO-loaded nanoparticles in the treatment of various diseases. In this aspect, chitosan (CS) appears as an exceptional encapsulating agent owing to its beneficial attributes. This review highlights the use of bioactive EOs and their constituents against breast cancer cells. Challenges associated with the use of EOs in biomedical applications are addressed. Essential information on the benefits of CS as an encapsulant, the advantages of nanoencapsulated EOs, and the cytotoxic actions of CS-based nanoencapsulated EOs against breast cancer cells is emphasised. Overall, the nanodelivery of bioactive EOs employing polymeric CS represents a promising avenue against breast cancer cells in preclinical studies.

Rapid Preparation of Highly Stretchable and Fast Self-Repairing Antibacterial Hydrogels for Promoting Hemostasis and Wound Healing

Hydrogel dressings have emerged as a vital resource in wound management, offering several advantages over conventional wound dressing materials. Their inherent biocompatibility, ability to replicate the native extracellular matrix, and capacity to provide an ideal environment for cell survival make them particularly valuable. Nevertheless, the mechanical properties of many hydrogel dressings are an area that warrants improvement, as it currently constrains their application range. This limitation is especially evident when skin wounds are addressed in highly active or easily scratched areas. In this study, we present the development of a highly stretchable self-repairing hydrogel by cross-linking poly(vinyl alcohol) (PVA) through dynamic boron ester bonds, coupled with the hydrogen bonding of carboxymethyl cellulose sodium (CMC) via an efficient one-pot method without adding any catalyst. This innovative PVA/CMC hydrogel exhibited remarkable antibacterial properties achieved through the incorporation of bergamot oil, which was dispersed in a β-cyclodextrin solution. The hydrogel's elongation at the point of rupture reached an impressive 1910%, and it was capable of rapid self-healing in just 3 min upon bonding. Additionally, the hydrogel demonstrated excellent hemostatic properties, effectively mitigating blood loss and exudation. In vivo wound models have shown that PVA/CMC significantly expedites wound healing by reducing bacterial infections, inflammatory responses, and blood loss and by promoting collagen deposition. In summary, this research provides crucial insights into its potential as an advanced wound dressing material, particularly well-suited for addressing wounds in places with frequent activities or easy scratches.

Antiviral Natural Products, Their Mechanisms of Action and Potential Applications as Sanitizers and Disinfectants

Plant extracts, natural products and plant oils contain natural virucidal actives that can be used to replace active ingredients in commercial sanitizers and disinfectants. This review focuses on the virucidal mechanisms of natural substances that may exhibit potential for indoor air and fomite disinfection. Review of scientific studies indicates: (1) most natural product studies use crude extracts and do not isolate or identify exact active antiviral substances; (2) many natural product studies contain unclear explanations of virucidal mechanisms of action; (3) natural product evaluations of virucidal activity should include methods that validate efficacy under standardized disinfectant testing procedures (e.g., carrier tests on applicable surfaces or activity against aerosolized viruses, etc.). The development of natural product disinfectants requires a better understanding of the mechanisms of action (MOA), chemical profiles, compound specificities, activity spectra, and the chemical formulations required for maximum activity. Combinations of natural antiviral substances and possibly the addition of synthetic compounds might be needed to increase inactivation of a broader spectrum of viruses, thereby providing the required efficacy for surface and air disinfection.

Synergistic In Vitro Antiviral Effect of Combinations of Ivermectin, Essential Oils, and 18-(Phthalimid-2-yl)ferruginol against Arboviruses and Herpesvirus

Combining antiviral drugs with different mechanisms of action can help prevent the development of resistance by attacking the infectious agent through multiple pathways. Additionally, by using faster and more economical screening methods, effective synergistic drug candidates can be rapidly identified, facilitating faster paths to clinical testing. In this work, a rapid method was standardized to identify possible synergisms from drug combinations. We analyzed the possible reduction in the antiviral effective concentration of drugs already approved by the FDA, such as ivermectin (IVM), ribavirin (RIBA), and acyclovir (ACV) against Zika virus (ZIKV), Chikungunya virus (CHIKV), and herpes virus type 2 (HHV-2). Essential oils (EOs) were also included in the study since they have been reported for more than a couple of decades to have broad-spectrum antiviral activity. We also continued studying the antiviral properties of one of our patented molecules with broad-spectrum antiviral activity, the ferruginol analog 18-(phthalimid-2-yl)ferruginol (phthFGL), which presented an IC99 of 25.6 μM for the three types of virus. In general, the combination of IVM, phthFGL, and oregano EO showed the greatest synergism potential against CHIKV, ZIKV, and HHV-2. For instance, this combination achieved reductions in the IC99 value of each component up to ~8-, ~27-, and ~12-fold for CHIKV, respectively. The ternary combination of RIBA, phthFGL, and oregano EO was slightly more efficient than the binary combination RIBA/phthFGL but much less efficient than IVM, phthFGL, and oregano EO, which indicates that IVM could contribute more to the differentiation of cell targets (for example via the inhibition of the host heterodimeric importin IMP α/β1 complex) than ribavirin. Statistical analysis showed significant differences among the combination groups tested, especially in the HHV-2 and CHIKV models, with p = 0.0098. Additionally, phthFGL showed a good pharmacokinetic profile that should encourage future optimization studies.

Effectiveness of Mouthwashes in Managing Oral Diseases and Conditions: Do They Have a Role?

Antimicrobial mouthwashes are considered to reduce dental plaque biofilm and thus the potential to prevent plaque-induced oral diseases, particularly periodontal diseases. The effectiveness of mouthwashes relates to this antiplaque role, as well as, their tooth-whitening potential and ability to mask/mange malodour (halitosis). There is also a growing interest in the use of mouthwashes as an adjunctive measure in post surgical and post-dental care, while the COVID-19 pandemic has given a new lease of life to mouthwashes as an oral antispetic that may be useful in reducing the oral viral load. The mode of action of mouthwashes varies, depending on their active ingredients, concentrations, and mode and frequency of use, as does their potential effectiveness. This article aims to provide a narrative overview of the evidence of the effectiveness of the most widely used mouthwashes in managing oral diseases, oral conditions, and adjunctive care roles.

Plants and Their Derivatives as Promising Therapeutics for Sustainable Control of Honeybee (Apis mellifera) Pathogens

The most important pollinator for agricultural crops is the Western honeybee (Apis mellifera). During the winter and summer seasons, diseases and stresses of various kinds endanger honeybee numbers and production, resulting in expenses for beekeepers and detrimental effects on agriculture and ecosystems. Researchers are continually in search of therapies for honeybees using the resources of microbiology, molecular biology, and chemistry to combat diseases and improve the overall health of these important pollinating insects. Among the most investigated and most promising solutions are medicinal plants and their derivatives. The health of animals and their ability to fight disease can be supported by natural products (NPs) derived from living organisms such as plants and microbes. NPs contain substances that can reduce the effects of diseases by promoting immunity or directly suppressing pathogens, and parasites. This literature review summarises the advances that the scientific community has achieved over the years regarding veterinary treatments in beekeeping through the use of NPs. Their impact on the prevention and control of honeybee diseases is investigated both in trials that have been conducted in the laboratory and field studies.

Chemical Composition of Litsea pungens Essential Oil and Its Potential Antioxidant and Antimicrobial Activities

Litsea pungens is a plant with medicinal and edible properties, where the fruits are edible and the leaves have medicinal properties. However, there is limited research on the chemical and pharmacological activities of the plant. In this study, essential oils were extracted by steam distillation and their antioxidant and antibacterial activities were further evaluated. Gas chromatography-mass spectrometry (GC-MS) was used to identify the chemical components of L. pungens fresh fruit essential oil (FREO) and L. pungens fresh flower essential oil (FLEO), rapeseed oil (RO) and commercial Litsea oil (CEO). The results showed that 12 chemical components were identified in FREO. Twelve chemical components were identified from FLEO, four chemical components were identified from CEO, and thirteen chemical components were identified from RO. Except for RO, the other three oils were mainly composed of terpenes, among which limonene is the main chemical component. In terms of antioxidant activity, FREO, FLEO, CEO and RO have antioxidant capacity, mainly reflected in the scavenging DPPH free radicals and the iron ion chelating ability, and the antioxidant activity shows a certain dose effect, but the antioxidant activity of FLEO is the weakest among the four oils. Meanwhile, under the stress of hydrogen peroxide, CEO demonstrated a significant antioxidant protective effect on cells. It is worth mentioning that compared with the positive control, the FREO exhibited a better antibacterial rate. When the concentration of essential oil is 20 mg/mL, the bacteriostatic rate can reach 100%. Therefore, it could be a promising candidate among medicinal and edible plants.

Essential Oil of Bursera morelensis Promotes Cell Migration on Fibroblasts: In Vitro Assays

Essential oils (EOs) are complex mixtures of volatile natural compounds. We have extensively studied the EO of Bursera morelensis, which demonstrates antibacterial, antifungal, anti-inflammatory, and wound-healing activities. The objective of this work was to determine the effect of this EO on fibroblast migration in a three-dimensional in vitro model. For the three-dimensional in vitro model, a series of fibrin hydrogel scaffolds (FSs) were built in which fibroblasts were cultured and subsequently stimulated with fibroblast growth factor (FGF) or EO. The results demonstrated that these FSs are appropriate for fibroblast culture, since no decrease in cell viability or changes in cell proliferation were found. The results also showed that this EO promotes cell migration four hours after stimulation, and the formation of cell projections (filopodia) outside the SF was observed. From these results, we confirmed that part of the mechanism of action of the essential oil of B. morelensis during the healing process is the stimulation of fibroblast migration to the wound site.

Mechanistic Evidence of Andrographis paniculata (Burm. f.) Wall. ex Nees, Pelargonium sidoides DC., Echinacea Species and a Combination of Hedera helix L., Primula veris L./Primula elatior L. and Thymus vulgaris L./Thymus zygis L. in the Treatment of Acute, Uncomplicated Respiratory Tract Infections: A Systematic Literature Review and Expert Interviews

Reducing inappropriate antibiotic (AB) use by using effective non-antibiotic treatments is one strategy to prevent and reduce antimicrobial resistance (AMR). Andrographis paniculata (Burm. f.) Wall. ex Nees, Pelargonium sidoides DC., Echinacea species and a combination of ivy (Hedera helix L.), primrose (Primula veris L./Primula elatior L.) and thyme (Thymus vulgaris L./Thymus zygis L.) have promising clinical effects in uncomplicated, acute upper respiratory tract infections (URTI) treatment. However, mechanistic evidence of these herbal treatments is lacking. The objective of this Pstudy is to provide an overview of mechanistic evidence for these effects. Thirty-eight databases were searched. Included studies were mechanistic studies (in vitro, animal, and human studies and reviews) on these herbs; published before June 2021. Non-mechanistic studies or studies on combinations of herbs other than ivy/primrose/thyme were excluded. Furthermore, three experts in traditional, complementary and integrative healthcare (TCIH) research and pharmacognosy were interviewed to collect additional expert knowledge. The results show that A. paniculata acts through immunomodulation and antiviral activity, possibly supplemented by antibacterial and antipyretic effects. P. sidoides acts through antiviral, indirect antibacterial, immunomodulatory and expectorant effects. Echinacea species likely act through immunomodulation. The combination of ivy/primrose/thyme combines secretolytic and spasmolytic effects from ivy with antibacterial effects from thyme. Studies on primrose were lacking. This mechanistic evidence supports the difference-making evidence from clinical studies, contributes to evidence-based recommendations for their use in URTI treatment, and guides future mechanistic studies on URTI treatments.

Essential Oils: Chemistry and Pharmacological Activities

In this review, we provide an overview of the current understanding of the main mechanisms of pharmacological action of essential oils and their components in various biological systems. A brief introduction on essential oil chemistry is presented to better understand the relationship of chemical aspects with the bioactivity of these products. Next, the antioxidant, anti-inflammatory, antitumor, and antimicrobial activities are discussed. The mechanisms of action against various types of viruses are also addressed. The data show that the multiplicity of pharmacological properties of essential oils occurs due to the chemical diversity in their composition and their ability to interfere with biological processes at cellular and multicellular levels via interaction with various biological targets. Therefore, these natural products can be a promising source for the development of new drugs.

COVID-19 pandemic sheds a new research spotlight on antiviral potential of essential oils - A bibliometric study

Background

Essential oils are thought as potential therapies in managing coronavirus disease 2019 (COVID-19). Many researchers have put their efforts to tackle the pandemic by exploring antiviral candidates which consequently changes the research landscape. Herein, we aimed to assess the effect of COVID-19 pandemic toward the landscape of essential oil research.

Methods

This study employed bibliometric analysis based on the metadata of published literature indexed in the Scopus database. The search was performed on December 15^th, 2022 by using keyword 'essential oil' and its synonyms. We grouped the data based on publication year; pre-COVID-19 (2014-2019) and during COVID-19 (2020-2024, some studies have been published earlier). Further, we separated the COVID-19-focused research from COVID-19 (2020-2024) by introducing a new keyword 'COVID-19' during the search. All metadata were processed using VoSviewer and Biblioshiny for network visualization analysis. Selections of frequently occurring keywords, clusters of keyword co-occurrence, and the list of most impactful papers were performed by two independent reviewers.

Results

Metadata from a total of 35,262 publications were included for bibliometric analysis, comprised of three groups of datasets namely pre-COVID-19 (n = 18,670), COVID-19 (n = 16,592), and COVID-19-focused (n = 281). Five research topics clusters were found from pre-COVID-19 dataset, eight - from COVID-19 dataset, and nine - from COVID-19-focused dataset. COVID-19 cluster containing the keyword 'antiviral' emerged in the COVID-19 dataset, whereas none of the previous research topic clusters contained the keyword 'antiviral'. Antiviral, angiotensin-converting enzyme 2 (ACE2) inhibitory, and anti-inflammation activities were among the top occurring keywords in studies covering both essential oil and COVID-19. Studies on essential oil used for managing COVID-19 were most reported by authors from the United States (documents = 37, citations = 405), Australia (documents = 16, citations = 115) and Italy (documents = 23, citations = 366).

Conclusion

A significant increase was found during COVID-19 pandemic for publications covering essential oil themes, but only a small portion was occupied by COVID-19 research. The COVID-19 pandemic does not alter the ongoing progress of essential oil research but rather offers a new spotlight on the antiviral potential of essential oils. Hence, the COVID-19 pandemic has provided an opportunity to investigate deeper the antiviral potential of essential oils.

Production of secondary metabolites using tissue culture-based biotechnological applications

Plants are the sources of many bioactive secondary metabolites which are present in plant organs including leaves, stems, roots, and flowers. Although they provide advantages to the plants in many cases, they are not necessary for metabolisms related to growth, development, and reproduction. They are specific to plant species and are precursor substances, which can be modified for generations of various compounds in different plant species. Secondary metabolites are used in many industries, including dye, food processing and cosmetic industries, and in agricultural control as well as being used as pharmaceutical raw materials by humans. For this reason, the demand is high; therefore, they are needed to be obtained in large volumes and the large productions can be achieved using biotechnological methods in addition to production, being done with classical methods. For this, plant biotechnology can be put in action through using different methods. The most important of these methods include tissue culture and gene transfer. The genetically modified plants are agriculturally more productive and are commercially more effective and are valuable tools for industrial and medical purposes as well as being the sources of many secondary metabolites of therapeutic importance. With plant tissue culture applications, which are also the first step in obtaining transgenic plants with having desirable characteristics, it is possible to produce specific secondary metabolites in large-scale through using whole plants or using specific tissues of these plants in laboratory conditions. Currently, many studies are going on this subject, and some of them receiving attention are found to be taken place in plant biotechnology and having promising applications. In this work, particularly benefits of secondary metabolites, and their productions through tissue culture-based biotechnological applications are discussed using literature with presence of current studies.

Eco-friendly and effective antimicrobial Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils against bacteria and SARS-CoV-2

Melaleuca alternifolia essential oil (MaEO) is a green antimicrobial agent suitable for confection eco-friendly disinfectants to substitute conventional chemical disinfectants commonly formulated with toxic substances that cause dangerous environmental impacts. In this contribution, MaEO-in-water Pickering emulsions were successfully stabilized with cellulose nanofibrils (CNFs) by a simple mixing procedure. MaEO and the emulsions presented antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Moreover, MaEO deactivated the SARS-CoV-2 virions immediately. FT-Raman and FTIR spectroscopies indicate that the CNF stabilizes the MaEO droplets in water by the dipole-induced-dipole interactions and hydrogen bonds. The factorial design of experiments (DoE) indicates that CNF content and mixing time have significant effects on preventing the MaEO droplets' coalescence during 30-day shelf life. The bacteria inhibition zone assays show that the most stable emulsions showed antimicrobial activity comparable to commercial disinfectant agents such as hypochlorite. The MaEO/water stabilized-CNF emulsion is a promissory natural disinfectant with antibacterial activity against these bacteria strains, including the capability to damage the spike proteins at the SARS-CoV-2 particle surface after 15 min of direct contact when the MaEO concentration is 30 % v/v.

Bornyl acetate: A promising agent in phytomedicine for inflammation and immune modulation

BACKGROUND

Bornyl acetate (BA), as a bicyclic monoterpene, is an active volatile component widely found in plants across the globe. BA can be used as essence and food flavor agent and is widely used in perfumes and food additives. It remains a key component in several proprietary Chinese medicines.

PURPOSE

This review summarized the pharmacological activity and research prospects of BA, making it the first of its kind to do so. Our aim is to provide a valuable resource for those pursuing research on BA.

METHODS

Databases including PubMed, Web of Science, and CNKI were used based on search formula "(bornyl acetate) NOT (review)" from 1967 to 2022. For the relevant knowledge of TCM, we quoted Chinese literature. Articles related to agriculture, industry, and economics were excluded.

RESULTS

BA showed rich pharmacological activities: It inhibits the NF-κB signal pathway via affecting the phosphorylation of IKB and the production of IKKs, inhibits the MAPK signal pathway via inhibiting the phosphorylation of ERK, JNK, and p38, down-regulates pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6, up-regulates IL-11, reduces NO production, regulates immune response via up-regulating CD86⁺, decreases catecholamine secretion, and reduces tau protein phosphorylation. In addition to the pharmacological activities of BA, its toxicity and pharmacokinetics were also discussed in this paper.

CONCLUSION

BA has promising pharmacological properties, especially anti-inflammatory and immunomodulatory effects. It also has sedative properties and potential for use in aromatherapy. Compared to traditional NSAIDs, it has a more favorable safety profile while maintaining efficacy. BA has potential for developing novel drugs for treating various conditions.

Comparative Virucidal Activities of Essential Oils and Alcohol-Based Solutions against Enveloped Virus Surrogates: In Vitro and In Silico Analyses

The large-scale use of alcohol (OH)-based disinfectants to control pathogenic viruses is of great concern because of their side effects on humans and harmful impact on the environment. There is an urgent need to develop safe and environmentally friendly disinfectants. Essential oils (EOs) are generally recognized as safe (GRAS) by the FDA, and many exhibit strong antiviral efficacy against pathogenic human enveloped viruses. The present study investigated the virucidal disinfectant activity of solutions containing EO and OH against DENV-2 and CHIKV, which were used as surrogate viruses for human pathogenic enveloped viruses. The quantitative suspension test was used. A solution containing 12% EO + 10% OH reduced > 4.0 log10 TCID₅₀ (100% reduction) of both viruses within 1 min of exposure. In addition, solutions containing 12% EO and 3% EO without OH reduced > 4.0 log10 TCID₅₀ of both viruses after 10 min and 30 min of exposure, respectively. The binding affinities of 42 EO compounds and viral envelope proteins were investigated through docking analyses. Sesquiterpene showed the highest binding affinities (from -6.7 to -8.0 kcal/mol) with DENV-2 E and CHIKV E1-E2-E3 proteins. The data provide a first step toward defining the potential of EOs as disinfectants.

Evaluation of the Antioxidant and Antimicrobial Potential of SiO2 Modified with Cinnamon Essential Oil (Cinnamomum Verum) for Its Use as a Nanofiller in Active Packaging PLA Films

One of the main causes of food spoilage is the lipid oxidation of its components, which generates the loss of nutrients and color, together with the invasion of pathogenic microorganisms. In order to minimize these effects, active packaging has played an important role in preservation in recent years. Therefore, in the present study, an active packaging film was developed using polylactic acid (PLA) and silicon dioxide (SiO₂) nanoparticles (NPs) (0.1% w/w) chemically modified with cinnamon essential oil (CEO). For the modification of the NPs, two methods (M1 and M2) were tested, and their effects on the chemical, mechanical, and physical properties of the polymer matrix were evaluated. The results showed that CEO conferred to SiO₂ NPs had a high percentage of 2,2-diphenyl-l-picrylhydrazyl (DPPH) free radical inhibition (>70%), cell viability (>80%), and strong inhibition to E. coli, at 45 and 11 µg/mL for M1 and M2, respectively, and thermal stability. Films were prepared with these NPs, and characterizations and evaluations on apple storage were performed for 21 days. The results show that the films with pristine SiO₂ improved tensile strength (28.06 MPa), as well as Young's modulus (0.368 MPa) since PLA films only presented values of 27.06 MPa and 0.324 MPa, respectively; however, films with modified NPs decreased tensile strength values (26.22 and 25.13 MPa), but increased elongation at break (from 5.05% to 10.32-8.32%). The water solubility decreased from 15% to 6-8% for the films with NPs, as well as the contact angle, from 90.21° to 73° for the M2 film. The water vapor permeability increased for the M2 film, presenting a value of 9.50 × 10^-8 g Pa^-1 h^-1 m^-2. FTIR analysis indicated that the addition of NPs with and without CEO did not modify the molecular structure of pure PLA; however, DSC analysis indicated that the crystallinity of the films was improved. The packaging prepared with M1 (without Tween 80) showed good results at the end of storage: lower values in color difference (5.59), organic acid degradation (0.042), weight loss (24.24%), and pH (4.02), making CEO-SiO₂ a good component to produce active packaging.

Rambutan-liked Pickering emulsion stabilized by cellulose nanocrystals for enhancing anti-bacterial activity and anti-inflammatory effect of Chimonanthus nitens Oliv. essential oil

Owing to volatility and poor water solubility, the medical application of Chimonanthus nitens Oliv. essential oil (CEO) in the fields of medicine was strictly limited. To tackle this problem, a novel CEO loaded rambutan-liked Pickering emulsion (CEO-RPE) with a spiky surface was effectively designed by coating with carboxymethyl cellulose sodium modified cellulose nanocrystals (CCN) as stabilizer. The effect of CCN concentration on the formation and stabilization of CEO-RPE was investigated. The results showed that CEO-RPE stabilized by 1 % CCN had a smaller droplet size and exhibited a rambutan-liked surface, and was stabilized against concentrated salt and high pH condition due to the steric barrier of CCN that covered in the droplet surface. Subsequently, the antibacterial performance of CEO-RPE was investigated against E. coli, S. aureus, P. aeruginosa, and S. pneumoniae by determining the minimum inhibitory concentration (MIC). The results showed that the CEO-RPE exhibited higher antibacterial activity compared to CEO, which could be attributed to its effective adhesion to the cell membrane of bacteria. In addition, the results of anti-inflammatory experiments showed that CEO-RPE also exhibited strong anti-inflammatory effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats. Therefore, the CCN stabilized rambutan-liked Pickering emulsion seemed to be a promising strategy to increase the antibacterial and anti-inflammatory activity of CEO.

Botanicals: A promising approach for controlling cecal coccidiosis in poultry

Avian species have long struggled with the problem of coccidiosis, a disease that affects various parts of the intestine, including the anterior gut, midgut, and hindgut. Among different types of coccidiosis, cecal coccidiosis is particularly dangerous to avian species. Chickens and turkeys are commercial flocks; thus, their parasites have remained critical due to their economic importance. High rates of mortality and morbidity are observed in both chickens and turkeys due to cecal coccidiosis. Coccidiostats and coccidiocidal chemicals have traditionally been added to feed and water to control coccidiosis. However, after the EU banned their use because of issues of resistance and public health, alternative methods are being explored. Vaccines are also being used, but their efficacy and cost-effectiveness remain as challenges. Researchers are attempting to find alternatives, and among the alternatives, botanicals are a promising choice. Botanicals contain multiple active compounds such as phenolics, saponins, terpenes, sulfur compounds, etc., which can kill sporozoites and oocysts and stop the replication of Eimeria. These botanicals are primarily used as anticoccidials due to their antioxidant and immunomodulatory activities. Because of the medicinal properties of botanicals, some commercial products have also been developed. However, further research is needed to confirm their pharmacological effects, mechanisms of action, and methods of concentrated preparation. In this review, an attempt has been made to summarize the plants that have the potential to act as anticoccidials and to explain the mode of action of different compounds found within them.

Exploring the Mechanism of Bergamot Essential Oil against Asthma Based on Network Pharmacology and Experimental Verification

Asthma is a chronic respiratory disease. Bergamot essential oil (BEO) is extracted from the bergamot peel, which is widely used as a medicinal and food plant in China. Modern pharmacological studies have confirmed that BEO has anti-inflammatory properties, suggesting potential in treating asthma. First, the main active ingredients of BEO were detected and analyzed by gas chromatography-mass spectrometry (GC-MS). Network pharmacology methods were used to explore the possible core targets and main pathways of BEO in asthma treatment. Then ovalbumin (OVA)-induced in vivo and lipopolysaccharide (LPS)-induced in vitro models were established to investigate the antiasthmatic effects of BEO. BEO showed a good antiasthmatic effect by improving lung inflammation and inhibiting collagen deposition. Then, enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qPCR) were used to explore the possible mechanism of BEO in asthma treatment. Furthermore, experimental verification showed that BEO could suppress the release of inflammatory factors in vitro and inhibit the activation of MAPK and JAK-STAT signaling pathways. This study demonstrated the anti-inflammatory effects of BEO against asthma. Moreover, it supplies a theoretical basis for the clinical application of BEO.

In Vitro Antiviral Potential, Antioxidant, and Chemical Composition of Clove (Syzygium aromaticum) Essential Oil

Viral infections are spread all around the world. Although there are available therapies, their safety and effectiveness are constrained by their adverse effects and drug resistance. Therefore, new natural antivirals have been used such as essential oils, which are natural products with promising biological activity. Accordingly, the present study aimed to identify the components of clove (Syzygium aromaticum) essential oil (EOCa) and verify its antioxidant and antiviral activity. The oil was analyzed using GC/MS, and the antioxidant capacity was evaluated as a function of the radical scavenging activity. A plaque reduction test was used to measure the antiviral activity against herpes simplex virus (HSV-1), hepatitis A virus (HAV), and an adenovirus. GC/MS analysis confirmed the presence of eugenol as the main component (76.78%). Moreover, EOCa had powerful antioxidant activity with an IC50 of 50 µg/mL. The highest antiviral potential was found against HAV, with a selectivity index (SI) of 14.46, while showing poor selectivity toward HSV-1 with an SI value of 1.44. However, no relevant effect was detected against the adenovirus. The antiviral activity against HAV revealed that its effect was not related to host cytotoxicity. The findings imply that EOCa can be utilized to treat diseases caused by infections and free radicals.

Non-Alcohol Hand Sanitiser Gels with Mandelic Acid and Essential Oils

Antimicrobial hand gels have become extremely popular in recent years due to the COVID-19 pandemic. Frequent use of hand sanitising gel can lead to dryness and irritation of the skin. This work focuses on the preparation of antimicrobial acrylic acid (Carbomer)-based gels enhanced by non-traditional compounds-mandelic acid and essential oils-as a substitute for irritating ethanol. Physicochemical properties (pH and viscosity), stability and sensory attributes of the prepared gels were investigated. Antimicrobial activity against representative Gram-positive and Gram-negative bacteria and yeasts was determined. The prepared gels with mandelic acid and essential oil (cinnamon, clove, lemon, and thyme) proved to have antimicrobial activity and even better organoleptic properties than commercial ethanol-based antimicrobial gel. Further, results confirmed that the addition of mandelic acid had a desirable effect on gel properties (antimicrobial, consistency, stability). It has been shown that the essential oil/mandelic acid combination can be a dermatologically beneficial hand sanitiser compared to commercial products. Thus, the produced gels can be used as a natural alternative to alcohol-based daily hand hygiene sanitisers.

Virucidal Activity of Lemon Essential Oil against Feline Calicivirus Used as Surrogate for Norovirus

Norovirus (NoV) is regarded as a common cause of acute gastrointestinal illness worldwide in all age groups, with substantial morbidity across health care and community settings. The lack of in vitro cell culture systems for human NoV has prompted the use of cultivatable caliciviruses (such as feline calicivirus, FCV, or murine NoV) as surrogates for in vitro evaluation of antivirals. Essential oils (EOs) may represent a valid tool to counteract viral infections, particularly as food preservatives. In the present study, the virucidal efficacy of lemon EO (LEO) against FCV was assessed in vitro. The gas chromatography hyphenated with mass spectrometry (GC/MS) technique was used to reveal the chemical composition of LEO. The following small molecules were detected as major components of LEO: limonene (53%), β-pinene (14.5%), γ-terpinene (5.9%), citral (3.8%), α-pinene (2.4%), and β-thujene (1.94%). LEO at 302.0 μg/mL, exceeding the maximum non cytotoxic limit, significantly decreased viral titre of 0.75 log₁₀ TCID50/50 μL after 8 h. Moreover, virucidal activity was tested using LEO at 3020.00 μg/mL, determining a reduction of viral titre as high as 1.25 log₁₀ TCID50/50 μL after 8 h of time contact. These results open up perspectives for the development of alternative prophylaxis approaches for the control of NoV infection.

Antibacterial activity and metabolomic analysis of linalool against bovine mastitis pathogen Streptococcus agalactiae

Streptococcus agalactiae is among the major causative pathogens of bovine mastitis, as well as crucial pathogen leading to human morbidity and mortality. Being a promising natural antibacterial agent, linalool has been broadly applied in medicine and food processing. However, its antibacterial effect against S. agalactiae has barely been elucidated. This study is the first to investigate the antibacterial activity and action mechanism of linalool against S. agalactiae causing bovine mastitis. Linalool exhibited significant antibacterial activity against S. agalactiae, with an inhibition zone diameter of 23 mm and a minimum inhibitory concentration of 1.875 μL/mL. In addition, linalool damaged cell structural integrity of S. agalactiae, leading to the leakage of intracellular components (alkaline phosphatase, nucleic acids and protein). Linalool also exhibited a scavenging effect on biofilm. Moreover, untargeted metabolomics analysis revealed that linalool stress substantially disrupted intracellular metabolism of S. agalactiae. Linalool caused energy metabolism disorder, and obstructed nucleic acid synthesis in S. agalactiae. Furthermore, downregulation of amino acids (e.g., proline, alanine) and upregulation of saturated fatty acids provide strong evidence for linalool induced cell wall and membrane damage. Overall, linalool exhibited strong antibacterial activity against S. agalactiae by destroying the cell structure and disrupting intracellular metabolism. This study provides a new insight and theoretical foundation for linalool application in preventing S. agalactiae infection.

Screening and Validation of Odorants against Influenza A Virus Using Interpretable Regression Models

Influenza is a respiratory infection caused by the influenza virus that is prevalent worldwide. One of the most contagious variants of influenza is influenza A virus (IAV), which usually spreads in closed spaces through aerosols. Preventive measures such as novel compounds are needed that can act on viral membranes and provide a safe environment against IAV infection. In this study, we screened compounds with common fragrances that are generally used to mask unpleasant odors but can also exhibit antiviral activity against a strain of IAV. Initially, a set of 188 structurally diverse odorants were collected, and their antiviral activity was measured in vapor phase against the IAV solution. Regression models were built for the prediction of antiviral activity using this set of odorants by taking into account their structural features along with vapor pressure and partition coefficient (n-octanol/water). The models were interpreted using a feature weighting approach and Shapley Additive exPlanations to rationalize the predictions as an additional validation for virtual screening. This model was used to screen odorants from an in-house odorant data set consisting of 2020 odorants, which were later evaluated using in vitro experiments. Out of 11 odorants proposed using the final model, 8 odorants were found to exhibit antiviral activity. The feature interpretation of screened odorants suggested that they contained hydrophilic substructures, such as hydroxyl group, which might contribute to denaturation of proteins on the surface of the virus. These odorants should be explored as a preventive measure in closed spaces to decrease the risk of infections of IAV.

Role of ethno-phytomedicine knowledge in healthcare of COVID-19: advances in traditional phytomedicine perspective

Background

Since the outbreak of the COVID-19 virus, ethnomedicinal plants have been used in diverse geographical locations for their purported prophylactic and pharmacological effects. Medicinal plants have been relied on by people around the globe for centuries, as 80% of the world’s population rely on herbal medicines for some aspect of their primary health care needs, according to the World Health Organization.

Main body

This review portrays advances in traditional phytomedicine by bridging the knowledge of ethno-phytomedicine and COVID-19 healthcare. Ethnomedicinal plants have been used for symptoms related to COVID-19 as antiviral, anti-infective, anti-inflammatory, anti-oxidant, antipyretic, and lung–gut immune boosters. Traditionally used medicinal plants have the ability to inhibit virus entry and viral assembly, bind to spike proteins, membrane proteins, and block viral replications and enzymes. The efficacy of traditional medicinal plants in the terms of COVID-19 management can be evaluated by in vitro, in vivo as well as different in silico techniques (molecular docking, molecular dynamics simulations, machine learning, etc.) which have been applied extensively to the quest and design of effective biotherapeutics rapidly. Other advances in traditional phytomedicines against COVID-19 are controlled clinical trials, and notably the roles in the gut microbiome. Targeting the gut microbiome via medicinal plants as prebiotics is also found to be an alternative and potential strategy in the search for a COVID-19 combat strategy.

Conclusions

Since medicinal plants are the sources of modern biotherapeutics development, it is essential to build collaborations among ethnobotanists, scientists, and technologists toward developing the most efficient and the safest adjuvant therapeutics against the pandemic of the twenty-first century, COVID-19.

Essential oils block cellular entry of SARS-CoV-2 delta variant

Aiming to fill a gap in the literature, we aimed to identify the most promising EOs blocking in vitro cellular entry of SARS-CoV-2 delta variant without conferring human cytotoxicity and provide insights into the influence of their composition on these activities. Twelve EOs were characterized by gas chromatography coupled to mass spectrometry. The antiviral and cytotoxicity activities were determined using the cell-based pseudoviral entry with SARS-CoV-2 delta pseudovirus and the XTT assay in HeLa cells expressing human angiotensin-converting enzyme 2 (HeLa ACE-2), respectively. Syzygium aromaticum, Cymbopogon citratus, Citrus limon, Pelargonium graveolens, Origanum vulgare, "Illicium verum", and Matricaria recutita showed EC₅₀ lowered or close to 1 µg/mL but also the lowest CC₅₀ (0.20-1.70 µg/mL), except "I. verum" (30.00 µg/mL). Among these, "I. verum", C. limon, P. graveolens and S. aromaticum proved to be promising alternatives for SARS-CoV-2 delta variant inhibition (therapeutic index above 4), which possibly was related to the compounds (E)-anetole, limonene and beta-pinene, citronellol, and eugenol, respectively.

Plant Nanovesicles for Essential Oil Delivery

Essential oils' therapeutic potential is highly recognized, with many applications rising due to reported anti-inflammatory, cardioprotective, neuroprotective, anti-aging, and anti-cancer effects. Nevertheless, clinical translation still remains a challenge, mainly due to essential oils' volatility and low water solubility and stability. The present review gathers relevant information and postulates on the potential application of plant nanovesicles to effectively deliver essential oils to target organs. Indeed, plant nanovesicles are emerging as alternatives to mammalian vesicles and synthetic carriers due to their safety, stability, non-toxicity, and low immunogenicity. Moreover, they can be produced on a large scale from various plant parts, enabling an easier, more rapid, and less costly industrial application that could add value to waste products and boost the circular economy. Importantly, the use of plant nanovesicles as delivery platforms could increase essential oils' bioavailability and improve chemical stability while reducing volatility and toxicity issues. Additionally, using targeting strategies, essential oils' selectivity, drug delivery, and efficacy could be improved, ultimately leading to dose reduction and patient compliance. Bearing this in mind, information on current pharmaceutical technologies available to enable distinct routes of administration of loaded vesicles is also discussed.

A Plant Worthy of Further Study-Volatile and Non-Volatile Compounds of Portenschlagiella ramosissima (Port.) Tutin and Its Biological Activity

New and detailed data are presented on the phytochemical composition of the volatile and non-volatile organic compounds of the Mediterranean endemic species Portenschlagiella ramosissima (Port.) Tutin. Both the essential oil and hydrosol were obtained from the air-dried plant by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The volatile compounds from the fresh and air-dried plants and from the hydrosol were isolated for the first time by headspace solid-phase microextraction using two fibres of different polarity. The benzene derivative group was the predominant group in all samples, with myristicin being the most abundant component of all. The non-volatile compounds of the methanol extract were analyzed by ultra-high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionisation, and three flavonoid glycosides, one anthocyanidin glycoside, and lipid derivatives were detected. Both the chemical composition and biological activities of this plant have been described in a very limited number of publications, making it an interesting source for further study. The antiphytoviral activity of the essential oil and hydrosol showed that both extracts significantly reduced the number of lesions on the leaves of local host plants infected with tobacco mosaic virus. Moderate antiproliferative activity of the methanol extract was detected in three cancer cell lines, cervical cancer cell line, human colon cancer cell line and human osteosarcoma cell line, using the MTS-based cell proliferation assay. Based on the results, we highlight this plant as a new source of bioactive compounds and natural phytotherapeutic agent that deserves further investigation.

Essential Oils and Their Compounds as Potential Anti-Influenza Agents

Essential oils (EOs) are chemical substances, mostly produced by aromatic plants in response to stress, that have a history of medicinal use for many diseases. In the last few decades, EOs have continued to gain more attention because of their proven therapeutic applications against the flu and other infectious diseases. Influenza (flu) is an infectious zoonotic disease that affects the lungs and their associated organs. It is a public health problem with a huge health burden, causing a seasonal outbreak every year. Occasionally, it comes as a disease pandemic with unprecedentedly high hospitalization and mortality. Currently, influenza is managed by vaccination and antiviral drugs such as Amantadine, Rimantadine, Oseltamivir, Peramivir, Zanamivir, and Baloxavir. However, the adverse side effects of these drugs, the rapid and unlimited variabilities of influenza viruses, and the emerging resistance of new virus strains to the currently used vaccines and drugs have necessitated the need to obtain more effective anti-influenza agents. In this review, essential oils are discussed in terms of their chemistry, ethnomedicinal values against flu-related illnesses, biological potential as anti-influenza agents, and mechanisms of action. In addition, the structure-activity relationships of lead anti-influenza EO compounds are also examined. This is all to identify leading agents that can be optimized as drug candidates for the management of influenza. Eucalyptol, germacrone, caryophyllene derivatives, eugenol, terpin-4-ol, bisabolene derivatives, and camphecene are among the promising EO compounds identified, based on their reported anti-influenza activities and plausible molecular actions, while nanotechnology may be a new strategy to achieve the efficient delivery of these therapeutically active EOs to the active virus site.

Elsholtzia: A genus with antibacterial, antiviral, and anti-inflammatory advantages

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Elsholtzia (family Labiaceae) is an important source of folk traditional Chinese medicine, mainly used to relieve the symptoms of cold, fever, pneumonia and so on. However, currently available data on its traditional and pharmacological advantages have not been comprehensively reviewed.

AIM OF THE REVIEW

This review provides up-to-date and comprehensive information on the ethnopharmacological, phytochemical, pharmacological properties and toxicity of Elsholtzia, highlights the antibacterial, antiviral, and anti-inflammatory advantages of the genus, and explores its therapeutic potential.

MATERIALS AND METHODS

Use Google Scholar, Scifinder, PubMed, Springer, Elsevier, Wiley, Web of Science and other online database search to collect the research literatures on application, chemistry and biological activity of Elsholtzia published before December 2021. Their scientific names have been verified using The Plant List and World Flora Online websites.

RESULTS

A total of 42 species of Elsholtzia are widely distributed all over the world, especially in Yunnan Province (China). Since Elsholtzia genus is commonly used in the folk to treat respiratory infectious diseases such as cold and fever, growing numbers of studies have confirmed their antiviral, antibacterial and anti-inflammatory activities. So far, about 221 non-volatile compounds and 1008 volatile compounds have been identified from Elsholtzia plants, mainly containing flavonoids and terpenoids showing convincing antibacterial, antiviral and anti-inflammatory activities. Further research found that their antibacterial and antiviral spectrums are broad, and volatile oils are considered to be the main antibacterial components. Their anti-inflammatory mechanism is mainly through the inhibition of NF-κB and MAPKs signaling pathways. Toxicological studies have not established its toxicity.

CONCLUSIONS

By summarizing the latest information on genus Elsholtzia, their traditional uses, material basis and mechanisms of action in antiviral, antibacterial and anti-inflammatory aspects were described, providing new insights for the genus and its importance as a potential natural resource of antiviral and anti-inflammatory drugs, giving evidence and new ideas for the development of herbal medicines.

Essential Oils from Colombian Plants: Antiviral Potential against Dengue Virus Based on Chemical Composition, In Vitro and In Silico Analyses

Currently, there are no therapies to prevent severe dengue disease. Essential oils (EOs) can serve as primary sources for research and the discovery of phytomedicines for alternative therapy. Fourteen EOs samples were obtained by distillation from six plants used in Colombian folk medicine. GC/MS analysis identified 125 terpenes. Cytopathic effect (CPE) reduction assays revealed differences in antiviral activity. EOs of Lippia alba, citral chemotype and carvone-rich fraction; Lippia origanoides, phellandrene chemotype; and Turnera diffusa, exhibited strong antiviral activity (IC50: 29 to 82 µg/mL; SI: 5.5 to 14.3). EOs of Piper aduncum, Ocimum basilicum, and L. origanoides, carvacrol, and thymol chemotypes, exhibited weak antiviral activity (32 to 53% DENV-CPE reduction at 100 µg/mL; SI > 5.0). Cluster and one-way ANOVA analyses suggest that the strong antiviral activity of EOs could be attributed to increased amounts of non-phenolic oxygenated monoterpenes and sesquiterpene hydrocarbons. Docking analyses (AutoDock Vina) predicted binding affinity between the DENV-2 E protein and terpenes: twenty sesquiterpene hydrocarbons (−8.73 to −6.91 kcal/mol), eight oxygenated monoterpenes (−7.52 to −6.98 kcal/mol), and seven monoterpene hydrocarbons (−7.60 to −6.99 kcal/mol). This study reports for the first time differences in the antiviral activity of EOs against DENV, corresponding to their composition of monoterpenes and sesquiterpenes.

Development of propolis and essential oils containing oral/throat spray formulation against SARS-CoV-2 infection

A broad range of evidence has confirmed that natural products and essential oils might have the potential to suppress COVID-19 infection. Therefore, this study aimed to develop an oral/throat spray formulation for prophylactic use in the oral cavity or help treatment modalities. Based on a reference survey, several essential oils, a cold-pressed oil, and propolis were selected, and cytotoxicity and antiviral activity of each component and the developed spray formulation were examined against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection using Vero E6 cells. Anti-inflammatory, antimicrobial, and analgesic activities as well as mutagenicity and anti-mutagenicity of the formulation were analysed. Forty-three phenolics were identified in both propolis extract and oral/throat spray. The spray with 1:640-fold dilution provided the highest efficacy and the cytopathic effect was delayed for 54 h at this dilution, and the antiviral activity rate was 85.3%. A combination of natural products with essential oils at the right concentrations can be used as a supplement for the prevention of SARS-CoV-2 infection.

Essential Oils as Multicomponent Mixtures and Their Potential for Human Health and Well-Being

Essential oils (EOs) and their individual volatile organic constituents have been an inherent part of our civilization for thousands of years. They are widely used as fragrances in perfumes and cosmetics and contribute to a healthy diet, but also act as active ingredients of pharmaceutical products. Their antibacterial, antiviral, and anti-inflammatory properties have qualified EOs early on for both, the causal and symptomatic therapy of a number of diseases, but also for prevention. Obtained from natural, mostly plant materials, EOs constitute a typical example of a multicomponent mixture (more than one constituent substances, MOCS) with up to several hundreds of individual compounds, which in a sophisticated composition make up the property of a particular complete EO. The integrative use of EOs as MOCS will play a major role in human and veterinary medicine now and in the future and is already widely used in some cases, e.g., in aromatherapy for the treatment of psychosomatic complaints, for inhalation in the treatment of respiratory diseases, or topically administered to manage adverse skin diseases. The diversity of molecules with different functionalities exhibits a broad range of multiple physical and chemical properties, which are the base of their multi-target activity as opposed to single isolated compounds. Whether and how such a broad-spectrum effect is reflected in natural mixtures and which kind of pharmacological potential they provide will be considered in the context of ONE Health in more detail in this review.

Preprocedural mouth rinses for preventing transmission of infectious diseases through aerosols in dental healthcare providers

BACKGROUND

Aerosols and spatter are generated in a dental clinic during aerosol-generating procedures (AGPs) that use high-speed hand pieces. Dental healthcare providers can be at increased risk of transmission of diseases such as tuberculosis, measles and severe acute respiratory syndrome (SARS) through droplets on mucosae, inhalation of aerosols or through fomites on mucosae, which harbour micro-organisms. There are ways to mitigate and contain spatter and aerosols that may, in turn, reduce any risk of disease transmission. In addition to personal protective equipment (PPE) and aerosol-reducing devices such as high-volume suction, it has been hypothesised that the use of mouth rinse by patients before dental procedures could reduce the microbial load of aerosols that are generated during dental AGPs.

OBJECTIVES

To assess the effects of preprocedural mouth rinses used in dental clinics to minimise incidence of infection in dental healthcare providers and reduce or neutralise contamination in aerosols.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 4 February 2022.

SELECTION CRITERIA

We included randomised controlled trials and excluded laboratory-based studies. Study participants were dental patients undergoing AGPs. Studies compared any preprocedural mouth rinse used to reduce contaminated aerosols versus placebo, no mouth rinse or another mouth rinse. Our primary outcome was incidence of infection of dental healthcare providers and secondary outcomes were reduction in the level of contamination of the dental operatory environment, cost, change in mouth microbiota, adverse events, and acceptability and feasibility of the intervention.

DATA COLLECTION AND ANALYSIS

Two review authors screened search results, extracted data from included studies, assessed the risk of bias in the studies and judged the certainty of the available evidence. We used mean differences (MDs) and 95% confidence intervals (CIs) as the effect estimate for continuous outcomes, and random-effects meta-analysis to combine data  MAIN RESULTS:  We included 17 studies with 830 participants aged 18 to 70 years. We judged three trials at high risk of bias, two at low risk and 12 at unclear risk of bias.  None of the studies measured our primary outcome of the incidence of infection in dental healthcare providers.  The primary outcome in the studies was reduction in the level of bacterial contamination measured in colony-forming units (CFUs) at distances of less than 2 m (intended to capture larger droplets) and 2 m or more (to capture droplet nuclei from aerosols arising from the participant's oral cavity). It is unclear what size of CFU reduction represents a clinically significant amount. There is low- to very low-certainty evidence that chlorhexidine (CHX) may reduce bacterial contamination, as measured by CFUs, compared with no rinsing or rinsing with water. There were similar results when comparing cetylpyridinium chloride (CPC) with no rinsing and when comparing CPC, essential oils/herbal mouthwashes or boric acid with water. There is very low-certainty evidence that tempered mouth rinses may provide a greater reduction in CFUs than cold mouth rinses. There is low-certainty evidence that CHX may reduce CFUs more than essential oils/herbal mouthwashes. The evidence for other head-to-head comparisons was limited and inconsistent.  The studies did not provide any information on costs, change in micro-organisms in the patient's mouth or adverse events such as temporary discolouration, altered taste, allergic reaction or hypersensitivity. The studies did not assess acceptability of the intervention to patients or feasibility of implementation for dentists.  AUTHORS' CONCLUSIONS: None of the included studies measured the incidence of infection among dental healthcare providers. The studies measured only reduction in level of bacterial contamination in aerosols. None of the studies evaluated viral or fungal contamination. We have only low to very low certainty for all findings. We are unable to draw conclusions regarding whether there is a role for preprocedural mouth rinses in reducing infection risk or the possible superiority of one preprocedural rinse over another. Studies are needed that measure the effect of rinses on infectious disease risk among dental healthcare providers and on contaminated aerosols at larger distances with standardised outcome measurement.

Antioxidant and Immunomodulatory Activities of Essential Oil Isolated from Anti-Upper Respiratory Tract Infection Formulation and Their Chemical Analysis

This study evaluates the in vitro antioxidant and immunomodulation activities of essential oils isolated from an anti-upper respiratory tract infection (URTI) formulation with a view to their therapeutic potential. The chemical components of the essential oil were analysed by gas chromatography-mass spectrometry (GC-MS). The antioxidative activity of the oils was investigated with regard to their ability to scavenge DPPH●, ABTS●+, and hydroxyl free radical (•OH). Their immunostimulatory activities were determined using murine macrophage cells. The main components of the oil with pharmacological and biological activities include 1,8-eucalyptol (42.9%), patchouli alcohol (19.9%), trans-erinolide (9.2%), and guaiacol (5%). The oils displayed high DPPH, ABTS, and hydroxyl radical scavenging activities and anti-inflammatory activities by reducing tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production. The results indicate that essential oils have the potential to be used in products for anti-URTI treatment.

Anti-Coronavirus Efficiency and Redox-Modulating Capacity of Polyphenol-Rich Extracts from Traditional Bulgarian Medicinal Plants

Background: The use of various herbal therapists as part of traditional medicine in different parts of the world, including Bulgaria, is due to the knowledge accumulated over the centuries by people about their valuable biological activities. In this study, we investigate extracts from widely used Bulgarian medicinal plants for their ability to prevent the coronavirus infection of cells by testing different mechanisms of antiviral protection, their polyphenol content, and redox-modulating capacity. Methods: The influence on the stage of viral adsorption, the inhibition of extracellular virions, and the protective effect on uninfected cells of the plant’s extracts were reported by the end-point dilution method, and virus titer (in Δ lgs) was determined as compared to the untreated controls. The total content of polyphenols and flavonoids was also determined. We tested the antioxidant power of the extracts by their ability to inhibit the generation of superoxide anionic radicals and to scavenge DPPH radicals. We determined their iron-reducing, copper-reducing, and metal-chelating antioxidant powers. Results: Most of the extracts tested suppress the extracellular virions of HCov. They also inhibit the stage of viral adsorption to the host cell to varying degrees and have a protective effect on healthy cells before being subjected to viral invasion. The examined extracts contained significant levels of polyphenols and quercetin-like flavonoids and showed remarkable antioxidant, radical, and redox-modulating effects. Conclusions: All of these 13 extracts from Bulgarian medicinal plants tested can act as antioxidants and antiviral and symptomatic drugs for the management of coronavirus infection.

Preliminary Study on Phytochemical Constituents and Biological Activities of Essential Oil from Myriactis nepalensis Less

In response to the need for novel therapeutic strategies to combat the development of microbial resistance, plant essential oils may represent a promising alternative source. This study set out to characterize the chemical composition and assess the antibacterial potential of Myriactis nepalensis Less. essential oil (MNEO). Essential oil isolated from M. nepalensis by hydrodistillation was analyzed using a GC–MS technique. The antibacterial properties of MNEO alone and combined with antibiotics (chloramphenicol and streptomycin) were tested via the disc diffusion, microbroth dilution, and checkerboard methods. MNEO was represented by oxygenated sesquiterpenes (60.3%) and sesquiterpene hydrocarbons (28.6%), with caryophyllene oxide, spathulenol, humulene epoxide II, β-elemene, neointermedeol, and β-caryophyllene as the main compounds. MNEO exhibited a strong antibacterial effect against Gram-positive bacteria, with MIC and MBC values of 0.039 mg/mL and 0.039–0.156 mg/mL, respectively, and synergistic effects were observed in both combinations with chloramphenicol and streptomycin. Furthermore, the antibiofilm and cytotoxic activities of MNEO were also evaluated. The crystal violet assay was used for quantification of Staphylococcus aureus biofilm formation, and an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was conducted to determine cell viability. The results revealed MNEO could dose-dependently inhibit Staphylococcus aureus biofilm formation and possessed potential cytotoxic on both normal and cancer cells (IC50 values from 13.13 ± 1.90 to 35.22 ± 8.36 μg/mL). Overall, the results indicate that MNEO may have promising applications in the field of bacterial infections.

Potential Use of Tea Tree Oil as a Disinfectant Agent against Coronaviruses: A Combined Experimental and Simulation Study

The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.

Quantitative Removal of Pyrrolizidine Alkaloids from Essential Oils by the Hydrodistillation Step in Their Manufacturing Process

Pyrrolizidine alkaloids are naturally occurring toxins produced by certain weeds that can, if accidentally co-harvested, contaminate plant-based food, feed, and herbal medicinal products. Focusing on herbal medicinal products, the presence of pyrrolizidine alkaloids is restricted by regulatory prescribed thresholds to assure patient safety. Among the multitude of different herbal active substances utilized in herbal medicinal products, the class of pharmaceutically effective essential oils is considered to exhibit a negligible contribution to pyrrolizidine alkaloid contamination. Within the present investigation, this hypothesis should be scientifically scrutinized. For this purpose, an experimental set-up was chosen that reproduces the typical manufacturing step of hydrodistillation. Essential oils of eucalyptus and lemon were selected exemplarily and spiked with 3 representative pyrrolizidine alkaloids (retrorsine, retrorsine-N-oxide, and lycopsamine), whereupon hydrodistillation was performed. Analysis of the resulting distillates by LC-MS/MS proved that artificially added pyrrolizidine alkaloids were removed completely. Moreover, quantitative pyrrolizidine alkaloid recovery in the aqueous phases was observed. Hence, it was experimentally confirmed that herbal medicinal products employing hydrodistilled essential oils of pharmaceutical quality are intrinsically free of pyrrolizidine alkaloids due to the particularities of their manufacturing process. Furthermore, it can be concluded from theoretical considerations that essential oils produced by cold pressing have a negligible risk of carrying pyrrolizidine alkaloid contamination. Our findings provide a strong indication that the requirement for analytical pyrrolizidine alkaloid testing of essential oils for pharmaceutical use should be fundamentally reconsidered.

Preparation and characterization of oregano essential oil-loaded Dioscorea zingiberensis starch film with antioxidant and antibacterial activity and its application in chicken preservation

In this study, abundant starch was separated from the industrial crop Dioscorea zingiberensis C.H. Wright (DZW), and a novel bioactive packaging film loaded with oregano essential oil (OEO) was prepared and characterized. NaClO solution worked as a bleacher to prepare uniform starch powder from DZW tubers. OEO was selected from among three essential oils of Labiatae family plants for its strongest antibacterial activity. After the addition of OEO into the starch-based film, the UV-vis shielding property and antioxidant activity were enhanced. Meanwhile, the films still have a considerable performance in transparency, mechanical strength and water vapor permeability after incorporated with OEO. Furthermore, the 3% OEO-loaded starch film exhibited the strongest antibacterial activity against Bacillus subtilis, Escherichia coli and Staphylococcus aureus. It effectively lowered the total viable count of fresh chicken under 4 °C preservation conditions. These results revealed that the OEO-loaded DZW starch film can exert a positive effect on maintaining the quality and extending the shelf life of fresh meat. Therefore, readily accessible DZW tubers and oregano are very promising resources for application in degradable bioactive packaging film.

Antiviral Activity of Selected Lamiaceae Essential Oils and Their Monoterpenes Against SARS-Cov-2

This study presents the very first report on the in vitro antiviral activity of selected essential oils of Lamiaceae plant species and their monoterpenes against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nineteen essential oils were obtained by hydrodistillation of dried plant material, and their monoterpene profiles were determined. In addition, the exact concentrations of each monoterpene that were found at a significant level were defined. Both essential oils and their monoterpene components were tested for cytotoxic and antiviral activity against SARS-CoV-2 in infected Vero 76 cells. The results showed that the essential oils of four Mentha species, i.e., M. aquatica L. cv. Veronica, M. pulegium L., M. microphylla K.Koch, and M. x villosa Huds., but also Micromeria thymifolia (Scop.) Fritsch and Ziziphora clinopodioides Lam., and five different monoterpenes, i.e., carvacrol, carvone, 1,8-cineol, menthofuran, and pulegone, inhibited the SARS-CoV-2 replication in the infected cells. However, the antiviral activity varied both among essential oils and monoterpenes. Carvone and carvacrol exhibited moderate antiviral activity with IC50 concentrations of 80.23 ± 6.07 μM and 86.55 ± 12.73 μM, respectively, while the other monoterpenes were less active (IC50 > 100.00 μM). Structure-activity relations of related monoterpenes showed that the presence of keto and hydroxyl groups is associated with the activity of carvone and carvacrol, respectively. Furthermore, the carvone-rich essential oil of M. x villosa had the greatest activity among all active essential oils (IC50 127.00 ± 4.63 ppm) while the other active oils exhibited mild (140 ppm < IC50 < 200 ppm) to weak antiviral activity (IC50 > 200 ppm). Both essential oils and monoterpenes showed limited or no cytotoxicity against Vero 76 cells. Hierarchical cluster analysis showed that the differences in the antiviral activity of essential oils were directly attributed to the antiviral efficacies of their particular single monoterpenes. The findings presented here on the novel antiviral property of plant essential oils and monoterpenes might be used in the development of different measures against SARS-CoV-2.

Heracleum persicum Essential Oil Nanoemulsion: A Nanocarrier System for the Delivery of Promising Anticancer and Antioxidant Bioactive Agents

Essential oils are important compounds for the prevention and/or treatment of various diseases in which solubility and bio-accessibility can be improved by nanoemulsion systems. Heracleum persicum oil nanoemulsion (HAE-NE) was prepared and biological properties were investigated against human breast cancer cells and normal human fibroblasts foreskin. Particle size, zeta potential and poly dispersity index were 153 nm, −47.9 mV and 0.35, respectively. (E)anethole (57.9%), terpinolene (13.8%), ɣ-terpinene (8.1%), myrcene (6.8%), hexyl butyrate (5.2%), octyl butanoate (4.5%) and octyl acetate (3.7%) was detected in nanoemulsion. Proliferation of cancer cells at IC50 = 2.32 μg/mL was significantly (p < 0.05) inhibited, and cell migration occurred at 1.5 μL/mL. The HAE-NE at 1.5, 2.5 and 3.5 µg/concentration up-regulated caspase 3 and enhanced sub-G1 peak of cell cycle with nil cytotoxic effects in the liver, kidney and jejunum of mice. Villus height, villus width, crypt depth and goblet cells in mice group fed with 10 and 20 mg/kg body weight of HAE-NE improved. Cellular redox state in the liver indicated 10 and 20 mg/kg body weight of nanoemulsion significantly up-regulated the expression of SOD, CAT and GPx genes. Heracleum persicum oil nanoemulsion could be an eco-friendly nanotherapeutic option for pharmaceutical, cosmetological and food applications.