Essential Oils and Their Natural Active Compounds Presenting Antifungal Properties

Antifungal Mechanism of Ruta graveolens Essential Oil: A Colombian Traditional Alternative against Anthracnose Caused by Colletotrichum gloeosporioides

Here, we report for the first time on the mechanisms of action of the essential oil of Ruta graveolens (REO) against the plant pathogen Colletotrichum gloeosporioides. In particular, the presence of REO drastically affected the morphology of hyphae by inducing changes in the cytoplasmic membrane, such as depolarization and changes in the fatty acid profile where straight-chain fatty acids (SCFAs) increased by up to 92.1%. In addition, REO induced changes in fungal metabolism and triggered apoptosis-like responses to cell death, such as DNA fragmentation and the accumulation of reactive oxygen species (ROS). The production of essential enzymes involved in fungal metabolism, such as acid phosphatase, β-galactosidase, β-glucosidase, and N-acetyl-β-glucosaminidase, was significantly reduced in the presence of REO. In addition, C. gloeosporioides activated naphthol-As-BI phosphohydrolase as a mechanism of response to REO stress. The data obtained here have shown that the essential oil of Ruta graveolens has a strong antifungal effect on C. gloeosporioides. Therefore, it has the potential to be used as a surface disinfectant and as a viable replacement for fungicides commonly used to treat anthracnose in the postharvest testing phase.

Surface-Charge Tuned Polymeric Nanoemulsions for Carvacrol Delivery in Interkingdom Biofilms

Biofilms, intricate microbial communities entrenched in extracellular polymeric substance (EPS) matrices, pose formidable challenges in infectious disease treatment, especially in the context of interkingdom biofilms prevalent in the oral environment. This study investigates the potential of carvacrol-loaded biodegradable nanoemulsions (NEs) with systematically varied surface charges─cationic guanidinium (GMT-NE) and anionic carboxylate (CMT-NE). Zeta potentials of +25 mV (GMT-NE) and -33 mV (CMT-NE) underscore successful nanoemulsion fabrication (∼250 nm). Fluorescent labeling and dynamic tracking across three dimensions expose GMT-NE's superior diffusion into oral biofilms, yielding a robust antimicrobial effect with 99.99% killing for both streptococcal and Candida species and marked reductions in bacterial cell viability compared to CMT-NE (∼4-log reduction). Oral mucosa tissue cultures affirm the biocompatibility of both NEs with no morphological or structural changes, showcasing their potential for combating intractable biofilm infections in oral environment. This study advances our understanding of NE surface charges and their interactions within interkingdom biofilms, providing insights crucial for addressing complex infections involving bacteria and fungi in the demanding oral context.

Natural products of plant origin: an emerging therapeutic for dermatomycosis

Dermatomycosis or superficial mycosis is considered one of the chronic fungal infections and a global challenge for the public health system. The severity of dermatomycosis is proportionately increasing with the emerging population of immunocompromised individuals, and it is becoming more prevalent, even life-threatening, in several tropical countries. In this context, improper long-term treatment with synthetic antifungal drugs and their related side effects imposes additional challenges in treating dermatomycosis. Thus, the present scenario highlights the need for a novel and accurate treatment with minimal or no side effects. The multifaceted therapeutic properties of various natural products have garnered the interest of scientific communities in recent years. Generally, plant-based products have low toxicity levels and offer diverse formulations and unique biomolecules for clinical applicability against dermatomycosis. Thus, this study presents an overview of the pathogenesis and different treatment strategies for dermatomycosis. In addition, we highlight the implementation of natural products of plant origin for treating dermatomycosis infections and reducing adverse events. Further, their mode of action and role in the development of pharmaceutical drugs are discussed.

Extracellular phospholipase production by Malassezia pachydermatis strains and its inhibition by selected antimycotics and plant essential oil components

Extracellular phospholipase (EPL) plays an important role in the pathogenesis of the yeast Malassezia pachydermatis. Currently, the attention of researchers is focused on studying the virulence factors involved in this process and searching solutions to reduce their activity. One of the options is the use of natural remedies as anti-virulence agents. This study is aimed at investigating the production of extracellular phospholipase in M. pachydermatis strains (18 samples) and followed by the time-dependent inhibitory effect of selected azole antifungals (itraconazole, posaconazole and voriconazole) and plant essential oil components (terpinen-4-ol, thymol, carvacrol, eugenol and geraniol), evaluated by Egg Yolk Agar plate method. Almost all strains (17 isolates, (94.4%) were found to be intense EPL producers. A significant, time-dependent inhibition of EPL was noted after 1-, 3- and 6-h exposure of Malassezia cells to itraconazole (26.4%, 47.2% and 50.9%, respectively) compared to exposure to posaconazole (26.4%, 28.3% and 28.3%, respectively) and voriconazole (18.8%, 20.8% and 35.8%, respectively). After one-hour exposure to plant essential oil components, the best inhibitory effect was recorded for eugenol (62.3%), followed by terpinen-4-ol and thymol (56.6%), geraniol (41.5%) and carvacrol (26.4%). A 3-h exposure revealed that thymol retained the best inhibitory effect (88.7%) on EPL production, followed by carvacrol (73.6%), eugenol (56.6%), terpinen-4-ol (52.8%) and geraniol (49.1%). After 6-h exposure, no growth of M. pachydermatis strains exposed to carvacrol was observed, and the inhibitory efficiency for the other tested essential oil (EO) components achieved 88.7%. The obtained results indicate the promising efficacy of plant essential oils components in the inhibition of virulence factors such as EPL production.

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.

Nature-Derived Gelatin-Based Antifungal Nanotherapeutics for combatting Candida albicans Biofilms

Infections caused by fungi are emerging global health challenges that are exacerbated by the formation of fungal biofilms. Further challenges arise from environmental contamination with antifungal agents, which promotes environmental acquisition of antifungal resistance. We report the generation of an efficient, sustainable, all-natural antifungal nanotherapeutic based on the integration of an antimicrobial natural essential oil into a gelatin-based nanoemulsion platform. Carvacrol-loaded gelatin nanoemulsions penetrated Candida albicans biofilms, resulting in death of C. albicans cells in biofilms, and displayed selective biofilm elimination without harmful effects on fibroblast cells in a fungal biofilm-mammalian fibroblast co-culture model. Furthermore, the nanoemulsions degraded in the presence of physiologically relevant biomolecules, reducing the potential for environmental pollution and ecotoxicity. Overall, the sustainability, and efficacy of the described gelatin nanoemulsion formulation provides an environmentally friendly strategy for treating biofilm-associated fungal infections, including those caused by drug-resistant fungi.

Formulation and Development of a Herbal Antifungal Gel Containing Origanum vulgare and Syzygium aromaticum Essential Oils Against Oral Candida albicans

Background Oral candidiasis is the most prevalent oral fungal infection, and existing antifungal agents have side effects such as drug intolerance, resistance, and toxicity. Herbal essential oils are emerging as an alternative therapeutic approach for treating fungal infections. Origanum vulgare (O. vulgare), commonly known as oregano, and Syzygium aromaticum (S. aromaticum), commonly known as clove, are known to have antifungal properties and are effective against fluconazole-resistant strains. A combination of essential oils has a synergistic effect and aids in achieving effective antifungal activity at sufficiently low concentrations, which could lead to reduced side effects and resistance. Aim of the study This study aimed to formulate and develop an herbal antifungal gel containing O. vulgare and S. aromaticum and evaluate its synergistic antifungal efficacy against oral Candida albicans (C. albicans). Methodology Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) determinations of O. vulgare and S. aromaticum essential oils were performed individually and in combination to assess the antifungal activity against C. albicans. Based on the obtained MIC and MFC of essential oils in combination, an herbal antifungal gel was formulated. Further, to determine the biocompatible nature of the gel, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed. Results We found that a combination of O. vulgare and S. aromaticum essential oils showed antifungal activity at a lesser concentration, with a MIC of 0.19 μl/ml and MFC of 0.39 μl/ml when compared to their individual concentrations. Based on our results, an antifungal herbal gel comprising a concentration of 0.6 μl/ml of both essential oils was developed to achieve synergistic antifungal activity against oral C. albicans. The MTT assay of the herbal gel did not show any cytotoxicity. Conclusion The novel herbal antifungal gel containing O. vulgare and S. aromaticum is biocompatible in nature and provides an alternative therapeutic approach for treating oral candidiasis.

Use of Nile tilapia (Oreocromis niloticus) processing residues in the production of pâtés with the addition of oregano (Origanum vulgare) essential oil

The effect of the use of Nilo tilapia filleting residues in the production of pâtés with the addition of oregano essential oil stored for 90 days at 4 °C was evaluated. For that, 5 treatments were performed as follows: TSA-control treatment; TES with the addition of sodium erythorbate; and formulation TOE1 with 600 ppm oregano essential oil; TOE2 with 1000 ppm essential oil; and TOE3 with 1400 ppm essential oil. The pâtés showed adequate technological and physicochemical characteristics and microbiological counts within the legislation standards. No significant differences were observed in the luminosity of the pâté formulations during storage, and the addition of oil contributed to the increase in a* values and stability of b* values. Regarding the lipid and protein oxidation, TOE3 showed lower values at the end of the shelf-life. The addition of essential oil did not affect the hardness and cohesiveness of the products. The fatty acids in greater amounts in the samples were linoleic, oleic, palmitic, and stearic acids. The analysis of biogenic amines indicated that only the treatments with the highest amounts of sodium erythorbate (TES and TOE1) showed losses of spermidine. It was observed that decreasing the inclusion of sodium erythorbate and increasing the inclusion of oregano essential oil resulted in a drop in cadaverine values. A total of 46 volatile compounds were detected in the samples with the highest amount of free fatty acids and all the formulations were well accepted sensorially.

Carvacrol-Induced Vacuole Dysfunction and Morphological Consequences in Nakaseomyces glabratus and Candida albicans

With the prevalence of systemic fungal infections caused by Candida albicans and non-albicans species and their resistance to classical antifungals, there is an urgent need to explore alternatives. Herein, we evaluate the impact of the monoterpene carvacrol, a major component of oregano and thyme oils, on clinical and laboratory strains of C. albicans and Nakaseomyces glabratus. Carvacrol induces a wide range of antifungal effects, including the inhibition of growth and hyphal and biofilm formation. Using biochemical and microscopic approaches, we elucidate carvacrol-induced hyphal inhibition. The significantly reduced survival rates following exposure to carvacrol were accompanied by dose-dependent vacuolar acidification, disrupted membrane integrity, and aberrant morphology. Germ tube assays, used to elucidate the relationship between vacuolar dysfunction and hyphal inhibition, showed that carvacrol significantly reduced hyphal formation, which was accompanied by a defective C. albicans morphology. Thus, we show a link between vacuolar acidification/disrupted vacuole membrane integrity and compromised candidal morphology/morphogenesis, demonstrating that carvacrol exerts its anti-hyphal activity by altering vacuole integrity.

Natural Compounds with Antifungal Properties against Candida albicans and Identification of Hinokitiol as a Promising Antifungal Drug

Candida albicans is an opportunistic yeast that causes most fungal infections. C. albicans has become increasingly resistant to antifungal drugs over the past decade. Our study focused on the identification of pure natural compounds for the development of antifungal medicines. A total of 15 natural compounds from different chemical families (cinnamic derivatives, aromatic phenols, mono- and sesquiterpenols, and unclassified compounds) were screened in this study. Among these groups, hinokitiol (Hi), a natural monoterpenoid extracted from the wood of the cypress family, showed excellent anti-C. albicans activity, with a MIC value of 8.21 µg/mL. Hi was selected from this panel for further investigation to assess its antifungal and anti-inflammatory properties. Hi exhibited significant antifungal activity against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. It also reduced biofilm formation and hyphal growth. Treatment with Hi protected Caenorhabditis elegans against infection with C. albicans and enhanced the expression of antimicrobial genes in worms infected with C. albicans. Aside from its antifungal activities against C. albicans, Hi challenge attenuated the LPS-induced expression of pro-inflammatory cytokines (IL-6, IL-1β, and CCL-2) in macrophages. Overall, Hi is a natural compound with antifungal and anti-inflammatory properties, making Hi a promising platform with which to fight against fungal infections.

Synergistic Treatment of Multidrug-Resistant Bacterial Biofilms Using Silver Nanoclusters Incorporated into Biodegradable Nanoemulsions

Multidrug resistance (MDR) in bacteria is a critical global health challenge that is exacerbated by the ability of bacteria to form biofilms. We report a combination therapy for biofilm infections that integrates silver nanoclusters (AgNCs) into polymeric biodegradable nanoemulsions (BNEs) incorporating eugenol. These Ag-BNEs demonstrated synergistic antimicrobial activity between the AgNCs and the BNEs. Microscopy studies demonstrated that Ag-BNEs penetrated the dense biofilm matrix and effectively disrupted the bacterial membrane. The Ag-BNE vehicle also resulted in more effective silver delivery into the biofilm than AgNCs alone. This combinacional system featured disruptionof biofilms by BNEs and enhanced delivery of AgNCs for synergy to provide highly efficient killing of MDR biofilms.

Chemical Profiling, Anticholinesterase, Antioxidant, and Antibacterial Potential of the Essential Oil from Myrcianthes discolor (Kunth) McVaugh, an Aromatic Tree from Southern Ecuador

Myrcianthes discolor, an aromatic native tree from southern Ecuador, was collected to determine the chemical composition and the biological activity of its essential oil (EO). The EO was obtained by steam-distillation and analyzed by gas chromatography coupled to a mass and a FID detector (GC-MS and GC-FID) and a non-polar DB5-MS column. Enantioselective GC-MS analysis was performed in a chiral capillary column. The antimicrobial, antioxidant, and anticholinesterase potency of the EO was carried out by the broth microdilution method, radical scavenging assays using 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and by measuring the inhibition of the acetylcholinesterase (AChE) enzyme. A total of 58 chemical compounds were identified, corresponding to 94.80% of the EO composition. Sesquiterpenes hydrocarbons represented more than 75% of the composition. The main compounds detected were E-caryophyllene with 29.40 ± 0.21%, bicyclogermacrene with 7.45 ± 0.16%, β-elemene with 6.93 ± 0.499%, α-cubebene with 6.06 ± 0.053%, α-humulene with 3.96 ± 0.023%, and δ-cadinene with 3.02 ± 0.002%. The enantiomeric analysis revealed the occurrence of two pairs of pure enantiomers, (−)-β-pinene and (−)-α-phellandrene. The EO exerted a strong inhibitory effect against AChE with an IC50 value of 6.68 ± 1.07 µg/mL and a moderate antiradical effect with a SC50 value of 144.93 ± 0.17 µg/mL for the ABTS radical and a weak or null effect for DPPH (3599.6 ± 0.32 µg/mL). In addition, a strong antibacterial effect against Enterococcus faecium was observed with a MIC of 62.5 μg/mL and Enterococcus faecalis with a MIC of 125 μg/mL. To the best of our knowledge, this is the first report of the chemical composition and biological profile of the EO of M. discolor, and its strong inhibitory effect over AChE and against two Gram-positive pathogenic bacteria, which encourage us to propose further studies to validate its pharmacological potential.

Chemical Profiles, In Vitro Antioxidant and Antifungal Activity of Four Different Lavandula angustifolia L. EOs

Lavandula angustifolia L., known as lavender, is an economically important Lamiaceae due to the production of essential oils (EOs) for the food, cosmetic, pharmaceutical and medical industries. The purpose of this study was to determine the chemical composition of EOs isolated from four inflorescences of L. angustifolia L. collected in different geographical areas: central-southern Italy (LaCC, LaPE, LaPS) and southern France (LaPRV). The essential oils, obtained by steam distillation from plants at the full flowering stage, were analyzed using gas chromatography coupled with mass spectrometry (GC-MS). More than 70 components identified in each sample showed significant variability among the main constituents. The four EOs analyzed contained the following as main component: linalool (from 30.02% to 39.73%), borneol (13.65% in LaPE and 16.83% in La PS), linalyl acetate (24.34% in LaCC and 31.07% in LaPRV). The EOs were also evaluated for their in vitro antifungal activity against two white rot fungi (Phanerochaete chrysosporium and Trametes cingulata) as potential natural biodeteriogens in the artworks field, and against Sclerotium rolfsii, Botrytis cinerea and Fusarium verticilloides responsible for significant crop yield losses in tropical and subtropical areas. The results confirm a concentration-dependent toxicity pattern, where the fungal species show different sensitivity to the four EOs. The in vitro antioxidant activity by DPPH assay showed better scavenging activity on LaCC (IC₅₀ 26.26 mg/mL) and LaPRV (IC₅₀ 33.53 mg/mL), followed by LaPE (IC₅₀ 48.00 mg/mL) and LaPS (IC₅₀ 49.63 mg/mL). The potential application of EOs as a green method to control biodeterioration phenomena on a work of art on wood timber dated 1876 was evaluated.

A systematic review and meta-analysis of the use of plant essential oils and extracts in the development of antimicrobial edible films for dairy application

The purpose of this review was to assess the use of plant essential oils and extracts (PEOE) in the development of antimicrobial edible films for dairy application through a systematic review and meta-analysis. All studies published in multiple databases were explored via PRISMA protocol on November 1, 2022. According to the results, the interquartile range of pathogen reduction potential of essential oil (EO) in dairy products, irrespective of EO, film and product type, was 0.10 - 4.70 log CFU g^-1 per % concentration. The findings from 38 articles indicate that among all EOs or their compounds, Zataria multiflora Boiss in protein film, thyme in protein film, Z. multiflora Boiss EO in protein film, Trans-cinnamaldehyde in carbohydrate film and lemongrass EO in protein film had extraordinary pathogen reduction potential on important foodborne pathogens. In the case of plant extract, fish gelatin film with Lepidium sativum extract, whey protein isolate film loaded with oregano EO and carboxymethyl cellulose film with clove EOs had the highest antimicrobial effect on mesophilic bacteria (9.50 log CFU g^-1 per % concentration), yeast-mold (2.63 log CFU g^-1 per % concentration) and mesophilic/ psychrophilic counts (> 9.06 log CFU g^-1 per % concentration), respectively. Listeria monocytogenes is the primary species of interest; whereas, mesophiles and mold-yeast populations were the most investigated microbiota/mycobiota in cheese with PEOE-incorporated film. In light of these findings, the choice of PEOE at appropriate concentrations with the selection of appropriate edible film may improve the safety, sensory, and shelf life of dairy products.

Clove Essential Oil and Its Main Constituent, Eugenol, as Potential Natural Antifungals against Candida spp. Alone or in Combination with Other Antimycotics Due to Synergistic Interactions

The occurrence of candidiasis, including superficial infections, has recently increased dramatically, especially in immunocompromised patients. Their treatment is often ineffective due to the resistance of yeasts to antimycotics. Therefore, there is a need to search for new antifungals. The aim of this study was to determine the antifungal effect of clove essential oil (CEO) and eugenol (EUG) towards both reference and clinical Candida spp. strains isolated from the oral cavity of patients with hematological malignancies, and to investigate their mode of action and the interactions in combination with the selected antimycotics. These studies were performed using the broth microdilution method, tests with sorbitol and ergosterol, and a checkerboard technique, respectively. The CEO and EUG showed activity against all Candida strains with a minimal inhibitory concentration (MIC) in the range of 0.25-2 mg/mL. It was also found that both natural products bind to ergosterol in the yeast cell membrane. Moreover, the interactions between CEO and EUG with several antimycotics-cetylpyridinium chloride, chlorhexidine, silver nitrate and triclosan-showed synergistic or additive effects in combination, except nystatin. This study confirms that the studied compounds appear to be a very promising group of phytopharmaceuticals used topically in the treatment of superficial candidiasis. However, this requires further studies in vivo.

Candida albicans Reactive Oxygen Species (ROS)-Dependent Lethality and ROS-Independent Hyphal and Biofilm Inhibition by Eugenol and Citral

Candida albicans is part of the normal human flora but is most frequently isolated as the causative opportunistic pathogen of candidiasis. Plant-based essential oils and their components have been extensively studied as antimicrobials, but their antimicrobial impacts are poorly understood. Phenylpropenoids and monoterpenes, for example, eugenol from clove and citral from lemon grass, are potent antifungals against a wide range of pathogens. We report the cellular response of C. albicans to eugenol and citral, alone and combined, using biochemical and microscopic assays. The MICs of eugenol and citral were 1,000 and 256 μg/mL, respectively, with the two exhibiting additive effects based on a fractional inhibitory concentration index of 0.83 ± 0.14. High concentrations of eugenol caused membrane damage, oxidative stress, vacuole segregation, microtubule dysfunction and cell cycle arrest at the G₁/S phase, and while citral had similar impacts, they were reactive oxygen species (ROS) independent. At sublethal concentrations (1/2 to 1/4 MIC), both oils disrupted microtubules and hyphal and biofilm formation in an ROS-independent manner. While both compounds disrupt the cell membrane, eugenol had a greater impact on membrane dysfunction. This study shows that eugenol and citral can induce vacuole and microtubule dysfunction, along with the inhibition of hyphal and biofilm formation. IMPORTANCE Candida albicans is a normal resident on and in the human body that can cause relatively benign infections. However, when our immune system is severely compromised (e.g., cancer chemotherapy patients) or underdeveloped (e.g., newborns), this fungus can become a deadly pathogen, infecting the bloodstream and organs. Since there are only a few effective antifungal agents that can be used to combat fungal infections, these fungi have been exposed to them over and over again, allowing the fungi to develop resistance. Instead of developing antifungal agents that kill the fungi, some of which have undesirable side effects on the human host, researchers have proposed to target the fungal traits that make the fungus more virulent. Here, we show how two components of plant-based essential oils, eugenol and citral, are effective inhibitors of C. albicans virulence traits.

"In vivo" and "in vitro" antimicrobial activity of Origanum vulgare essential oil and its two phenolic compounds on clinical isolates of Candida spp

A limited therapeutic arsenal is currently available against Candida infections that show high resistance to antifungal agents. For this reason, there is a great need to prioritize testing therapeutic agents for the treatment of candidiasis. The use of essential oils and their phytoconstituents has been emphasized as a new therapeutic approach. The cell surface hydrophobicity (CSH), polysaccharide content, antimicrobial activity of essential oil from Origanum vulgare L. (OVEO), and its two phenolic compounds carvacrol and thymol were evaluated in four different Candida spp. (Candida albicans and emerging non-albicans Candida (NAC) species, such as C. glabrata, C. tropicalis, and C. krusei). The results showed the differences between Candida species; for example, C. tropicalis revealed higher resistance than other strains to different natural molecule treatments. The ultrastructural variabilities in the biomembranes and cell walls of these Candida spp. might explain the different biological effects observed after OVEO, carvacrol and thymol treatments. Therefore, to study the biological effects of these natural compounds on Candida strains, the samples were observed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Moreover, the release of cellular materials and their "in vivo" antimicrobial activity on infected G. mellonella larvae were evaluated. The novelty of this study is the demonstration that exists a close correlation between both structural architecture of cell walls and biomembranes' organization with cell fungal responses to essential oils treatments. Overall, these results suggest practical limits to the predictability.

Antifungal Activity of Lavandula angustifolia Essential Oil against Candida albicans: Time-Kill Study on Pediatric Sputum Isolates

The aim of our study was to determine the susceptibility of 15 Candida albicans sputum isolates on fluconazole and caspofungin, as well as the antifungal potential of Lavandula angustifolia essential oil (LAEO). The commercial LAEO was analyzed using gas chromatography-mass spectrometry. The antifungal activity was evaluated using EUCAST protocol. A killing assay was performed to evaluate kinetics of 2% LAEO within 30 min treatment. LAEO with major constituents’ linalool (33.4%) and linalyl acetate (30.5%) effective inhibited grows of C. albicans in concentration range 0.5–2%. Fluconazole activity was noted in 67% of the isolates with MICs in range 0.06–1 µg/mL. Surprisingly, 40% of isolates were non-wild-type (non-WT), while MICs for WT ranged between 0.125–0.25 µg/mL. There were no significant differences in the LAEO MICs among fluconazole-resistant and fluconazole-susceptible sputum strains (p = 0.31) and neither among caspofungin non-WT and WT isolates (p = 0.79). The 2% LAEO rapidly achieved 50% growth reduction in all tested strains between 0.2 and 3.5 min. Within 30 min, the same LAEO concentration exhibited a 99.9% reduction in 27% isolates. This study demonstrated that 2% solution of LAEO showed a significant antifungal activity which is equally effective against fluconazole and caspofungin susceptible and less-susceptible strains.

Variability in Biological Activities of Satureja montana Subsp. montana and Subsp. variegata Based on Different Extraction Methods

Winter savory (Satureja montana L.) is a well-known spice and medicinal plant with a wide range of activities and applications. Two subspecies of S. montana, subsp. montana and subsp. variegata, were used for the preparation of seven different extracts: steam distillation (essential oil (EO) and hydrolate (HY)), subcritical water (SWE), ultrasound-assisted (UAE-MeOH and UAE-H₂O), and microwave-assisted (MAE-MeOH and MAE-H₂O) extraction. The obtained EOs, HYs, and extracts were used for an in vitro evaluation of the antioxidant activity (DPPH, ABTS, reducing power, and superoxide anion methods) and in vitro antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella Typhimurium, Saccharomyces cerevisiae, and Candida albicans. The antimicrobial screening was conducted using disk-diffusion assessment, minimal inhibitory concentration, time–kill kinetics modeling, and pharmacodynamic study of the biocide effect. The total phenolic content (TPC) was highest in EO, followed by SWE, MAE, and UAE, and the lowest was in HY. The highest antimicrobial activity shows EO and SWE for both varieties, while different UAE and MAE extracts have not exhibited antimicrobial activity. The natural antimicrobials in the S. montana extract samples obtained by green extraction methods, indicated the possibility of ecologically and economically better solutions for future in vivo application of the selected plant subspecies.

Effects of Origanum vulgare and Scutellaria baicalensis on the Physiological Activity and Biochemical Parameters of the Blood in Rats on a High-Fat Diet

The pharmacological effects of medicinal plants play a primary role in the mild correction of body weight in humans and animals, reducing the accumulation of fat in their bodies during a state of obesity. Origanum vulgare L. and Scutellaria baicalensis Georgi are widely used as food additives and medicinal plants, but their comprehensive physiological evaluation in model animals in a state of obesity has not been carried out. In a 30-day laboratory experiment on male rats which had developed obesity through a hypercaloric diet, the effects of adding the dry crushed grass O. vulgare or dry crushed roots of S. baicalensis to their feed was evaluated. During the experiment, the rats fed with O. vulgare increased in body weight to only 105.5% of their initial weight, while the body weight of the control group increased to 111.5%, and that of animals fed on S. baicalensis increased to 124.0% of their initial body weight. The average daily increase in the rats’ body weight when O. vulgare was added to their diet decreased to 205 mg/day, and when S. baicalensis was added, on the contrary, it increased to 1417 mg/day, compared to 700 mg/day among the control group. Under the influence of O. vulgare, the lipid metabolism of the rats normalized: the atherogenic index decreased to 33.7%, compared with the values of the control group, due to an increase in the concentration of high-density lipoproteins from cholesterol. The concentration of triglycerides decreased, and the concentration of glucose decreased. The roots of S. baicalensis being added into the diet of rats increased the activity of alkaline phosphatase and decreased the concentration of urea. The atherogenic index also decreased (by up to 35.5% in the control group) and the concentration of high-density lipoprotein cholesterol increased, while the concentrations of triglycerides and glucose decreased. The physical activity of the rats showed a slight tendency to decrease when both O. vulgare and S. baicalensis were added to their diet. Both plant species contributed to a decrease in the emotional status of animals, which was most pronounced when the O. vulgare grass was added to the feed. The results of the study demonstrate the potential of the use of O. vulgare and S. baicalensis as herbal supplementations for the correction of hyperlipidemia and type-2 diabetes mellitus in overweight patients.

Antifungal and antimycotoxic activities of 3 essential oils against 3 mycotoxinogenic fungi

Fungal toxins can have various adverse health effects, including carcinogenic, teratogenic or hepatotoxic impacts. In addition, fungal alteration has also a negative impact on agricultural plant production. The use of chemical fungicides to control mycotoxin contamination is increasingly controversial and regulated. More environmentally friendly methods are therefore being explored. Essential oils, as compounds extracted from plants, are liquids whose specific aromatic compounds give each essential oil its own unique characteristics. Due to their rich chemical composition, essential oils (EOs) have many interesting properties, including antifungal activities. The objective of the present study was to analyze volatile chemical composition of EOs (Cymbopogon schoenanthus, Cymbopogon nardus and Eucalyptus camaldulensis) by GC/MS and to investigate their effects on the growth, sporulation and mycotoxin production of Aspergillus flavus, Aspergillus carbonarius and Fusarium verticillioides (aflatoxin B1, ochratoxin A and fumonisin B1, respectively). In addition, EOs influence on aflatoxin B1 (AFB1) and fumonisin B1 (FB1) biosynthesis pathways was explored using real-time qRT-PCR. The results obtained in vitro, by direct contact with the EOs and by diffusion of their volatile compounds, showed that the essential oils had inhibitory effects on the growth and the production of mycotoxins of the 3 fungal strains and modified the expression of some toxin synthesis genes. We conclude that the recorded effects were dependent on the combined effects of the EOs type, the fungal strains and the doses studied.

Antifungal and anti-virulence activity of six essential oils against important Candida species - a preliminary study

Opportunistic infections with Candida species are becoming more problematic, considering their increasing virulence and resistance to antifungal drugs.

AIM

To assess the antifungal and anti-virulence activity of basil, cinnamon, clove, melaleuca, oregano and thyme essential oils (EOs) on five Candida species (C. albicans, C. auris, C. krusei C. parapsilosis and C. guillermondii).

METHODS

The MIC, growth rate, antibiofilm activity, regulation of gene expression (ALS3, SAP2, HSP70) and germ-tube formation were evaluated by specific methods.

RESULTS

Most EOs inhibited Candida species growth and reduced the expression of some virulence factors. Cinnamon and clove EO showed the most significant inhibitory effects.

CONCLUSIONS

The tested EOs are promising agents for facilitating the management of some Candida infections.

Electrospun Polymer Nanofibers with Antimicrobial Activity

Nowadays, nanofibers with antimicrobial activity are of great importance due to the widespread antibiotic resistance of many pathogens. Electrospinning is a versatile method of producing ultrathin fibers with desired properties, and this technique can be optimized by controlling parameters such as solution/melt viscosity, feeding rate, and electric field. High viscosity and slow feeding rate cause blockage of the spinneret, while low viscosity and high feeding rate result in fiber discontinuities or droplet formation. The electric field must be properly set because high field strength shortens the solidification time of the fluid streams, while low field strength is unable to form the Taylor cone. Environmental conditions, temperature, and humidity also affect electrospinning. In recent years, significant advances have been made in the development of electrospinning methods and the engineering of electrospun nanofibers for various applications. This review discusses the current research on the use of electrospinning to fabricate composite polymer fibers with antimicrobial properties by incorporating well-defined antimicrobial nanoparticles (silver, titanium dioxide, zinc dioxide, copper oxide, etc.), encapsulating classical therapeutic agents (antibiotics), plant-based bioactive agents (crude extracts, essential oils), and pure compounds (antimicrobial peptides, photosensitizers) in polymer nanofibers with controlled release and anti-degradation protection. The analyzed works prove that the electrospinning process is an effective strategy for the formation of antimicrobial fibers for the biomedicine, pharmacy, and food industry.

Meta-analysis of the antifungal activities of three essential oils as alternative therapies in dermatophytosis infections

Aims

This work examines the available scientific evidence about the efficiency of essential oils (EO) as an alternative therapy to traditional treatment of fungal infections, including onychomycosis, assessing the effect of the three EO most frequently studied for their antifungal activity (thyme, cinnamon and tea tree EO) against three causative agents of fungal diseases in humans: Trichophyton rubrum, Trichophyton mentagrophytes complex and Candida albicans.

Methods and Results

The PRISMA statement protocol was followed to conduct a bibliographical search and 54 articles that met all the inclusion criteria were retrieved. Differences were observed in the MIC and MFC values depending on the micro‐organism strain and the EO used. The lowest MIC were observed with Cinnamomum zeylanicum EO (0.013–1120 μl ml⁻¹) against the three micro‐organisms. For MFC, the lowest value was found for Thymus vulgaris EO (4.2 μl ml⁻¹) against Trichophyton rubrum.

Conclusions

The antifungal effects of EO could be a very promising solution to overcome the therapeutic shortcomings of antimycotic medication. More experiments are needed to examine the properties of these oils to devise effective and nonaggressive therapies for treatment of dermatophytosis.

Significance and Impact of Study

The results indicate that EO remain good candidates for future treatments and could provide a solution for failed medications and/or adverse reactions to current pharmacological treatments.

In Vitro Pharmacological Screening of Essential Oils from Baccharis parvidentata and Lippia origanoides Growing in Brazil

In this study, the in vitro antimicrobial, antiparasitic, antiproliferative and cytotoxic activities of essential oil from Baccharis parvidentata Malag. (EO-Bp) and Lippia origanoides Kunth (EO-Lo) were explored. The relevant effects were observed against the parasitic protozoans Plasmodium falciparum, Trypanosoma cruzi, Trypanosoma brucei and Leishmania amazonensis (ranging 0.6 to 39.7 µg/mL) and malignant MCF-7, MCF-7/HT, 22Rv1, and A431 cell lines (ranging 6.1 to 31.5 µg/mL). In parallel, EO-Bp showed better selective indexes in comparison with EO-Lo against peritoneal macrophages from BALB/c mice and MRC-5 cell line. In conclusion, EO-Lo is known to show a wide range of health benefits that could be added as another potential use of this oil with the current study. In the case of EO-Bp, the wide spectrum of its activities against protozoal parasites and malignant cells, as well as its selectivity in comparison with non-malignant cells, could suggest an interesting candidate for further tests as a new therapeutic alternative.

Nanoemulsions (O/W) containing Cymbopogon pendulus essential oil: development, characterization, stability study, and evaluation of in vitro anti-bacterial, anti-inflammatory, anti-diabetic activities

Essential oil from Cymbopogon pendulus is immensely useful in various sectors like food, pharmaceutical, and cosmetic industries. Since this oil is hydrophobic, unstable, and volatile, hence encapsulation by using nanoemulsions technology is the best way to protect it. This study reports biosynthesis of O/W (oil/water) nanoemulsions based on essential oil from Cymbopogon pendulus and analysis of its biological activities. O/W nanoemulsions were prepared by using tween 20/80, sodium dodecyl sulphate as surfactants, and ethanol as co-surfactants. Fingerprinting of nanoemulsions using UV, fluorescent, and FT-IR was studied along with other parameters like pH and conductivity. Biological activities like antibacterial, anti-inflammatory, and anti-diabetic activities and drug release pharmokinetics were evaluated. Ethanol containing nanoemulsions was noticeably smaller than other nanoemulsions. Encapsulation efficiency of nanoemulsions was in the range from 41 to 60%. Nanoemulsions were spherical in shape and stable even after 50 days of storage. Appreciable biological activities like anti-bacterial, anti-inflammatory, and anti-diabetic activities were detected. Drug kinetic study revealed that nanoemulsions exhibited Korsmeyer-Peppas model. Based on this, the possible role of lemon grass oil-based nanoemulsions in cosmetic, food, and pharma sectors has been discussed.

Volatile Organic Compounds from Basil Essential Oils: Plant Taxonomy, Biological Activities, and Their Applications in Tropical Fruit Productions

Basils of the genus Ocimum are aromatic plants grown widely throughout the tropical and temperate regions. The essential oils obtained from their aerial parts are enriched with volatile organic compounds with high market demand for food and pharmaceutical industries. The volatile organic compounds have been shown to exhibit biological activities. Therefore, their novel applications have been extensively explored in the last few decades. The most widely available basils in the tropical areas include white holy basil (O. sanctum var. Shyama), red holy basil (O. sanctum var. Rama), Thai basil (O. basilicum var. thyrsiflorum), lemon basil (O. citriodorum), and tree basil (O. gratissimum). Over 60 volatiles of different classes have been exclusively described, and some of them could be useful as biomarkers for genotype specification. The major volatile ingredient is the phenylpropanoids, such as methyl eugenol, which has the potential as a natural product for mitigating Oriental fruit fly (Bactrocera dorsalis) during tropical fruit production. Moreover, basil essential oils are also used to control diseases of the fruits during post-harvest storage. As a result, the application of basil essential oils as a sustainable defect control strategy for tropical fruit value chains seems intriguing. This review provides comprehensive information on plant taxonomy and volatile compositions of the essential oil fractions from different basil species. Their biological activities and applications are also discussed, mainly during the pre- and post-production of tropical fruits. Additionally, the available techniques to enhance the efficacy of the volatile active compounds are also described.

Chitosan nanoparticles loaded with garlic essential oil: A new alternative to tebuconazole as seed dressing agent

In this study, garlic essential oil (GEO) has been encapsulated in chitosan nanoparticles (NPCH) with sodium tripolyphosphate (TPP). Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectrophotometry, thermogravimetric analysis (TGA) and X-ray diffraction (XRD) techniques were applied to characterize GEO-NPCH. The obtained nanoparticles exhibited a regular distribution and spherical shape with size range of 200-400 nm as revealed by scanning electron microscopy (SEM). The maximum encapsulation efficiency (EE) and loading capacity (LC) of GEO-loaded chitosan nanoparticles were about 32.8% and 19.8% respectively. Nanoparticle formulations of GEO were found to have antifungal activity against Aspergillus versicolor, A. niger and Fusarium oxysporum. In addition, they showed growth promoting effects by increasing emergence, shoot and root fresh weight on wheat, oat and barley.

Antifungal Polymeric Materials and Nanocomposites

Rising global populations due to medicinal advancements increases the patient population susceptible to superficial and severe fungal infections. Fungi often implicated in these diseases includes the dermatophytes (Microsporum spp., Epidermophtyon spp., Trichophyton spp.) as well as species of the Candida spp., Aspergillosis spp. and Cryptococcus spp. genera. In addition, increasing global populations leads to increasing agricultural demands. Thus, fungal infections of preharvested crops and stored food by plant pathogens such as Magnaporthe oryzae and Fusarium oxysporum can have detrimental socioeconomic effects due to food insecurity. Current antifungal strategies are based mainly on small molecule antifungal drugs. However, these drugs are limited by poor solubility and bioavailability. Furthermore, antifungal resistance against these drugs are on the rise. Thus, antimicrobial polymers offer an alternative antifungal strategy. Antifungal polymers are characterised by cationic and hydrophobic regions where the cationic regions have been shown to interact with microbial phospholipids and membranes. These polymers can be synthetic or natural and demonstrate distinct antifungal mechanisms ranging from fungal cell membrane permeabilisation, cell membrane depolarisation or cell entry. Although the relative importance of such mechanisms is difficult to decipher. Due to the chemical properties of these polymers, they can be combined with other antimicrobial compounds including existing antifungal drugs, charcoals, lipids and metal ions to elicit synergistic effects. In some cases, antifungal polymers and nanocomposites show better antifungal effects or reduced toxicity compared to the widely used small molecule antifungal drugs. This review provides an overview of antimicrobial polymers and nanocomposites with antifungal activity and the current understanding of their antifungal mechanisms.

Honokiol and Magnolol: Insights into Their Antidermatophytic Effects

Dermatophyte infections represent a significant public health concern, with an alarming negative impact caused by unsuccessful therapeutic regimens. Natural products have been highlighted as a promising alternative, due to their long-standing traditional use and increasing scientific recognition. In this study, honokiol and magnolol, the main bioactives from Magnolia spp. bark, were investigated for their antidermatophytic activity. The antifungal screening was performed using dermatophyte standard strains and clinical isolates. The minimal inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) were determined in accordance with EUCAST-AFST guidelines, with minor modifications. The effects on ergosterol biosynthesis were assessed in Trichophyton rubrum cells by HPLC-DAD. Putative interactions with terbinafine against T. rubrum were evaluated by the checkerboard method. Their impact on cells' viability and pro-inflammatory cytokines (IL-1β, IL-8 and TNF-α) was shown using an ex vivo human neutrophils model. Honokiol and magnolol were highly active against tested dermatophytes, with MIC and MFC values of 8 and 16 mg/L, respectively. The mechanism of action involved the inhibition of ergosterol biosynthesis, with accumulation of squalene in T. rubrum cells. Synergy was assessed for binary mixtures of magnolol with terbinafine (FICI = 0.50), while honokiol-terbinafine combinations displayed only additive effects (FICI = 0.56). In addition, magnolol displayed inhibitory effects towards IL-1β, IL-8 and TNF-α released from lipopolysaccharide (LPS)-stimulated human neutrophils, while honokiol only decreased IL-1β secretion, compared to the untreated control. Overall, honokiol and magnolol acted as fungicidal agents against dermatophytes, with impairment of ergosterol biosynthesis.

In vitro antidermatophytic activity of bioactive compounds from selected medicinal plants

Fungal infections are among the most difficult diseases to manage in humans. Eukaryotic fungal pathogens share many similarities with their host cells, which impairs the development of antifungal compounds. Therefore, it is desirable to harness the pharmaceutical potential of medicinal plants for antifungal drug discovery. In this study, the antifungal activity of sixteen plant extracts was investigated against selected dermatophytic fungi. Of the sixteen plants, the cladode (leaf) of Asparagus racemosus, and seed extract of Cassia occidentalis showed antifungal activity against Microsporum gypseum, Microsporum nanum, Trichophyton mentagrophytes and Trichophyton terrestre. The plant antifungal compounds were located by direct bioassay against Cladosporium herbarum. IR and NMR spectrometry analyses of these compounds identified the presence of saponin (in A. racemosus) and hydroxy anthraquinone (in C. occidentalis) in these antifungal compounds. The antidermatophytic activity of plant anthraquinone and saponins with reports of little or no hemolytic activity, makes these compounds ideal for alternative antifungal therapy and warrants further in-depth investigation in vivo.

Apiaceae Essential Oils: Boosters of Terbinafine Activity against Dermatophytes and Potent Anti-Inflammatory Effectors

Dermatophyte infections represent an important public health concern, affecting up to 25% of the world's population. Trichophyton rubrum and T. mentagrophytes are the predominant dermatophytes in cutaneous infections, with a prevalence accounting for 70% of dermatophytoses. Although terbinafine represents the preferred treatment, its clinical use is hampered by side effects, drug-drug interactions, and the emergence of resistant clinical isolates. Combination therapy, associating terbinafine and essential oils (EOs), represents a promising strategy in the treatment of dermatophytosis. In this study, we screened the potential of selected Apiaceae EOs (ajowan, coriander, caraway, and anise) to improve the antifungal activity of terbinafine against T. rubrum ATCC 28188 and T. mentagrophytes ATCC 9533. The chemical profile of EOs was analyzed by gas chromatography. The minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of EOs/main compounds were determined according to EUCAST-AFST guidelines, with minor modifications. The checkerboard microtiter method was used to identify putative synergistic combinations of EOs/main constituents with terbinafine. The influence of EOs on the viability and pro-inflammatory cytokine production (IL-1β, IL-8 and TNF-α) was determined using an ex vivo human neutrophils model. The binary associations of tested EOs with terbinafine were found to be synergistic against T. rubrum, with FICI values of 0.26-0.31. At the tested concentrations (6.25-25 mg/L), EOs did not exert cytotoxic effects towards human neutrophils. Anise EO was the most potent inhibitor of IL-1β release (46.49% inhibition at 25 mg/L), while coriander EO displayed the highest inhibition towards IL-8 and TNF-α production (54.15% and 54.91%, respectively). In conclusion, the synergistic combinations of terbinafine and investigated Apiaceae EOs could be a starting point in the development of novel topical therapies against T. rubrum-related dermatophytosis.

In vitro antifungal effect of a plant-based product, CIN-102, on antifungal resistant filamentous fungi and their biofilms

Introduction. The increase of invasive fungal infections (IFIs) and associated treatment failure in populations at risk is driving us to look for new treatments.Hypothesis. The CIN-102 compound, derived from cinnamon essential oil, could be a new antifungal class with an activity, in particular, on strains resistant to current antifungals but also on biofilms, a factor of virulence and resistance of fungi.Aim. The aim of this study is to show the activity of CIN-102 on various strains resistant to current antifungals, on the biofilm and to determine the possibility of resistance induced with this compound.Methodology. We studied the MIC of CIN-102 and of current antifungals (voriconazole and amphotericin B) using CLSI techniques against eight different strains of three genera of filamentous fungi involved in IFIs and having resistance phenotypes to current antifungals. We also determined their effects on biofilm formation, and the induced resistance by voriconazole (VRC) and CIN-102.Results. MIC values determined for CIN-102 were between 62.5 and 250 µg ml^-1. We demonstrated the antifungal effect of CIN-102 on biofilm, and more particularly on its formation, with 100 % inhibition achieved for most of the strains. CIN-102 at a sub-inhibitory concentration in the medium did not induce resistance in our strains, even after 30 generations.Conclusions. In this study we show that CIN-102 is effective against resistant filamentous fungi and against biofilm formation. In addition, our strains did not acquire a resistance phenotype against CIN-102 over time, unlike with VRC. CIN-102 is therefore an interesting candidate for the treatment of IFIs, including in cases of therapeutic failure linked to resistance, although further studies on its efficacy, safety and mechanism of action are needed.

The effect of plant metabolites on coronaviruses: A comprehensive review focusing on their IC50 values and molecular docking scores

Coronaviruses have caused worldwide outbreaks in different periods. SARS (severe acute respiratory syndrome), was the first emerged virus from this family, followed by MERS (Middle East respiratory syndrome) and SARS-CoV-2 (2019-nCoV or COVID 19), which is newly emerged. Many studies have been conducted on the application of chemical and natural drugs for treating these coronaviruses and they are mostly focused on inhibiting the proteases of viruses or blocking their protein receptors through binding to amino acid residues. Among many substances which are introduced to have an inhibitory effect against coronaviruses through the mentioned pathways, natural components are of specific interest. Secondary and primary metabolites from plants, are considered as potential drugs to have an inhibitory effect on coronaviruses. IC50 value (the concentration in which there is 50% loss in enzyme activity), molecular docking score and binding energy are parameters to understand the ability of metabolites to inhibit the specific virus. In this study we did a review of 154 papers on the effect of plant metabolites on different coronaviruses and data of their IC50 values, molecular docking scores and inhibition percentages are collected in tables. Secondary plant metabolites such as polyphenol, alkaloids, terpenoids, organosulfur compounds, saponins and saikosaponins, lectins, essential oil, and nicotianamine, and primary metabolites such as vitamins are included in this study.

The Inhibition of Non-albicans Candida Species and Uncommon Yeast Pathogens by Selected Essential Oils and Their Major Compounds

The epidemiology of yeast infections and resistance to available antifungal drugs are rapidly increasing, and non-albicans Candida species and rare yeast species are increasingly emerging as major opportunistic pathogens. In order to identify new strategies to counter the threat of antimicrobial resistant microorganisms, essential oils (EOs) have become an important potential in the treatment of fungal infections. EOs and their bioactive pure compounds have been found to exhibit a wide range of remarkable biological activities. We investigated the in vitro antifungal activity of nine commercial EOs such as Thymus vulgaris (thyme red), Origanum vulgare (oregano), Lavandula vera (lavender), Pinus sylvestris (pine), Foeniculum vulgare (fennel), Melissa officinalis (lemon balm), Salvia officinalis (sage), Eugenia caryophyllata (clove) and Pelargonium asperum (geranium), and some of their main components (α-pinene, carvacrol, citronellal, eugenol, γ-terpinene, linalool, linalylacetate, terpinen-4-ol, thymol) against non-albicans Candida strains and uncommon yeasts. The EOs were analyzed by GC-MS, and their antifungal properties were evaluated by minimum inhibitory concentration and minimum fungicidal concentration parameters, in accordance with CLSI guidelines, with some modifications for EOs. Pine exhibited strong antifungal activity against the selected non-albicans Candida isolates and uncommon yeasts. In addition, lemon balm EOs and α-pinene exhibited strong antifungal activity against the selected non-albicans Candida yeasts. Thymol inhibited the growth of all uncommon yeasts. These data showed a promising potential application of EOs as natural adjuvant for management of infections by emerging non-albicans Candida species and uncommon pathogenic yeasts.

Effects of three essential oils and their nano-emulsions on Listeria monocytogenes and Shigella flexneri in Egyptian Talaga cheese

Talaga cheese is a soft Egyptian cheese that has been associated with foodborne pathogens such as Listeria monocytogenes and Shigella flexneri. Essential oils (EOs) play a pivotal role in sustainably controlling foodborne diseases and as a potential preservative in soft cheeses. However, limited data is available comparing the antibacterial activity of EOs and their nano-emulsions (NEs) when inoculated into Talaga cheese. Therefore, this study aimed to examine the antibacterial activity of carvacrol, clove, and cumin EOs, in addition to their NEs, against L. monocytogenes (NCTC 13372/ATCC® 7644) and S. flexneri (ATCC®12022^TW⁎) inoculated into laboratory-manufactured Egyptian Talaga cheese during refrigerated storage. The NEs had a Z-average diameter of 32.98 ± 29.75 nm, 45.2 ± 34.25 nm, and 50.23 ± 15.7 nm and a PDI of 0.326, 0.245, and 0.307 for carvacrol, clove, and cumin NEs, respectively. The flow of active functional groups of EOs and NEs as clarified by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) showed the spherical-shaped droplet structure of the prepared NEs. The minimum inhibitory concentration (MIC) of all EOs and their NEs was 0.78% against L. monocytogenes and 1.56% against S. flexneri, while those of carvacrol EO and its NE were 0.78% against both microorganisms. By supplementation in cheese, NEs significantly reduced the counts of inoculated pathogens from 8.2 log₁₀cfu/g to 1.5 log₁₀cfu/g after 2 to 3 weeks compared to EOs, which reduced them after 4 to 5 weeks. The carvacrol NE showed excellent antibacterial activity with no cheese sensory impairment. It reduced L. monocytogenes by 99% (R%) after 7 days and after 3 weeks for S. flexneri at 0.78% concentration, while higher concentrations and a longer period were required for the other NEs to show an inhibitory effect. NEs showed a greater antimicrobial effect than their non-emulsified counterparts, especially when interacting with food items, and carvacrol NE at a low concentration (0.78%) demonstrated its efficacy as an antibacterial and natural food preservative.

Oregano Essential Oil Micro- and Nanoencapsulation With Bioactive Properties for Biotechnological and Biomedical Applications

Due to the preservative, antioxidant, antimicrobial, and therapeutic properties of oregano essential oil (OEO), it has received an emerging interest for biotechnological and biomedical applications. However, stability and bioactivity can be compromised by its natural volatile and hydrophobic nature, and by external factors including light, heat, or oxygen. Therefore, micro- and nanoencapsulation are being employed to guarantee oregano oil protection from outside aggressions and to maximize its potential. Oregano oil encapsulation is an interesting strategy used to increase its stability, enhance its bioactivity, and decrease its volatility. At the same time, the versatility that micro- and nanocarriers offer, allows to prepare tailored systems that can provide a controlled and targeted release of the encapsulated principle, influence its bioactive activities, or even provide additional properties. Most common materials used to prepare these carriers are based on lipids and cyclodextrins, due to their hydrophobic nature, polymers due to their versatility in composition, and hybrid lipid-polymer systems. In this context, recently developed micro- and nanocarriers encapsulating oregano oil with applications in the biotechnological and biomedical fields will be discussed.

Synergistic Activity of New Diclofenac and Essential Oils Combinations against Different Candida spp

According to recent studies, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) have shown a good antimicrobial and antifungal activity. Their association with essential oils (EOs) could be useful for the treatment of infections caused by Candida spp. The aim of this studyis to evaluate the synergistic antifungal activity of new combinations between Diclofenac Sodium Salt (DSS), a widely used NSAID, with EOs of Mentha × piperita, Pelargonium graveolens and Melaleuca alternifolia. The in-vitro antifungal activity was determined on different Candida strains. The determination of the chemical composition of EOs was carried out by gaschromatography-massspectrometry (GC-MS). Susceptibility testing of planktonic cells was performed by using the broth microdilution assay and checkerboard methods. Minimum Inhibitory Concentrations (MIC) of DSS was in a range from 1.02 to 2.05 μg/mL reaching a MIC value of 0.05 μg/mL when combined with Pelargonium graveolens (FICI = 0.23–0.35) or Menthapiperita (FICI = 0.22–0.30) EOs. These preliminary results show thatthe combination of the EOs with DSS improves the antifungal activity on all the tested Candida strains.

Differential Antimicrobial Effect of Essential Oils and Their Main Components: Insights Based on the Cell Membrane and External Structure

The biological activity of essential oils and their major components is well documented. Essential oils such as oregano and cinnamon are known for their effect against bacteria, fungi, and even viruses. The mechanism of action is proposed to be related to membrane and external cell structures, including cell walls. This study aimed to evaluate the biological activity of seven essential oils and eight of their major components against Gram-negative and Gram-positive bacteria, filamentous fungi, and protozoans. The antimicrobial activity was evaluated by determination of the Minimal Inhibitory Concentration for Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella Typhimurium, Shigella sonnei, Aspergillus niger, Aspergillus ochraceus, Alternaria alternata, and Fusarium oxysporium, the half-maximal inhibitory concentration (IC₅₀) for Trypanosoma cruzi and Leishmania mexicana, and the median lethal dose (LD₅₀) for Giardia lamblia. Results showed that oregano essential oil showed the best antibacterial activity (66–100 µg/mL), while cinnamon essential oil had the best fungicidal activity (66–116 µg/mL), and both showed excellent antiprotozoal activity (22–108 µg/mL). Regarding the major components, thymol and carvacrol were also good antimicrobials (23–200 µg/mL), and cinnamaldehyde was an antifungal compound (41–75 µg/mL). The major components were grouped according to their chemical structure as phenylpropanoids, terpenoids, and terpinenes. The statistical analysis of the grouped data demonstrated that protozoans were more susceptible to the essential oils, followed by fungi, Gram-positive bacteria, and Gram-negative bacteria. The analysis for the major components showed that the most resistant microbial group was fungi, which was followed by bacteria, and protozoans were also more susceptible. Principal Component Analysis for the essential oils demonstrated the relationship between the biological activity and the microbial group tested, with the first three components explaining 94.3% of the data variability. The chemical structure of the major components was also related to the biological activity presented against the microbial groups tested, where the three first principal components accounted for 91.9% of the variability. The external structures and the characteristics of the cell membranes in the different microbial groups are determinant for their susceptibility to essential oils and their major components

Drug Repurposing in Medical Mycology: Identification of Compounds as Potential Antifungals to Overcome the Emergence of Multidrug-Resistant Fungi

Immunodepression, whether due to HIV infection or organ transplantation, has increased human vulnerability to fungal infections. These conditions have created an optimal environment for the emergence of opportunistic infections, which is concomitant to the increase in antifungal resistance. The use of conventional antifungal drugs as azoles and polyenes can lead to clinical failure, particularly in immunocompromised individuals. Difficulties related to treating fungal infections combined with the time required to develop new drugs, require urgent consideration of other therapeutic alternatives. Drug repurposing is one of the most promising and rapid solutions that the scientific and medical community can turn to, with low costs and safety advantages. To treat life-threatening resistant fungal infections, drug repurposing has led to the consideration of well-known and potential molecules as a last-line therapy. The aim of this review is to provide a summary of current antifungal compounds and their main resistance mechanisms, following by an overview of the antifungal activity of non-traditional antimicrobial drugs. We provide their eventual mechanisms of action and the synergistic combinations that improve the activity of current antifungal treatments. Finally, we discuss drug repurposing for the main emerging multidrug resistant (MDR) fungus, including the Candida auris, Aspergillus or Cryptococcus species.

The influence of ergosterol on the action of the hop oil and its major terpenes on model fungi membranes. Towards understanding the mechanism of action of phytocompounds for food and plant protection

The aim of this work was to find the correlation between the content of ergosterol in fungi membrane and the action of the hop essential oil, myrcene and humulene on its properties. To reach this goal, the monolayers and bilayers composed of phosphatidylcholine, phosphatidyethanol amine and ergosterol, differing in the concentration of sterol, were used as model membrane systems. The impact of the essential oil and its major terpenes on one component ergosterol film was also investigated. It was found that pure isolated terpenes, in contrast to the hop oil being the mixture of them, do not incorporate into pure ergosterol membrane, however, they cause the loss of monolayer material from the interface. These results are in contrast to the effect of these terpenes on phospholipid films reported previously and they may suggest a strong effect of ergosterol on the behavior of terpenes in the mixed systems. Surprisingly, for model membranes, the effect of myrcene was qualitatively similar to the effect of the hop oil and ergosterol was found to regulate the incorporation of both these substances into the film. In contrast, very strong correlation between ergosterol content and the action of humulene was found. Namely, the ability of humulene to change model membrane properties was found to increase with ergosterol concentration. Additionally, the differentiating effect of ergosterol on humulene action in membranes was much more pronounced than for myrcene or the hop oil. Interestingly, at the highest ergosterol level the influence of humulene was even stronger than the effect of the hop oil. This is very important finding suggesting that ergosterol may regulate the sensitivity of particular membrane to the impact of humulene. Summarizing, ergosterol substantially differentiates the effect of the hop oil, myrcene and humulene on the lipid systems and it can be the molecule important for antifungal effect of the essential oil and terpenes.

Characterisation of the antifungal effects of a plant-based compound, CIN-102, on the main septal filamentous fungi involved in human pathology

OBJECTIVES

Today, the increase of invasive fungal infections and the emergence of resistant strains are observed in medical practice. New antifungals are expected, and the plant world offers a panel of potentially active molecules. CIN-102 is a mixture of seven different compounds of plant origin developed from the formulation of cinnamon essential oil.

METHODS

The in vitro activity of CIN-102 was characterised against Aspergillus spp., Fusarium spp. and Scedosporium spp. by studying the minimum inhibitory concentration (MIC), inoculum effect, germination inhibition, fungal growth, post-antifungal effect (PAFE) and synergy.

RESULTS

MICs determined for the three genera followed a unimodal distribution and their mean values ranged from 62-250 μg/mL. CIN-102 demonstrated an inoculum effect similar to voriconazole and amphotericin B, 100% inhibition of spore germination and a PAFE.

CONCLUSION

CIN-102 has significant activity against filamentous fungi involved in human pathologies and should be further explored as a potential new treatment. Other studies regarding its mechanisms of action as well as animal investigations are awaited.

From bulk to nano-delivery of essential phytochemicals: recent progress and strategies for antibacterial resistance

Bacterial biofilms caused by antibiotic resistance are a severe cause of infection threatening human health nowadays. The primary causes of this emerging threat are poor penetration of conventional antibiotics and the growing number of varied strains of resistant bacteria. Recently, bulk phytochemical oils have been widely explored for their potential as antibacterial agents. However, due to their poor solubility, low stability, and highly volatile properties, essential oils are not effective for in vitro and in vivo antibacterial applications and require further preparation. In this review, we discuss the recent progress and strategies to overcome the drawbacks of bulk phytochemical oils using nano-delivery, as well as the current challenges and future outlook of these nano-delivery systems against bacterial resistance.