Chemical Composition, Antifungal and Insecticidal Activities of the Essential Oils from Tunisian Clinopodium Nepeta Subsp. nepeta and Clinopodium Nepeta Subsp. Glandulosum

Antimicrobial Metabolites of Caucasian Medicinal Plants as Alternatives to Antibiotics

This review explores the potential of antimicrobial metabolites derived from Caucasian medicinal plants as alternatives to conventional antibiotics. With the rise of antibiotic resistance posing a global health threat, there is a pressing need to investigate alternative sources of antimicrobial agents. Caucasian medicinal plants have traditionally been used for their therapeutic properties, and recent research has highlighted their potential as sources of antimicrobial compounds. Representatives of 15 families of Caucasian medicinal plant extracts (24 species) have been explored for their efficacy against these pathogens. The effect of these plants on Gram-positive and Gram-negative bacteria and fungi is discussed in this paper. By harnessing the bioactive metabolites present in these plants, this study aims to contribute to the development of new antimicrobial treatments that can effectively combat bacterial infections while minimizing the risk of resistance emergence. Herein we discuss the following classes of bioactive compounds exhibiting antimicrobial activity: phenolic compounds, flavonoids, tannins, terpenes, saponins, alkaloids, and sulfur-containing compounds of Allium species. The review discusses the pharmacological properties of selected Caucasian medicinal plants, the extraction and characterization of these antimicrobial metabolites, the mechanisms of action of antibacterial and antifungal plant compounds, and their potential applications in clinical settings. Additionally, challenges and future directions in the research of antimicrobial metabolites from Caucasian medicinal plants are addressed.

Yield and Composition of the Essential Oil of Clinopodium nepeta subsp. spruneri as Affected by Harvest Season and Cultivation Method, i.e., Outdoor, Greenhouse and In Vitro Culture

Clinopodium nepeta subsp. spruneri is an aromatic herb with a mint-oregano flavor, used in Mediterranean regions in traditional medicine. The aerial parts of the plant are rich in essential oil that has antioxidant, antimicrobial and anti-inflammatory properties as well as insecticidal activity. The aim of our work was to determine the yield and composition of the essential oil of the plant, in relation to the harvest season and cultivation method, i.e., outdoor, greenhouse and in vitro culture, using gas chromatography-mass spectrometry (GC-MS) as an analytical tool. Essential oil yield fluctuated similarly in outdoor and greenhouse plants during the year (0.9-2.6%), with higher percentages (2.1-2.6%) in the hottest periods June-October (flowering stage) and April (vegetative stage), and was similar to the yield in in vitro plants (1.7%). More compounds were identified in the oil of outdoor and greenhouse plants (35) compared to that of in vitro plants (21), while the main compounds were the same, i.e., pulegone (13.0-32.0%, highest in February-April, 15.0% in vitro), piperitenone oxide (3.8-31.8%, lowest in February, 34.2% in vitro), piperitone epoxide (4.6-16.4%, highest in February, 15.5% in vitro), D-limonene (2.1-8.8%, lowest in February, 10.0% in vitro), isomenthone (2.3-23.0%, highest in February, 4.6% in vitro), germacrene D (1.9-6.5% highest in December-April, 2.9% in vitro) and dicyclogermacrene (2.1-5.3%, highest in December-April, 5.2% in vitro). Therefore, greenhouse and in vitro cultures were equally efficient in yielding essential oil and its constituents as outdoor cultivation, while in outdoor and greenhouse cultivations, the harvest season, mainly due to the prevailing ambient temperatures, affected the essential oil yield and its percentage composition.

Effect of Essential Oils of Apiaceae, Lamiaceae, Lauraceae, Myrtaceae, and Rutaceae Family Plants on Growth, Biofilm Formation, and Quorum Sensing in Chromobacterium violaceum, Pseudomonas aeruginosa, and Enterococcus faecalis

The biological role played by essential oils extracted from aromatic plants is progressively being recognized. This study evaluated the potential antibacterial activity of ten essential oils against Chromobacterium violaceum, Pseudomonas aeruginosa, and Enterococcus faecalis by measuring their minimum inhibitory concentration. We found that essential oils exert different antimicrobial effects, with Origanum vulgare and Foeniculum vulgare demonstrating the most significant inhibitory effect on bacterial growth for C. violaceum and E. faecalis. The growth of P. aeruginosa was not affected by any essential oil concentration we used. Sub-inhibitory concentrations of essential oils reduced in C. violaceum and E. faecalis biofilm formation, violacein amount, and gelatinase activity, all of which are biomarkers of the Quorum Sensing process. These concentrations significantly affect the global methylation profiles of cytosines and adenines, thus leading to the hypothesis that the oils also exert their effects through epigenetic changes. Considering the results obtained, it is possible that essential oils can find a broad spectrum of applications in counteracting microbial contamination and preserving sterility of surfaces and foods, as well as inhibiting microbial growth of pathogens, alone or in combination with traditional antibiotics.

An Overview of Herbal Nutraceuticals, Their Extraction, Formulation, Therapeutic Effects and Potential Toxicity

Herbal nutraceuticals are foods derived from plants and/or their derivatives, such as oils, roots, seeds, berries, or flowers, that support wellness and combat acute and chronic ailments induced by unhealthful dietary habits. The current review enlists various traditional as well as unexplored herbs including angelica, burnet, caraway, laurel, parsley, yarrow, and zedoary, which are rich sources of bioactive components, such as aloesin, angelicin, trans-anethole, and cholesteric-7-en-3β-ol. The review further compares some of the extraction and purification techniques, namely, Soxhlet extraction, ultrasound assisted extraction, microwave assisted extraction, supercritical fluid extraction, accelerated solvent extraction, hydro-distillation extraction, ultra-high-pressure extraction, enzyme assisted extraction, pulsed electric field extraction, bio affinity chromatography, cell membrane chromatography, and ligand fishing. Herbal nutraceuticals can be purchased in varied formulations, such as capsules, pills, powders, liquids, and gels. Some of the formulations currently available on the market are discussed here. Further, the significance of herbal nutraceuticals in prevention and cure of diseases, such as diabetes, obesity, dementia, hypertension, and hypercholesterolemia; and as immunomodulators and antimicrobial agents has been discussed. Noteworthy, the inappropriate use of these herbal nutraceuticals can lead to hepatotoxicity, pulmonary toxicity, cytotoxicity, carcinogenicity, nephrotoxicity, hematotoxicity, and cardiac toxicity. Hence, this review concludes with a discussion of various regulatory aspects undertaken by the government agencies in order to minimize the adverse effects associated with herbal nutraceuticals.

Traditional Herbal Remedies Used for Managing Anxiety and Insomnia in Italy: An Ethnopharmacological Overview

Anxiety and insomnia are among the most common mental health disorders and are a major cause of disability around the world. Traditional herbal medicines are receiving significant attention in global health debates. Several Italian regions maintain rural traditions and are among the most extensively studied areas of Europe regarding medicinal plant uses. The present overview aims to highlight the use of wild and cultivated plants, specifically as sedatives and for insomnia treatment in Italy, and to collect, analyze, and summarize the available literature about their pharmacological activity as well as clinical and pre-clinical studies concerning the most cited plants. In total, 106 wild taxa are used in Italy for sedative purposes. The plant species belong to 76 genera and 32 families, of which the most cited are Asteraceae (24.2%) and Lamiaceae (21.1%). Leaves (29%) and flowers (27%) are the plant parts mostly used as infusion (70%) and decoction (25%). Out of 106 taxa documented, only the most cited are analyzed in this overview (A. arvensis L., C. nepeta L., C. monogyna Jacq., H. lupulus L., L. nobilis L., L. angustifolia Mill., M. sylvestris L., M. chamomilla L., M. officinalis L., O. basilicum L., P. rhoeas L., P. somniferum L., R. officinalis L., T. platyphyllus Scop., and V. officinalis L.). Among the fifteen species selected, only seven have been studied for their pharmacological activity as hypnotic-sedatives. Future pre-clinical and clinical studies are needed to better clarify the mechanism of action of bioactive compounds and confirm the potential of these alternative therapies.

Design, Synthesis, Antibacterial, Antifungal and Anticancer Evaluations of Novel β-Pinene Quaternary Ammonium Salts

β-pinene is a monoterpene isolated from turpentine oil and numerous other plants' essential oils, which has a broad spectrum of biological activities. In the current work, six novel β-pinene quaternary ammonium (β-PQA) salts were synthesized and evaluated in vitro for their antifungal, antibacterial and anticancer activities. The in vitro assay results revealed that compounds 4a and 4b presented remarkable antimicrobial activity against the tested fungi and bacteria. In particular, compound 4a showed excellent activities against F. oxysporum f.sp. niveum, P. nicotianae var.nicotianae, R. solani, D. pinea and Fusicoccumaesculi, with EC50 values of 4.50, 10.92, 9.45, 10.82 and 6.34 μg/mL, respectively. Moreover, compound 4a showed the best antibacterial action against E. coli, P. aeruginosa, S. aureus and B. subtilis, with MIC at 2.5, 0.625, 1.25 and 1.25 μg/mL, respectively. The anticancer activity results demonstrated that compounds 4a, 4b, 4c and 4f exhibited remarkable activity against HCT-116 and MCF-7 cell lines, with IC50 values ranged from 1.10 to 25.54 μM. Notably, the compound 4c displayed the strongest cytotoxicity against HCT-116 and MCF-7 cell lines, with the IC50 values of 1.10 and 2.46 μM, respectively. Furthermore, preliminary antimicrobial mechanistic studies revealed that compound 4a might cause mycelium abnormalities of microbial, cell membrane permeability changes and inhibition of the activity of ATP. Altogether, these findings open interesting perspectives to the application of β-PQA salts as a novel leading structure for the development of effective antimicrobial and anticancer agents.

A Novel Chemical Profile of a Selective In Vitro Cholinergic Essential Oil from Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae), a Native Andean Species of Ecuador

A novel chemical profile essential oil, distilled from the aerial parts of Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae), was analysed by Gas Chromatography-Mass Spectrometry (GC-MS, qualitative analysis) and Gas Chromatography with Flame Ionization Detector (GC-FID, quantitative analysis), with both polar and non-polar stationary phase columns. The chemical composition mostly consisted of sesquiterpenes and sesquiterpenoids (>70%), the main ones being (E)-β-caryophyllene (17.8%), α-copaene (10.5%), β-bourbonene (9.9%), δ-cadinene (6.6%), cis-cadina-1(6),4-diene (6.4%) and germacrene D (4.9%), with the non-polar column. The essential oil was then submitted to enantioselective GC analysis, with a diethyl-tert-butyldimethylsilyl-β-cyclodextrin diluted in PS-086 chiral selector, resulting in the following enantiomeric excesses for the chiral components: (1R,5S)-(-)-α-thujene (67.8%), (1R,5R)-(+)-α-pinene (85.5%), (1S,5S)-(-)-β-pinene (90.0%), (1S,5S)-(-)-sabinene (12.3%), (S)-(-)-limonene (88.1%), (S)-(+)-linalool (32.7%), (R)-(-)-terpinen-4-ol (9.3%), (S)-(-)-α-terpineol (71.2%) and (S)-(-)-germacrene D (89.0%). The inhibition activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) of C. taxifolium essential oil was then tested, resulting in selective activity against BChE with an IC50 value of 31.3 ± 3.0 μg/mL (positive control: donepezil, IC50 = 3.6 μg/mL).

Use of Essential Oils in Veterinary Medicine to Combat Bacterial and Fungal Infections

Essential oils (EOs) are secondary metabolites of plants employed in folk medicine for a long time thanks to their multiple properties. In the last years, their use has been introduced in veterinary medicine, too. The study of the antibacterial properties of EOs is of increasing interest, because therapies with alternative drugs are welcome to combat infections caused by antibiotic-resistant strains. Other issues could be resolved by EOs employment, such as the presence of antibiotic residues in food of animal origin and in environment. Although the in vitro antimicrobial activity of EOs has been frequently demonstrated in studies carried out on bacterial and fungal strains of different origins, there is a lack of information about their effectiveness in treating infections in animals. The scientific literature reports some studies about in vitro EOs' activity against animal clinical bacterial and fungal isolates, but in vivo studies are very scanty. The use of EOs in therapy of companion and farm animals should follow careful studies on the toxicity of these natural products in relation to animal species and route of administration. Moreover, considering the different behavior of EOs in relation to both species and strain pathogen, before starting a therapy, an aromatogram should be executed to choose the oil with the best antimicrobial activity.

Anti-Candida Activity of Essential Oils from Lamiaceae Plants from the Mediterranean Area and the Middle East

Extensive documentation is available on plant essential oils as a potential source of antimicrobials, including natural drugs against Candida spp. Yeasts of the genus Candida are responsible for various clinical manifestations, from mucocutaneous overgrowth to bloodstream infections, whose incidence and mortality rates are increasing because of the expanding population of immunocompromised patients. In the last decade, although C. albicans is still regarded as the most common species, epidemiological data reveal that the global distribution of Candida spp. has changed, and non-albicans species of Candida are being increasingly isolated worldwide. The present study aimed to review the anti-Candida activity of essential oils collected from 100 species of the Lamiaceae family growing in the Mediterranean area and the Middle East. An overview is given on the most promising essential oils and constituents inhibiting Candida spp. growth, with a particular focus for those natural products able to reduce the expression of virulence factors, such as yeast-hyphal transition and biofilm formation. Based on current knowledge on members of the Lamiaceae family, future recommendations to strengthen the value of these essential oils as antimicrobial agents include pathogen selection, with an extension towards the new emerging Candida spp. and toxicological screening, as it cannot be taken for granted that plant-derived products are void of potential toxic and/or carcinogenic properties.