Constituents Of Essential Oil Research Articles

Essential oils from fennel plants as valuable chemical products: gas chromatography–mass spectrometry, FTIR, quantum mechanical investigation, and antifungal activity

AbstractIn the present study, the biomass produced by fennel plants (Foeniculum vulgare Mill.) was converted to yield bioactive chemicals, and the hydrodistillation method was used to extract the essential oils (EOs) from both the leaves and the umbels. The antifungal activity of the EOs was tested using bioassay against the development of Fusarium oxysporum MW854649 and Alternaria solani MT279570. Molecular spectroscopic detection techniques were used to evaluate the EO products using gas chromatography–mass spectrometer (GC–MS) and Fourier transform infrared spectroscopy (FTIR). GC–MS equipped with single quadruple analyzers have been used to measure the electron ionization (EI) mass spectra of the primary constituents of fennel EOs at 70 eV. The main chemical compounds in the EO from leaves were anethole, estragole, D-limonene, trans-β-ocimene, and fenchone, with percentages of 37.94, 35.56, 17.46, 1.53, and 1.49%, respectively. The abundant compounds in the EO from umbels were estragole, anethole, D-limonene, fenchone, and γ-terpinene, with percentages of 51.18, 25.08, 12.22, 6.57, and 2.86%, respectively. EI mass spectral fragmentation of the major compounds D-limonene, estragole, anethole, and fenchone has been investigated. Umbels and leaf EOs at 5000 mg/L displayed the strongest suppression of fungal growth against A. solani, with values of 87.78% and 79.63%, respectively, compared to the positive control (94.44%). The EOs from umbels and leaves at 5000 mg/L showed the highest inhibition of fungal growth against F. oxysprium as compared to the positive control (94.44%), with values of 77.77% and 72.96%, respectively. All of the important ions—including a few distinctive fragment ions—have comprehensive fragmentation pathways defined. Based on EI, the main routes of fragmentation for the primary compounds have been identified. The existence of alkenes, aliphatic alcohols, ethers, carboxylic acids, ester compounds, alkanes, hydrogen-bonded alcohols, and phenols was demonstrated by the FTIR analysis of fennel EOs. On the other hand, the reactive behavior of the studied molecules has been investigated using two quantum mechanics method: the modified neglect of diatomic overlap (MNDO), a semi-empirical method, and the density functional theory (DFT)/B3LYP hybrid density functional method with the 6-311G (d, p) basis set in the ground state for gas phase. The optimum geometries have been obtained through the execution of computations and electrostatic potential. The obtained analytical and calculated results were then used to understand the activity of the studied EOs in further medical applications.

Essential Oil Constituents as Anti-Inflammatory and Neuroprotective Agents: An Insight through Microglia Modulation

Microglia are key players in the brain’s innate immune response, contributing to homeostatic and reparative functions but also to inflammatory and underlying mechanisms of neurodegeneration. Targeting microglia and modulating their function may have therapeutic potential for mitigating neuroinflammation and neurodegeneration. The anti-inflammatory properties of essential oils suggest that some of their components may be useful in regulating microglial function and microglial-associated neuroinflammation. This study, starting from the ethnopharmacological premises of the therapeutic benefits of aromatic plants, assessed the evidence for the essential oil modulation of microglia, investigating their potential pharmacological mechanisms. Current knowledge of the phytoconstituents, safety of essential oil components, and anti-inflammatory and potential neuroprotective effects were reviewed. This review encompasses essential oils of Thymus spp., Artemisia spp., Ziziphora clinopodioides, Valeriana jatamansi, Acorus spp., and others as well as some of their components including 1,8-cineole, β-caryophyllene, β-patchoulene, carvacrol, β-ionone, eugenol, geraniol, menthol, linalool, thymol, α-asarone, and α-thujone. Essential oils that target PPAR/PI3K-Akt/MAPK signalling pathways could supplement other approaches to modulate microglial-associated inflammation to treat neurodegenerative diseases, particularly in cases where reactive microglia play a part in the pathophysiological mechanisms underlying neurodegeneration.

Investigating the pharmacological potential of phytol on experimental models of gastric ulcer in rats.

Phytol is a diterpene constituent of many essential oils, belonging to the group of unsaturated acyclic alcohols. Although phytol possesses antimycobacterial and anti-inflammatory effects, no reports of a gastrointestinal action are available from the literature. Due to the well-known shortcomings of classical anti-ulcer drugs (e.g. side effects or relapses), natural products may offer an attractive alternative. In this study, a potential gastroprotective activity of phytol was evaluated using acute and chronic ulcer models in rats. Phytol 12.5, 25 and 50mg/kg, administered orally 1h prior to induction of gastric lesions by absolute ethanol, inhibited the lesion area by 96, 90 and 95%, respectively. When lesions were induced by ischemia and reperfusion, phytol 12.5 and 25mg/kg per os decreased the lesion areas by 89 and 46%, respectively. In the third acute ulcer model (lesions induced by ibuprofen), phytol 12.5mg/kg reduced the lesion area by 55%. Phytol restored the decreased level of reduced glutathione, the increased levels of myeloperoxidase and malondialdehyde and the decreased levels of catalase and superoxide dismutase in rats with gastric ulcer induced by ethanol to levels obtained in vehicle group. Finally, in a chronic model in which gastric ulcer was induced by acetic acid directly instilled into the stomach, phytol administered orally over a time period of 7 days at 12.5, 25, 50 and 100mg/kg reduced lesion areas by 84, 81, 83 and 68%. Our data suggest a gastroprotective and cicatrizing effect of phytol, possibly associated with its antioxidant effect.

Effect of environmental conditions and seasons on the growth, yield, and essential oil composition of Foeniculum vulgare L.

Foeniculum vulgare (Fennel) oils have an essential function in the food and therapeutic industries. The study’s purpose was to describe how different environmental circumstances and locations in Egypt affected the fennel oil yields and compositions. To assess the growth, yield, and essential oil constituents of F. vulgare at four differing agro-ecological regions in Egypt (El-Minia Governorate, Bahariya Oasis, El-Sharkia Governorate, and Aswan Governorate) at two different planting dates, in-field study was performed throughout the seasons 2019/2020 and 2020/2021. According to the data, there are highly significant differences between locations and sowing dates; the second date (15th November) is the best date for planting fennel plants. Plants grown in the Bahariya Oasis location had the maximum oil yield in mL/plant and L/acre, whereas the Aswan location had the highest percentage of EO. Eight EO samples underwent GC-MS analysis and chemometric analysis, including principal component analysis (PCA) and agglomerative hierarchical clustering (AHC), yielding identification of a total of 22 compounds. EOs from plants grown in various environments varied significantly in terms of their chemical composition, mainly components‘ concentrations. The main components were identified as estragole (66.62-89.73%), D-limonene (5.76-17.04%), and fenchone (2.02-9.23%). In samples gathered on November 15, 2020-2021, at the Bahariya Sekem Farm, anethole was found at a high concentration (12.79%), despite the compound’s absence or minimal presence in the other EOs. According to the current study findings, modulation of the cultivation and ecological circumstances can be used for the improvement of funnel EO.

Anticonvulsant activity of Tetrahydrolinalool: behavioral, electrophysiological, and molecular docking approaches.

Tetrahydrolinalool (THL) is an acyclic monoterpene alcohol, produced during linalol metabolism and also a constituent of essential oils. As described in the literature, many monoterpenes present anticonvulsant properties, and thus we became interested in evaluating the anticonvulsant activity of Tetrahydrolinalool using in mice model as well as in silico approaches. Our results demonstrated that THL increased latency to seizure onset and also reduced the mortality, in picrotoxin induced seizure tests. The results may be related to GABAergic regulation, which was also suggested in seizure testing induced by 3-mercapto-propionic acid. In the strychnine-induced seizure testing, none of the groups pretreated with THL modulated the parameters indicative of anticonvulsant effect. The electrophysiological results revealed that THL treatment reduces seizures induced by pentylenetetrazole. The in silico molecular docking studies showed that the interaction between THL and a GABAA receptor model formed a stable complex, in comparison to the crystaligraphic structure of diazepam, a structurally related ligand. In conclusion, all the evidences showed that THL presents effective anticonvulsant activity related to the GABAergic pathway, being a candidate for treatment of epileptic syndromes.

Fatty acid and essential oil compositions of seeds of coriander (Coriandrum sativum L.) Cultivated in different regions of Ethiopia

Coriander (Coriandrum sativum L.) seeds are used as spices. In this study, fatty acids extracted from the coriander seeds collected from three places (Sululta, Jimma and Wolaita Sodo) in Ethiopia were determined as their methyl ester using GC-MS. The fatty acid components were assessed using linoleic acid ethyl ester as an external standard. Sululta sample showed five fatty acids, while Wolaita Sodo and Jimma three each with highest amount of petroselinic acid: 68.41%, 72.53%, and 64.4%, respectively, of the total fatty acids. Linoleic acid (omega-6) was found in the range of 18.24-22.37%. The polyunsaturated versus saturated (P/S) index values were found to be 1.69-2.39, which indicated that coriander seeds from the three sites have a good capacity to prevent the development of cardiovascular and some chronic diseases. The number of compounds identified in the essential oils of coriander seeds from Jimma, Sululta, and Wolaita Sodo were 7, 9, and 15 with total percent areas of 99.64, 75.14, and 96.68, respectively. The major component in the essential oils was linalool ranging from 36.72-88.50% of the total amount. In general, the chemical constituents of fatty acids and essential oils of coriander seeds indicates its good nutritional quality and usefulness for human health. KEY WORDS: Coriander seeds, Fatty acids, P/S index, Essential oils, Nutritional quality, Spice Bull. Chem. Soc. Ethiop. 2024, 38(4), 863-876. DOI: https://dx.doi.org/10.4314/bcse.v38i4.4

In silico Exploration of Essential Oil Constituents in Combating Multidrug-Resistant Staphylococcus aureus Infected Wounds

This research explores the multifaceted pharmacological actions of essential oils and its constituents, derived as secondary metabolites from aromatic plants, with a particular focus on their potent wound healing and antibacterial activities, elucidating their significance in therapeutic approach towards infected wounds. An in silico screening was carried out to identify the interaction between the bioactive essential oil contituents (EOC) such as cinnamaldehyde, citral, geraniol, linalool, and p-cymene, docked against various target proteins associated with antibiotic resistance and wound healing, including mec A (PDB ID- 4DK1), nor A (PDB ID- 7LO8), TGF- β1 (PDB ID- 1PY5), TGF- β2 (PDB ID- 1M9Z), VEGF (PDB ID-3QTK), GSK-3β (PDB ID-1Q5K) and MMP-9 (PDB ID-5UE4). The docking was done with AutoDock V 4.0 using five EOCs against seven receptors and the binding energy was gaged. The binding energy of EOCs were observed to be ranging from -5.3 kcal/mol to -2.55 kcal/mol. Notably, all the screened EOCs exhibited favourable binding affinity with GSK-3β, indicating their potential role in the inflammatory phase of wound healing. Additionally, towards antibiotic resistance, all EOC displayed adequate binding affinity with norA, suggesting their potential in modulating multidrug resistant efflux pumps. Compliance with Lipinski's rule, positions these EOC as promising candidates for drug development, particularly in the context of wound healing and antibiotic resistance. This study holds the promise of contributing novel insights to the field of wound care and combating antibiotic resistance, paving the way for innovative approaches in addressing the challenges posed by multi-drug resistant Staphylococcus aureus (MDRSA) infected wounds.

What routes makes Essential Oils effective in Aromatherapy? A current perspective study

Aromatherapy, the therapeutic application of essential oils extracted from plants, has emerged as a prominent practice in complementary and alternative medicine. Essential oils, renowned for their aromatic compounds, are utilized in a variety of therapeutic modalities to enhance physical, emotional, and mental health. Understanding the administration routes of essential oils is crucial for maximizing their therapeutic potential and ensuring safety. The method of administration—whether inhalation, topical application, or ingestion—significantly influences the absorption, distribution, and efficacy of the bioactive compounds in essential oils. For instance, inhalation directly interacts with the olfactory system, potentially impacting mood and stress levels, while topical application facilitates localized effects and transdermal absorption, providing targeted therapeutic benefits. Ingestion, though less common, requires careful consideration due to the potent nature and potential toxicity of essential oils. This paper emphasizes the importance of selecting the appropriate administration route based on desired outcomes and safety considerations. It also explores the concept of synergy, where the interaction of multiple essential oil constituents can enhance therapeutic effects, exemplified by the compounds in lavender and eucalyptus oils. This study highlights the challenges in aromatherapy research, including the need for standardization, quality assurance, and rigorous methodological approaches to validate the therapeutic efficacy of essential oils.

A Comparison between Bulgarian Tanacetum parthenium Essential Oil from Two Different Locations.

Tanacetum parthenium L. (Asteraceae) is a perennial herbaceous plant with a long-standing historical use in traditional medicine. Recently Tanacetum parthenium L. essential oil has been associated with a promising potential for future applications in the pharmaceutical industry, in the cosmetics industry, and in agriculture. Investigations on the essential oil (EO) have indicated antimicrobial, antioxidant, and repellent activity. The present study aimed to evaluate the chemical composition of Bulgarian T. parthenium essential oil from two different regions, to compare the results to those reported previously in the literature, and to point out some of its future applications. The essential oils of the air-dried flowering aerial parts were obtained by hydrodistillation using a Clevenger-type apparatus. The chemical composition was evaluated using gas chromatography with mass spectrometry (GC-MS). It was established that the oxygenated monoterpenes were the predominant terpene class, followed by the monoterpene hydrocarbons. Significant qualitative and quantitative differences between both samples were revealed. Camphor (50.90%), camphene (16.12%), and bornyl acetate (6.05%) were the major constituents in the feverfew EO from the western Rhodope Mountains, while in the EO from the central Balkan mountains camphor (45.54%), trans-chrysanthenyl acetate (13.87%), and camphene (13.03%) were the most abundant components.

Effectiveness of a formulation based on Ocimum gratissimum essential oil and cashew gum as inhibitors of quality loss and melanosis in shrimp

In this study, two nanoemulsions were formulated with essential oil (EO) of Ocimum gratissimum with (EON) or without (EOE) cashew gum (CG). Subsequently, inhibition of melanosis and preservation of the quality of shrimp stored for 16 days at 4 ± 0.5 °C were evaluated. A computational approach was performed to predict the system interactions. Dynamic light scattering (DLS) and atomic force microscopy (AFM) were used for nanoparticle analysis. Gas chromatography and flame ionization detector (GC-FID) determined the chemical composition of the EO constituents. Shrimps were evaluated according to melanosis's appearance, psychrotrophic bacteria's count, pH, total volatile basic nitrogen, and thiobarbituric acid reactive substances. EON exhibited a particle size three times smaller than EOE. The shrimp treated with EON showed a more pronounced sensory inhibition of melanosis, which was considered mild by the 16th day. Meanwhile, in the other groups, melanosis was moderate (EOE) or severe (untreated group). Both EON and EOE treatments exhibited inhibition of psychrotrophic bacteria and demonstrated the potential to prevent lipid oxidation, thus extending the shelf life compared to untreated fresh shrimp. EON with cashew gum, seems more promising due to its physicochemical characteristics and superior sensory performance in inhibiting melanosis during shrimp preservation.

Antimicrobial Activity of Individual Volatile Compounds from Various Essential Oils.

Interest in natural remedies has grown recently due to a variety of public health concerns such as microbial antibiotic resistance. This global health concern necessitates innovative approaches to combat bacterial infections. Building upon established therapeutic uses of essential oils, this research focused on the volatile constituents of essential oils. The volatile antimicrobial activity of these constituents was studied by employing a derivative of a modified disk diffusion assay for quantitative comparisons. This study emphasizes the significance and value of exploring natural compounds as alternatives to traditional antibiotics and provides insights into their mechanisms and applications in contending with bacterial pathogens.

The First Study on Cultivating Roman Chamomile (Chamaemelum nobile (L.) All.) for Its Flower and Essential Oil in Southeast Serbia

Roman chamomile (Chamaemelum nobile (L.) All.) is a perennial herbaceous medicinal plant species that has not yet been thoroughly researched in terms of the influence of growing conditions on its morphological characteristics, flower yield, and the content and quality of its essential oil (EO). The plant material was harvested in the subsequent two production years at three localities in Southeast Serbia, differing in soil type (Alluvial soil, Rendzina, and Calcomelanosol). Based on two-year average values, the best results were obtained from plants grown on Rendzina, including the yield of fresh flowers (1850.2 g/m2), the highest plant height (49.3 cm), the number of branches (4.1), leaves (11.6), and flower heads (3.6), the flower diameter (1.6 cm), and the essential oil content (1.6%). The major EO constituent obtained from the plants growing on Rendzina and Calcomelanosol was 3-methyl pentyl angelate (20.8% and 15.2%, respectively). In the EO obtained from the plants growing on Alluvial soil, the major EO constituent was isobutyl angelate (13.0%), while the content of 3-methyl pentyl angelate was close to it (12.2%). The outcomes of this study provide guidelines for further research related to the cultivation of a Roman chamomile genotype on various soil types in a hilly region of Southeast Serbia, where most cultivated plants cannot be grown.

Determination of chemical compositions of rosemary and sweet marjoram essential oils and their blends and their antifungal potential against potato rubbery rot disease agent Geotrichum candidum

AbstractIn this study, the chemical compositions of rosemary (Rosmarinus officinalis Spenn.) and sweet marjoram (Origanum majorana L.) essential oils, both individually and in various blend ratios, were investigated by using Gas Chromatography-Mass Spectrometry. Their antifungal activities were also determined against the potato rubbery rot disease agent, Geotrichum candidum, under in vitro and in vivo conditions. Camphor (20.69%) and terpinen-4-ol (35.13%) were determined as primary constituents in rosemary and sweet marjoram essential oils, respectively. Sweet marjoram and rosemary essential oils completely inhibited mycelial growth of G. candidum at 55.0 and 65.0 µL/Petri concentrations, respectively. Essential oils at these concentrations were found as fungicidal. Notably, a synergistic fungicidal antifungal effects were also observed in essential oil blends. Blend of sweet marjoram and rosemary essential oil in a 3:1 ratio (O75R25) significantly enhanced antifungal activity at the relatively lower concentration (45.0 µL/Petri). Microscopic observations revealed structural deformations in exposed hyphae, including cytoplasmic coagulation and vacuolization. Essential oil blend (O75R25), sweet marjoram and rosemary essential oils completely inhibited the disease lesion caused by G. candidum on potato tubers at concentrations of 100.0, 125.0, and 150.0 µL/L air, respectively. These findings emphasized that essential oil blends of rosemary and sweet marjoram have synergistic antifungal potential and can be used as effective biofungicides against plant fungal diseases.

Hologram quantitative structure-activity relationship on the gas chromatographic retention index of plant essential oil constituents

The gas chromatography retention index (RI) is an important parameter for the identification of different types of compounds in the field of chromatographic analysis; however, the experimental collection of RI values is a extremely cumbersome process. Thus, there is an urgent need for the establishment of a simple, efficient, and accurate model for the prediction of the RI values of compounds. In this study, first, the experimental RI values for 60 plant essential oil constituents were obtained. Next, a model describing the hologram quantitative structure-activity relationship (HQSAR) between the structural properties of the essential oil constituents and their RI values was investigated and constructed. The optimal HQSAR model was established by setting the model parameters "fragment size", "fragment distinction", "hologram length" and "principal components" to "1-4", "C, Ch", "199", and "4", respectively. Finally, the predictive ability of the model was verified using external test set validation and leave-one-out cross-validation (LOO-CV). The experimental results were as follows, the root mean square error of prediction (RMSEP), predictive determination coefficient ([Formula: see text]), concordance correlation coefficient (CCC), and mean relative error (MRE) for external test set validation were 40.45, 0.984, 0.968, and 2.20%, respectively. Meanwhile, the root mean square error of cross validation (RMSECV) and MRE for LOO-CV were 72.56 and 4.17%, respectively. These findings demonstrate that the established HQSAR model has a good predictive ability and can accurately predict the RI values of plant essential oil constituents. In addition, the molecular contribution maps of the HQSAR model revealed that the RI values of aromatic compounds increase when hydroxyl groups are connected to their alkyl chains. Aliphatic compounds feature long chain alkyl groups, which can lead to an increase in RI values. The above phenomena highlight the promising application prospects of HQSAR for studying the RI values of plant essential oil constituents. Therefore, this study provides a reliable theoretical basis for predicting the RI values of other essential oil constituents.

Gc-ms analysis of leaf and rhizome essential oil of zingiber purpureum roxb. From bangladesh

Essential oils (EOs) are among the most important plant secondary metabolites. Zingiber purpureum Roxb. is a tropical ginger from Bangladesh, but its chemical constituents of leaves and rhizomes, both EOs, may have pharmacological effects. The aim of this study was carried out to analyze the qualitative composition of both Essential oils (EOs) of both leaf and rhizomes of Z. purpureum. The EOs from the leaves and rhizomes were extracted by hydrodistillation. Chemical constituents of the EOs were separated and identified by gas chromatography/mass spectrometry (GC/MS), and the relative percentage of each constituent was determined by area normalization. In total, 81 compounds were identified from leaf EOs, whereas 44 were from rhizome EOs. The common compounds identified from both rhizome and leaf EOs were triquinacene, 1,4, bis (methoxy), b-phellandrene and b-sesquiphellandrene, respectively. Besides, the major constituents of leaf EOs were sabinine (14.99%), b-pinene (14.32%), caryophyllene oxide (13.85%), and caryophyllene (9.47%), whereas the rhizome EOs confirmed (Z)-ocimene (21.97%), 4-terpineol (18.45%), γ-terpinene (3.86%) and cis-sabinenehydrate (3%). These EOs could be a promising source for the development of nutraceuticals, functional foods, and pharmaceutical products due to their potent activities and exploitation. Bangladesh J. Bot. 53(1): 153-158, 2024 (March)

Combinations of Lemongrass and Star Anise Essential Oils and Their Main Constituent: Synergistic Housefly Repellency and Safety against Non-Target Organisms.

The present study evaluated the housefly repellency of single-component formulations and combinations of lemongrass and star anise essential oils (EOs) and their main constituents. The efficacies of the combinations were compared against those of single-component formulations and DEET. Safety bioassays of all formulations and DEET on non-target species-guppy, molly, dwarf honeybee, and stingless bee-were conducted. GC-MS analysis showed that the main constituent of lemongrass EO was geranial (46.83%) and that of star anise EO was trans-anethole (92.88%). All combinations were highly synergistic compared to single-component formulations, with an increased repellent value (IR) of 34.6 to 51.2%. The greatest synergistic effect was achieved by 1.0% lemongrass EO + 1.0% trans-anethole combination, with an IR of 51.2%. The strongest, 100% repellent rate at 6 h was achieved by 1.0% geranial + 1.0% trans-anethole. They were twice as effective as DEET and caused obvious damage to housefly antennae under microscopic observation. All single-component formulations and combinations were benign to the four tested non-target species. In contrast, DEET was highly toxic to them. The synergistic repellency and biosafety of these two combinations are compellingly strong support for developing them into an effective green repellent.

Exploring the therapeutic potential of cinnamon and clove essential oils for mitigating foodborne diseases: bioactivity and molecular interactions

Foodborne diseases remain a global concern due to their widespread impact on public health. Contaminated food can lead to outbreaks of illness that affect millions of people each year, leading to significant economic burdens and strain on healthcare systems. This study delves into the potential of cinnamon and clove essential oils to combat foodborne diseases. Essential oils extracted via the Soxhlet method using ethanol as solvent, these oils exhibit potent antibacterial, anti-inflammatory, antioxidant and anticancer properties. Gas chromatography-mass spectrometry analysis was performed to analyze the chemical constituents in both essential oils. Employing the Lipinski rule, bioactive compounds are screened and docked against a viral replication responsible protein of norovirus and the neurotoxin (botulinum toxin) of Clostridium botulinum both responsible for severe foodborne illnesses. Acetyleugenol demonstrates strong binding affinity, while the pyrimidine derivative from cinnamon sourced from Mbeya, Tanzania forms pi-sulfur interactions with both target molecules. This research emphasizes how essential oils confront foodborne diseases, granting valuable perspectives on potential compounds for extended examination and therapeutic interventions.

The Effect of Salinity and Drought on the Essential Oil Yield and Quality of Various Plant Species of the Lamiaceae Family (Mentha spicata L., Origanum dictamnus L., Origanum onites L.)

Mentha spicata L., Origanum dictamnus L., and Origanum onites L. are aromatic plants that produce very important essential oils. They are considered model plants with beneficial health properties due to their antioxidant content. Enhancing the yield while maintaining the quality of essential oil is of significant commercial importance. Salinization and drought cause various effects on the yield and quality of the bioactive constituents in essential oil. By assessing the response of these plants and their secondary metabolites accumulation to different salt stress and irrigation levels, this study aims to gain insights into how plants adapt to and cope with salinity and drought. A pot experiment was conducted in the spring of 2020 to assess the effect of salinity and drought stress on the growth and essential oils content of the three aromatic plant species mentioned above. The soil mixture used was perlite and peat in a ratio of 1:1:6, while four salinity treatments (25, 50, 100, and 150 mΜ NaCl) and two levels of irrigation were applied (100% and 50%). Salinity significantly affects total chlorophyll concentration especially in higher concentrations (100 and 150 mM) in M. spicata plants, especially under 50% soil water irrigation. Under the same conditions, M. spicata contained the higher proline concentration, which was significantly greater than that in O. dictamnus and O. onites. Similar variations of malondialdehyde and hydrogen hyperoxide were revealed among the three species, with significantly higher values in M. spicata when subjected to both excess salinity and drought conditions. The major compounds identified in M. spicata were carvone, in O. dictamnus carvacrol, and p-cymene and in O. onites carvacrol. It is important to highlight that O. onites had the highest concentration of essential oil, and that the concentration increased with the increase of NaCl. This suggests that the presence of NaCl in the soil may have a stimulating effect on the production of essential oil in O. onites. However, it is plausible that the stress caused by NaCl triggers a physiological response in O. onites, leading to increased production of essential oil. This could be a protective mechanism to enhance the plant’s resistance to the stressor. Overall, O. onites and O. dictamnus appeared to be more resistant to these stress conditions than M. spicata, since they maintained their growth and essential oil quality indicators at higher levels. These two species possess mechanisms that prevent or minimize lipid peroxidation, thus protecting their cell membranes and maintaining their ultrastructure integrity.

Comparative study of volatile oil constituents, anti-microbial properties, and antibiofilm activities in Eucalyptus camaldulensis and Eucalyptus globulus: insights from central Saudi Arabia

Eucalyptus is a fragrant plant with a highly volatile oil content grown worldwide. This study investigated the phytochemical and biological features of two Eucalyptus species, E. camaldulensis and E. globulus, cultivated in Central Saudi Arabia. Phytochemical analysis revealed 17 compounds in E. camaldulensis and 13 in E. globulus, with α-pinene and 1,8-cineole being both plants’ most abundant volatile components. The antimicrobial activity revealed that Salmonella typhimurium ATCC 13311 and Candida albicans ATCC 10231 are the most susceptible to E. camaldulensis, with the zone of inhibition diameters (ZIDs) of 17.0 ± 0.2 mm and 22.0 ± 0.3 mm, respectively. In contrast, for E. globulus, methicillin-resistant Staphylococcus aureus and Candida albicans ATCC 10231 were the most susceptible, with ZIDs of 13.0 ± 0.2 mm and 20.0 ± 0.2 mm, respectively. E. camaldulensis had minimum inhibitory concentration (MIC) range from 1.56 to 12.5 μL/mL, minimum biocidal concentration (MBC) range from 3.125 to 25.0 μL/mL, minimum biofilm inhibitory concentration (MBIC) range from 3.125 to 25.0 μL/mL, and minimum biofilm eradication concentration (MBEC) from 6.25 to 50.0 μL/mL, while E. globulus had MIC range from 3.125 to 12.5 μL/mL, MBC range from 6.25 to 25.0 μL/mL, MBIC range from 6.25 to 25.0 μL/mL, and MBEC range from 12.5 to 50.0 μL/mL, for the tested organisms. E. camaldulensis demonstrated better antimicrobial activity than E. globulus against the tested organisms, making it a promising antimicrobial drug candidate. Further research is required to determine its effectiveness in treating different human infections.

Antimicrobial effects of catnip (Nepeta cataria L.) essential oil against canine skin infection pathogens

Background and Aim: Catnip essential oils have antimicrobial effects against bacteria, yeast, and fungi; however, there is limited information regarding their antimicrobial activity against pathogens that cause canine skin infections. This study aimed to identify the phytochemical constituents of catnip essential oil and assay its antimicrobial activity against Staphylococcus pseudintermedius, Malassezia pachydermatis, Microsporum canis, Microsporum gypseum, Microsporum gallinae, and Trichophyton mentagrophytes. Materials and Methods: Catnip essential oil was extracted by hydrodistillation, and its chemical constituents were analyzed by gas chromatography–mass spectrometry (GC–MS). In vitro antimicrobial activity was investigated using broth microdilution and time-kill tests. To evaluate the effect of catnip essential oil on microbial morphology and cell membrane integrity, scanning electron microscopy (SEM) and leakage studies were conducted. Results: GC–MS analysis revealed that the principal components of catnip essential oil were cis- and trans-nepetalactone (57.09% of peak area), trans-, cis-nepetalactone (39.69% of peak area), trans-caryophyllene (1.88% of peak area), and caryophyllene oxide (1.34% of peak area). The minimum inhibitory concentration, minimum bactericidal concentration, and minimum fungicidal concentration values determined by broth microdilution ranged from 0.0625 mg/mL to 4.0 mg/ mL. Time-kill testing showed that the germicidal effects of catnip essential oil were time and concentration-dependent, respectively. Environmental SEM and cell leakage analysis indicated that catnip essential oil disrupted the integrity of cell membranes in the tested microorganisms. Conclusion: Catnip essential oil has potential as an alternative antimicrobial against a wide range of canine skin infection pathogens, including S. pseudintermedius, M. pachydermatis, Mi. canis, Mi. gypseum, Mi. gallinae, and T. mentagrophytes. Keywords: antimicrobial activity, canine dermatitis, catnip, Nepeta cataria.