Constituents Of Essential Oil Research Articles

Essential oil constituents as the chemosystematic markers in Eugenia L. (Myrtaceae): An evolutionary perspective

Essential oil constituents as the chemosystematic markers in Eugenia L. (Myrtaceae): An evolutionary perspective

In vitro and Quantitative and Structure Activity Relationship (QSAR) evaluation of the antifungal activity of terpenoid constituents of essential oils against Alternaria alternata and Fusarium oxysporum

Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed to resistance development in pathogens. An alternative to searching for and developing new antifungal agents is using essential oils and their main components, which have biological activities of interest in medicine and food production. To evaluate in vitro and in silico the antifungal activities of terpenoids against Alternaria alternata and Fusarium oxysporum. The minimum inhibitory concentration and minimum fungicidal concentration values of 27 constituents of essential oils used against Alternaria alternata and Fusarium oxysporum were evaluated in vitro. In addition, using genetic algorithms, quantitative models of the structure-activity relationship were used to identify the structural and physicochemical properties related to antifungal activity. The evaluated compounds proved to be effective antifungals. Thymol was the most active with a minimum inhibitory concentration of 91.6 ± 28.8 μg/ml for A. alternata and F. oxysporum. Quantitative structure-activity relationship models revealed the octanolwater cleavage ratio as the molecular property, and the phenols as the main functional group contributing to antifungal activity. Terpenoids exhibit relevant antifungal activities that should be incorporated into the study of medicinal chemistry. Inclusion of in silico assays in the in vitro evaluation is a valuable tool in the search for and rational design of terpene derivatives as new potential antifungal agents.

Synergism in Two-Component Insecticides with Dillapiole against Fall Armyworm.

The fall armyworm (Spodoptera frugiperda), a polyphagous insect pest, is a major threat to food production, rapidly spreading through all the tropical areas in the world. Resistance has developed to the control protocols used so far (pyrethroids, organophosphorus, and genetically modified plants), and alternative strategies must be found. The bioactivity in essential oils is usually associated with the major constituents, but synergistic interactions among the constituents (even minor ones) can improve the levels of activity considerably. Herein, we tested the insecticidal activity of several constituents of the essential oil from Piper aduncum, an Amazonian Piperaceae, both separately and as binary mixtures, through their application on the dorsal side of the larva pronotum. Dillapiole proved to be, isolated, the most active compound in this oil (LD50 = 0.35 ppm). In binary mixtures, a strong synergistic effect was observed for the pairs of dillapiole with β-caryophyllene (LD50 = 0.03 ppm), methyl eugenol (LD50 = 0.05 ppm), and α-humulene (LD50 = 0.05 ppm). In some cases, however, antagonism was recorded, as for dillapiole + β-pinene (LD50 = 0.44 ppm). The use of binary mixtures of essential oil constituents as low-environmental-toxicity insecticides allows a fine tuning of the insecticidal activity, and the exploitation of synergy effects.

Continual misidentification of 5-oxolinalool as 2-methylnon-2-en-4-one in essential oils

ABSTRACT When employing GC and GC-MS, constituents of essential oils are most frequently identified by comparing retention indices and mass spectra with those reported in the literature or analytical libraries. While this allows for a rapid analysis, incorrect data can lead to a constituent being repeatedly misidentified. This was demonstrated in this work for 5-oxolinalool (6-hydroxy-2,6-dimethylocta-2,7-dien-4-one), an oxygenated monoterpene that was often erroneously identified as 2-methylnon-2-en-4-one. After encountering an unknown constituent of the essential oil of Sambucus nigra L. (Viburnaceae) flowers, we sought to acquire relevant analytical data on both compounds. Even though their mass spectra were rather similar (with 2-methylnon-2-en-4-one missing the peak at m/z 71), their retention indices were found to be significantly different. It follows that a revision of all prior identifications of 2-methylnon-2-en-4-one as an essential-oil constituent is needed.

Antioxidant and diuretic effects of flower extract of Laurus nobilis

Diuretic medications are widely used and can come with negative effects. Because they are effective and have fewer adverse effects than other treatments for renal illness, medicinal plants have become increasingly important. This study aimed to investigate the antioxidant ability and the impact of Laurus nobilis extract (flower) on diuresis in rats. Two doses of 200 mg and 400 mg of Laurus nobilis extract were used to treat rats for thirty days. Then, we assessed all changes induced in urine and plasma parameters of rats, using furosemide as a standard drug. Further, we evaluated the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant ability (DPPH and FRAP) of the tested extract. The results obtained show that the administration of a single dose of Laurus nobilis extract improved the urine flow significantly after 4 h of treatment. Similarly, both doses of the tested extract enhanced sodium, potassium, and chloride excretion without inducing hypokalemia. A similar tendency was recorded for both urine and creatinine, while the results of the furosemide group revealed a significant hypokalemia effect of the standard drug. Laurus nobilis demonstrated superior antioxidant and diuretic effects without inducing hypokalemia due to the higher content of phenolic and flavonoid content. However, more advanced studies are required to explore the constituents of Laurus nobilis extracts and essential oils, as well as to test their pertinent biological activities.

Essential Oils of Garcinia spp. and Their Biological Activities

Garcinia is the largest genus in the Clusiaceae family. Plants of Garcinia are widely distributed in Africa, Asia, Australia, Central America, Madagascar, and Polynesia. There are over 400 species of Garcinia found in the lowland tropical forests. Garcinia are known for their medicinal values due to the presence of biologically active constituents. Plants with medicinal values play a key role in human health and disease prevention. Plant-based natural products such as essential oils (EOs) have been employed for centuries owing to their beneficial effects. Generally, EOs are a mixture of volatile chemical constituents comprising mainly terpenoids and phenylpropanoids. They play diverse roles as biologically active agents. To date, EOs have found wide applications in pharmaceutical, food, flavour and fragrance. This review discusses the volatile chemical constituents of EOs extracted from different plant parts of Garcinia. The biological activities of Garcinia EOs are highlighted to explore their therapeutic potential.

Hydroxypropyl Methylcellulose and Gum Arabic Composite Edible Coatings Amended with Geraniol to Control Postharvest Brown Rot and Maintain Quality of Cold-Stored Plums.

In this study, the effect of hydroxypropyl methylcellulose (HPMC) and gum Arabic (GA) edible coatings amended with 0.2% geraniol (GE) were evaluated for the control of brown rot, caused by Monilinia fructicola, on artificially inoculated plums (Prunus salicina Lindl., cv. Angeleno) stored for 5 weeks at 1 °C. Brown rot is the most important pre- and postharvest fungal disease of stone fruits, causing severe economic losses worldwide. Geraniol is an important constituent of many essential oils that can be obtained as a byproduct from different industrial procedures, such as those of the juice industry. Fruit postharvest quality was also evaluated after 5 and 8 weeks of storage at 1 °C, followed by 3 days at 7 °C plus 5 days at 20 °C, simulating packinghouse, transport, and retail shelf-life conditions, respectively. HPMC coatings containing 0.2% GE reduced the incidence and severity of brown rot by 37.5 and 64.8%, respectively, compared to uncoated fruit after 5 weeks of storage at 1 °C. HPMC-coated plums, with and without GE, showed the highest level of firmness, the lowest change in external peel color parameters (L*, a*, b*, C*, hue), and the lowest flesh bleeding compared to uncoated control and GA-coated samples throughout the entire storage period, which correlated with a higher gas barrier of these coatings without negatively affecting sensory quality. Furthermore, the HPMC-0.2% GE coating provided the highest gloss to coated plums, showing the potential of this coating as a safe and environmentally friendly alternative to conventional fungicides and waxes for brown rot control and quality maintenance of cold-stored plums.

Cuticular property affects the insecticidal synergy of major constituents in thyme oil against houseflies, Musca domestica

Plant essential oils are intricate blends comprising predominantly of monoterpenes and some sesquiterpenes. These oils display diverse bioactivities against targeted organisms, often arising from complex interactions among their constituents, which may demonstrate synergistic or antagonistic effects. Despite their wide use as botanical insecticides, the mechanisms behind these interactions and their effects on bioactivity are poorly understood. This study investigated the synergistic interaction of thymol and p-cymene, two major constituents of Thymus vulgaris essential oil, on the larvae and adults of the housefly, Musca domestica. The results showed that p-cymene synergized the insecticidal activity of thymol in adult houseflies, but not in larvae. GC–MS analyses and bioassays indicated the increased cuticular penetration of thymol by p-cymene was the mechanism of synergy, which was observed only in the adults. Two potential routes were proposed: the expansion of the wetting area, or the disruption of cuticular integrity through dissolving the wax layer. The sequential application and large-volume treatment bioassay results suggested that the former was the more likely mechanism. Also, the hydrophobicity of the cuticle seemed critical for this stage-specific synergy. Wax-devoid adults failed to show synergistic toxicity, whereas artificially wax-coated larvae gained a synergistic effect. Overall, the findings provide insights into the synergistic mechanism of insecticidal activity of plant essential oils and suggest potential applications in developing effective strategies using penetration-enhancing synergists.

Antifungal Properties of Pinus eldarica and Pinus longifolia Fruit Extracts against Candida Species Isolated from Vulvovaginal Candidiasis Patients

Introduction:Candidiasis is a disease with serious problems in women. With the increasing drug resistance and risks of the drugs, we investigated the effect of different cone extracts of Pinus eldarica and Pinus longifolia against Candida species isolated from vulvovaginal candidiasis patients.Materials and Methods::Candida species isolated from 50 patients were identified by routine mycological methods, including morphology of corn mil agar, chromium agar, germination, and biochemical methods. The anti-candida properties of the extracts and essential oils of Pinus eldarica and Pinus longifolia were investigated using agar diffusion and microdilution test. The essential oil was then analyzed by Gas chromatography-mass spectrometry (GC-MS).Results:The major constituents of Pinus longifolia essential oil included 23.16% alpha-pinene, 2.59% beta-caryophyllene, 23.61% delta-3-carene, 0.24% carcin-4-hydroxy, 13.56% m-cymene, 0.45% alpha-humulene, and 2.12% junipene. The major constituents of Pinus eldarica essential oil included 29.13% alpha-pinene, 14.22% beta-caryophyllene, 11.70% delta-3-carene, -14.22% carcin-4-hydroxy, 4.29% beta-pinene, 3.59%, alpha humulene, and 8.86% junipene. The results of antifungal tests showed that aqueous, ethanolic, and methanolic extracts had a weak anti-candida effect. By changing the solvent and using petroleum ether solvent, it was found that petroleum ether extract and cone essential oil of Pinus longifolia and Pinus eldarica exhibited a relatively strong anti-candida effect.Discussion and Conclusion:Comparison of Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) of four extracts of Pinus longifolia and Pinus eldarica against different Candida showed that the lowest MIC and MFC were related to essential oil, petroleum ether extract, methanolic extract, ethanolic extract, and aqueous extract, respectively.

The insecticidal activity of essential oil constituents against pyrethroid-resistant Anopheles funestus (Diptera: Culicidae).

Malaria vector control relies on the use of insecticides for indoor residual spraying and long-lasting bed nets. However, insecticide resistance to pyrethroids among others, has escalated. Anopheles funestus, one of the major African malaria vectors, has attained significant levels of resistance to pyrethroids. Overexpressed P450 monooxygenases have been previously identified in pyrethroid resistant An. funestus. The escalating resistance against conventional insecticides signals an urgent need for identification of novel insecticides. Essential oils have gained recognition as promising sources of alternative natural insecticides. This study investigated six essential oil constituents, farnesol, (-)-α-bisabolol, cis-nerolidol, trans-nerolidol, methyleugenol, santalol (α and β isomers) and essential oil of sandalwood, for the adulticidal effects against pyrethroid-resistant An. funestus strain. The susceptibility against these terpenoids were evaluated on both pyrethroid-susceptible and resistant An. funestus. Furthermore, the presence of overexpressed monooxygenases in resistant An. funestus was confirmed. Results showed that both the pyrethroid-susceptible and resistant An. funestus were susceptible to three EOCs; cis-nerolidol, trans-nerolidol and methyleugenol. On the other hand, the pyrethroid-resistant An. funestus survived exposure to both farnesol and (-)-α-bisabolol. This study however does not show any direct association of the overexpressed Anopheles monooxygenases and the efficacy of farnesol and (-)-α-bisabolol. The enhanced activity of these terpenoids against resistant An. funestus that has been pre-exposed to a synergist, piperonyl butoxide, suggests their potential effectiveness in combination with monooxygenase inhibitors. This study proposes that cis-nerolidol, trans-nerolidol and methyleugenol are potential agents for further investigation as novel bioinsecticides against pyrethroid-resistant An. funestus strain.

Xanthine oxidase, α-glucosidase and α-amylase inhibitory activities of the essential oil from Piper lolot: In vitro and in silico studies

IntroductionPiper lolot is a species of herb used as a popular food in Vietnam. Furthermore, the species has been used as a Vietnamese traditional medicine to treat many diseases. MethodsChemical constituents in the essential oil from leaves of Piper lolot were determined using GC/MS analysis. The anti-gout and anti-diabetic activities of the essential oil were determined through the inhibitory assays against xanthine oxidase, α-glucosidase and α-amylase enzymes. In addition, molecular docking simulations were used to elucidate the inhibitory mechanism between the main compounds and the enzymes. ResultsThe dominant constituents of the Piper lolot essential oils were determined as β-caryophyllene (20.6%), β-bisabolene (11.6%), β-selinene (8.4%), β-elemene (7.7%), trans-muurola-4(14),5-diene (7.4%), and (E)-β-ocimene (6.7%). The essential oil displayed xanthine oxidase, α-amylase, and α-glucosidase inhibitory activities with IC50 values of 28.4, 130.6, and 59.1 μg/mL, respectively. The anti-gout and anti-diabetic activities of the essential oil from the P. lolot species are reported for the first time. Furthermore, molecular docking simulation was consistent to in vitro experiments. ConclusionThe present study provides initial evidence that the essential oil of P. lolot may be a potential natural source to develop new diabetes preparations.

Chemical Composition and In Vitro Antimicrobial, Antioxidant, and Tyrosinase-Inhibiting Activity of Essential Oils Extracted From the Leaves and Twigs of Calocedrus macrolepis var. formosana

In this study, we focused on evaluating the antimicrobial, antioxidant, and tyrosinase-inhibiting properties of leaf and twig essential oils from Calocedrus macrolepis var. formosana. Additionally, we determined the major components associated with these effects. The findings revealed that α-pinene (36.4%) and limonene (23.6%) were the dominant components in the leaf essential oil, while α-pinene (36.2%), ferruginol (22.5%), and limonene (13.1%) were the major constituents in the twig essential oil. However, when comparing the biological activities of the 2 essential oils, the twig essential oil demonstrated excellent inhibitory effects against skin pathogens, as well as strong antioxidant and tyrosinase-inhibiting activities, in contrast to the leaf essential oil. The twig essential oil also exhibited excellent antimicrobial activity against 5 skin pathogenic strains, with the strongest inhibitory effect being that against Staphylococcus aureus, S epidermidis, and Candida albicans, which was accompanied by an inhibition zone of 46 to 48 mm, a minimum inhibitory concentration (MIC) of 125 μg/mL, and a minimum bactericidal concentration (MBC) of 250 μg/mL. The inhibitory activity of the twig essential oil against lipid peroxidation was found to be potent, as evidenced by an IC50 value of 216 ± 1.9 μg/mL. It also exhibited strong scavenging activity against free radicals, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 = 121.6 ± 0.5 μg/mL) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (IC50 = 136.8 ± 1.6 μg/mL) cation radicals. In addition, it exhibited a high cupric ion reducing–antioxidant capacity (CUPRAC), with the A0.50 value determined to be 186.28 ± 0.5 μg/mL. It also exhibited adequate activity in terms of inhibiting in vitro tyrosinase activity, as evidenced by an IC50 value of 168.5 ± 0.6 μg/mL. Further analysis revealed that ferruginol was the active component responsible for the antimicrobial, antioxidative, and tyrosinase-inhibiting activities observed in twig oil. These findings suggest that the twig oil is a promising candidate for further research because of its favorable antimicrobial, antioxidative, and tyrosinase-inhibiting activity.

Volatile Oil Constituents, Bioactivity and Formulations of Essential Oil from Psidium guajava

Volatile Oil Constituents, Bioactivity and Formulations of Essential Oil from Psidium guajava

Essential Oil Constituent, Antimicrobial Activity, and Mosquito Larvicidal Activity of Murraya glabra (Guillaumin) Swingle from Vietnam

Essential Oil Constituent, Antimicrobial Activity, and Mosquito Larvicidal Activity of Murraya glabra (Guillaumin) Swingle from Vietnam

In-silico prediction and in vitro validation of antioxidant, antibacterial and antifungal potential of Black Turmeric (Curcuma caesia Roxb.) essential oils and its constituents

The growing interest in the health and pharmaceutical industries has led to a significant increase in demand for essential oils. Curcuma caesia, as a member of the Zingiberaceae family, has been used for its high-quality essential oils (EOs) with remarkable therapeutic properties. The current study aimed at predicting the in-silico interactions of C. caesia volatile constituents against the protein responsible for oxidative and microbial stress in order to investigate their potential for industrial and pharmaceutical applications. The accuracy of the in-silico predictions was confirmed by carrying out the in vitro validation of the antioxidant, antibacterial, and antifungal activity of the EOs derived from the rhizome and leaves, as well as its volatile constituents. EOs from the rhizome and leaf samples of C. caesia were extracted through the hydro distillation method and yielded a percentage (%) of 1.80 ± 0.02 and 0.95 ± 0.02 (fresh weight basis, v/w), respectively. A total of 38 and 29 volatile constituents were identified in the rhizome and leaf EOs by gas-chromatography mass spectrometry analysis, representing 92.55% and 90.75% of the total peak area, respectively. The rhizome and leaf EOs showed oxygenated sesquiterpene (39.91% and 27.69%) as the predominate fractions followed by sesquiterpene hydrocarbons (13.36% and 18.44%). Curzerenone (18.09%), epicurzerenone (12.47%), eucalyptol (11.57%), camphor (5.94%), and germacrone (4.47%) were the major constituents in the rhizome EO, whereas, the leaf EO was dominated by eucalyptol (12.53%), camphor (7.23%), curzerenone (5.24%), germacrone (4.81%) and curzerene (4.9%). The in vitro biological activities such as antioxidant, antibacterial, and antifungal potential of C. caesia EOs were evaluated. The antioxidant evaluation using enzymatic and non-enzymatic assays, showed excellent potential of C. caesia EOs as compared to standard drugs. Specifically, in the enzymatic assay, leaf EO of C. caesia was resulted into the reduction of ROS and an increase in the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) in OZ-stimulated PMNs. The EOs also displayed a remarkable antibacterial activity against Staphylococcus aureus, elucidating it as the most susceptible strain. Further, the in-silico prediction of the constituents was conducted using Swiss-ADME, and molecular docking analysis. Swiss-ADME revealed the drug-likeness and safety properties of constituents present in C. caesia EOs. The molecular docking study was carried out to interpret the possible interactions of phytoconstituents qualified in the Swiss-ADME study with two bacterial proteins (Tyrosyl-tRNA synthetase from Staphylococcus aureus (PDB ID: 1JIJ) and Glucosamine 6-phosphate synthase from Escherichia coli (PDB ID: 1XFF)), one fungal protein (N-myristoyl transferase from Candida albicans (PDB ID: 1IYL)) and one oxidative protein (Human peroxiredoxin 5 (PDB ID: 1HD2)). Furthermore, to validate the result of molecular docking, the biological activity of higher affinity constituents was also evaluated. As a result, the in vitro findings supported the in-silico prediction. Therefore, C. caesia or its constituents like curzerenone, camphor, eucalyptol, epicurzerenone, germacrone, viridifloral, muurola-4,10(14)-dien-1-ol, and globulol might be a valuable source for developing antioxidant and antimicrobial drugs. To the best of present author’s knowledge, this is the first scientific report on the in-silico prediction of C. caesia constituents against bacterial, fungal and oxidative proteins through molecular docking, which may contribute to the development of various alternatives against multi-drug resistance.

Effect of seed-borne Fusarium species on constituents of essential oils from seeds of black cumin populations

Effect of seed-borne Fusarium species on constituents of essential oils from seeds of black cumin populations

Seaweed extract and arbuscular mycorrhiza co-application affect the growth responses and essential oil composition of Foeniculum vulgare L.

The influence of arbuscular mycorrhiza fungi (AMF) inoculation, seaweed extract (SWE) foliar use, and their co-applications were evaluated on the growth-associated traits, antioxidant potential, essential oil profile, and the nutrients content of fennel plants. A factorial experiment was conducted as a completely randomized design with two factors and four replications in the greenhouse. The factors were: AMF inoculation (not inoculated and inoculated with 5gkg-1) and SWE foliar application (0, 0.5, 1.5, or 3gL-1). The highest root colonization percentage was recorded in plants treated with AMF + 3gL-1 of SWE. The top recorded plant height, leaf number, leaf dry weight, biomass, thousand seed weight (TSW), total soluble proteins and total soluble carbohydrates content, antioxidant activity, and essential oil content belonged to AMF + 3gL-1 of SWE. Furthermore, the co-application of AMF + SWE resulted in a considerable enhancement of the photosynthetic pigments content and, in N, P, K, Fe, Zn, and Mn contents in the shoots and roots. The GC-FID and GC-MS analysis revealed that (E)-anethole (73.28-76.18%), fenchone (5.94-8.26%), limonene (4.64-6.58%), methyl chavicol (2.91-3.18%), and (Z)-β-ocimene (1.36-2.01%) were the principal essential oil constituents. The top (E)-anethole and fenchone contents were obtained by AMF + SWE. Altogether, the simultaneous application of AMF and SWE could be introduced as an environment-friendly strategy to reach reliable growth responses, especially in fennel plants' enriched with some precious essential oil constituents.

A colorimetric assay for the detection of monoterpenes in hemp (Cannabis sativa) essential oil

Monoterpenes are the most abundant constituents in hemp essential oil that contribute to its sensory properties and bioactivities. However, monoterpenes are prone to oxidation when exposed to the air under ambient conditions. For quality assurance purpose, there is a need in the industry for rapid testing methods to determine monoterpene contents in hemp products. In this study, a colorimetric indicator assay was developed for rapid determination of monoterpenes in hemp (Cannabis sativa) essential oil. For comparisons, monoterpenes contents in lavender (Lavandula angustifolia), eucalyptus (Eucalyptus globulus) and sweet orange (Citrus sinensis) essential oils were also determined. The developed assay was based on an indicator solution containing palladium chloride that complexed with pararosaniline hydrochloride dye. Upon the palladium-facilitated oxidation of monoterpenes via the Wacker process, the complex was destabilized, and free pararosaniline molecules were released into the solution, exhibiting an intense magenta color. From ultraviolet–visible and nuclear magnetic resonance spectra, the color response rate of the indicator solution was dependent on terpene structure, type of essential oil, terpene loading and the reaction temperature. Fourier transform–infrared (FT–IR) spectroscopy and gas chromatography–mass spectrometry (GC–MS) results showed that the main components in hemp essential oil are myrcene and ocimene, which elicited greater extents of color changes as compared to other monoterpenes (limonene, α-pinene, β-pinene and terpinolene). The colorimetric indicator is potentially useful for rapid assessment of monoterpene oxidation in hemp essential oil and other cannabis-based products.

Anticorrosive Effects of Essential Oils Obtained from White Wormwood and Arâr Plants

This article is part of the contribution to the development of two medicinal plants widely used by the Moroccan population: white wormwood (Artemisia herba-alba) andArâr (Juniperus phoenicea), species belonging to the Asteraceae and Cupressaceae families, respectively. The present work was conducted to investigate the chemical composition and anticorrosive properties of essential oils (EOs) extracted from these plants. The chemical analysis of the essential oils (EOs) was carried out by GC-MS/MS. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and quantum chemical calculations by density-functional theory at B3lYP were used to study the anticorrosive effect of the researched oils on mild steel in 1 M hydrochloric acid solution. Moreover, SEM-EDX analysis was used to identify the surface morphology of mild steel surface. GC-MSMS results showed the presence of 32 potentially active compounds in the EOs of Artemisia herba-alba. The average yield of the EOs was about 1.39 ± 0.17 mL/100 g dry matter. Beta thujone (30.07%) and alpha thujone (13.32%) are the main components, while for the EOs of Juniperus phoenicea, the study showed the presence of 30 constituents, with alpha-pinene (43.61%) and manoyl oxide (11.5%) as the main components. The average yield of HE was 1.10 ± 0.03 mL/100 g dry matter. The findings demonstrated an important anticorrosive action of EOs from Artemisia herba-alba and Juniperus phoenicea. Notably, the experimental results showed good efficiency of the studied essential oils and correlated well with the density-functional theory (DFT) calculations. The results of potentiodynamic polarization measurements showed that hydrazone acted as a mixed-type inhibitor. The EIS results showed an increase in charge transfer resistance accompanied by a noticeable decrease in Cdl values, revealing that both studied oils were effective as reliable inhibitors for the protection of mild steel in 1 M HCl solution. Also, the efficiency decreased with decreasing inhibitor concentrations. Surface studies ensure the effectiveness of both investigated oils and the reduction of the surface roughness of mild steel. Furthermore, DFT results of the major constituents of Artemisia herba-alba and Juniperus phoenicea EOs revealed insights into the chemical reactivity of the tested oils while supporting the experimental conclusions and showed outstanding adsorption ability of both investigated EOs on the steel surface.

Chemical composition and antimicrobial activity of essential oil obtained from the rhizomes of Kaempferia champasakensis: in vitro and molecular docking studies

Kaempferia champasakensis Picheans. & Koonterm (Zingiberaceae) is locally known as “Dia Lien hoa trang” in Vietnam. Despite a previous study on the essential oils (EO) of K. champasakensis leaves, no other studies have reported the chemical components and biological activities of K. champasakensis. Therefore, this study aims to identify the chemical constituents of the EO from the rhizomes of K. champasakensis and evaluate their antimicrobial activity, which has been re-confirmed through molecular docking studies. The gas chromatography-mass spectrometry (GC/MS) analysis revealed sixty-one constituents (95.4%) present in the EO of K. champasakensis rhizomes. Among them, camphene (40.7%), α-pinene (10.2%), and β-pinene (7.6%) were identified as the main compounds in the EO. Bioassays indicated its antimicrobial activity in the order of inhibitory effectiveness: Staphylococcus aureus > Enterococcus faecalis ≈ Candida albicans > Bacillus cereus ≈ Escherichia coli > Salmonella enterica > Pseudomonas aeruginosa. The molecular docking study of ligand-protein interactions involving the major constituents of EO was conducted against target proteins related to Staphylococcus aureus, Enterococcus faecalis, Candida albicans, Bacillus cereus, and Escherichia coli main activities. The results revealed that α-pinene exhibited strong binding affinity against E. coli, β-pinene demonstrated more effective inhibition against E. faecalis and B. cereus, and camphene primarily exhibited activity against C. albicans and S. aureus. Furthermore, the analysis of interactions between the main compounds and the selected proteins was elucidated in the current study. This is the first time that chemical components of the EO of K. champasakensis rhizomes and their antimicrobial activity have been reported. These findings contributed to the basis for further studies on the chemical compositions and biological effects of K. champasakensis.