Effect Of Essential Oil Research Articles

Toxicity, Behavioral Effects, and Chitin Structural Chemistry of Reticulitermes flaviceps Exposed to Cymbopogon citratus EO and Its Major Constituent Citral.

Simple SummaryReticulitermes flaviceps, as a main wood-boring pest, causes economically significant damage to wood materials. In this study, gas chromatography–mass spectrometry was used to detect and characterize the chemical constituents of lemongrass essential oil (Cymbopogon citratus (DC.) Stapf.), and we evaluated the associated vapor insecticidal effect on R. flaviceps worker adults. Lemongrass EO and its major constituent, citral, presented significant vapor toxicity against R. flaviceps, where the walking and gripping abilities of treated insects were reduced. Chitin content, thermal stability, and crystallinity were also reduced in the treated worker adults. The results of this study suggest that lemongrass EO can potentially be used to develop eco-friendly natural remedies for the management of R. flaviceps.Botanical pesticides are considered the most promising alternative to synthetic pesticides, considering their less negative impacts on the environment and human health. Here, we analyzed the components of lemongrass Cymbopogon citratus essential oil (EO) and evaluated its vapor activity against Reticulitermes flaviceps, in terms of the walking and gripping abilities of workers. In addition, the effects of lemongrass EO and its major component on the cuticular content and structure of chitin in termites were also observed. Our results indicate that cis-citral (36.51%) was the main constituent of lemongrass. In the vapor toxicity assay, the LC50 values of lemongrass EO and citral were 0.328 and 0.177 μL/L, respectively. When worker antennae were treated with lemongrass EO and citral, their walking and gripping capabilities were significantly inhibited. In addition, the cuticular content, thermal stability, and crystallinity of chitin in the termites were decreased after treatment with citral. Collectively, this study provides a basis for developing and utilizing lemongrass and citral as a new environment-friendly insecticide resource to control R. flaviceps.

Exploring the effect of a microencapsulated citrus essential oil on in vitro fermentation kinetics of pig gut microbiota.

Essential oils (EOs) have emerged as a potential alternative to antibiotics in pig breeding due to their antimicrobial properties. Citrus EOs, a common by-product of the orange juice industry, can be an interesting alternative from a financial perspective due to their huge offer in the global market. Thus, the effect of a citrus EO, and specifically different formulations of Brazilian Orange Terpenes (BOT), on pig gut microbiota was evaluated by means of an in vitro fermentation model simulating different sections of the pig gut (stomach, ileum, and colon). Treatments consisted in: BOT in its unprotected form (BOT, 1.85 and 3.70 mg/mL), microencapsulated BOT (MBOT, 3.50 and 7.00 mg/mL), colistin (2 μg/mL), and a control. BOT and MBOT altered in a similar way the total bacterial 16S rRNA gene copies in the stomach only from 18 h of incubation onwards, and no metabolite production in terms of short-chain fatty acids (SCFAs) was detected. In ileal and colonic fermentations, BOT and MBOT affected ileal and colonic microbiota in terms of total bacterial 16S rRNA gene copies, reduced phylogenetic diversity, and altered composition (p < 0.05) as evidenced by the significant reduction of certain bacterial taxa. However, more pronounced effects were found for MBOT, indicating its higher antimicrobial effects compared to the unprotected BOT, and suggesting that the antibacterial efficiency of the unprotected BOT was probably enhanced by microencapsulation. Furthermore, MBOT stimulated lactate production in ileal fermentations and greatly stimulated overall SCFA production in colonic fermentations. This indicates that besides the shifts in ileal and colonic microbiota by the delivered EO (BOT), the wall material of microcapsules (chitosan/modified starch) might have worked as an additional carbon source with prebiotic functioning, stimulating growth and metabolic activity (SCFAs) of colonic bacteria.

Immortelle (Helichrysum italicum (Roth) G. Don) Essential Oil Showed Antibacterial and Biofilm Inhibitory Activity against Respiratory Tract Pathogens

The biofilm formation of bacteria in different parts of the human body can influence the success of antibiotic therapy. Essential oils (EOs) and their components are becoming increasingly popular in point of view of medicinal applications, because of their antibacterial efficacy. The immortelle EO has been used traditionally as an expectorant; however, there are no studies summarizing its antibacterial effect against respiratory tract bacteria. Our aim was to investigate the antibacterial and biofilm inhibitory activity of immortelle (Helichrysum italicum) EO against respiratory tract pathogens such as Haemophilus influenzae, H. parainfluenzae, Pseudomonas aeruginosa and Streptococcus pneumoniae. In order to prove the antibacterial effect of the immortelle EO, broth microdilution and biofilm inhibition tests, and membrane damage assay were investigated. Scanning electron microscopy was used to identify the structural modifications in bacterial cells. Our results showed that immortelle EO has antibacterial and anti-biofilm effects against respiratory tract bacteria used in this study. H. parainfluenzae was the most sensitive to each treatment, however, P. aeruginosa was the most resistant bacteria. In conclusion, the studied EO may have a role in the treatment of respiratory tract infections due to their antibacterial and anti-biofilm activity.

Oviposition deterrence and repellent activities of selected essential oils against Tuta absoluta Meyrick (Lepidoptera: Gelechiidae): laboratory and greenhouse investigations

Tuta absoluta, an invasive pinworm characterized by high reproductive potential and adaptation to different agroecological conditions, cause serious damage to tomato crops. Chemical control with synthetic insecticides is widely used to control this pest, although pesticides exhibit side effects on non-target organisms and negatively impact the environment, with the occurrence of resistance to some active substances in the target pest. The use of essential oils (EOs) from aromatic or officinal plants could represent an environmentally safe control method, alternative to synthetic insecticide application. In this work we investigated the effect of EOs from Spanish oregano, laurel, basil, garlic, peppermint, cypress, and eucalyptus EOs on T. absoluta oviposition deterrence and larval repellency. Results showed a remarkable oviposition deterrence using laurel, Spanish oregano, basil, and garlic EOs in both laboratory and greenhouse experiments. In no-choice repellence tests carried 1, 2, 6, and 22 h after treatment application, peppermint and Spanish oregano EOs showed the most lasting effects while cypress and eucalyptus EOs were not effective after 6 and 22 h, respectively. In choice tests, at either 5 or 22 h after treatment application, low preference for the test over control by larvae was observed in all treatments, except for basil EO. The most promising effects were observed in Spanish oregano and laurel treatments where no larvae were detected. Repellent effectiveness of EOs does not seem to be influenced when larvae did not get a chance to do a choice between treated and untreated leaves. This study highlights the effectiveness of EOs of aromatic or officinal plants as an alternative to synthetic insecticides for the control of T. absoluta.

Cytotoxic Effect of the Essential oils from Erigeron Canadensis L. on Human Cervical Cancer HeLa Cells in Vitro.

Erigeron Canadensis L. (E. canadensis) is a widely distributed invasive weed species in China. Potentially anti-cancer qualities may exist in its essential oils (EOs). The purpose of this study was to analyze the components of the EOs of E. canadensis and their effects on the normal liver cell lines L02 and the human cervical cancer cell lines HeLa. The EOs from the upper region of E. canadensis were prepared, its components were identified by GC/MS. Cell viability, cell morphology observation, AO/EB dual fluorescence staining assay, flow cytometry, mitochondrial membrane potential, western blot, caspase inhibitor test, and oxidative stress tests were used to investigate the impact of the EOs on HeLa cells. Network pharmacological analysis was employed to study the potential mechanism of the EOs in the treatment of cervical cancer. According to the findings, the EOs had 21 chemical components, of which limonene made up 65.68 %. After being exposed to the EOs, the cell viability of HeLa and L02 dramatically declined. The inhibition of EOs was more effective than that of limonene when used in an amount equivalent to that in the EOs. L02 cells were less susceptible to the cytotoxicity of EOs than HeLa cells were. Furthermore, EOs altered the cell cycle in HeLa cells and caused oxidative stress and apoptosis. Compared with the control group, the reactive oxygen species (ROS) levels increased in HeLa cells at first and then decreased, total superoxide dismutase (SOD) and catalase (CAT) activities in HeLa cells significantly decreased. G1 phase cells decreased whereas G2/M phase cells increased. The rate of apoptosis rose. Reduced mitochondrial membrane potential and Caspase-3, -9, and -12 protein expression were both observed. Nerolidol, dextroparaffinone, and α-pinene were shown to be the primary components for the suppression of HeLa cells, according to the results of the prediction of pharmacologic targets. In conclusion, findings of this study indicated the EOs may have the potential to curb the growth of cervical cancer cells. Further research is needed to explore the in vivo effect of EOs.

Essential oil composition ofCallistemon citrinus(Curtis) and its protective efficacy againstTribolium castaneum(Herbst) (Coleoptera: Tenebrionidae).

Tribolium castaneum is one of the major pests of stored grains which causes extensive damages. To control this insect pest many synthetic chemical pesticides are used. However, continuous usage of synthetic fumigants causes pest resurgence, toxic residues, genetic resistance in pests, environmental contamination and health hazards etc., To avert these problems, essential oils are used as bio-fumigants to control the stored pests. They could act as best alternatives to synthetic fumigant in closed environment. Hence, the present study aimed to evaluate the pesticidal activity of Callistemon citrinus oil against Tribolium castaneum. GC-MS analysis of C. citrinus essential oil (EO) showed 10 compounds; among them, the major constituent was eucalyptol (1, 8-cineole) at 40.44%. The lethal concentration (LC50) values were 37.05 μL/L (adults) and 144.31 μL/L (larvae) at 24 and 48 hrs respectively. Exposure to C. citrinus EO significantly reduced the beetle fecundity, ovicidal activity, egg hatchability, larvae survival and emergence of adult. The effect of EO on enzymatic activity of T. castaneum adults was examined using Acetylcholinesterase, α-Carboxylesterase, β-Carboxylesterase, Glutathione-S-Transferase, Acid and Alkaline phosphatase assays. The results indicated that the activity of detoxification enzymes drastically varied when compared with control. This EO had toxicant effects on all stages of the life of T. castaneum.

Direct and Indirect Effects of Essential Oils for Sustainable Crop Protection.

Plant essential oils (EOs) are gaining interest as biopesticides for crop protection. EOs have been recognized as important ingredients of plant protection products including insecticidal, acaricidal, fungicidal, and nematicidal agents. Considering the growing importance of EOs as active ingredients, the domestication and cultivation of Medicinal and Aromatic Plants (MAPs) to produce chemically stable EOs contributes to species conservation, provides the sustainability of production, and decreases the variations in the active ingredients. In addition to these direct effects on plant pests and diseases, EOs can induce plant defenses (priming effects) resulting in better protection. This aspect is of relevance considering that the EU framework aims to achieve the sustainable use of new plant protection products (PPPs), and since 2020, the use of contaminant PPPs has been prohibited. In this paper, we review the most updated information on the direct plant protection effects of EOs, focusing on their modes of action against insects, fungi, and nematodes, as well as the information available on EOs with plant defense priming effects.

Sublethal effects of plant essential oils toward the zoophytophagous mirid Nesidiocoris tenuis

Zoophytophagous hemipteran predators provide relevant biological control services and their applications are consolidated in greenhouse pest management. The use of plant essential oils (EOs) for sustainable crop protection is being currently promoted. However, further knowledge of the potential side effects of EOs on predatory mirids (Hemiptera: Miridae) is required. Here, we evaluated the non-target impact of four EOs (anise, fennel, garlic and lavender) on the generalist predator Nesidiocoris tenuis (Reuter) in the laboratory. The baseline toxicity of EOs was firstly assessed on N. tenuis adults following topical contact exposure. Then, the predator reproduction and orientation behavior was tested following the exposure to three estimated EO lethal concentrations (LC1, LC10 and LC30). Garlic EO had the lowest estimated LCs (e.g., LC30 1.34 mg mL−1), being thus the most toxic compound among the tested EOs. The estimated LC30s for lavender, anise and fennel EOs were 2.75, 4.55 and 5.17 mg mL−1, respectively. The fertility and the orientation behavior of N. tenuis females was negatively affected by all the EOs at the highest tested concentration. Nevertheless, anise EO at LC1 and LC10 caused no sublethal effects on N. tenuis. Our findings suggest that careful attention should be given when EOs are used in combination with N. tenuis in pest management programs.

Application of Essential Oils to Control the Biodeteriogenic Microorganisms in Archives and Libraries

Microbial contamination control in indoor environments, such as libraries and archives, represents a challenge. Essential oils (EOs), well-known for their antimicrobial properties, have been applied in pharmaceutical and food industry from many years. In the present study, Thymus vulgaris and Origanum vulgare EO antimicrobial efficacy on paper-born microorganisms, Staphylococcus epidermidis, Rhodotorula mucilaginosa and Alternaria alternata, was investigated to protect water-damaged paper documents and to control indoor air quality for operator’s health safety. T. vulgaris EO was the most effective: Minimum Inhibitory Concentration (MIC) values obtained for S. epidermidis and R. mucilaginosa, with a broth macro-dilution method, were 7.5 µg/mL and 5.63 µg/mL, respectively. T. vulgaris EO (0.75% v/v), nebulized immediately after the inoculation on agar plates or paper sheets, showed a high inhibition effect against the three biodeteriogenic microorganisms, also when lyophilized on paper sheets; in this last case, the EO has a higher efficacy when applied immediately after the freeze drying. Regarding the EO effect against A. alternata, the inhibition percentage of the mycelial growth, MGI, (81.4%), observed for nonsporulated mycelium, was higher than that for the sporulated one (51.4%). Finally, T. vulgaris EO (0.75% v/v) was effectively applied on a real contaminated book cover by means of EO impregnated contact sheets. Obtained results demonstrated that tested EOs were able to delay or completely inhibit paper-born microorganism growth for both flood-independent or -dependent contamination.

Evaluation of the Cardiac Electrophysiological and Haemodynamic Effects of Elsholtzia ciliata Essential Oil on Swine.

The demand for the development of novel medicines with few side effects and no proarrhythmic properties is increasing. Extensive research on herbal extracts has been conducted with the expectation that the compounds will exert precise effects without harmful side effects. Elsholtzia ciliata (Thunb.) Hyl. essential oil (EO) possesses antiarrhythmic properties similar to those of class 1B antiarrhythmics, such as prolonging myocardial activation of the QRS complex and shortening the QT interval. In this study, we determined the kinetic profile of EO phytocompounds and the effects of EO on heart electrical activity and arterial blood pressure. For this study, we chose to use local breed pigs that were anaesthetized. The effects of an intravenous bolus of EO on ECG parameters, arterial blood pressure, heart rate variability, and blood levels of haematological and biochemical parameters were registered and evaluated. Following an intravenous injection of a bolus, EO exerted a vasodilatory effect, resulting in significant reductions in arterial blood pressure. EO also increased the heart rate and altered ECG parameters. The bolus of EO prolonged the QRS complex, shortened the QT interval, and nonmonotonically altered the PQ interval. After the administration of a bolus of EO, the activity of the autonomic nervous system was altered. This study confirms that EO possesses similar properties to class 1B antiarrhythmics and exerts a hypotensive effect; it reduces arterial blood pressure possibly by modulating peripheral vascular resistance.

An in vitro study of the origanum minutiflorum O. Schwarz & P. H. Davis and Coriandrum sativum L. essential oils as chronic tonsillitis therapeutics: antibacterial, antibiofilm, antioxidant, and cytotoxic activities

ABSTRACT The chemical composition and biological activity of essential oils (EOs) from leaves of Origanum minutiflorum O. Schwarz & P.H.Davis, and seeds of Coriandrum sativum L. were investigated. Chemical analyses of EOs were performed and the major components were carvacrol (81.5%) and linalool (69.6%), respectively. The antimicrobial activity was assessed against several bacteria originating from the tonsillar tissue. Activities of EOs against Staphylococcus aureus biofilm were investigated, as well as the effect of the mixture of these EOs and antibiotics against the pathogen. The antioxidant activity of both EOs was determined by TBARS assay, and examined wild oregano EO showed better activity. Also, cytotoxicity of EOs was evaluated in vitro and both EOs showed potential to inhibit further proliferation of tumor cells. This study reported for the first time the effects of EOs on chronic tonsillitis causative pathogens, supporting their role as a natural bioactive therapeutic agent with possible antimicrobial applications.

Protective Effect of Some Essential Oils Against Gamma-Radiation Damages in Tetrahymena pyriformis Exposed to Cobalt-60 Source.

The main purpose of this study was to investigate the protective effect of Rosmarinus officinalis, Origanum compactum, Lavandula angustifolia, and Eucalyptus globulus essential oils (EOs) against gamma-radiation-induced damages on Tetrahymena pyriformis growing in presence of cobalt-60 source. The chemical composition of the 4 EOs was analyzed by gas chromatography-mass spectrometry. The protective effects of EOs on growth, on morphology, and on some metabolic enzymes and antioxidant markers have been evaluated. Thus, addition of EOs significantly improves the growth parameters (generation number and time) in irradiating conditions. All EOs allowed restoring growth parameters over more than 90% compared to the controls. The morphological analysis indicated that T. pyriformis cells growing in irradiating conditions were able to regain their normal form in presence of the different EOs. Our results indicate that the 4 EOs also have protective effects on some metabolic enzymes. They allowed recovering totally or partially the glyceraldehyde 3-phosphate dehydrogenase and the succinate dehydrogenase activities compared to the controls. Moreover, the addition of EOs reduced the lipid peroxidation level and decreased the activities of catalase and superoxide dismutase induced by the gamma-radiation exposure. A more pronounced protective effect was found for O. compactum and L. angustifolia EOs compared to R. officinalis and E. globulus EOs. These results suggest that the studied EOs are efficient natural antioxidants that could offer protection against gamma-radiation-induced damages and can therefore be useful in clinical medicine.

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

AimsThis 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 ResultsThe 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.ConclusionsThe 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 StudyThe 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.

Microbiological Effect of Lemongrass Cymbopogon Citratus and Spearmint Mentha Spicata Essential Oils as Preservatives and Flavor Additives in Yogurt

This study was designed to evaluate the antimicrobial effect of Cymbopogon citratus and Mentha spicata essential oils, separately and mixed, against the microorganisms in yogurt, as well as study the possibility of these essential oils (EO) as natural preservatives and flavors additives/enhancers in yogurt product. Yogurt samples were treated with lemongrass and spearmint EOin different concentrations (250, 500, 1000 ppm: 6250µg/50 ml yogurt, 12500 µg/50 ml yogurt and 25000 µg/50 ml yogurt respectively). The control and treated samples were preserved both at room (25°C) and refrigerator (5°C) temperatures. In control, the contamination was observed through 2 weeks at 25°C and for about one month at 5°C. The samples treated with lemongrass and spearmint EOs (500pmm), the contamination showed up late, after 45 and 30 days at 25°C respectively. While at 5°C, the contamination appeared after 90 and 60 days respectively. The effect of lemongrass and spearmint EO, separately or mixed (synergistic effect), on the growth of fungi that was isolated from spoiled samples, was studied in different concentrations (125, 250, 500 ppm). Microbilogical examination was done in the control and treated yogurt samples. There was a significant difference (P≤ 0.05) between microbial spoilage (coliform, yeast and fungi) count during different periods of incubation which decreased in the samples treated with essential oils as compared with the control. The results of the percentage of growth inhibition revealed that lemongrass EO, around 80-100%, is the best in inhibiting the molds and yeasts causing yogurt damage as compared to the use of spearmint EO which was 27-60%, and the synergistic effect of about 35-39%. The results of the toxicity assay of the maximum effect of EO in vivo proved their validity for consumption when added both as preservative and flavor. The concentrations used for the dosage ranged from 250 ppm to 5000 ppm.

Essential oil‐based active polymer‐based packaging system: A review of its effect on the antimicrobial, antioxidant, and sensory properties of beef and chicken meat

Meat is characterized by high perishability and a short shelf-life under improper storage. The evolution of food packaging in response to the growing need for clean-label technology has resulted in a sustainable, effective, safe, and natural method of prolonging the shelf-life of food using eco-friendly technologies. Active packaging presents a peculiar approach to preserving and packaging foods such as fresh and processed meat. They are composed of films and/or coatings obtained from natural sources of polysaccharides, lipids, and proteins that are edible, biodegradable, and can act as carriers of active ingredients from natural sources. Essential oils (EOs) are plant-extracted volatile aromatic compounds that have been the center of attention several types of research owing to their potential in food as natural additives and active ingredients with antimicrobial and antioxidant properties. Their utilization into biodegradable components for instance edible films to develop an active packaging system with enhanced functionalities and usefulness to the packaging and food industry is described. This review provides critical insights into the inclusion of EOs into bio-based materials with an emphasis on muscle food applications. Encapsulation was also emphasized as a key factor in optimizing the usage, stability, and efficiency of EOs in active packaging. The shelf-life of food is prolonged by the packaging system through preventing the actions of external aggressors such as oxygen and moisture, delaying the proliferation of spoilage and pathogenic microorganisms, slowing oxidative processes, and extending the duration that products are organoleptically acceptable. While cost and commercialization are the main concern for food industry professionals, consumers' main concerns are safety and awareness. In a nutshell, EO-based active packaging holds a lot of potential for shelf-life extension of meat and quality preservation. Novelty impact statement EO-based active packaging system has the potential to offer clean-label technology to consumers while alleviating food wastage and utilization of plastics by extending the shelf-life of food through eco-friendly processes. Encapsulation can improve the stability and effectiveness of EOs as antioxidants and antimicrobial agents, as well as address the challenges that have limited their application in the food system.

Chemical Composition and Antibacterial and Antioxidant Activities of Stem Bark Essential Oil and Extracts of Solanecio gigas.

Herbal medication developed from natural resources has to have antibacterial and antioxidant effects. The aim of this research is to look at the chemical makeup of Solanecio gigas (S. gigas) stem bark essential oil (EO), as well as the effectiveness of EO and extracts (chloroform, ethyl acetate, and methanol) against human pathogenic bacteria and their antioxidant activity. The GC-MS analysis identified 23 components, accounting for 98.7% of the total oil containing Methylene chloride (49.2%), sabinene (10.5%), 1-nonene (11.3%), Terpinen-4-ol (6.9%), Camphene (4.3%), γ-terpinene (3.6%), α-phellandrene (2.9%) β-myrcene (2.6%), 1,2,5-Oxadiazol-3-carboxamide, 4,4′-azobis-2,2′-dioxide (2.4%), α-terpinene (1.9%), 1-Octanamine, N-methyl- (1.9%), ρ-cymene (1.6%) as major components. The antibacterial efficacy of the EO and extracts (25, 50, 100, and 200 mg/ml) was demonstrated by the inhibitory zones (8.5 ± 0.47–23.3 ± 0.36 and 7.2 ± 0.25–22.0 ± 0.45 mm), respectively. The MIC values of the extracts and the EO were 120–150 and 240 to <1100 μg/ml, respectively. The EO also demonstrated a significant antibacterial impact. The EO and methanolic extract had free radical scavenging activities with IC50 value, 13.8 ± 0.48 and 4.2 ± 0.04 μg/ml, respectively. In comparison to the other extracts, the methanolic extract had the greatest phenolics (100.2 ± 0.13 μg GAE/mg of dry extract) and flavonoid contents (112.1 ± 0.18 μg CE/mg of dry extract).

Essential Oils in Urban Insect Management-A Review.

The allures of city life have culminated in the rise of urban populations resulting in conditions that promote the establishment of certain insect pests. Globally, the public health significance of these urban insect pests is enormous, ranging from billions of dollars to loss of lives. Most chemical insecticides no longer provide the anticipated level of control, and significant insecticide resistance has been reported. Therefore, there has been a spike in interest for alternatives to conventional insecticides. Among them, natural products from plants such as essential oils (EOs) and essential oil components (EOCs) have enjoyed the most attention owing to widespread reports of efficacy and toxicity even against insecticide-resistant urban insects. Yet, there is no comprehensive synthesis on the extent and impact of the management of urban insects using EOs or EOCs. Such a review is highly relevant since it provides a means to assess the extent of progress made, shortfalls, limitations, and prospects. More so, we hope it can be used to make informed decisions and develop relevant policies reliably. We present the ranges of insecticidal effects of EOs, EOCs, and commercially available EO-based products from laboratory and field studies. Finally, we discuss the gaps in our knowledge and prospects for the sustainable use of EOs.

Extraction, Chemical Composition, and Protective Effect of Essential Oil from Chimonanthus nitens Oliv. Leaves on Dextran Sodium Sulfate-Induced Colitis in Mice.

In this study, the essential oil (EO) was extracted by steam distillation from Chimonanthus nitens Oliv, and the extraction process was optimized by response surface methodology. The optimum process conditions are as follows: extraction time of 4.57 h, soaking time of 1.33 h, and solid-liquid ratio of 1 : 21.4. Under these conditions, the theoretical yield of EO is 1.5624%. The EO compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 52 chemical components were detected, among which the content of 3-(4,8-dimethylnona-3,7-dienyl)-furan was the highest, accounting for 21.43% of the total peak area. The EO showed good antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), and reducing power. In this study, we observed the protective effect of EO on ulcerative colitis (UC) induced by dextran sodium sulfate (DSS) in mice. EO effectively delayed weight loss and reduced DAI score. Histological examination also observed a significant reduction in damage in the EO group. The colon length of mice in DSS group was the shortest, and the colon length of mice in EO treatment group was longer than that in model group, but shorter than that in normal group (NOR : 8.17 ± 0.39 cm; DSS : 5.57 ± 0.93 cm; L − EO : 6.47 ± 0.78 cm; M − EO : 5.98 ± 0.58 cm; and H − EO : 6.1 ± 0.52 cm). The GSH activity in the L-EO and SASP groups was significantly higher than that in the DSS group (P < 0.01). SOD activity in L-EO and M-EO groups was also significantly higher than that in DSS treatment group (P < 0.01). MDA was decreased in the EO treatment groups and the SASP group (L-EO, H-EO, SASP: P < 0.01; M-EO: P < 0.05). MPO of EO treatment group was lower than that of model group (the L-EO group was not significant, M-EO: P < 0.05, H-EO: P < 0.05). This study shows that EO can effectively improve the symptoms of colitis.

Antifungal Activities of Pure and ZnO-Encapsulated Essential Oil of Zataria multiflora on Alternaria solani as the Pathogenic Agent of Tomato Early Blight Disease.

The utilization of plant essential oils (EOs) and nanomaterials due to their safety compared with synthetic chemicals has been considered in the management of plant diseases. In this study, the inhibitory effects of Zataria multiflora, Nepeta haussknechtii, Artemisia sieberi, and Citrus aurantifolia EOs in pure and Zinc Oxide (ZnO) nanocapsulated formulations were evaluated on the mycelial growth of Alternaria solani to find a suitable alternative for synthetic chemicals. The crystal structure and morphological properties of the fabricated nanomaterials were assessed via X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. The textural features of the prepared nanoparticles were investigated with Brunauer–Emmett–Teller (BET) analysis, and the presence of elements in the samples was studied with energy-dispersive X-ray (EDX) technique. The mycelial growth inhibitory (MGI) was performed in the laboratory by mixing with potato dextrose agar (PDA) medium at concentrations of 100, 300, 600, 1,000, 1,500, and 2,000 ppm. Based on the results, major differences were monitored between different concentrations. At the highest studied concentration, the inhibition of Z. multiflora EO was 100%, which was 43.20, 42.37, and 21.19% for N. haussknechtii, A. sieberi, and C. aurantifolia, respectively, and the inhibition of their nanocapsules was 100, 51.32, 55.23, and 26.58%, respectively. In the greenhouse study, Z. multiflora EO and its nanocapsule (ZnO-ZmEO) were compared with the ZnO and chlorothalonil fungicide based on the highest inhibitory of Z. multiflora in vitro. The highest antifungal effect was related to the ZnO-ZmEO by 53.33%. Therefore, the ZnO-ZmEO formulation can be recommended as a biofungicide for managing and controlling tomato early blight disease after further research.

Synergistic larvicidal and repellent effects of essential oils of three Origanum species on Rhipicephalus annulatus tick.

Ticks are of great economic importance worldwide, both because they represent major obstacles to livestock productivity and because of their ability to transmit diseases to humans and animals. Although synthetic acaricides are the most common method for tick control, their overuse has led to the development of resistance as well as unacceptable residual levels in animal products and in the environment in general. There is therefore an urgent need to identify alternative treatments. Among such alternative approaches for tick control is plant essential oil (EO) therapy. In the present study, we investigated the synergistic effect of EOs of three oregano species-Origanum onites, O. majorana and O. minutiflorum-against Rhipicephalus annulatus larvae. Gas chromatography-mass spectrometry profiles of the three EOs revealed that carvacrol was their major component, with a concentration of 86.2% in O. majorana, 79.1% in O. minutiflorum and 77.4% in O. onites. The results of larvicidal assays revealed that the doses that lead to the death of 50% of the ticks (LC50) were 22.99, 25.08 and 27.06 µL/mL for O. majorana, O. minutiflorum and O. onites EOs, respectively, whereas the doses that lead to the death of 99% (LC99) were 41.26, 43.62 and 48.96 µL/mL. In addition, the LC50 and LC99 of the three oils combined was lower (viz., 4.01 and 6.97 µL/mL) than that of each oil alone. The tested EOs were also able to repel larvae of R. annulatus to varying degrees, with O. onites oil exhibiting the greatest repellent effect, as shown by the lowest RC50 dose, followed by O. minutiflorum and O. majorana. Interestingly, this means that the oil that was least effective in killing the larvae was the most effective in repelling them. The calculated synergistic factor of any combination was higher than 1 which means that combinations have a synergistic effect. In conclusion, the combination of all three oils showed higher toxic and repellent activities than either oil separately or combinations of any two oils, suggesting synergistic effects with low doses. Further studies including field trials and the establishment of the mode of action and side effects are urgently needed to expand on these findings, and other tick stages such as adults should also be tested.