Toxicity Of Essential Oil Research Articles

Volatile profiling coupled with multivariate analysis, antiproliferative and anti-inflammatory activities of rhizome essential oil of four Hedychium species from India

Ethnopharmacological relevanceThe genus Hedychium of family Zingiberaceae comprises several perennial rhizomatous species widely used in perfumery and traditional folk medicine to treat diseases related to asthma, diarrhoea, nausea, stomach disorders, inflammation and tumours. Several species of Hedychium have remained under-explored with respect to their chemical composition and biological activities. Aim of the studyThe current research aimed to explore the chemical composition and evaluate the antiproliferative and anti-inflammatory activities of rhizome essential oil from four Hedychium species (H. coccineum, H. gardnerianum, H. greenii and H. griffithianum). Materials and methodsCompound identification was accomplished using a Clarus 580 gas chromatography system in conjunction with mass spectrometry (GC-MS). The multivariate data statistics using chemometrics (PCA, PLS-DA, sPLS-DA) and cluster analysis (Dendrogram, Heat maps, K-means) were used to compare the similarity and relationship among Hedychium metabolomes. MTT assay was employed to visualize the antiproliferative property against MCF7, HepG2 and PC3 cancerous cell lines. The toxicity of essential oils was determined using 3T3-L1 non-tumorigenic/normal cells. Lipopolysaccharide (LPS)-induced RAW 264.7 cells were used to investigate the anti-inflammatory properties of Hedychium essential oils by measuring the production of nitric oxide (NO) using the Griess reagent method. Furthermore, the levels of prostaglandin (PGE2) and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) was assessed using the ELISA technique. ResultsIn total, 82 compounds were identified in four targeted species of Hedychium from which 1,8-cineole (52.71%), β-pinene (32.83%), α-pinene (19.62%), humulene epoxide II (19.86%) and humulene epoxide I (19.10%) were the major constituents. Monoterpenes (8.5–59.9%) and sesquiterpenes (2.87–54.11%) were the two class of compounds, found as the most prevalent in the extracted essential oils. The multivariate analysis classified the four Hedychium species into three different clusters. Hedychium essential oils exhibited potent antiproliferative activity against MCF7, HepG2 and PC3 cancer cell lines with IC50 values less than 150 μg/mL where H. gardnerianum exhibited the highest selective cytotoxicity against human breast and prostate adenocarcinoma cells with an IC50 value of 44.04 ± 1.07 μg/mL and 56.11 ± 1.44 μg/mL, respectively. The essential oils on normal (3T3-L1) cells displayed no toxicity with higher IC50 values thereby concluding as safe to use for normal human health without causing any side effects. Besides, the essential oils at 100 μg/mL concentration revealed remarkable anti-inflammatory activity in LPS-activated RAW 264.7 murine macrophages by inhibiting the production of inflammatory mediators, with H. greenii exhibiting the maximum anti-inflammation response by significantly suppressing the levels of NO (84%), PGE2 (87%), TNF-α (94.3%), IL-6 (95%) and IL-1β (85%) as compared to LPS treated group. ConclusionThe present findings revealed that the Hedychium species traditionally used in therapeutics could be a potential source of active compounds with antiproliferative and anti-inflammatory properties.

Current status, technology, regulation and future perspectives of essential oils usage in the food and drink industry.

Nowadays, essential oils (EOs) have a wide use in many applications such as in food, cosmetics, pharmaceutical and animal feed products. Consumers' preferences concerning healthier and safer foodstuffs lead to an increased demand for natural products, in replacement of synthetic substances, used as preservatives, flavourings etc. EOs, besides being safe, are promising alternatives as natural food additives, and much research has been carried out on their antioxidant and antimicrobial activity. The initial purpose of this review is to discuss conventional and 'green' extraction techniques along with their basic mechanism for the isolation of EOs from aromatic plants. This review aims to provide a broad overview of the current knowledge about the chemical constitution of EOs while considering the existence of different chemotypes, since bioactivity is attributed to the chemical composition - qualitative and quantitative - of EOs. Although the food industry primarily uses EOs as flavourings, an overview on recent applications of EOs in food systems and active packaging is provided. EOs exhibit poor solubility in water, oxidation susceptibility, negative organoleptic effect and volatility, restricting their use. Encapsulation techniques have been proven to be one of the best approaches to preserve the biological activities of EOs and minimize their effects on food sensory qualities. Herein, different encapsulation techniques and their basic mechanism for loading EOs are discussed. EOs are highly accepted by consumers, who are often under the misconception that 'natural' means safe. This is, however, an oversimplification, and the possible toxicity of EOs should be taken into consideration. Thus, in the final section of the current review, the focus is on current EU legislation, safety assessment and sensory evaluation of EOs. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Contact Toxicity and Repellent Efficacy of Kaempferia rotunda L. to Three Stored Product Insects and Synergistic Interactions between Two Major Compounds Benzyl Benzoate and Bornyl Acetate

This paper analyzed the chemical constituents of the essential oil (EO) of Kaempferia rotunda L. and the bioactivities of the predominant compounds. Results obtained from GC/MS analysis indicated 14 compounds, which accounted for 96.66% of the total extract. Among them, the most abundant compound was benzyl benzoate (81.13%), followed by bornyl acetate (4.51%). EO from the medicinal plant K. rotunda inhibited the potent toxicity of Lasioderma serricorne and Liposcelis bostrychophila (LD50=17.1μg/adult and 18.6 μg/adult). K. rotunda oil also exerted strong repellency against three target insects at high concentrations. Based on the theory of the grey correlation analysis, EO from K. rotunda performed better than benzyl benzoate but worse than bornyl acetate on the repellency against Tribolium castaneum. Benzyl benzoate possessed excellent contact toxicity with three target insects. Meanwhile, the binary mixture of two main compounds (benzyl benzoate and bornyl acetate) was evaluated for contact toxicity with T.castaneum for the first time. The synergistic effect in natural ratios has been observed, suggesting that unique mechanisms of action should be responsible for EO toxicity. Plant-derived insecticides appear suitable for developing control means against stored product insects.

Effects of Piper nigrum L. Fruit Essential Oil Toxicity against Stable Fly (Diptera: Muscidae).

The efficacy of Piper nigrum L. fruit essential oil (EO) against Stomoxys calcitrans (stable fly), a blood-feeding fly distributed worldwide, was investigated. This study aimed to evaluate the insecticidal activity of EO based on contact and fumigant toxicity tests. Chemical analysis of the EO using gas chromatography-mass spectrometry revealed that sabinene (24.41%), limonene (23.80%), β-caryophyllene (18.52%), and α-pinene (10.59%) were the major components. The results demonstrated that fly mortality increased with increasing EO concentration and time during the first 24 h of exposure. The median lethal dose was 78.37 µg/fly for contact toxicity, while the 90% lethal dose was 556.28 µg/fly. The median lethal concentration during fumigant toxicity testing was 13.72 mg/L air, and the 90% lethal concentration was 45.63 mg/L air. Our findings suggested that essential oil extracted from P. nigrum fruit could be a potential natural insecticidal agent for control of stable fly. To examine the insecticidal properties of P. nigrum fruit EO, further field trials and investigation into the efficacy of nano-formulations are required.

Survival and Demography of the Tomato Borer (Tuta absoluta) Exposed to Citrus Essential Oils and Major Compounds †

Tuta absoluta is a pest of importance: quick to disperse and difficult to control due to the cases of resistance to insecticide active ingredients. Thus, studies using essential oils (EOs) to search for new molecules should be intensified. The objective of the present study was to evaluate the toxicity of EOs from Citrus aurantifolia (lime), Citrus aurantium (petitgrain) and Citrus aurantium bergamia (bergamot) and its major compounds against T. absoluta in a topical application test. Additionally, the demographic parameters of T. absoluta were studied after the topical application of EOs. The median lethal time (LT50) of the population was 12h for the three EOs tested. The median lethal concentration (LC50) was 33.75, 38.78 and 35.05 µg µL−1 for C. aurantifolia, C. aurantium and C. aurantium bergamia, respectively. As found using gas chromatography coupled to mass spectrometry (GC-MS) quantification, 44.74% of the EO of C. aurantifolia is α-terpineol, while 55.45% and 58.12% of the EO of C. aurantium and C. aurantium bergamia, respectively, is linalyl acetate. The toxicity of the major compounds was tested at concentrations equivalent to the LC50 of the EOs, that is, 16.2 µg µL−1 for α-terpineol, and 25.8 µg µL−1 for linalyl acetate, using topical application. Both of the major compounds showed less toxicity than the EOs. In the sublethal effects tests, all the EOs negatively affected the demographic parameters of T. absoluta, with a decrease in the duration of larval instars, duration of the pupal period, fecundity, oviposition and viability of the eggs, implying a reduction in the population growth parameters of this pest. The EOs of lime, petitgrain and bergamot are toxic to T. absoluta, and low concentrations cause deleterious effects on the reproductive and population parameters of T. absoluta.

Duguetia lanceolata A. St.-Hil. (Annonaceae) Essential Oil: Toxicity against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) and Selectivity for the Parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)

The fall armyworm (FAW) Spodoptera frugiperda is a polyphagous pest that is difficult to control due to populations resistant to various active ingredients. Thus, the objective of this study was to evaluate the toxicity of essential oils (EOs) from the organs of Annona neolaurifolia, Duguetia lanceolata, and Xylopia brasiliensis, against the FAW and its natural enemy, Trichogramma pretiosum. The most active EOs were those from the leaves and stem bark of D. lanceolata, which presented LD90 to S. frugiperda equal to 70.76 and 127.14 µg of EO/larvae, respectively. The major compounds in the EO of D. lanceolata (leaves) were β-caryophyllene and caryophyllene oxide. Although individually inactive against the FAW, when combined, those compounds reduced the insect’s probability of survival. However, the mortality was lower than that caused by EO. This result suggests that other components of EO contribute to the activity against FAW. Furthermore, the EO of the leaves from D. lanceolata presented low toxicity to the egg-larva stage of T. pretiosum, but was toxic to other phases. Thus, EO from D. lanceolata is potentially useful for developing new products to control S. frugiperda.

Comparative toxicity of essential oils, their emulsifiable concentrates and nanoemulsion formulations against the bean aphid, Aphis fabae

The present study aims to prepare emulsifiable concentrate (EC) and nanoemulsion formulations from the plant essential oils of Lavandula angustifolia (Mill.), Ambrosia maritima (L.), Commiphora myrrha (Nees) Engl., Juniperus virginiana (L.), Rheum palmatum (L.) and Tagetes minuta (L.). The efficiency of these essential oils along with their formulations were compared against the bean aphid, Aphis fabae (Scopoli). Results disclosed that all EC preparations passed the emulsion stability and foam formation tests. The particle droplet size of the nanoemulsions varied from 64.3 to 264.7 nm. The toxicity of EC formulations was slightly higher than the corresponding nanoemulsion formulations. Both EC and nanoemulsion of R. palmatum were the most efficient (LC50 = 1003.60 and 1105.34 mg L−1, respectively). EC preparations had no adverse effects on seed beans. The absence of organic solvents and the high aphicidal activity of EC formulations might make these preparations suitable for controlling A. fabae.

Toxicity and larvicidal activity on Aedes aegypti of citronella essential oil submitted to enzymatic esterification.

The essential oil of citronella (Cymbopogon winterianus) has several biological activities, among them the insect repellent action. Some studies showed that cinnamic acid esters can be applied as natural pesticides, insecticides and fungicides. In this context, the objective of the present work was to evaluate the production of esters from citronella essential oil with cinnamic acid via enzymatic esterification. Besides, the essential oil toxicity before and after esterification against Artemia salina and larvicidal action on Aedes aegypti was investigated. Esters were produced using cinnamic acid as the acylating agent and citronella essential oil (3:1) in heptane and 15 wt% NS 88011 enzyme as biocatalysts, at 70 °C and 150 rpm. Conversion rates of citronellyl and geranyl cinnamates were 58.7 and 69.0% for NS 88011, respectively. For the toxicity to Artemia salina LC50 results of 5.29 μg mL-1 were obtained for the essential oil and 4.36 μg mL-1 for the esterified oils obtained with NS 88011. In the insecticidal activity against Aedes aegypti larvae, was obtained LC50 of 111.84 μg mL-1 for the essential oil of citronella and 86.30 μg mL-1 for the esterified oils obtained with the enzyme NS 88011, indicating high toxicity of the esters. The results demonstrated that the evaluated samples present potential of application as bioinsecticide.

Insecticidal plants as trade opportunities and use by small vegetable producers: an example using essential oils to control Diaphania hyalinata (Lepidoptera: Crambidae).

Production and sale of botanical insecticides depend on knowing the potential opportunities for these products. Essential oils from plants secondary metabolism can control pests, especially in agricultural systems where synthetic insecticides are limited, as in organic agriculture. The objective of this study was to evaluate the toxicity of essential oils to Diaphania hyalinata (Lepidoptera: Crambidae) and to show regions with the potential to use Cinnamomum zeylanicum, Citrus sinensis, and Syzygium aromaticum in the formulation and commercialization of insecticides to control this insect. The C. zeylanicum oil was more toxic to larvae and pupae and the S. aromaticum to eggs of D. hyalinata. Essential oils are an alternative for the management of D. hyalinata. The production of pesticides from essential oils of C. zeylanicum, C. sinensis, and S. aromaticum to control D. hyalinata has high potential in America. Also, Asia, Africa, Europe, the Middle East, and Asia can extract these plants to formulate insecticide molecules for the America countries.

Chemical Composition, Repellent Action, and Toxicity of Essential Oils from Lippia origanoide, Lippia. alba Chemotypes, and Pogostemon cablin on Adults of Ulomoides dermestoides (Coleoptera: Tenebrionidae).

The essential oils (EOs) from bioactive species can provide an alternative tool for the management of stored grain insects that is less environmentally damaging than synthetic chemicals. The aim of this study was to assess the repellent action and toxicity of EOs obtained from phellandrene-rich Lippia origanoides, carvone-rich Lippia alba, citral-rich L. alba, and Pogostemon cablin aerial parts on adults of Ulomoides dermestoides. These EOs were isolated by hydrodistillation and characterized by gas chromatography coupled to mass spectrometry (GC-MS). The repellency assay was carried out using the area preference method, and the toxicity evaluated utilizing a filter paper contact test. The major components (>10%) of the studied EOs were sabinene (16.9%), trans-β-caryophyllene (18.6%) and α-humulene (10.1%) for phellandrene-rich L. origanoides EO; limonene (40.1%) and carvone (37.7%) for carvone-rich L. alba EO; geranial (24.5%), geraniol (19.0%), and neral (11.9%) for citral-rich L. alba EO; and α-guaiene (13.3%), α-bulnesene (15.7%), and patchoulol (35.3%) for P. cablin EO. All EOs displayed 100% repellency at a concentration of 16 μL/mL, with lower toxicity than that elicited by the commercial repellent DEET. EO concentrations up to 8 µL/mL did not induce any mortality on the beetle. These findings show that the EOs provide active and safe molecules for natural repellent formulations to prevent and control insect infestations of stored products.

Essential Oils Composition, Antibacterial Activity and Toxicity Study of Artemisia Species Growing in Ethiopia

Artemisia essential oils have been used in flavors, scents, mice repellents, cleansers, beauty care products, fragrances, and conventional pharmaceuticals. This work analyzed the phytoconstituents, in vitro antibacterial activity, and toxicity of essential oils of three Artemisia species growing in Wolaita, Ethiopia. GC-MS has been used to analyze chemical composition. In vitro antibacterial activity was assessed by disc diffusion and broth dilution techniques. The MTT assay was used to conduct toxicity studies. The main components of the essential oil extracted from Artemisia afra Jacq. ex Willd. were camphor (19.2%), followed by 1,8-cineole (17.8%), artemisia ketone (15.2%), artemisyl acetate (6.9%), and camphene (6.6%). In the Artemisia annua L. oil, the main constituents were camphor (21.8%), artemisia alcohol (18.1%), santolina triene (11.6%), -copaene (9.1%), sabinene (4.5%), and δ-cadinene (4.0%). In addition, the main phytochemicals of Artemisia abyssinica Sch.Bip. ex A.Rich. oil were yomogi alcohol (39.3%), followed by cis β-farnesene (10.9%), β-selinene (6.7%), β-copaene (5.2%), and nerolidol (5.1%). The essential oils of A. afra, A. annua, and A. abyssinica showed significant antibacterial activity at low molar concentrations, with MIC values of 0.31, 0.15, and 0.62 μL against Staphylococcus aureus and 0.62, 0.31, and 1.25 μL against E. coli, respectively, compared with standard broad-spectrum gentamicin (0.25 μL). A. afra, A. annua, and A. abyssinica oils were showed weak toxicity to Vero cell lines with IC50 values of 178.47 µg/mL, 183.86 µg/mL, and 187.46 µg/mL, respectively. This result suggests that EOs are promising antibacterial agents given their weak toxic effects on normal cell lines at low concentrations.

The Antimicrobial and Toxicity Influence of Six Carrier Oils on Essential Oil Compounds

Essential oil compounds have been identified as alternative antimicrobials; however, their use is limited due to their toxicity on human lymphocytes, skin, and reproduction. Carrier oils can reduce the toxicity of essential oils, which raises the question as to whether such activity would extend to the essential oil compounds. Thus, this study aimed to investigate the antimicrobial and toxicity activity of essential oil compounds in combination with carrier oils. The antimicrobial properties of the essential oil compounds, alone and in combination with carrier oils, were determined using the broth microdilution assay. The toxicity was determined using the brine shrimp lethality assay. Antimicrobial synergy (ΣFIC ≤ 0.50) occurred in 3% of the samples when tested against the ESKAPE pathogens. The compound thymoquinone in combination with the carrier oil Prunus armeniaca demonstrated broad-spectrum synergistic activity and a selectivity index above four, highlighting this combination as the most favorable. The carrier oils reduced the toxicity of several compounds, with Calendula officinalis and P. armeniaca carrier oils being responsible for the majority of the reduced toxicity observed. This study provides insight into the interactions that may occur when adding a carrier oil to essential oil compounds.

Can Essential Oils Be a Natural Alternative for the Control of Spodoptera frugiperda? A Review of Toxicity Methods and Their Modes of Action

Spodoptera frugiperda is a major pest of maize crops. The application of synthetic insecticides and the use of Bt maize varieties are the principal strategies used for its control. However, due to the development of pesticide resistance and the negative impact of insecticides on the environment, natural alternatives are constantly being searched for. Accordingly, the objective of this review was to evaluate the use of essential oils (EOs) as natural alternatives for controlling S. frugiperda. This review article covers the composition of EOs, methods used for the evaluation of EO toxicity, EO effects, and their mode of action. Although the EOs of Ocimum basilicum, Piper marginatum, and Lippia alba are the most frequently used, Ageratum conyzoides, P. septuplinervium. O. gratissimum and Siparuna guianensis were shown to be the most effective. As the principal components of these EOs vary, then their mode of action on the pest could be different. The results of our analysis allowed us to evaluate and compare the potential of certain EOs for the control of this insect. In order to obtain comparable results when evaluating the toxicity of EOs on S. frugiperda, it is important that methodological issues are taken into account.

Compositions analysis and insecticidal activity of Aconitum polycarpum Chang ex W.T.Wang petroleum ether fractions and essential oils

Ethnopharmacological relevanceThe Aconitum genus plants as a natural pesticide for insecticide and rodent control has been recorded in Chinese folk. However, the insecticide effect, mechanism, and active composition of Aconitum polycarpum Chang ex W.T.Wang have not been studied further. Aim of the studyThis study was designed to analyze the chemical composition, evaluate contact toxicity of petroleum ether extracts (PEEs) and essential oils (EOs) of A. polycarpum, and further explore their possible insecticidal mechanism. Materials and methodsThe roots of A. polycarpum were extracted with 90% methanol, and then extracted with petroleum ether to obtain PEEs; the EOs was extracted by distillation. The chemical compositions of PEEs and EOs were analyzed by GC-MS. Contact toxicity was evaluated by the immersion method. Exploring insecticidal mechanisms through in vitro enzyme inhibitory activity. Results12 compounds were identified from PEEs by GC-MS, mainly including aliphatic (94.8%), the main compositions were Octadecadienol (ODO) (aliphatic, 53.2%) and L-Ascorbyl dipalmitate (LADP) (aliphatic, 36.1%). 24 compounds were identified in EOs. About 44.6% of the identified components were terpenoids and their derivatives, and the rest were mainly aliphatic (34.7%) and phenols (3.0%). The main chemical components were L (−)-Borneol (LB) (terpenoid, 28.3%), LADP (aliphatic, 19.1%), and Isoborneol (terpenoid, 9.1%). The contact toxicity indicated that the PEEs showed great contact toxicity against Spodoptera exigua (LC50 = 126.2 mg/L). Meanwhile, LADP (LC50 = 128.1 mg/L) and ODO (LC50 = 121.3 mg/L) was similar to that of Cyhalothrin (LC50 = 124.2 mg/L) in contact toxicity. In addition, we found that LADP and ODO exhibited excellent inhibitory activity against CarE (IC50 = 58.0, 56.1 mg/L, respectively) by measuring in vitro enzyme inhibitory activity, which was superior than Cyhalothrin (IC50 = 68.1 mg/L). ConclusionsThe chemical compositions and contact toxicity of EOs and PEEs of A. polycarpum were analyzed and evaluated, and their insecticidal mechanisms were preliminarily discussed for the first time. It proved PEEs of A. polycarpum and its main components (LADP and ODO) exhibited excellent contact toxicity against S. exigua, and CarE was identified as a potential target for contact toxicity. This study indicated that the insecticidal activity of petroleum ether extracts from A. polycarpum is quite promising, and provides a practical and scientific basis for the development and application of botanical pesticides.

Insecticidal and oviposition deterrent effects of pure and combined essential oils of Salvia subg. Perovskia species against Phthorimaea operculella

Volatile organic compounds especially terpenoid derivatives possess bioactivities including insecticidal effects, and they sometimes act synergistically when mixed. The potato tuber moth (PTM), Phthorimaea operculella Zeller, is one of the most serious pests of potatoes in Iran. Since the potato is an important source of human food, safe and non-chemical control of its pest is indispensable. This study evaluated the fumigant toxicity of pure and two mixtures of essential oils (EOs) of three Salvia subg. Perovskia species against P. operculella. GC–MS phytochemical profiling of species showed 1,8-cineole (12.55%) and linalyl acetate (11.48%), as dominant in S. yangii-EO, geranyl acetate (55.64%), and 1,8-cineole (10.50%) as major constituents in S. abrotanoides-EO, and δ-3-carene (29.29%) and 1,8-cineol (18.08%), as major compounds of S. artemisioides-EO. The EOs, especially combined types were toxic against the pest and showed ovicidal and repellent efficacies. Adults showed considerable sensitivity to the 25:75 mixture ratio of S. yangii and S. abrotanoides EOs (LC50 = 5.82 µL/L air) in comparison to eggs (LC50 = 10.10 µL/L air). The combined EOs also reduced the ovipositional rate. In addition, pure S. abrotanoides EOs showed great fumigant toxicities (11.09 µL/L air) effects against one-old-day eggs. The combination of EOs including 1,8 cineol and geranyl acetate as corresponding compounds, may affect survival, energy resource transfer during oogenesis, and oviposition, which are likely mechanisms involved with essential oil toxicity. As a result, Salvia essential oils can be used for the development of eco-friendly, safe, and effective botanical pesticides in integrated PTM management strategies.

Pediculicidal Activity of Foeniculum vulgare Essential Oil in Treatment of Pediculus capitis as a Public Health Problem.

Pediculosis, caused by Pediculus spp is an important public health problem in urban and rural areas around the world. Natural compounds such as plant essential oils (EOs) have been suggested as a potential alternative for insect pest control recently. The purpose of this study was to investigate the toxicity of Foeniculum vulgare essential oil against the head louse, Pediculus capitis under laboratory conditions. Fennel essential oil components were analyzed using GC-mass apparatus. Immersion and contact filter paper bioassays were used to evaluate fennel essential oil toxicity at the two-fold concentrations of 2.5, 5, 10, 20, and 40% against nit and nymph/adult stages of the head louse. Trans-anethole, α-Thujone, and limonene, which consisted of 76.08%, 10.37%, and 5.34% were the most components of fennel oil respectively. The LC50 values for the adult /nymphs were 11.5, 6.4, 3.9, 3.1 and 2.5% and LC99 values were 29.5, 15.2, 12.8, 10.8, and 7.4% at 10, 20, 30, 45 and 60 minutes after exposure respectively. The lethal times (LT50) for adults/nymphs were 5.2, 8.1, 9.5, 20.5, and 45.8 minutes and LT99 were 138.6, 91.3, 23.8, 21.7, and 13.9 minutes in the concentrations of 2.5, 5, 10, 20 and 40%, respectively. LC50 and LC99 values were 2.32% and 7.36% after 5 days for the eggs. Fennel essential oil at the concentration of 15% after 20min is suggested to develop as an appropriate formulation to evaluate in clinical trials.

Exploring Contact Toxicity of Essential Oils against Sitophilus zeamais through a Meta-Analysis Approach.

Sitophilus zeamais is a primary pest of maize. Our aim was to perform a qualitative review and meta-analyses with 56 scientific articles published from 1 January 2000 to 1 October 2022 dealing with direct (topical application) and indirect (impregnation of essential oils, EOs, onto filter paper or maize grains) contact toxicity of EOs against S. zeamais. Three independent meta-analyses of single means of LD50 (direct contact) and LC50 (indirect contact) were conducted using a random effect model. Essential oils more frequently evaluated were those belonging to Asteraceae, Apiaceae, Lamiaceae, Myrtaceae, Piperaceae, and Rutaceae. The LC50 global mean values were 33.19 µg/insect (CI95 29.81-36.95) for topical application; 0.40 µL/cm2 (CI95 0.25-0.65) for filter paper indirect contact; and 0.50 µL/g maize (CI95 0.27-0.90) for maize grains indirect contact. The species Carum carvi, Salvia umbratica, Ilicium difengpi, Periploca sepium, Cephalotaxus sinensis, Murraya exotica, Rhododendron anthopogonoides, Ruta graveolens, Eucalyptus viminalis, Ocotea odorifera, Eucalyptus globulus, Eucalyptus dunnii, Anethum graveolens, Ilicium verum, Cryptocarya alba, Azadirachta indica, Chenopodium ambrosioides, Cupressus semperivens, Schinus molle, Piper hispidinervum, Mentha longifolia, and Croton pulegiodorus showed LC50 or LD50 values lower than the global means, indicating good insecticidal properties. Our results showed that EOs have great potential to be used as bioinsecticides against S. zeamais.

Volatile Constituents and Toxicity of Essential Oils Extracted From Aerial Parts of Plantago Lanceolata and Plantago Major Growing in Iran

Background:Plantago lanceolata L. (P. lanceolate) and Plantago major L. (P. major) belong to the Plantaginaceae family and are widely used in traditional medicine. Objectives: This study aims to qualitatively identify the crucial compounds and evaluate the toxicity effects of essential oils of two Plantago species. Methods: The plantains were collected from Zanjan Province, Iran. The essential oils were extracted by hydrodistillation and then analyzed using gas chromatography coupled with mass spectrometry (GC/MS). The toxicity effects of the essential oils were evaluated on HCT-116 and HEK-293 cell lines (in vitro MTT assay) and Artemia salina (A.salina) (in vivo assay). The constituents of the essential oils were identified by calculating their retention indices under temperature-programmed conditions for n-alkanes (C8 -C20) in the Agilent 19091S-433 column. Results: The main identified constituents were metaraminol (14.04%), bifemelane (8.73%), metossamina (8.16%), and pterin-6-carboxylic acid (5.11%) in P. lanceolata and 2-dodecen-1-yl (-) succinic anhydride (15.29%), benzenemethanol, α-(1-aminoethyl)-2,5- dimethoxy-(11.83%), dl-phenylephrine (7.51%), and nortriptyline (5.15%) in P. major. The essential oils of P. major exhibited more antiproliferative properties on HCT-116 at 72 h compared to P. lanceolata (IC50: 102.66 µg/mL). At 400 µg/mL of P. lanceolata and P. major, the percentage of the lethality of nauplii was 8% and 12%, respectively (LC50:2242.57 µg/ mL and 1783.7 µg/mL). The present study showed that the most of constituents of oils were alcohols and amines. Conclusion: Some of the compounds identified in the Plantago species essential oils have important pharmaceutical properties. This study reported the cytotoxicity of essential oils on the colon cancer cell line. However, the essential oils were not toxic against A.salina at the examined concentrations.

Toxicity of Some Essential Oils Constituents against Oriental Fruit Fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).

Simple SummaryThe massive use of synthetic pesticides to manage agricultural pests results in environmental pollution and health hazards. The secondary plant metabolites, which are majorly dominated by terpenoids, have the potential to be developed into novel alternatives to synthetic chemicals. Therefore, the present study aimed at evaluating the toxicity, oviposition deterrence, and repellent activities of six majorly dominated essential oil constituents against adults and immature stages of oriental fruit flies, Bactrocera dorsalis. Our results highlight the potential of the selected essential oil constituents to be developed as a novel alternative to synthetic pesticides against B. dorsalis.The massive use of synthetic pesticides to manage agricultural pests results in environmental pollution and health hazards. The secondary plant metabolites, which are majorly dominated by terpenoids, have the potential to be developed into novel alternatives to synthetic chemicals. Therefore, in our current investigation, six majorly dominated essential oil constituents were evaluated for their toxicity against adults and immature stages of oriental fruit flies, Bactrocera dorsalis, a worldwide fruit pest. The results indicated that carvacrol was the most toxic essential oil constituent (EOC) to adult flies, with LC50 of 19.48 mg/mL via fumigant assay, followed by thujone 75% mortality via ingestion toxicity test against adult fruit flies. Similarly, when larvae were dipped in different concentrations of EOCs, carvacrol appeared as the most toxic EOC with the lowest LC50 (29.12 mg/mL), followed by (−)-alpha-pinene (26.54 mg/mL) and (R)-(+)-limonene (29.12 mg/mL). In the oviposition deterrence tests, no egg was observed on oranges seedlings treated with 5% of each EOC (100% repellency). Regarding the repellency assay, a significantly higher number of flies (77%) were repelled from the Y-tube olfactometer arm containing (−)-alpha-pinene, followed by carvacrol (76%). Our results showed that the selected essential oil constituent has the potential to be developed as an alternative to synthetic pesticides against B. dorsalis. However, further research is required to assess the activities of these EOCs under open-field conditions.

Bioactivity of essential oils from Croton grewioides and its major compounds: toxicity to soybean looper Chrysodeixis includens and selectivity to the predatory stink bug Podisus nigrispinus.

Natural biological control is a key factor that ensures the regulation of insect pest populations in agroecosystems. However, the indiscriminate use of pesticides has compromised this environmental service. Thus, the search for environmentally safe pesticides is an increasing requirement for sustainable food production. In this study, we analyzed the toxicity of essential oils from two accessions (CGR112 and CGR126) of Croton grewioides and its major compounds, methyl eugenol and eugenol, on the soybean pest Chrysodeixis includens. In addition, we investigated the sublethal effects of these compounds on the predatory bug Podisus nigrispinus, analyzing its developmental, reproduction and life table parameters. Essential oils and their major compounds were toxic to C. includens and P. nigrispinus. In general, the presence of eugenol made the essential oil more toxic to the pest and selective to the natural enemy. Eugenol was the most toxic compound for 2nd instar larvae of C. includens at LD50, followed by CGR126 essential oil from C. grewioides which was equally toxic at higher doses. The estimated lethal times for essential oils to cause mortality in 50% of the population of C. includens were less than 15h. There was selectivity of the essential oil of CGR126 accession of C. grewioides at lethal doses above 90%. Although the treatments showed little effect on the development of P. nigrispinus, body mass and reproductive parameters were negatively affected, with the exception of the essential oil of CGR126 accession of C. grewioides. The essential oil of C. grewioides may be a promising active ingredient for the synthesis of new insecticides, which are efficient against C. includens and at the same time are safer for the natural enemy P. nigrispinus.