Antimicrobial and Larvicidal Activities of Different Ocimum Essential Oils Extracted by Ultrasound-Assisted Hydrodistillation

Infectious diseases and their vectors have remained a concern for human population from their historical origin. Microbial pathogens have also emerged as a potent threat to the healthcare systems even in developed countries. Essential oils remain a less explored method for infectious disease control; besides, the ultrasound-assisted extraction (UAE) of essential oil production has emerged as promising source of bioactive volatiles over conventional methods. This study analyzed the possible use of UAE- Essential oils (EOs) from different species of Ocimum plants (Ocimum basilicum (OB), O. gratissimum (OG), O. tenuiflorum (OT), and O. canum (OC)) in the management of microbial pathogens and mosquito larval control. The antibacterial activity was estimated in terms of a disc diffusion assay and minimum inhibitory concentrations against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. The larvicidal property was found using three important mosquito vectors and the LC₅₀ value was determined. Furthermore, antioxidant and anti-inflammatory properties were estimated in terms of radical scavenging activities and the inhibition of lipoxygenase enzyme activity. The EOs exhibited significant DPPH radical scavenging (high in OG), hydrogen-peroxide scavenging (OB) and lipoxygenase inhibition (OB). The antibacterial activity was high in OB and OG (p < 0.05) and the larvicidal activity was of higher sensitivity against Aedis and Culex, whereas Armigeres was more resistant. However, no sign of toxicity in the Allium cepa model or non-targeted organism Guppy fishes was observed. Overall, the UAE extracted Ocimum essential oils were found to be effective against various human pathogenic microbial organisms, with OB and OG being highly active. Likewise, the EOs was also able to induce mortality in the larval forms of various mosquito vectors.     

Biological Activity of Essential Oils of Four Juniper Species and Their Potential as Biopesticides

The objective of this study was to assess the biological activity of essential oils (EOs) of four Juniperus species obtained via two different distillation methods and their potential as biopesticides. The studied factors were juniper species (Juniperus communis L., J. oxycedrus L., J. pygmaea C. Koch., and J. sibirica Burgsd), plant sex (male (M) and female (F)), and distillation method (hydrodistillation via a standard Clevenger apparatus (ClevA) and semi-commercial (SCom) steam distillation). The hypothesis was that the EO will have differential antioxidant, antimicrobial, and insecticidal activities as a function of plant species, plant sex, and distillation method. The two distillation methods resulted in similar EO composition within a given species. However, there were differences in the EO content (yield) due to the sex of the plant, and also differences in the proportions of some EO components. The concentration of α-pinene, β-caryophyllene, δ-cadinene and δ-cadinol was dissimilar between the EO of M and F plants within all four species. Additionally, M and F plants of J. pygmaea, and J. sibirica had significantly different concentrations of sabinene within the respective species. The EOs obtained via ClevA extraction showed higher antioxidant capacity within a species compared with those from SCom extraction. All of the tested EOs had significant repellent and insecticidal activity against the two aphid species Rhopalosiphum padi (bird cherry-oat aphid) and Sitobion avenae (English grain aphid) at concentrations of the EO in the solution of 1%, 2.5%, and 5%. The tested EOs demonstrated moderate activity against selected pathogens Fusarium spp., Botrytis cinerea, Colletotrichum spp., Rhizoctonia solani and Cylindrocarpon pauciseptatum. The results demonstrate that the standard ClevA would provide comparable EO content and composition in comparison with SCom steam distillation; however, even slight differences in the EO composition may translate into differential bioactivity.     

Toxics or Lures? Biological and Behavioral Effects of Plant Essential Oils on Tephritidae Fruit Flies

The family Tephritidae (Diptera) includes species that are highly invasive and harmful to crops. Due to globalization, international trade, and human displacement, their spread is continuously increasing. Unfortunately, the control of tephritid flies is still closely linked to the use of synthetic insecticides, which are responsible for detrimental effects on the environment and human health. Recently, research is looking for alternative and more eco-friendly tools to be adopted in Integrated Pest Management (IPM) programs. In this regard, essential oils (EOs) and their main compounds represent a promising alternative to chemical insecticides. EOs are made up of phytoconstituents formed from the secondary metabolism of many plants and can act as attractants or toxics, depending on the dose. Because of this unique characteristic, EOs and their main constituents are promising tools that can be used both in Sterile Insect Technique (SIT) programs and in the “lure and kill” technique, exploiting the attractiveness of the product in the former case and its toxicity in the latter. In this article, current knowledge on the biological and behavioral effects of EOs and their main constituents on tephritid fruit flies is reviewed, mainly focusing on species belonging to the Anastrepha, Bactrocera, Ceratitis, and Zeugodacus genera. The mechanisms of action of EOs, their real-world applications, and challenges related to their use in IPM are critically discussed.     

Composition,Anti-MRSA Activity and Toxicity of Essential Oils from Cymbopogon Species

Many of the essential oils obtained from medicinal plants possess proven antimicrobial activity and are suitable for medicinal purposes and applications in the food industry. The aim of the present work was the chemical analysis of 19 essential oils (EOs) from seven different Cymbopogon species (C. nardus, C. citratus, C winterianus, C. flexuosus, C. schoenanthus, C. martinii, C. giganteus). Five different chemotypes were established by GC/MS and TLC assay. The EOs, as well as some reference compounds, i.e., citronellol, geraniol and citral (neral + geranial), were also tested for their antimicrobial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA) by the microdilution method and direct bioautography. The toxicity of EOs was evaluated by Danio rerio ‘Zebrafish’ model assay. All examined EOs showed moderate to high activity against MRSA, with the highest activity noted for C. flexuosus—lemongrass essential oil, both in microdilution and direct autobiography method. Significant difference in the toxicity of the examined EOs was also detected.     

Occurrence of methylated arsenic species in parts of plants growing in polluted soils

Arsenic compounds were determined in extracts of branches, leaves and roots from plants growing in a mining contaminated area. The selected species were Dryopteris filix-max, Quercus pubescens, Dipsacus fullonum, Alnus glutinosa, Buxus sempervirens and Brachythecium cf. reflexum. Total arsenic content in the subsamples was analysed by ICPMS after acidic digestion. In general, concentrations in the plant parts followed the gradient roots?>?branches?>?leaves indicating that they are arsenic-resistant plants. Arsenic species were determined in water/methanol (9?+?1, v/v) extracts by HPLC-ICPMS. Different levels of organoarsenicals were found depending on plant part and plant species. Higher percentages of organoarsenic compounds were recorded in branches and leaves (up to 35% in the boxtree sample), than in roots (0.7–5.2% in the same plant species). The absence of organic arsenic species in the soil where the plants were collected and the low levels of organoarsenicals found in the roots, indicate that the studied plants have the ability to accumulate or synthesise organoarsenic compounds in relatively high percentages, and this information contributes to enlarge the knowledge of arsenic uptake and speciation in plants.     

Chemical composition and antimicrobial activity of the essential oils of Artemisia absinthium,Artemisia scoparia,and Artemisia sieberi grown in Saudi Arabia

Essential oils (EOs) are one of the most significant products of plant metabolites, the current research work was performed to determine and compare the chemical compositions of the EOs extracted from three different species of Artemisia (absinthium, sieberi, and scoparia) growing in Saudi Arabia and to test their antimicrobial potential against different bacterial and fungal strains. The EOs were isolated by hydro-distillation and analyzed by combining a gas chromatography–flame ionization detector (GC–FID) with the gas chromatography–mass spectroscopy (GC–MS) technique. Chemical analysis revealed that the three species had four compounds in common, i.e., limonene, camphor, terpinen-4-ol, and ethyl 2-methylbutyrate, while the main components identified in the EOs of A. absinthium and A. sieberi were cis-davanone (34.7% and 36.1%, respectively) and camphor (16.2% and 24.1%, respectively). In contrast, the keto compounds dominated in the oil of A. scoparia with 2-nonanone (55%) and 2-undecanone (24.5%) representing more than 80% of the total oil content. In addition, the antimicrobial activity of the isolated oils was evaluated by the broth microdilution method, revealing that all the EOs isolated from the examined Artemisia species displayed growth inhibiting actions in a concentration-dependent manner on selected tested microorganism species. The findings of the study also suggested that the tested EOs could be used to develop effective natural antimicrobial remedies with potential application in the fields of cosmetic industry, food manufacturing and medicine.     

The Design of Experiment as a Tool to Model Plant Trace-Metal Bioindication Abilities

Bioindicator plants are species that have the capacity to linearly uptake some elements (metal and metalloids) from the growing substrate, thus reflecting their concentration in the soil. Many factors can influence the uptake of these elements by plants, among which is the simultaneous presence of several metals, a common situation in contaminated or natural soils. A novel approach that can be used to validate the bioindication ability of a species growing on a polymetallic substrate is the design of experiment (DoE) approach. The aim of the present study was to apply the DoE in full factorial mode to model the Cu, Cd, Pb, Zn, and Cr bioindication capacity of Polygonum aviculare, used as the model plant. The results showed that P. aviculare has the ability to bioindicate Cd and Cr with a linear uptake (from 0.35 to 6.66, and 0.1 to 3.4 mg kg⁻¹, respectively) unaffected by the presence of other metals. Conversely, the uptake of Pb, Cu, and Zn is strongly influenced by the presence of all the studied metals, making their concentration in the plant shoot not proportional to that of the soil. In conclusion, these preliminary results confirmed that the DoE can be used to predict the bioindicator abilities of a plant for several elements at the same time and to evaluate the interactions that can be established between variables in the growing medium and in the plant itself. However, more studies including other plant species are needed to confirm the effectiveness of this method.     

Comparison of MAHD with UAE and Hydrodistillation for the Analysis of Volatile Oil From Four Parts of Perilla frutescens Cultivated in Southern China

Three different isolation techniques, specifically microwave-assisted hydrodistillation (MAHD), ultrasound-assisted extraction (UAE), and conventional hydrodistillation (HD) were employed to obtain essential oils from whole plants, leaves, roots, and stems of Perilla frutescens. The essential oils were analyzed using gas chromatography with flame ionization detection and gas chromatography with mass spectrometry. Variations in chemical composition were observed; these were attributed to differences in plant organs. Variations in the percentages of the main constituents of the oils extracted based on plant organ were irregular and affected the quantity and composition of the oils. Oil yields were affected by the method of extraction and extraction organ variation. The maximum volume of oil was extracted from leaves via MAHD and the minimum was extracted from roots via UAE. Oil yields ranged from 0.05% to 0.53%. The contents of essential oil varied significantly with the plant organ. In the essential oils of the plant parts studied were showed a predominance of oxygenated monoterpenes. Variation of extraction methods and organs may influence the oil components either qualitatively or quantitatively.     

Radical scavenging and antimicrobial activities of Croton zehntneri,Pterodon emarginatus and Schinopsis brasiliensis essential oils and their major constituents: estragole,trans-anethole, β-caryophyllene and myrcene

The essential oils (EOs) from the Brazilian species Croton zehntneri, Pterodon emarginatus and Schinopsis brasiliensis were examined for their chemical constituents, and antioxidant and antimicrobial activities. The composition of EOs was determined by using gas chromatography coupled with mass spectrometry analysis, while the antioxidant activity was evaluated through the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Furthermore, the antimicrobial activity was investigated against Escherichia coli and Pseudomonas aeruginosa (both Gram-negative), Staphylococcus aureus (Gram-positive) and Candida parapsilosis (fungus). The main components of C. zehntneri, P. emarginatus and S. brasiliensis were identified as estragole, trans-anethole, β-caryophyllene and myrcene. Among the EOs, P. emarginatus showed the highest antioxidant activity, with an IC₅₀ of 7.36 mg/mL and a Trolox equivalent antioxidant capacity of 3748 μmol/g determined by DPPH and ORAC assays, respectively. All EOs showed low activities against the bacterial strains tested, whereas the C. zehntneri oil and its main constituent estragole exhibited an appreciable antifungal activity against C. parapsilosis.     

Antimicrobial activity and phytochemical analysis of crude extracts and essential oils from medicinal plants

We aimed to establish a phytochemical analysis of the crude extracts and performed GC-MS of the essential oils (EOs) of Eugenia uniflora L. (Myrtaceae) and Asteraceae species Baccharis dracunculifolia DC, Matricaria chamomilla L. and Vernonia polyanthes Less, as well as determining their antimicrobial activity. Establishment of the minimal inhibitory concentrations of the crude extracts and EOs against 16 Staphylococcus aureus and 16 Escherichia coli strains from human specimens was carried out using the dilution method in Mueller-Hinton agar. Some phenolic compounds with antimicrobial properties were established, and all EOs had a higher antimicrobial activity than the extracts. Matricaria chamomilla extract and E. uniflora EO were efficient against S. aureus strains, while E. uniflora and V. polyanthes extracts and V. polyanthes EO showed the best antimicrobial activity against E. coli strains. Staphylococcus aureus strains were more susceptible to the tested plant products than E. coli, but all natural products promoted antimicrobial growth inhibition.     

Mentha pulegium L.: A Plant Underestimated for Its Toxicity to Be Recovered from the Perspective of the Circular Economy

The aim of the study was to investigate the micromorphology of Mentha pulegium leaves and flowers harvested in three different Sicilian (Italy) areas with peculiar pedo-climatic conditions, and to characterize the phytochemical profile, the phytotoxic activity, and the eco-compatibility of their essential oils (EOs) for potential use as safe bioherbicides. Light microscopy (LM) and scanning electron microscopy (SEM) highlighted that M. pulegium indumentum consists of non-glandular and glandular trichomes of different types. Peltate trichomes of plants from the different sites showed few significant differences in dimension and abundance, but they were characterized by a surprisingly high number of secretory cells both in leaves and flowers. Phytochemical analyses showed that oxygenated monoterpenes were the most abundant class in all the EOs investigated (92.2–97.7%), but two different chemotypes, pulegone/isomenthone and piperitone/isomenthone, were found. The complex of morphological and phytochemical data indicates that soil salinity strongly affects the expression of the toxic metabolite pulegone, rather than the EO yield. Phytotoxicity tests showed a moderate activity of EOs against the selected species as confirmed by α-amylase assay. Moreover, the low toxicity on brine shrimp provided a rationale for the possible use of investigated EOs as eco-friendly herbicides.     

The composition of the essential oils ofThymus marschallianus

The essential oil ofThymus marschallianus was obtained by steam distillation of freshly-gathered flowering plants growing at various heights of the Trans-Ili Ala-Tau range (Kazakhstan). The number of components detected was 49, of which 35 were identified. No appreciable differences in the composition of the essential oil with a change in the height of growth of the plant were observed. The essential oil ofTh. marschallianus and of a number of species growing in various countries have been compared.     

GC-MS Analysis of the essential oils of some plants of the Asteraceae Dumort family

An investigation has been made of the chemical composition of essential oils (EOs) of plants of the familyAsteraceae Dumort: Achillea filipendulinaLam., Artemisia persicaBoiss., Artemisia leucodesSchrenk, and Artemisia lehmannianaBunge.It has been shown that the composition of the EOs. of plants of one and the same species depends on the conditions and growth sites.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan [IKhRV AN RUz]. Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 568–572, July–August, 1995. Original article submitted November 14, 1994.     

The Chemical Composition of Oils and Cakes of Ochna serrulata (Ochnaceae) and Other Underutilized Traditional Oil Trees from Western Zambia

Currently, the negative effects of unified and intensive agriculture are of growing concern. To mitigate them, the possibilities of using local but nowadays underused crop for food production should be more thoroughly investigated and promoted. The soybean is the major crop cultivated for vegetable oil production in Zambia, while the oil production from local oil-bearing plants is neglected. The chemical composition of oils and cakes of a three traditional oil plant used by descendants of the Lozi people for cooking were investigated. Parinari curatellifolia and Schinziophyton rautanenii oils were chiefly composed of α-eleostearic (28.58–55.96%), linoleic (9.78–40.18%), and oleic acid (15.26–24.07%), whereas Ochna serrulata contained mainly palmitic (35.62–37.31%), oleic (37.31–46.80%), and linoleic acid (10.61–18.66%); the oil yield was high (39–71%). S. rautanenii and O. serrulata oils were rich in γ-tocopherol (3236.18 μg/g, 361.11 μg/g, respectively). The O. serrulata oil also had a very distinctive aroma predominantly composed of p-cymene (52.26%), m-xylene (9.63%), γ-terpinene (9.07%), o-xylene (7.97), and limonene (7.23%). The cakes remaining after oil extraction are a good source of essential minerals, being rich in N, P, S, K, Ca, and Mg. These plants have the potential to be introduced for use in the food, technical, or pharmaceutical industries.     

Antibacterial Effects of Essential Oils of Seven Medicinal-Aromatic Plants Against the Fish Pathogen Aeromonas veronii bv. sobria: To Blend or Not to Blend?

Despite progress achieved, there is limited available information about the antibacterial activity of constituents of essential oils (EOs) from different medicinal-aromatic plants (MAPs) against fish pathogens and the complex interactions of blended EOs thereof. The present study aimed to investigate possible synergistic antimicrobial effects of EOs from seven Greek MAPs with strong potential against Aeromonas veronii bv. sobria, a fish pathogen associated with aquaculture disease outbreaks. The main objective was to evaluate whether blending of these EOs can lead to increased antimicrobial activity against the specific microorganism. A total of 127 combinations of EOs were prepared and their effect on A. veronii bv. sobria growth was tested in vitro. We examined both the inhibitory and bactericidal activities of the individual EOs and compared them to those of the blended EOs. The vast majority of the investigated combinations exhibited significant synergistic and additive effects, while antagonistic effects were evident only in a few cases, such as the mixtures containing EOs from rosemary, lemon balm and pennyroyal. The combination of EOs from Greek oregano and wild carrot, as well as the combinations of those two with Spanish oregano or savoury were the most promising ones. Overall, Greek oregano, savoury and Spanish oregano EOs were the most effective ones when applied either in pure form or blended with other EOs.     

In vitro inhibitory activity of essential oil vapors against Ascosphaera apis

This work evaluates the in vitro inhibitory activity of 70 essential oils (EOs) in the vapor phase for the control of Chalkbrood disease caused by Ascosphaera apis Maassen ex Claussen (Olive et Spiltoir). Two wild strains isolated from infected honey bee colonies together with one standard collection strain were tested by the microatmosphere method. From 70 EOs, 39 exhibited an antifungal effect against A. apis standard and wild strains. The greatest antifungal action was observed for EO vapors from Armoracia rusticana, followed by Thymus vulgaris, Cymbopogon flexosus, Origanum vulgare and Allium sativum. An investigation of chemical composition by GC-MS revealed, that the most active EOs contained allyl isothiocyanate, citral, carvacrol and diallyl sulfides as the main constituents. The chemical composition plays a key role, as activities of different EOs from the same botanical species were different according to their composition.     

Traditional medicine in Syria: folk medicine in Aleppo governorate

The use of Traditional Arabic Medicine (TAM) for various diseases has been popular but scarcely studied in Syria. In the present study, we carried out ethnobotanical and ethnopharmacological research on the plants traditionally used to cure various diseases in northern Syria. The information was collected from the city and villages of the Aleppo governorate "Mohaafazah" in the north of Syria, collecting data directly on the basis of a detailed survey of inhabitants and herbalists. In this survey, we found that hundreds of plant species are still in use in TAM for the treatment of various diseases. We selected the most common 100 species, used in the treatment of more than 25 diseases. Among these plants, 53 are used for treating gastrointestinal disorders, 38 for respiratory system diseases, including asthma, bronchitis and cough, 34 for skin diseases, 21 for diabetes, 17 for kidney and urinary disorders, 16 for cardiac disorders, 14 for infertility and sexual impotency, 13 for treating liver diseases, 13 for several types of cancer, 9 for enhancing breast milk excretion, 8 for weight loss, 5 for reducing cholesterol, and three for weight gain. Plants were collected and identified: scientific Latin names, local names, the used parts of the plant, the herbal preparations and the local medical uses are described. Scientific literature concerning the activity of the investigated species is also reported and discussed according to their traditional uses.     

Exploitation of Marginal Hilly Land in Tuscany through the Cultivation of Lavandula angustifolia Mill.: Characterization of Its Essential Oil and Antibacterial Activity

Lavandula angustifolia Mill., known as one of the best essential oil-bearing plants, is an aromatic plant that is well cultivated in many Mediterranean regions due to its adaptability to variations in climatic and edaphic conditions. Therefore, its essential oil (EO) composition and its antimicrobial activity change as a consequence of abiotic and biotic factors. The chemical composition of L. angustifolia EO collected during four consecutive years of growth was one of the aims of this work. The volatile profile evidenced the prevalence of linalool and linalool acetate even though they switched their positions according to age. Plants in their first year were characterized by a high amount of sesquiterpene compounds (22.1% of the identified fraction). This percentage decreased during plant growth, not representing more than 5.3% in the fourth year. It is interesting to note that both the third- and fourth-year plants showed a content of monoterpenes that exceeded 90% of the total identified constituents. The EO extracted from the oldest plants evidenced higher activity on the studied strains, with more sensitivity on the Gram-positive ones. Tuscan lavender EO, especially that obtained from the four-year-old plants, is of great interest for its potential industrial applications and constitutes an example for the valorization of marginal Tuscan land and good-quality production.     

The composition of the essential oils ofThymus marschallianus

The essential oil ofThymus marschallianus was obtained by steam distillation of freshly-gathered flowering plants growing at various heights of the Trans-Ili Ala-Tau range (Kazakhstan). The number of components detected was 49, of which 35 were identified. No appreciable differences in the composition of the essential oil with a change in the height of growth of the plant were observed. The essential oil ofTh. marschallianus and of a number of species growing in various countries have been compared.Institute of Chemical Sciences, Academy of Sciences of the Kazakh SSR, Alma-Ata. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 510–514, July–August, 1985.     

Essential Oil of Cannabis sativa L: Comparison of Yield and Chemical Composition of 11 Hemp Genotypes

Cannabis sativa L. is an annual species cultivated since antiquity for different purposes. While, in the past, hemp inflorescences were considered crop residues, at present, they are regarded as valuable raw materials with different applications, among which extraction of the essential oil (EO) has gained increasing interest in many fields. The aim of the present study is the evaluation of the yield and the chemical composition of the EO obtained by hydrodistillation from eleven hemp genotypes, cultivated in the same location for two consecutive growing seasons. The composition of the EOs was analyzed by GC–MS, and then subjected to multivariate statistical analysis. Sesquiterpenes represented the main class of compounds in all the EOs, both in their hydrocarbon and oxygenated forms, with relative abundances ranging from 47.1 to 78.5%; the only exception was the Felina 32 sample collected in 2019, in which cannabinoids predominated. Cannabinoids were the second most abundant class of compounds, of which cannabidiol was the main one, with relative abundances between 11.8 and 51.5%. The statistical distribution of the samples, performed on the complete chemical composition of the EOs, evidenced a partition based on the year of cultivation, rather than on the genotype, with the exception of Uso-31. Regarding the extraction yield, a significant variation was evidenced among both the genotypes and the years of cultivation.