Exploring the Diverse Biological Properties of Cannabidiol: A Focus on Plant Growth Stimulation.

The aim of the current study was to compare some biological activities of edible oils enriched with 10 % of cannabidiol (CBD samples) from the Slovak market. In addition, hemp, coconut, argan, and pumpkin pure oils were also examined. The study evaluated the fatty acids content, as well as antibacterial, antifungal, antioxidant, cytotoxic, and phytotoxic activities. The CBD samples presented antimicrobial activity against the tested bacterial strains at higher concentrations (10000 and 5000 mg/L) and antifungal activity against Alternaria alternata, Penicillium italicum and Aspergillus flavus. DPPH⋅ and FRAP assays showed greater activity in CBD-supplemented samples compared to pure oils and vitamin E. In cell lines (IPEC-J2 and Caco-2), a reduced cell proliferation and viability were observed after 24 hours of incubation with CBD samples. The oils showed pro-germinative effects. The tested activities were linked to the presence of CBD in the oils.

Anti-Cholinesterase and Anti-α-Amylase Activities and Neuroprotective Effects of Carvacrol and p-Cymene and Their Effects on Hydrogen Peroxide Induced Stress in SH-SY5Y Cells.

Several researchers have demonstrated the health and pharmacological properties of carvacrol and p-cymene, monoterpenes of aromatic plants. This study investigated these compounds' possible anti-cholinesterase, anti-α-amylase, and neuroprotective effects. We evaluated the anti-acetylcholinesterase and anti-α-amylase activities at different concentrations of the compounds. The maximum non-toxic dose of carvacrol and p-cymene against SH-SY5Y neuroblastoma cells was determined using an MTT assay. The neuroprotective effects of the compounds were evaluated on H2O2-induced stress in SH-SY5Y cells, studying the expression of caspase-3 using Western blotting assays. Carvacrol showed inhibitory activities against acetylcholinesterase (IC50 = 3.8 µg/mL) and butyrylcholinesterase (IC50 = 32.7 µg/mL). Instead, the anti-α-amylase activity of carvacrol resulted in an IC50 value of 171.2 µg/mL After a pre-treatment with the maximum non-toxic dose of carvacrol and p-cymene, the expression of caspase-3 was reduced compared to cells treated with H2O2 alone. Carvacrol and p-cymene showed in vitro anti-enzymatic properties, and may act as neuroprotective agents against oxidative stress. Further studies are necessary to elucidate their possible use as coadjutants in preventing and treating AD in diabetic patients.

Pulicaria incisa (Lam.) DC. as a Potential Source of Antioxidant, Antibacterial, and Anti-Enzymatic Bioactive Molecules: Phytochemical Constituents, In Vitro and In Silico Pharmacological Analysis.

Plants with medicinal benefits are a crucial source of compounds for developing drugs. This study was designed to determine the chemical composition, antibacterial, antibiofilm, antioxidant, and anti-enzymatic activities of Pulicaria incisa (Lam.) DC. We also reported the molecular interaction between identified molecules and several receptors associated with antimicrobial and antibiofilm activities. A total of seventeen and thirteen compounds were identified in aqueous and methanolic extracts of P. incisa, respectively. The methanolic extract yielded a higher total content of polyphenols and flavonoids of about 84.80 ± 2.8 mg GAE/g and 28.30 ± 1.2 mg QE/g, respectively. Significant antibacterial activity was recorded for both extracts, with minimum inhibitory concentration (MIC) values ranging from 30 to 36 µg/mL, and the result was comparable to the reference antibiotic control. Antibiofilm assays revealed that both extracts were able to reduce the attachment of bacterial cells to 96-well plates, but the highest antibiofilm activity was recorded against Staphylococcus aureus. The methanolic extract also showed anti-enzymatic potency and high antioxidant activity, as demonstrated by all assays used, including DPPH, FRAP, and ABTS. These results were further validated by in silico approaches, particularly the molecular interaction of the identified compounds with the targeted receptors. These findings present P. incisa as a significant source of antibacterial, antibiofilm, antioxidant, and anti-enzymatic molecules.

Juniperus horizontalis Moench: Chemical Composition, Herbicidal and Insecticidal Activities of Its Essential Oil and of Its Main Component, Sabinene.

The composition, herbicidal, larvicidal, and toxic activities of Juniperus horizontalis Moench essential oil and sabinene, its main component, were evaluated. The seed germination percentage and root length of eight different plant species (crops and weeds) were measured for in vitro herbicidal activity tests. Different doses (100, 50, 10, 5, 1, 0.5 µg/mL) of the samples were applied to seeds for 120 h. The same doses were applied to test the toxicity of the samples on Tubifex tubifex (sludge worm) and Chironomus aprilinus (blood worm). Four doses (435, 652.5, 870, and 1740) of samples were in a larvicidal test on Tenebrio molitor L. (mealworm), and bioassays were checked after 24 and 48 h. The analysis of the oil allowed for the identification of dominant components as sabinene (38.7%), α-pinene (10.0%), elemol (8.6%), γ-terpinene (8.3%), limonene (7.8%) and α-thujene (5.3%). The results showed that the effect of oil on root length inhibition was significant in all crop species. The doses which affected root growth were not toxic to Tubifex tubifex and Chironomus aprilinus. Finally, the obtained results in the larvicidal bioassay indicate that the potential of J. horizontalis in yellow mealworm survivorship limitation can be a starting point for future research.

The Essential Oil Compositions of Three Teucrium Taxa Growing Wild in Sicily: HCA and PCA Analyses.

The chemical composition and the qualitative and quantitative variability of the essential oils of three taxa belonging to the Teucrium genus were studied. The investigated taxa, that grow wild in Sicily, were Teucrium flavum L. (section Chamaedrys (Mill.) Scheb.), Teucrium montanum and Teucrium capitatum L. of section Polium (Mill.) Scheb. Essential oils were extracted by hydrodistillation and analyzed by GC-MS. In total, 74 compounds were identified. Sesquiterpene hydrocarbons were found to be the main group for T. flavum (48.3%). T. capitatum consisted essentially of monoterpene hydrocarbons (72.7%), with α-pinene (19.9%), ß-pinene (27.6%) and sylvestrene (16.6%) as the most abundant compounds whereas ledene oxide (12.1%), epiglobulol (13.5%) and longifolenaldehyde (14.5%) were identified as the main constituents among the oxygenated sesquiterpenes (63.5%) of T. montanum. Furthermore, a complete literature review on the composition of the essential oils of all the other accessions of these Teucrium taxa, studied so far, was performed. Hierarchical Cluster Analysis (HCA) and Principal Component Analyses (PCA) were used in order to demonstrate geographical variations in the composition of the essential oils.

Eucalyptus gunnii and Eucalyptus pulverulenta 'Baby Blue' Essential Oils as Potential Natural Herbicides.

The phytotoxicity and eco-compatibility of essential oils (EOs) from Eucalyptus gunnii (EG) and E. pulverulenta 'Baby Blue' (EP), cultivated in Italy for their cut foliage, were investigated. Leaf micromorphology, EOs phytochemical characterization, and phytotoxicity were analysed. EP revealed a significantly higher oil gland density and a higher EO yield with respect to EG. In both EOs, 1,8-cineole was the major compound (~75%), followed by α-pinene in EG (13.1%) and eugenol in EP (7.5%). EO phytotoxicity was tested on both weeds (Lolium multiflorum, Portulaca oleracea) and crops (Raphanus sativus, Lactuca sativa, Lepidium sativum, Solanum lycopersicum, Pisum sativum, Cucumis sativus). EG EO inhibited germination of P. oleracea, R. sativus, and S. lycopersicum seeds (ranging from 61.5 to 94.6% for the higher dose used), while affecting only radical elongation in S. lycopersicum (ranging from 66.7 to 82.6%). EP EO inhibited germination of P. oleracea and R. sativus (ranging from 41.3 to 74.7%) and affected radical elongation of L. sativum and L. multiflorum (ranging from 57.4 to 76.0%). None of the EOs affected the germination and radical growing of L. sativa, P. sativum, and C. sativus. Moreover, EP EO was more active than EG EO in inhibiting α-amylase, a key enzyme for seed growth regulation. Brine shrimp lethality assay showed that both EOs are safe for aquatic organisms, suggesting their high eco-compatibility. The data collected provide useful information for future applications of these EOs in agriculture as safe and selective bioherbicides.

Thymol Chemotype Origanum vulgare L. Essential Oil as a Potential Selective Bio-Based Herbicide on Monocot Plant Species.

Searching for new bio-based herbicides is crucial for decreasing chemical pollution, protecting the environment, and sustaining biodiversity. Origanum vulgare is considered a promising source of essential oil with herbicidal effect. The mode of action is not known. The present study focused on (1) comparison of phytotoxic activity of Origanum vulgare EO on monocot (Triticum aestivum and Hordeum vulgare) and dicot species (Lepidium sativum and Sinapis alba); (2) and evaluating other antimicrobial biological activities against phytopatogen bacteria (Clavibacter michiganensis, Pseudomonas syringae pv. phaseolicola, Pseudomonas savastanoi, and Xanthomonas campestris); antifungal activity against Monilinia fructicola, Aspergillus niger, Penicillium expansum, and Botrytis cinerea; cytotoxic activity and antioxidant activity. According to the GC/MS analyses, the EO belongs to the thymol chemotype O. vulgare with its high content of thymol (76%). Germination of all four species was not influenced by EO. The phytotoxic effect was statistically significant in the monocot species, while in the dicot species the opposite was observed-a stimulation effect, which was also statistically significant. Strong biological activity of O. vulgare EO was noted on all phytopatogen bacteria and fungi in the highest dose. Cytotoxic activity showed an IC50 = 50.5 µg/mL. Antioxidant activity showed an IC50 = 106.6 µg/mL after 45 min experimental time. Based on the presented results, it is possible to conclude that thymol chemotype O. vulgare essential oil could be potentially used as a herbicide with selective effects on monocot plant species.

Antimicrobial Activity and Chemical Composition of Essential Oil Extracted from Solidago canadensis L. Growing Wild in Slovakia.

Plant essential oils (EOs) are one of the most relevant natural products due to their biological, medicinal, and nutritional properties. The promising biological effects of many plants EOs encourage researchers to study their biochemical properties to be used as possible natural alternatives for commercial pesticides and not only as herbal medicines. The current research has been conducted to study the microbicide effect of Solidago canadensis L. EO to control some common plant diseases caused by several postharvest phytopathogenic fungi (Monilinia fructicola, Botrytis cinerea, Aspergillus niger, and Penicillium expansum) in comparison with Azoxystrobin as a large spectrum fungicide. The antibacterial activity has been carried out against some phytopathogenic bacteria (Bacillus megaterium and Clavibacter michiganensis (G+ve) and Xanthomonas campestris, Pseudomonas fluorescens, and Pseudomonas syringae pv. phaseolicola (G-ve)) compared to the synthetic antibiotic Tetracycline. Minimum inhibitory concentration was carried out to determine the lowest effective EO dose using a 96-well microplate. The cell membrane permeability was also evaluated by measuring the electric conductivity (EC) to examine the possible mechanisms of action of S. canadensis EO. Chemical characterization of EO has been carried out using gas chromatography and mass spectrometry (GC-MS). Thirty-two identified components in S. canadensis EO presented 97.7% of total compounds in EO. The principal compounds were identified as germacrene D (34.9%), limonene (12.5%), α-pinene (11.6%), ß-elemene (7.1%), and bornyl acetate (6.3%). In addition, S. canadensis EO demonstrated promising in vitro antimicrobial activities against the majority of tested phytopathogens at all tested concentrations.

Chromobacterium violaceum and Pseudomonas aeruginosa PAO1: Models for Evaluating Anti-Quorum Sensing Activity of Melaleuca alternifolia Essential Oil and Its Main Component Terpinen-4-ol.

The problem of antibiotic resistance among pathogens encourages searching for novel active molecules. The aim of the research was to assay the anti-quorum sensing (anti-QS) and antibiofilm potential of Melaleuca alternifolia essential oil and its main constituent, terpinen-4-ol, to prevent the infections due to methicillin-resistant Staphylococcus aureus strains as an alternate to antibiotics. The tea tree oil (TTO) was evaluated for its potential in inhibiting QS-dependent phenomena such as violacein production in Chromobacterium violaceum, swarming motility of Pseudomonas aeruginosa PAO1, and biofilm formation in MRSA strains on glass. The results showed that terpinen-4-ol was able to inhibit MRSA strain biofilm formation on the glass strips by 73.70%. TTO inhibited the violacein production at a mean inhibitory concentration (MIC) value of 0.048 mg/mL by 69.3%. At 100 µg/mL TTO and terpinen-4-ol exhibited inhibition in swarming motility of PAO1 by 33.33% and 25%, respectively. TTO revealed anti-QS and anti-biofilm activities at very low concentrations, but it could be further investigated for new molecules useful for the treatment of MRSA infections.

Chemical and Biological Evaluation of Essential Oils from Cardamom Species.

To highlight the importance of the spices in the Mediterranean diet, the aim of the paper was to study the essential oil compositions and to clarify the potential differences in the biological activities of the three cardamom species. In the study, we compared the phytochemical profiles and biological activities of essential oils from Elettaria cardamomum, Aframomum corrorima and Amomum subulatum. The oils were analyzed using the GC and GC/MS techniques and were mainly constituted of the oxygenated monoterpenes which represents 71.4%, 63.0%, and 51.0% of all compounds detected in E. cardamomum, A. corrorima and A. subulatum essential oils, respectively, 1,8-cineole was the main common compound between the tree tested volatile oil. The essential oils showed significant antimicrobial activity against Gram-positive and Gram-negative microorganisms tested especially the fungal strains. The Ethiopian cardamom was the most active essential oil with fungal growth inhibition zone ranging from 12.67 to 34.33 mm, MICs values ranging from 0.048 to 0.19 mg/mL, and MBCs values from 0.19 to 1.75 mg/mL. The three tested essential oils and their main component (1,8-cineole) significantly increased the production of elastase and protease production, and motility in P. aeruginosa PAO1 in a dose dependent manner. In fact, at 10 mg/mL concentration, the three essential oils showed more than 50% of inhibition of elastolytic and proteolytic activities in P. aeruginosa PAO1. The same oils inhibited also the violacein production in C. violaceum strain. It was also noticed that at high concentrations, the A. corrorima essential oil significantly inhibited the germination of radish. A thorough knowledge of the biological and safety profiles of essential oils can produce applications of economic importance.

Laurus nobilis: Composition of Essential Oil and Its Biological Activities.

Laurus nobilis is native to the southern Mediterranean region and cultivated mainly in Europe and the USA as an ornamental and medicinal plant. The chemical composition of the essential oil (EO) from leaves of L. nobilis, collected in Southern Italy, was studied by GC and GC-MS. In all, 55 compounds were identified, accounting for 91.6% of the total oil. 1,8-Cineole (31.9%), sabinene (12.2%), and linalool (10.2%) were the main components. Antimicrobial and antifungal activities of EO and 1,8-cineole were determined in vitro. The cytotoxicity of the EO was evaluated against SH-SY5Y cell line, as well as the influence of the EO on the expression of adenylate cyclase 1 (ADCY1), suggesting possible oil effects on the Central Nervous System.

Chemical Composition and in Vitro Antimicrobial, Cytotoxic, and Central Nervous System Activities of the Essential Oils of Citrus medica L. cv. 'Liscia' and C. medica cv. 'Rugosa' Cultivated in Southern Italy.

Citrus medica cv. 'liscia' and C. medica cv. 'rugosa' are two taxa of citron, belonging to the biodiversity of South Italy, in particular of Amalfi Coast, in the Campania region. The chemical composition of the essential oils (EOs) from fruit peels of both C. medica cultivars was studied by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses. In all, 100 compounds were identified, 82 for C. medica cv. 'liscia', accounting for 91.4% of the total oil, and 88 for C. medica cv. 'rugosa', accounting for 92.0% of the total oil. Monoterpene hydrocarbons are the main constituents in both oils of C. medica cv. 'liscia' (79.1%) and C. medica cv. 'rugosa' (80.2%). In both oils, limonene (67.2%-62.8%) and camphene (8.5%-10.9%) are the main constituents. The antimicrobial activity of the EOs was assayed against some bacterial strains: Bacillus cereus (DSM 4313), Bacillus cereus (DSM 4384), Staphylococcus aureus (DSM 25693), Pseudomonas aeruginosa (ATCC 50071), and Escherichia coli (DSM 8579). Low concentrations of C. medica cv. 'rugosa' EO showed an inhibitory effect on P. aeruginosa and higher concentrations inhibited more B. cereus (4384) and E. coli than S. aureus. The cytotoxicity of the EO was evaluated against SH-SY5Y cell line. The influence of the EO on the expression of adenylate cyclase 1 (ADCY1) was also studied. The antimicrobial activity registered confirm their traditional uses as food preserving agents and led us to hypothesize the possible use of these oils as antimicrobials. The alterations in ADCY1 expression suggested a role for limonene in effects on the central nervous system.

The protective effect of Hypericum connatum on stress-induced escape deficit in rat is related to its flavonoid content.

Context Hypericum perforatum L. (Hypericaceae), used in moderate depression treatment, is active in experimental tests for antidepressant activity. For H. connatum Lam., a South American species lacking hyperforin, antidepressant effects have not been demonstrated. Objective This study evaluates the antidepressant-like effect of H. connatum in rats and identifies the components involved in this activity. Materials and methods First, the effects of acute and 14-d oral administrations of an extract derived from H. connatum aerial parts were studied using the Escape Deficit (ED) test. Next, methanol-extracted flavonoid-enriched fractions B and C and fraction-purified flavonoids (quercetin, rutin and isoquercitrin) were evaluated in the ED test after acute administration. To rule out possible confounding effects of the flavonoids, we examined nociceptive threshold using the tail-flick test and anxious behaviour using the elevated plus maze (EPM) test. Results Hypericum connatum increased reactivity of unavoidable stress-exposed rats after acute (0.5 and 1 g/kg: ED = 18.6/30 and 19.8/30, respectively) and repeated administration (0.5 g/kg twice daily: ED = 17.8/30). Protective effects were observed for fractions B and C (250 mg/kg: ED = 18.1/30 and 18.8/30, respectively), quercetin (2.5, 5 and 10 mg/kg: ED = 15.3/30, 18.3/30 and 21.6/30, respectively), rutin (5 and 10 mg/kg: ED = 15.4/30 and 13.0/30, respectively) and isoquercitrin (2.5 mg/kg: ED = 19.2/30). The flavonoids did not modify nociceptive threshold or performance in the EPM test. Discussion and conclusion Hypericum connatum showed protective activity in the ED test, a correlate of potential antidepressant-like effects that appeared to be related to the flavonoid components of this species.

Studies on Chemical Composition, Antimicrobial and Antioxidant Activities of Five Thymus vulgaris L. Essential Oils.

This study is aimed at assessing the essential oil composition, total phenolic content, antimicrobial and antioxidant activities of Thymus vulgaris collected in five different area of the Campania Region, Southern Italy. The chemical composition of the essential oils was studied by GC-flame ionization detector (FID) and GC/MS; the biological activities were evaluated through determination of MIC and minimum bactericidal concentration (MBC) and evaluation of antioxidant activity. In total, 134 compounds were identified. The oils were mainly composed of phenolic compounds, and all oils belonged to the chemotype thymol. The antimicrobial activity of the five oils was assayed against ten bacterial strains. The oils showed different inhibitory activity against some Gram-positive pathogens. The total phenol content in the essential oils ranged from 77.6-165.1 mg gallic acid equivalents (GAE)/g. The results reported here may help to shed light on the complex chemotaxonomy of the genus Thymus. These oils could be used in many fields as natural preservatives of food and as nutraceuticals.

Seasonal variability of the main components in essential oil of Mentha × piperita L.

BACKGROUND: Mentha × piperita is an important and commonly used flavoring plant worldwide. Its constituents, primarily menthol and menthone, change in the essential oil depending on internal and external factors, of which environmental conditions appear very important. The experiment was established in 2010 for three vegetation season, in order to observe the quantitative changes of the main components of peppermint. The determination of menthol, menthone, limonene, menthyl acetate, menthofuran and ß-caryophyllene was registered. RESULTS: In the experimental season 2011 and 2012 a higher mean temperature than in 2010 and extreme rainfall in July 2011 and 2012 were recorded. Different environmental conditions affected the development of M. × piperita plants and the content and composition of the essential oil. CONCLUSION: Seasonal and maturity variations are interlinked with each other, because the specific ontogenic growth stage differed as the season progressed. Fluctuations in monthly and seasonal temperature and precipitation patterns affected the quality of peppermint essential oil.

Chemical composition and biological activity of the essential oil of Origanum vulgare ssp. hirtum from different areas in the Southern Apennines (Italy).

The chemical composition of the essential oils of Origanum vulgare ssp. hirtum, growing wild in three different localities in the Southern Apennines, was studied by GC-FID and GC/MS analyses. In total, 103 compounds were identified. The oils were mainly composed of phenolic compounds and all oils belonged to the chemotype carvacrol/thymol. The three essential oils were evaluated for their in vitro phytotoxic activity by determining their influence on the germination and initial radicle elongation of Sinapis arvensis L., Phalaris canariensis L., Lepidium sativum L., and Raphanus sativus L. The seed germination and radicle growth were affected in various degrees. Moreover, the antifungal activity of the three essential oils was assayed against three species causing pre- and postharvest fruit decay (Monilinia laxa, M. fructigena, and M. fructicola). At 1000 ppm, the three oils completely inhibited fungal growth. The hemolytic activity of the oils was assayed and showed no effect on the cell membranes of bovine erythrocytes.

Chemical composition and biological activities of Tunisian Cupressus arizonica Greene essential oils.

The chemical composition of the essential oils obtained by hydrodistillation of leaves, stems, and female cones of Cupressus arizonica Greene, grown in Tunisia, was studied by GC-FID and GC/MS analyses. Altogether, 62 compounds were identified, 62 in the leaf oil, 19 in the cone oil, and 24 in the stem oil. The cone and stem oils were mainly composed by monoterpene hydrocarbons (96.6 and 85.2%, resp.). In the leaf oil, the total sesquiterpene fraction constituted 36.1% and that of the monoterpene hydrocarbons 33.8% of the total oil composition. The three oils were evaluated for their in vitro herbicidal activity by determining their influence on the germination and the shoot and root growth of the four weed species Sinapis arvensis L., Lolium rigidum Gaudin, Trifolium campestre Schreb., and Phalaris canariensis L. At the highest doses tested (0.8 and 1.0 mg/ml), the leaf essential oil inhibited either totally or almost completely the seed germination and the shoot and root growth of S. arvensis and T. campestre. The oils were also tested for their antifungal activity; however, their effects on the fungal growth were statistically not significant.

Autoimmune cytopenias in chronic lymphocytic leukemia.

The clinical course of chronic lymphocytic leukemia (CLL) may be complicated at any time by autoimmune phenomena.The most common ones are hematologic disorders, such as autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP). Pure red cell aplasia (PRCA) and autoimmune agranulocytosis (AG) are, indeed, more rarely seen. However, they are probably underestimated due to the possible misleading presence of cytopenias secondary to leukemic bone marrow involvement or to chemotherapy cytotoxicity. The source of autoantibodies is still uncertain, despite the most convincing data are in favor of the involvement of resting normal B-cells. In general, excluding the specific treatment of underlying CLL, the managementof these complications is not different from that of idiopathic autoimmune cytopenias or of those associated to other causes. Among different therapeutic approaches, monoclonal antibody rituximab, given alone or in combination, has shown to be very effective.

Chemical composition and biological activity of the essential oil from leaves of Moringa oleifera Lam. cultivated in Mozambique.

The antioxidant capacity and antimicrobial activity of the essential oil of Moringa oleifera (Moringaceae) grown in Mozambique was investigated. The chemical composition was studied by means of GC and GC-MS analysis. Hexacosane (13.9%), pentacosane (13.3%) and heptacosane (11.4%) were the main components. Ultra High Performance Chromatography-DAD analysis detected the flavonoids quercetin (126 µg/g) and luteolin (6.2 µg/g). The essential oil exhibited a relatively low free radical scavenging capacity. The antimicrobial activity of the essential oil was assayed against two Gram-positive strains (Bacillus cereus, Staphylococcus aureus), two Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa), and five fungal strains of agro-food interest (Penicillium aurantiogriseum, Penicillium expansum, Penicillium citrinum, Penicillium digitatum, and Aspergillus niger spp.). B. cereus and P. aeruginosa, as well as the fungal strains were sensitive to the essential oil.

Chemical Identification of Secondary Metabolites from Rhizospheric Actinomycetes Using LC-MS Analysis: In Silico Antifungal Evaluation and Growth-Promoting Effects.

The rhizosphere is a rich source of actinomycetes which can produce several potential biologically active secondary metabolites. The principal goal for this research is to extract, purify, and characterize the bioactive secondary metabolites produced by three different strains of actinomycetes isolated from the rhizosphere of rosemary, black locust, and olive. The plant growth-promoting effect (PGPE) of the studied strains of actinomycetes on Ocimum basilicum L. (basil) and the disease-control effect on necrotic stem lesions of "black leg" caused by Fusarium tabacinum on basil were evaluated in silico. The cell-free culture filtrates from the studied actinomycetes isolates were evaluated in vitro for their antimicrobial activity against some common phytopathogens. The secondary metabolites obtained from the cell-free culture filtrates have been chemically characterized using high-resolution electrospray ionization of liquid-chromatography/mass-spectrometric detection (ESI-(HR)Orbitrap-MS). Results of the in silico trial showed that all studied isolates demonstrated PGPE on basil seedlings, improved some eco-physiological characteristics, and reduced the disease incidence of F. tabacinum. The extracted metabolites from the studied actinomycetes demonstrated antimicrobial activity in a Petri-plates assay. The chemical analysis revealed the presence of 20 different components. This research emphasizes how valuable the examined isolates are for producing bioactive compounds, indicating their putative antimicrobial activity and their potential employment as fungal biocontrol agents. In particular, the obtained results revealed the possibility of green synthesis of some important secondary metabolites, such as N-Acetyl-l-histidinol, Rhizocticin A, and Eponemycin, from actinomycetes. The bioactive metabolites may be successively used to develop novel bio-formulations for both crop protection and/or PGPE.