Antimicrobial, Herbicidal and pesticidal potential of Tunisian eucalyptus species: Chemoprofiling and biological evaluation.

The Eucalyptus genus, characterized by its imposing stature and fragrant foliage, has been a source of fascination for humanity over the centuries. The focus of the present investigation was directed towards the essentials oils (EOs) of five Eucalyptus trees cultivated in Tunisia. The GC-MS analysis unveiled unique compositional profiles, a finding substantiated by both Hierarchical Clustering Analysis (HCA) and Principal Component Analysis (PCA) conducted on the leaves EOs. These analyses resulted in the formation of discrete HCA clades, delineating 23 significant components. Notably, the percentage of eucalyptol emerged as the pivotal factor demarcating the separation between three distinct groups. The statistical analysis revealed a dose-dependent relationship in both phytotoxicity evaluation and antibacterial activity. The EOs from Eucalyptus loxophleba and E. salubris exhibited the highest phytotoxicity, inhibiting radical elongation and germination of various seeds, especially Sinapis arvensis and Raphanus sativus. The antimicrobial assessment demonstrated significant inhibitory effects of the EOs on bacterial strains, with MIC values spanning from 14 to exceeding 50 mg/ml. The EOs also affected biofilm formation and cellular metabolism, displaying varied efficacy among different Eucalyptus species against some bacterial strains. The EOs exhibited selective inhibition against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase. E. campaspe EO showed the highest AChE activity, while E. loxophleba and E. salubris EOs were most potent toward α-amylase. E. loxophleba EO demonstrated notable activity against α-glucosidase. Overall, these findings provide important data about the diverse biological activities of Eucalyptus EOs, suggesting potential applications in agriculture, medicine, and pharmacy.

Artemisia spp. Essential Oils: From Their Ethnobotanical Use to Unraveling the Microbiota Modulation Potential.

BACKGROUND: The 2015 Nobel Prize in Medicine, awarded for the discovery of artemisinin in Artemisia annua, reignited interest in aromatic plants, including Artemisia absinthium L. This article delves into the historical, ethnopharmacological and medicinal significance of A. absinthium, examining its bitter taste noted since ancient Greek times and its association with medicinal properties throughout history. Despite being banned in the 20th century due to perceived health risks; recent research has led to the reconsideration of A. absinthium's potential applications. This study focuses on the prebiotic efficacy of essential oils (EOs) from two Artemisia species: A. absinthium and A. annua. MATERIALS AND METHODS: A broth microdilution test, growth curve test and in vivo models were used to study the impact of low doses (from 0.5% v/v to 0.00048 v/v) of Artemisia spp-EO on the three probiotic strains (Lactobacillus, Lactobacillus casei and Saccharomyces boulardii). RESULTS: These essential oils, when used in minimal concentrations (lower than 0.06% v/v), are safe and exhibit prebiotic effects on major probiotic strains, supporting the traditional culinary use of Artemisia spp. CONCLUSION: This research opens avenues for potential applications in the food industry, emphasizing the need for further exploration into the prebiotic properties of Artemisia spp-EOs and their influence on the microbiota.

Artemisia arborescens (Vaill.) L.: Micromorphology, Essential Oil Composition, and Its Potential as an Alternative Biocontrol Product.

Artemisia arborescens is a Mediterranean evergreen shrub, with silver grey-green tomentose leaves and a strong scent. It has various ethnopharmacological uses and its secondary metabolites have demonstrated antimicrobial, antiviral, pharmaceutical, phytotoxic, and insecticidal activities. Different extracts obtained from aerial parts of this species are known for their allelopathic effect, but similar studies on its essential oil (EO) are lacking. Therefore, we carried out a pharmacognostic study, obtaining the characterization of the secretory structures and the EO produced. Trans-thujone and camphor are the main components, followed by aromadendrene, camphene, and 8-cedren-13-ol. EO phytotoxic activity was tested on weed plants (Lolium multiflorum Lam. and Sinapis arvensis L.) and crops (Raphanus sativus L. and Cucumis sativus L.), showing inhibition on both germination and radical growth of the two weeds tested. The effects of the EO against the bacterial plant pathogens Xanthomonas campestris pv. campestris (Gram-) and Pseudomonas syringae pv. tomato (Gram+) was also assayed. The minimum inhibitory concentration (MIC) was observed when it was used undiluted [100% v/v], and growth inhibition when diluted at different doses. The antimicrobial activity was also confirmed by the cellular material release and biofilm formation assays. The overall data show that A. arborescens EO can find application as a potential alternative biocontrol product against weeds and plant pathogens. This goal is particularly important from the perspective of replacing synthetic pesticides with natural products, which safeguard both the environment and the health of consumers.

Chemical Characterization and Biological Properties of Leguminous Honey.

Honey can beneficially act against different human diseases, helping our body to improve its health. The aim of the present study was first to increase knowledge of some biochemical characteristics (amount and composition of polyphenols and volatile organic compounds, vitamin C content) of five Italian legume honeys (alfalfa, astragalus, carob, indigo, and sainfoin). Furthermore, we evaluated their potential health properties by studying their antioxidant and in vitro anti-inflammatory activities and in vitro inhibitory effects on three enzymes involved in neurodegenerative diseases (acetylcholinesterase, butyrylcholinesterase, and tyrosinase). Alfalfa honey showed the highest total polyphenol content (TPC) (408 µg g-1 of product). Indigo honey showed the lowest TPC (110 µg g-1 of product). The antioxidant activity was noteworthy, especially in the case of sainfoin honey (IC50 = 6.08 mg), which also exhibited excellent inhibitory action against butyrylcholinesterase (74%). Finally, the correlation between the biochemical and functional results allowed us to identify classes of molecules, or even single molecules, present in these five honeys, which are capable of influencing the properties indicated above.

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.

Phytochemical study on the essential oils of Callitris glaucophylla Joy Thomps. & L.A.S. Johnson, and assessment of their antioxidant, anti-enzymatic and allelopathic effects.

Callitris glaucophylla Joy Thomps. & L.A.S. Johnson is a coniferous forest species of the Cupressaceae family native to Australia. This species is rich in essential oils (EOs) but few studies about variability and biological activity of these EOs are available in the literature. The purpose of this study was to evaluate the variability of production of C. glaucophylla EOs in relation to the different plant parts (needles, cones and stems) and to investigate their antioxidant, anti-enzymatic and herbicidal properties. EOs were obtained by hydro distillation and analyzed by GC and GC-MS. The antioxidant potential of EOs was assessed by ABTS, FRAP and DPPH assays, their phytotoxic activities were evaluated against germination and shoots and radical growth of Sinapis arvensis, Trifolium campestre, Lepidium sativum and Lolium rigidum. The EOs were evaluated for their possible anti-enzymatic effects with spectrophotometric assay. EOs resulted rich in monoterpenes hydrocarbons (61.04-77.82 %) and oxygenated monoterpenes (19.52-25.26 %). The main compounds were α-pinene as major compound in all plant parts (36.99-59.84 %), 1,8-cineole (19.88 % in stems) and limonene (18.94 % in needles). Herbicidal assays showed that all EOs have remarkable and significant phytotoxicity towards germination, roots, and aerial parts growth of the tested plants, depending on the EO, the doses and tested species. The EOs showed significant free radical scavenging potential and resulted more active against cholinesterases than α-glucosidase and α-amylase. The data obtained constitute an important contribution in selecting and valorizing appropriate forestry tree biomass as sources of antioxidant and phytotoxic molecules for sustainable application in food preservation and weeds control. The activities against the tested enzymes confirmed a possible use of these EOs as natural pesticides.

In Vitro Screening of Antimicrobial and Anti-Coagulant Activities, ADME Profiling, and Molecular Docking Study of Citrus limon L. and Citrus paradisi L. Cold-Pressed Volatile Oils.

Citrus, which belongs to the Rutaceae family, is a very widespread genus in the Mediterranean Basin. In Tunisia, various parts of these spontaneous or cultivated plants are used in common dishes or in traditional medicine. The purpose of this work was to investigate C. limon and C. paradisi essential oil (EO). The samples were studied for their chemical composition using SPME/MS, as well as their antibacterial and antifungal activities. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) methods were used to evaluate the anticoagulant potentialities. The obtained results show that both essential oils are rich in monoterpenes hydrocarbons, whereby limonene is the main compound in C. paradisi EO (86.8%) and C. limon EO (60.6%). Moreover, C. paradisi EO contains ß-pinene (13.3%), sabinene (2.2%) and α-pinene (2.1%). The antibacterial assay of the essential oils showed important bactericidal and fungicidal effects against all strains tested. In fact, the MICs values of C. limon EO ranged from 0.625 to 2.5 mg/mL against all Gram-positive and Gram-negative bacteria, and from 6.25 to 12.5 mg/mL for Candida spp. strains, while C. paradisi EO was more active against all bacteria with low MICs values ranging from 0.192 to 0.786 mg/mL, and about 1.5 mg/mL against Candida species. Both tested Citrus EOs exhibited interesting anticoagulant activities as compared to heparin. The molecular docking approach was used to study the binding affinity and molecular interactions of all identified compounds with active sites of cytidine deaminase from Klebsiella pneumoniae (PDB: 6K63) and the C (30) carotenoid dehydrosqualene synthase from Staphylococcus aureus (PDB: 2ZCQ). The obtained results show that limonene had the highest binding score of -4.6 kcal.mol-1 with 6K63 enzyme, and -6.7 kcal.mol-1 with 2ZCQ receptor. The ADME profiling of the major constituents confirmed their important pharmacokinetic and drug-like properties. Hence, the obtained results highlight the potential use of both C. limon and C. paradisi essential oils as sources of bioactive compounds with antibacterial, antifungal, and anti-coagulant activities.

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.

Chemical Composition, Antibacterial Properties, and Anti-Enzymatic Effects of Eucalyptus Essential Oils Sourced from Tunisia.

This study was conducted to examine the chemical composition of the essential oils (EOs) from six Tunisian Eucalyptus species and to evaluate their anti-enzymatic and antibiofilm activities. The EOs were obtained through hydro-distillation of dried leaves and subsequently analyzed using GC/MS. The main class of compounds was constituted by oxygenated monoterpenes, particularly prominent in E. brevifolia (75.7%), E. lehmannii (72.8%), and E. woollsiana (67%). Anti-enzymatic activities against cholinesterases, α-amylase, and α-glucosidase were evaluated using spectrophotometric methods. Notably, the E. brevifolia, E. extensa, E. leptophylla, E. patellaris, and E. woollsiana EOs displayed potent acetylcholinesterase (AChE) inhibition (IC50: 0.25-0.60 mg/mL), with E. lehmannii exhibiting lower activity (IC50: 1.2 mg/mL). E. leptophylla and E. brevifolia showed remarkable α-amylase inhibition (IC50: 0.88 mg/mL), while E. brevifolia and E. leptophylla significantly hindered α-glucosidase (IC50 < 30 mg/mL), distinguishing them from other EOs with limited effects. Additionally, the EOs were assessed for their anti-biofilm properties of Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The E. extensa EO demonstrated the main antibiofilm effect against E. coli and L. monocytogenes with an inhibition > 80% at 10 mg/mL. These findings could represent a basis for possible further use of Eucalyptus EOs in the treatment of human microbial infections and/or as a coadjutant in preventing and treating Alzheimer's disease and/or diabetes mellitus.

The 3-(3-oxoisoindolin-1-yl)pentane-2,4-dione (ISOAC1) as a new molecule able to inhibit Amyloid ß aggregation and neurotoxicity.

Amyloid ß 1-42 (Aß1-42) protein aggregation is considered one of the main triggers of Alzheimer's disease (AD). In this study, we examined the in vitro anti-amyloidogenic activity of the isoindolinone derivative 3-(3-oxoisoindolin-1-yl)pentane-2,4-dione (ISOAC1) and its neuroprotective potential against the Aß1-42 toxicity. By performing the Thioflavin T fluorescence assay, Western blotting analyses, and Circular Dichroism experiments, we found that ISOAC1 was able to reduce the Aß1-42 aggregation and conformational transition towards ß-sheet structures. Interestingly, in silico studies revealed that ISOAC1 was able to bind to both the monomer and a pentameric protofibril of Aß1-42, establishing a hydrophobic interaction with the PHE19 residue of the Aß1-42 KLVFF motif. In vitro analyses on primary cortical neurons showed that ISOAC1 counteracted the increase of intracellular Ca2+ levels and decreased the Aß1-42-induced toxicity, in terms of mitochondrial activity reduction and increase of reactive oxygen species production. In addition, confocal microscopy analyses showed that ISOAC1 was able to reduce the Aß1-42 intraneuronal accumulation. Collectively, our results clearly show that ISOAC1 exerts a neuroprotective effect by reducing the Aß1-42 aggregation and toxicity, hence emerging as a promising compound for the development of new Aß-targeting therapeutic strategies for AD treatment.

Chemical Composition of Essential Oils from Eight Tunisian Eucalyptus Species and Their Antifungal and Herbicidal Activities.

Eucalyptus species are known to produce metabolites such as essential oils (EOs) that play an important role in the control of weeds, pests and phytopathogenic fungi. The aims of this study were as follows: (i) to determine the chemical composition of the EOs derived from eight Eucalyptus species growing in Tunisia, and (ii) to study their possible antifungal and herbicidal activities. EOs were obtained by hydrodistillation from the dried leaves of eight Eucalyptus species, namely, E. angulosa, E. cladocalyx, E. diversicolor, E. microcoryx, E. ovata, E. resinifera, E. saligna and E. sargentii, and the determination of their composition was achieved by GC and GC-MS. The EOs' antifungal activities were tested against four Fusarium strains, and the EOs' herbicidal properties were evaluated on the germination and seedling growth of three annual weeds (Trifolium campestre, Lolium rigidum and Sinapis arvensis) and three cultivated crop species (Lepidium sativum, Raphanus sativus and Triticum durum). The EO yields ranged between 0.12 and 1.32%. The most abundant components found were eucalyptol, α-pinene, p-cymene, trans-pinocarveol, α-terpineol and globulol. All EOs showed significant antifungal activity against the four phytopathogenic Fusarium strains. E. cladocalyx EO exhibited the highest level of antifungal activity, and the greatest inhibition of seed germination was obtained even at lowest concentrations used. These findings suggested that E. resinifera, E. ovata and E. cladocalyx EOs could have applications in agriculture as possible biopesticides, as Fusarium antagonists and as bioherbicides.

In Vitro Prebiotic Effects and Antibacterial Activity of Five Leguminous Honeys.

Honey is a natural remedy for various health conditions. It exhibits a prebiotic effect on the gut microbiome, including lactobacilli, essential for maintaining gut health and regulating the im-mune system. In addition, monofloral honey can show peculiar therapeutic properties. We in-vestigated some legumes honey's prebiotic properties and potential antimicrobial action against different pathogens. We assessed the prebiotic potentiality of honey by evaluating the antioxidant activity, the growth, and the in vitro adhesion of Lacticaseibacillus casei, Lactobacillus gasseri, Lacticaseibacillus paracasei subsp. paracasei, Lactiplantibacillus plantarum, and Lacticaseibacillus rhamnosus intact cells. We also tested the honey's capacity to inhibit or limit the biofilm produced by five pathogenic strains. Finally, we assessed the anti-biofilm activity of the growth medium of probiotics cultured with honey as an energy source. Most probiotics increased their growth or the in vitro adhesion ability to 84.13% and 48.67%, respectively. Overall, alfalfa honey best influenced the probiotic strains' growth and in vitro adhesion properties. Their radical-scavenging activity arrived at 83.7%. All types of honey increased the antioxidant activity of the probiotic cells, except for the less sensitive L. plantarum. Except for a few cases, we observed a bio-film-inhibitory action of all legumes' honey, with percentages up to 81.71%. Carob honey was the most effective in inhibiting the biofilm of Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus; it retained almost entirely the ability to act against the bio-film of E. coli, L. monocytogenes, and S. aureus also when added to the bacterial growth medium instead of glucose. On the other hand, alfalfa and astragalus honey exhibited greater efficacy in acting against the biofilm of Acinetobacter baumannii. Indigo honey, whose biofilm-inhibitory action was fragile per se, was very effective when we added it to the culture broth of L. casei, whose supernatant exhibited an anti-biofilm activity against all the pathogenic strains tested. Conclusions: the five kinds of honey in different ways can improve some prebiotic properties and have an inhibitory biofilm effect when consumed.

GC/MS Profiling, Antibacterial, Anti-Quorum Sensing, and Antibiofilm Properties of Anethum graveolens L. Essential Oil: Molecular Docking Study and In-Silico ADME Profiling.

Anethum graveolens L. has been known as an aromatic, medicinal, and culinary herb since ancient times. The main purpose of this study was to determine the chemical composition, antibacterial, antibiofilm, and anti-quorum sensing activities of the essential oil (EO) obtained by hydro-distillation of the aerial parts. Twelve components were identified, representing 92.55% of the analyzed essential oil. Limonene (48.05%), carvone (37.94%), cis-dihydrocarvone (3.5%), and trans-carvone (1.07%) were the main identified constituents. Results showed that the obtained EO was effective against eight bacterial strains at different degrees. Concerning the antibiofilm activity, limonene was more effective against biofilm formation than the essential oil when tested using sub-inhibitory concentrations. The results of anti-swarming activity tested against P. aeruginosa PAO1 revealed that A. graveolens induced more potent inhibitory effects in the swarming behavior of the PAO1 strain when compared to limonene, with a percentage reaching 33.33% at a concentration of 100 µg/mL. The ADME profiling of the identified phytocompounds confirms their important pharmacokinetic and drug-like properties. The in-silico study using molecular docking approaches reveals a high binding score between the identified compounds and known target enzymes involved in antibacterial and anti-quorum sensing (QS) activities. Overall, the obtained results highlight the possible use of A. graveolens EO to prevent food contamination with foodborne pathogenic bacteria.

Investigation on Chemical Composition, Antioxidant, Antifungal and Herbicidal Activities of Volatile Constituents from Deverra tortuosa (Desf.).

This study aims to analyze the chemical composition of the essential oils (EOs) obtained from stems and umbels of D. tortuosa as well the assessment of their biological activity. EOs were extracted by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry (GC/MS). The antioxidant properties were determined by DPPH and ABTS assays. The phytotoxic potential was assessed against dicots weeds (Sinapis arvensis and Trifolium campestre), monocots weeds (Lolium rigidum) and the crop Lepidium sativum. The antifungal activity was evaluated against four target phytopathogenic fungal strains. High diversity of compounds was detected in D. tortuosa Eos, varying among plant parts and consisting mainly of α-pinene (24.47-28.56%), sabinene (16.2-18.6%), α-phellandrene (6.3-11.7%) and cis-ocimene (5.28-7.85%). D. tortuosa EOs exhibited remarkable antioxidant activity, as well as interesting variable antifungal activities depending on the dose and fungi strain. The herbicidal activity of EOs showed significant efficacy on the inhibition of germination and seedling growth of all tested herbs. These results suggest that the EOs of Deverra tortuosa represent a valuable source of antioxidant, antifungal and phytotoxic metabolites and could be potential candidates for pest management, contributing to the promotion of sustainable agriculture.

Potential therapeutic benefits of unconventional oils: assessment of the potential in vitro biological properties of some Rubiaceae, Cucurbitaceae, and Brassicaceae seed oils.

Introduction: Seed oils are versatile in the food sector and for pharmaceutical purposes. In recent years, their biological properties aroused the interest of the scientific world. Materials and methods: We studied the composition of fatty acids (FAs) and some in vitro potential therapeutic benefits of five cold-pressed commercial oils obtained from broccoli, coffee, green coffee, pumpkin, and watermelon seeds. In particular, we assayed the antioxidant activity (using diphenyl-1-picrylhydrazyl (DPPH) and azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays). In addition, through the fatty acid composition, we calculated the atherogenicity index (AI) and thrombogenicity index (TI) to evaluate the potential impact of such oils on cardiovascular diseases. Furthermore, we assessed the in vitro anti-inflammatory capacity of the oils (evaluated through their effectiveness in preventing protein degradation, using bovine serum albumin as protein standard) and the ability of the oils to inhibit in vitro activity of three among the essential enzymes, cholinesterases and tyrosinase, involved in the Alzheimer's and Parkinson's neurodegenerative diseases. Finally, we evaluated the capacity of the oils to inhibit the biofilm of some pathogenic bacteria. Results: The unsaturated fatty acids greatly predominated in broccoli seed oil (84.3%), with erucic acid as the main constituent (33.1%). Other unsaturated fatty acids were linolenic (20.6%) and linoleic (16.1%) acids. The saturated fatty acids fraction comprised the palmitic (6.8%) and stearic acids (0.2%). Broccoli seed oil showed the best AI (0.080) and TI (0.16) indexes. The oils expressed a good antioxidant ability. Except for the watermelon seed oil, the oils exhibited a generally good in vitro anti-inflammatory activity, with IC50 values not exceeding 8.73 micrograms. Broccoli seed oil and green coffee seed oil showed the best acetylcholinesterase inhibitory activity; coffee seed oil and broccoli seed oil were the most effective in inhibiting butyrylcholinesterase (IC50 = 15.7 µg and 20.7 µg, respectively). Pumpkin and green coffee seed oil showed the best inhibitory activity against tyrosinase (IC50 = 2 µg and 2.77 µg, respectively). In several cases, the seed oils inhibited the biofilm formation and the mature biofilm of some gram-positive and gram-negative bacteria, with Staphylococcus aureus resulting in the most sensitive strain. Such activity seemed related only in some cases to the capacity of the oils to act on the sessile bacterial cells' metabolism, as indicated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric method.

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.

Essential Oil Composition, Antioxidant Activity and Leaf Micromorphology of Five Tunisian Eucalyptus Species.

Eucalyptus species have been widely employed in the projects of reforestation in Tunisia. Although their ecological functions are controversial, these plants are indeed important to counteract soil erosion, and represent a fast-growing source of fuelwood and charcoal wood. In the present study, we considered five Eucalyptus species, namely Eucalyptus alba, E. eugenioides, E. fasciculosa, E. robusta, and E. stoatei cultivated in the Tunisian Arboreta. The aim was to carry out the micromorphological and anatomical characterization of the leaves, the extraction and phytochemical profile of the essential oils (EOs), and the evaluation of their biological properties. Four of the EOs showed the prevalence of eucalyptol (1,8-cineole) varying from 64.4 to 95.9%, whereas a-pinene predominated in E. alba EO (54.1%). These EOs showed in vitro antioxidant activity, and reduced the oxidative cellular stress as shown by their activity on reactive oxygen species (ROS) production, and modulation of the expression of antioxidant enzymes, such as glutamate-cysteine ligase (GCL) and heme oxygenase-1 (Hmox-1). Moreover, the EOs inhibited the production of nitric oxide (NO), showing anti-inflammatory activity. The data collected suggest that these EOs may be considered a promising therapeutic strategy for inflammation-based diseases and may represent an additional value for the economy of Tunisia.

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.