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Combination therapy at appropriately suitable doses presents a promising alternative to monotherapeutic drugs. In this study, Cinnamomum verum and Syzygium aromaticum essential oils and their major compounds have exhibited substantial leishmaniacidal potential against both promastigote and amastigote forms of Leishmania (L.) major. However, they displayed high cytotoxicity against Raw264.7 macrophage cells. Interestingly, when combined with each other or with amphotericin B, they demonstrated a synergistic effect (FIC<0.5) with low cytotoxicity. These combinations are able to modulate the production of nitric oxide (NO) by macrophages. Notably, the combination of S. aromaticum Essential oil with amphotericin B stimulates macrophage cells by increasing NO production to eliminate leishmanial parasites. Furthermore, investigation of the molecular mechanism of action of these synergistic combinations reveals potent inhibition of the sterol pathway through the inhibition of the CYP51 gene expression. The findings suggest that combination therapy may offer significant therapeutic benefits in both food and pharmaceutical fields. [ABSTRACT FROM AUTHOR]

Biofilm formation of the opportunistic pathogen Pseudomonas (P). aeruginosa is one of the major global challenges to control nosocomial infections due to their high resistance to antimicrobials and host defense mechanisms. The present study aimed to assess the antibacterial and the antibiofilm activities of Peganum (P). harmala seed extract against multidrug-resistant P. aeruginosa isolates. Chemical identification of the active compound and determination of its molecular mechanism of action were also investigated. Results showed that P. harmalan-butanol “n-BuOH” extract exhibited antibacterial activity against multidrug-resistant P. aeruginosa isolates. This extract was even more active than conventional antibiotics cefazolin and vaamox when tested against three P. aeruginosa multidrug-resistant isolates. In addition, P. harmala n-BuOH extract exhibited potent bactericidal activity against PAO1 strain at MIC value corresponding to 500 µg/mL and attained 100% killing effect at 24 h of incubation. Furthermore, P. harmala n-BuOH extract showed an antibiofilm activity against P. aeruginosa PAO1 and exhibited 80.43% inhibition at sub-inhibitory concentration. The extract also eradicated 83.99% of the biofilm-forming bacteria. The active compound was identified by gas chromatography–mass spectrometry as an indole alkaloid harmaline. Transcriptomic analysis showed complete inhibition of the biofilm-related gene pilA when PAO1 cells were treated with harmaline. Our results revealed that P. harmala seed extract and its active compound harmaline could be considered as a candidate for a new treatment of multidrug-resistant P. aeruginosa pathogens-associated biofilm infections. [ABSTRACT FROM AUTHOR]

Background: Ticks and tick-borne diseases are a severe economic and public-health problem for cattle producers. The emergence of acaricide resistance to synthetic chemical treatments has prompted interest in developing alternative tick control methods. Aim: The main objective of the current research was to identify the chemical structure of Carthamus tinctorius and Nasturtium officinale seed oils and to assess their anti-tick properties against Hyalomma scupense ticks both alone and in combination (1:1). Methods: Analytical methods were used to analyze the chemical components. For in vitro assays, adults of H. scupense were immersed in C. tinctorius and N. officinale seed oils at 100, 125, 200, and 300 mg/ml concentrations; for 5 minutes. Larvae of H. scupense were dipped in 25, 50, 100, 125, 200, and 300 mg/ml doses of seed oils; the mortality percentage was determined after 24 hours. Results: The seed oil safflower was mainly composed of linoleic acid (84.48%), followed by palmitic acid (6.54%) and stearic acid (3.77%). Meanwhile, watercress seed oil was mainly composed of linolenic acid (50.78%), gondoic acid (13.57%), linoleic acid (10.58%), palmitic acid (8.02%), and erucidic acid (6.62%). The Adults Immersion Test showed the sensitivity of ticks to C. tinctorius and N. officinale seed oil: C. tinctorius seed oil caused (95%) mortality of H. scupense at 300 mg/ml, while N. officinale seed oil induced (88.68%) mortality at the same concentration. At a 200 mg/ml concentration, C. tinctorius and N. officinale oil combined caused 100% mortality. Tested oils showed larvicidal efficacy. LC50 values for C. tinctorius and N. officinale seed oils were 84.16 and 61.78 mg/ml, respectively, in 24 hours. LC50 value of oils association (50% C. tinctorius: 50% N. officinale) was 47.96 mg/ml. The mixture of seed oils from two plants tested against H. scupense larvae and adult females at a 1:1 ratio showed synergistic interaction. Conclusion: Seed oils tested alone, and the mixture could be used as an alternative solution in the fight against ticks. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the leishmanicidal potential of the essential oil (EO) of Micromeria (M.) nervosa and to investigate its molecular mechanism of action by qPCR. Furthermore, in silicointeraction study of the major M. nervosa EO compounds with the enzyme cytochrome P450 sterol 14α-demethylase (CYP51) was also performed. M. nervosa EO was analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that α-pinene (26.44%), t-cadinol (26.27%), caryophyllene Oxide (7.73 ± 1.04%), and α-Cadinene (3.79 ± 0.12%) are the major compounds of M. nervosa EO. However, limited antioxidant activity was observed, as this EO was ineffective in neutralizing DPPH free radicals and in inhibiting β-carotene bleaching. Interestingly, it displayed effective leishmanicidal potential against promastigote (IC50 of 6.79 and 5.25 μg/mL) and amastigote (IC50 of 8.04 and 7.32 μg/mL) forms of leishmania (L.) infantum and L. major, respectively. Molecular mechanism investigation showed that M. nervosa EO displayed potent inhibition on the thiol regulatory pathway. Furthermore, a docking study of the main components of the EO with cytochrome P450 sterol 14α-demethylase (CYP51) enzyme revealed that t-cadinol exhibited the best binding energy values (−7.5 kcal/mol), followed by α-cadinene (−7.3 kcal/mol) and caryophyllene oxide (−7 kcal/mol). These values were notably higher than that of the conventional drug fluconazole showing weaker binding energy (−6.9 kcal/mol). These results suggest that M. nervosa EO could serve as a potent and promising candidate for the development of alternative antileishmanial agent in the treatment of leishmaniasis. [ABSTRACT FROM AUTHOR]

This study investigated the variability of antioxidant and antibacterial activities of essential oil (EO) from geranium (Pelargonium graveolens) aerial parts, collected from four Tunisian regions. The highest EO yield was obtained in Korba, followed by Beja, Tozeur and Sfax. In all regions, geranium EO was rich in oxygenated monoterpenes mainly due to the predominance of citronellol and geraniol. Antioxidant potential of geranium EO was evaluated by DPPH, ABTS, iron reducing power and β-carotene bleaching assays. Independently of region, geranium EO showed a weak antioxidant potential as compared to the positive control BHT. However, geranium EO was endowed with important antibacterial properties. In fact, Escherichia coli and Staphylococcus aureus were the most sensitive strains than Serratia marcescens, Pseudomonas aeruginosa, Pseudomonas aeruginosa and Enterococcus hirae. These findings suggested that geranium EO could be used as new and rich potential sources of many future multipurpose products for food preservation, pharmaceutical, and industrial applications. [ABSTRACT FROM AUTHOR]

The essential oils (EOs) of Coriandrum sativum, Carum carvi and Artemisia herba-alba have been screened for their insecticidal activity against Tribolium castaneum, Sitophilus oryzae and Lasioderma serricorne and for their antimicrobial activity against Gram (+), Gram (-) bacteria and against yeast strain. Artemisia herba-alba EO showed good insecticidal activity with 24-h against L. serricorne (LC50 = 29.7) and against T. castaneum (66.1 µg/mL) and antibacterial potentials against Staphyloccocus aureus (MIC = 0.125 mg/mL). The antimicrobial activities of C. carvi EO, rich in D-carvone (72.4%) and D-limonene (23.8%) were particularly remarkable, with LC50 of 27.9 µg/mL against L. serricorne. Similarly, coriander EO, with linalool (64.6%) as the major compound was selected for its antimicrobial activities (Candida albicans, MIC = 1 mg/mL). These findings demonstrated that the tested EOs could be used as a natural source of insecticidal and antimicrobial activity, which may have a variety of uses in the food and pharmaceutical sectors. [ABSTRACT FROM AUTHOR]

The goal of this work was to assess the in vitro acaricidal effects of Pistacia lentiscus essential oil and its pure active components against red poultry mites Dermanyssus gallinae as an alternative to chemical acaricide (formamidines). Essential oil was obtained using hydrodistillation and then analyzed using GC-MS. The following major components were identified: α-pinene (20.58 %), D -Limonene (18.16 %), β-Myrcène (15.06 %), 4-Terpineol (7.68 %), caryophyllene (5.45 %) and γ-terpinene (5.21 %). The toxicity of essential oil and its six monoterpenes were tested at concentrations ranging from 0.43 to 3.50 mg/cm2, using contact and spraying bioassays. Toxicity was expressed as a lethal concentration (LC 50 or LC 90). The experiment results revealed that activity was method and concentration dependent, and the spraying method was more effective than the contact bioassay for acaricidal activity. In this bioassay, the highest mortality was observed with 4-Terpineol. The LC 50 was estimated to be 0.184 mg/cm2 for this substance, followed by α-pinene, the LC 50 of which was estimated to be 0.203 mg/cm2. Caryophyllene and γ-terpinene were found less effective in controlling D. gallinae. P. lentiscus oil and its major compounds were also evaluated for anti-acetylcholinesterase (AChE) effects; 4-Terpineol was found to be the most effective AChE inhibitor with IC 50 values reaching 18.73 ± 2.83 µg/mL. This framework pointed out the importance of the traditional use of P. lentiscus as an ecofriendly alternative against ectoparasite of veterinary importance; D. gallinae. In vivo trials should also be conducted to assure the safe use of essential oils or individual compounds and to achieve efficient acaricidal property. [Display omitted] • Pistacia lentiscus essential oil and its six main constituents have a satisfactory acaricidal effect on D. gallinae in vitro. • Spraying method was more effective than the contact bioassay for acaricidal activity. • The highest mortality was observed with 4-Terpineol. • 4-Terpineol was found to be the most effective AChE inhibitor. [ABSTRACT FROM AUTHOR]

Nanoencapsulation is widely considered as a highly effective strategy to enhance essential oils' (EO) stability by protecting them from oxidative deterioration and evaporation. The present study aims to optimize and characterize an efficient technique for encapsulating Cinnamomum (C.) verum essential oil into chitosan nanoparticles using response surface methodology (RSM). Moreover, the optimized C. verum EO nanoparticle was investigated for its antibacterial (against Gram-positive and Gram-negative bacteria), antifungal (against Candida albicans), and antiparasitic activity (against Leishmania parasites). Five parameters were investigated using a Plackett–Burman and Box–Behnken statistical design: the chitosan molecular weight, TPP concentration, C. verum EO/chitosan ratio, mixing method, and the duration of the reaction. Encapsulation efficiency and anti-candida activity were considered as responses. The antibacterial, anticandidal, and anti-leishmanial activities were also assessed using a standard micro-broth dilution assay and the cytotoxicity assay was assessed against the macrophage cell line RAW 264.7. The optimized nanoparticles were characterized using Fourier transform infrared spectroscopy, Zeta potential, and scanning electron microscopy. The study results indicated that under optimal conditions, the nanoencapsulation of C. verum EO into chitosan nanoparticles resulted in an encapsulation efficiency of 92.58%, with a regular distribution, a nanoparticle size of 480 ± 14.55 nm, and a favorable Zeta potential of 35.64 ± 1.37 mV. The optimized C. verum EO/chitosan nanoparticles showed strong antifungal activity against C. albicans pathogens (CMI = 125 µg mL−1), notable antibacterial activity against both Gram-positive and Gram-negative bacteria (ranging from 125 to 250 µg mL−1), high leishmanicidal potential against the promastigotes form of L. tropica and L. major (IC50 = 10.47 and 15.09 µg mL−1, respectively), and a four-fold cytotoxicity reduction compared to non-encapsulated essential oil. These results suggest that C. verum EO-loaded chitosan nanoparticles could be a promising delivery system for the treatment of cutaneous Candida albicans infections. [ABSTRACT FROM AUTHOR]

The present study evaluated the acaricidal and anthelmintic action of Ocimum basilicum essential oil and its main components against ticks and helminth parasites as well as to relate these activities to acetylcholinesterase inhibition. The in vitro acaricidal activity against Hyalomma scupense was evaluated by Adult Immersion Test (AIT) and Larval Packet Test (LPT), while the in vivo nematocidal potential was assessed in laboratory mice infected with Heligmosomoides polygyrus using fecal egg count reduction (FECR) and total worm count reduction (TWCR). Chemical analyzes were performed by gas chromatography coupled to mass spectrometry (GC-MS). Estragole (80.87%) and linalool (16.12%) were the major compounds detected in O. basilicum essential oil. In the AIT assay for H. scupense tick, LC 50 of estragole, O. basilicum oil and linalool were 0.73, 0.81 and 0.97 mg/mL, respectively. In LPT, estragole, linalool and essential oil showed LC 50 of 0.22, 1.11 and 1.19 mg/mL, respectively. Against He. polygyrus, the highest activity was observed with estragole administered at 100 mg/kg body weight (bwt), which resulted in a FECR of 90.86% and a TWCR of 82.91%. The O. basilicum essential oil, estragole and linalool inhibited the enzyme acetylcholinesterase (AChE) extracted from both parasites species. Estragole was found the most active AChE inhibitor with IC 50 of 0.176 mg/mL for H. scupense and IC 50 of 0.138 mg/mL for He. polygyrus larvae. The results of the present study pointed out the importance of the traditional use of O. basilicum as an eco-friendly alternative against endo and ectoparasites. In vivo trials should also be conducted to confirm the above-mentioned activities and to assure the safe use of natural plants. [Display omitted] • Ocimum basilicum oil, estragole and linalool showed acaricidal and nematocidal activities. • Estragole exhibited the strongest acaricidal and nematocidal activities. Estragole was the most active AChE inhibitor. • The AChE inhibitory potential decreased in the following order: estragole > O. basilicum oil > linalool. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cupressus sempervirens , Mentha pulegium oil and their combination presented an in vitro acaricidal and repellency effects against H. scupense. • Combination oil is the most toxic compared with plants in individual use. • Essential oils have the potential to be applied as substitute for synthetic acaricides in the management of H. scupense hard ticks. The adulticidal, larvicidal, and repellent effects of Cupressus sempervirens, Mentha pulegium , and their combination (C. sempervirens and M. pulegium) against Hyalomma scupense were investigated, as well as their putative mode of action. The evaluation on H. scupense was performed with the adult immersion test at concentrations ranging from 2.5–20 mg/mL and the larval packet test from 0.625 to 20 mg/mlL. The same concentrations were used for combined oils. Essential oils were obtained using hydrodistillation and then analyzed using GC–MS. The following major components were identified: α-pinene (56.89 %) and δ-3-Carene (15.61 %) for C. sempervirens, while pulegone (70.50 %) and cis-Menthone (18.26 %) for M. pulegium. At 20 mg/mL concentration, C. sempervirens had (94.40 %) acaricide action and inhibited the egg from hatching, however at 10 mg/mL, it had 100 % larvicidal activity. Adulticidal and larvicidal activities of M. pulegium oil reached to 87.19 % and 81.02 % respectively, at 20 mg/mL concentration. The highest acaricidal property against H. scupense was exhibited by combination oils with minimum LC 50 values of 1.76 mg/mL on adultes and 0.60 mg/mL on larvae. The repellent activities were 100, 95.80 and 100 %, at the 20 mg/mL concentration used in 6 h, for C. sempervirens, M. pulegium and mixture oil respectively. Our findings revealed that the mixture of C. sempervirens and M. pulegium, at the ratio 1:1 (v: v) of each oil, showed high synergistic effect (SF > 1) and the use of combination oil (C. sempervirens 50 %: M. pulegium 50 %) is more toxic against H.scupense. Furthermore, the volatile oils examined revealed significant inhibition of H.scupense acetylcholinesterase activity AChE. Based on the findings of the present framework, these essential oils have the potential to be applied as substitute for synthetic acaricides in the management of H.scupense bovine ticks. [ABSTRACT FROM AUTHOR]

[Display omitted] • L. nobilis essential oil was dominated by 1.8-cineole. • Ethanolic leaves extracts present a higher amount of total phenolics, flavonoids and tannins. • Essential oil and crude extracts showed efficient in vitro acaricidal effect. The current study assayed the toxicity of Laurus nobilis essential oil and crude extracts obtained using solvents of increasing polarity (cyclohexane, acetone and ethanol), on two ectoparasites of veterinary importance, i.e. , Hyalomma scupense and Dermanyssus gallinae. The major components detected in bay laurel essential oil were dominated by 1.8-cineole (46.56 %), α-terpinenyl acetate (13.99 %), sabinene (7.69), α-pinene (5.75), linalool (5.50), methyleugenol (5.36 %) and β-pinene (3.97). The highest total phenolic and flavonoids contents were present in the ethalonic extract of L. nobilis leaves at an amount of 152.88 mg gallic acid equivalents per gram of dry weight (GAE/g DW) and 21.77 mg quercetin equivalent per gram of dry weight (QE/g DW), respectively. In vitro acaricidal effects of essensial oil and crude extract of L. nobilis against H. scupense were ascertained by adult immersion test of engorged females (AIT) and larval packet test (LPT) compared with a reference drug amitraz. The essential oil exhibited strong acaricidal activity against tick engorged female and inhibition of hatching eggs. After 24 h of exposure, at the highest tested concentration (100 mg/mL) essential oil induced 90.67 % mortality of H. scupense larvae (LC 50 = 10.69 mg/mL). Otherwise, essential oil exhibited high acaricidal activity compared to extracts, and among the extract, the ethanolic extract revealed the highest acaricidal efficacy (81.27 % female mortality). Results from mite contact toxicity showed that essential oil and extracts from L. nobilis were toxic to D. gallinae. Bay essential oil was both more toxic to mites, and faster in exerting this toxicity than other tested crude extracts. L. nobilis essential oil concentration leaded to enhance mortality of D. gallinae reaching the highest (100 %) mortality at 12 h with a concentration of 320 mg/mL. While, ethanolic extract acheived this rate after 24 h of exposure at same concentration. Cyclohexanic extract showed weak acaricidal activity. [ABSTRACT FROM AUTHOR]

• Healthy tomato plants harbor diverse endophytic bacteria colonizing mainly leaves. • 36 % of the strains produce antifungal volatiles against Botrytis cinerea. • Antagonistic bacteria belong to 9 Bacillus and 2 Enterobacter species. • Enterobacter volatile and Bacillus soluble compounds reduced B. cinerea infection. • 3-Methylbutan-1-ol reduces postharvest decay of B. cinerea on tomato fruit. Botrytis cinerea is one of the most important postharvest fungal pathogens causing significant losses in fresh fruits, vegetables and ornamentals. Synthetic fungicides are primarily used to control postharvest decay loss, but due to their hazardous use the recent trend is shifting toward safer and more eco-friendly alternatives. The use of antagonistic microorganisms is becoming popular throughout the world. This study investigated the antifungal, the plant growth promoting activities and the identity of volatile organic compounds (VOCs) produced by tomato-derived endophytic bacteria strains. The capacity of selected strains to prevent postharvest B. cinerea infection on tomato fruit through VOCs and soluble compounds was also studied. A collection of 50 bacterial strains was established from different organs of tomato plants sampled from six localities in Cape Bon region (Tunisia). Despite the small geographical scale, complexity and abundance of endophytic communities varied greatly according to the site of origin. Healthy tomato plants harbor diverse endophytic bacteria of Bacillus and Enterobacter genera colonizing mainly leaves with a significant enrichment with Bacillus strains. The in vitro dual culture assays showed that 36 % of the endophytic bacterial strains produce antifungal VOCs against B. cinerea. To our knowledge, this is the first report of VOCs antifungal activity produced by B. nakamurai, B. pseudomycoides, B. proteolyticus, B. thuringiensis, E. asburiae and E. cloacae against B. cinerea. About 14 % of bacterial strains produce VOCs with in vitro specific promoting effects on tomato seedling length or biomass production. The five selected antagonistic endophytic bacterial strains produced a core set of seven VOCs along with different strain-specific and known antifungal VOCs such as 3-Methylbutan-1-ol, sulfur-containing compounds, 2-Heptanone and Dodecanal. Tomato fruit bio-protection assay showed that the Enterobacter strain TR1 produces the most protective VOCs against B. cinerea infection with 3-Methylbutan-1-ol as a major volatile compound which totally suppressed B. cinerea growth and infection on tomato fruit at 0.442 mL L−1 headspace, whereas the Bacillus strains showed better protection against fungal infection when applied as vegetative cells on tomato fruit. These results support the use of the selected strains as potential biocontrol agents to reduce postharvest decay of B. cinerea , as well as 3-Methylbutan-1-ol as promising antifungal volatile to apply during postharvest commercialization of tomato fruit. [ABSTRACT FROM AUTHOR]

This study investigated insecticidal activity of Artemisia herba-alba essential oil (EO) against Tribolium castaneum adults and its impacts on wheat flour quality. GC/MS analysis of the EOs of A. herba-alba showed a predominance of β-thujone (27.79%), camphor (22.65%), chrysanthenone (17.97%) and α-thujone (13.56%). Therefore, the median effective concentrations (LC50 value) of Artemisia herba-alba essential oil used for preliminary screening tests were evaluated. Insect mortalities, occupation space conditions and wheat flour quality were investigated after 30 and 60 days of storage period. The results showed that mortality varies depending on occupation space and storage duration, which reached 42.15% and 59.8% after 30 and 60 days of storage, respectively. Furthermore, moisture, ash, gluten, falling number contents were examined according to international standards. Indeed, rheological dough parameters were examined using a Chopin alveograph and according to ISO standards. Results indicated that A. herba-alba essential oil changed wheat flour physicochemical parameters but did not affect dough rheological parameters which correspond to international ISO standards. [ABSTRACT FROM AUTHOR]

Abstract Four hundred and fifty bacteria were evaluated for antagonistic activity against bacterial soft rot of potato caused by Pectobacterium carotovorum sp strain II16. A strain Ar10 exhibiting potent antagonist activity has been identified as Bacillus amyloliquefaciens on the basis of biochemical and molecular characterization. Cell free supernatant showed a broad spectrum of antibacterial activity against human and phytopathogenic bacteria in the range of 10-60 AU/mL. Incubation of P. carotovorum cells with increasing concentrations of the antibacterial compound showed a killing rate of 94.8 and 96% at MIC and 2xMIC respectively. In addition, the antibacterial agent did not exert haemolytic activity at the active concentration and has been preliminary characterized by TLC and GC–MS as a glycolipid compound. Treatment of potato tubers with strain Ar10 for 72 h significantly reduced the severity of disease symptoms (100 and 85.05% reduction of necrosis deep / area and weight loss respectively). The same levels in disease symptoms severity was also recorded following treatment of potato tubers with cell free supernatant for 1 h. Data suggest that protection against potato soft rot disease may be related to glycolipid production by strain Ar10. The present study affords new alternatives for anti- Pectobacterium carotovorum bioactive compounds against the soft rot disease of potato. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the essential oil composition of Inula viscosa leaves by hydrodistillation (HDE), ultrasonic (UDE) and solvent (SE) extractions followed by hydrodistillation. The total polyphenol and flavonoid contents and their antioxidant effects were studied by different solvent of extraction: ethanol (ET), ethyl acetate (EA), methanol (ME) and aqueous (AE). The principal compounds for HDE were: 2-hexenal (3.70%), caryophyllene oxide (3.11%), γ-selinene (3.09%), 3-hexen-1-ol (2.00%), eugenol (1.70%) and trans-caryophyllene (1.34%), while for UDE were: γ-selinene (5.68%), caryophyllene oxide (4.87%), trans-caryophyllene (1.99%) and nerolidol (1.74%). The oil obtained by SE was shown to contain tridecane (3.89%), dodecane (3.08%), trans-caryophyllene (2.94%), caryophyllene oxide (2.56%) and nerolidol (2.53%). Significant changes on phenolic contents were found between the different solvent of extraction. ME and AE extracts led to the highest total polyphenol (PHL) and flavonoid (FL) amounts. The anti-radical activity and reducing power were maximal in AE and ME extract. HPLC examination established that the ferulic acid as major phenolic acid in ME and AE fractions, whereas luteolin was the main compound of EA and ET fractions. [ABSTRACT FROM AUTHOR]

• Solanaceae seeds harbor diverse endophytic bacteria colonizing mainly hypocotyl. • 11 % of endophytic bacteria produce persistent antifungal VOCs against R. solani. • 78 % of antagonistic strains showed growth promoting activity of tomato seedlings. • Antagonistic Bacillus strains produce Benzenamine, N-ethyl- as main VOC. • The Benzenamine, N-ethyl- reduced R. solani in vitro growth and infection on tomato fruit. Rhizoctonia solani is a broad spectrum fungal pathogen that infects crops in greenhouse and field conditions causing plants damping-off and fruit rot which provoke serious yield losses. This study prospected the use of bacterial volatile organic compounds (VOCs) to control R. solani infection on tomato seedlings and fruit in order to search for an alternative to the use of chemical pesticides. Seed-born bacterial endophytes were isolated from the cultivated Solanum lycopersicum and the wild Solanum linnaeanum species. This study showed a host- and organ-specific colonization of endophytic bacteria at early seedling stage with most of them colonizes the cotyledons in comparison to stems and roots. Overall, 51 % and 11 % of isolated endophytic bacteria produce antifungal VOCs against R. solani at 7 d and 14 d of dual culture, respectively. The majority (about 78 %) of the antagonistic bacterial endophytes showed promoting activity on tomato seedling growth. For the bioprotection tests the strains TRC7 and TRC10 of Bacillus subtilis and TRT11 of B. megaterium were selected as the most antagonistic and PGP endophytic bacteria and a non-antagonistic strain SMLR7 of Paenibacillus sp., with this later strain reported for the first time colonizing internal seed tissues of S. linnaeanum. The VOCs of the strain TRC7 showed the best pattern of decrease of R. solani rotting on tomato fruit, and increase the hypocotyl length, the radicle length, the fresh weight, and the vigor of tomato seedlings. The identification of the VOCs produced by the antagonistic Bacillus strains showed a core set of four compounds i.e. 2-Heptanone; Pyrazine, 2,5-dimethyl-; Naphthalene; and Benzenamine, N-ethyl- which was the most abundant. All the four VOCs showed antifungal activity against R. solani in vitro growth, and to our knowledge this activity is reported for the first time for Benzenamine, N-ethyl- and 2-Heptanone. The Benzenamine, N-ethyl- showed the best antifungal activity with an IC50 about 0.09 mL L−1 headspace and proved to be effective in reducing R. solani rotting on tomato fruit at the same concentration. So, this work provides evidence about VOCs-mediated biocontrol ability of Bacillus strains to reduce R. solani seedling damping-off and fruit rot of tomato making them valuable agents for pre- and postharvest control of this disease. [ABSTRACT FROM AUTHOR]

• Chemical composition and bioactivities of Eucalyptus essential oils varied significantly between the thirteen species. • 1,8-cineole was the main compound in majority of tested oils. spathulenol was the major one in E. camaldulensis. • Eucalyptus essential oils exhibited a weak antioxidant activity, but a remarkable bacterial inhibition growth. • E. camaldulensis had the strongest bioactivities. The aromatic medicinal plant Eucalyptus and its essential oils have been used since antiquity in folk medicine. The interest in this genus has increased remarkably over the last decade mostly because of their various biological activities. This study aimed to determine the chemical composition of essential oils of thirteen Eucalyptus species leaves and their antioxidant and antibacterial activities. Obtained results showed that E. maidenii had the highest essential oil yield (6.16 ± 1.55 %). Chemical composition (by GC/MS) was highly affected by the species factor (P < 0.001), with the abundance of the major compound 1,8-cineole (82.64 % in E. microcarpa) in most Eucalyptus species. Essential oils exhibited a moderate antioxidant activity, but an interesting bacteriostatic effect against all tested bacteria. Eucalyptus camaldulensis had the strongest bioactivities despite its major compound was spathulenol with efficacy concentration of 50 % EC 50 = 2.96 ± 0.11 mg/mL for the reducing power assay and presented an important inhibition zone (25.33 ± 2.84) and lowest minimum inhibitory concentration (MIC = 0.93 mg/mL) against Serratia marcescens bacteria. This result demonstrated that biological activities could be explained by the synergistic effect between major and minor compounds. [ABSTRACT FROM AUTHOR]