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Many studies have demonstrated the herbicidal effects of several essential oils and their possible use as substitutes for chemical herbicides. Several enzymes play a very significant role in seed germination: among these, α-amylase could be involved in essential oil phytotoxic processes. The aims of this study were to compare the chemical composition of the essential oils of two ecotypes of O. heracleoticum growing in Cilento (Southern Italy) and to study their possible use as natural herbicide using Raphanus sativus, Sinapis arvensis and Lolium multiflorum seeds. Moreover, a possible inhibitory activity on the α-amylase enzyme extracted from germinating seeds was evaluated as a possible mechanism of action. Both oils, characterized by GC-MS, belonged to a carvacrol chemotype. The alpha-amylase activity was determined using DNSA (dinitrosalicylic acid) assay quantifying the reducing sugar produced. Furthermore, the essential oils demonstrated phytotoxicity at the highest dose tested, and an inhibitory effect on α-amylase, probably correlated with the phytotoxic effects, was registered. The oils showed interesting phytotoxic and alpha-amylase inhibitory activities, which deserve to be further investigated. [ABSTRACT FROM AUTHOR]

The complex taxonomy of Eucalyptus genus, the renewed interest in natural compounds able to combat microbial strains, the overuse of synthetic pesticides, the consequent request for alternative control methods were the reasons for this research. The essential oils (Eos) of Eucalyptus bosistoana, Eucalyptus melliodora, Eucalyptus odorata, Eucalyptus paniculata, Eucalyptus salmonopholia, and Eucalyptus transcontinentalis were analyzed by GC/MS and their potential phytotoxic activity was evaluated against the germination and radicle elongation of Sinapis arvensis, Raphanus sativus and Lolium multiflorum. The antibiofilm activity was assayed against both Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii) bacteria. Monoterpenoids were the most representative constituents in all EOs and eucalyptol was the dominant component except in E. melliodora EO, in which p-cymene was the most abundant. In phytotoxic assays, the EOs from E. odorata and E. paniculata were the most active against germination and radical elongation of the tested seeds. Finally, the Eucalyptus EOs proved their capacity to effectively inhibit the adhesion process of all five pathogen strains, with percentages often reaching and exceeding 90%. These Eucalytpus EOs could have possible employments in the food, health and agricultural fields. [ABSTRACT FROM AUTHOR]

Solidago canadensis L. (SC) (Canadian goldenrod) is a dangerous plant invader in Europe, which suppress the indigenous flora. Essential oils (EOs) are considered biological control agents. GC-MS analysis for identification of main components was conducted and the potential phytotoxicity of six EOs were also evaluated. Limonene and β-thujone were dominant components in Salvia officinalis L., menthone and menthol in Mentha × piperita L., carvacrol in Origanum vulgare L., estragole/anisole and anethole in Foeniculum vulgare Mill., limonene and carvone in Anethum graveolens L., and anethole in Pimpinella anisum L. Along with EOs, anethole, anisole, camphor, carvone, estragole, limonene, menthol, menthone, thujone and thymol were used independently to evaluate phytotoxic effect against Canadian goldenrod seed germination. A significant inhibitory effect was registered for origanum (1.250 µg.ml−1). The influence of single components was significant. The highest phytotoxic activity was registered with anethole and estragole. Phenolic compounds were the inhibitoriest, followed by oxygenated and hydrocarbon monoterpenes. [ABSTRACT FROM AUTHOR]

The chemical composition of the essential oil of Helichrysum italicum (Roth) Don ssp. italicum, collected in the National Park of Cilento and Diano Valley, Southern Italy, was studied by means of GC and GC/MS. Forty four compounds of 45 constituents were identified in the oil, mainly oxygenated sesquiterpenes. The essential oil was evaluated for its potential in vitro phytotoxic activity against germination and early radicle elongation of radish and garden cress. The radicle elongation of radish was significantly inhibited at the highest doses tested, while germination of both seeds was not affected. [ABSTRACT FROM AUTHOR]

Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twentyseven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress), under laboratory conditions. The compounds, belonging to different chemical classes, showed different potency in affecting both parameters evaluated. The assayed compounds demonstrated a good inhibitory activity in a dosedependent way. In general, radish seed is more sensitive than garden cress and its germination appeares more inhibited by alcohols; at the highest concentration tested, the more active substances were geraniol, borneol, (±)-β-citronellol and α-terpineol. Geraniol and carvone inhibited, in a significant way, the germination of garden cress, at the highest concentration tested. Radicle elongation of two test species was inhibited mainly by alcohols and ketones. Carvone inhibited the radicle elongation of both seeds, at almost all concentrations assayed, while 1,8-cineole inhibited their radicle elongation at the lowest concentrations (10-5 M, 10-6 M). [ABSTRACT FROM AUTHOR]

Twelve essential oils from Mediterranean aromatic plants were tested for their phytotoxic activity, at different doses, against the germination and the initial radicle growth of seeds of Raphanus sativus, Lactuca sativa and Lepidium sativum. The essential oils were obtained from Hyssopus officinalis, Lavandula angustifolia, Majorana hortensis, Melissa officinalis, Ocimum basilicum, Origanum vulgare, Salvia officinalis and Thymus vulgaris (Lamiaceae), Verbena officinalis (Verbenaceae), Pimpinella anisum, Foeniculum vulgare and Carum carvi (Apiaceae). The germination and radicle growth of tested seeds were affected in different ways by the oils. Thyme, balm, vervain and caraway essential oils were more active against both germination and radicle elongation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Juniperus sabina L., commonly known as Savin, is an evergreen shrub from Cupressaceae family, grown as an ornamental all over the world. J. sabina contains two valuable metabolites: essential oil (EO) and podophyllotoxin. The EO is known for various bioactivities, while podophyllotoxin, is currently used as a precursor for anticancer drugs. The hypothesis of this work was that J. sabina plants from natural populations in Bulgaria would have desirable EO profiles and bioactivity. Furthermore, accessions with high concentrations of podophyllotoxin may be discovered. The objectives were: (1) Assessment of the EO profile and podophyllotoxin variability, including seasonal, within populations, and between populations of J. sabina in Bulgaria; (2) Evaluation of the potential biopesticidal effect of J. sabina EO from natural populations; and (3) Assessment of antioxidant and enzymatic activities of J. sabina EO. Overall, the EO content and composition varied between natural populations, within a population, between female (F) and male (M) plants, and between different seasons (months) of the year. Sabinene (10.1–66.8% of the total EO), myrtenyl acetate (0–57.2%), α -pinene (2.6–8.6%), myrcene (2.85–4.5%), α -thujone (0–10.9%), β -thujone (0–9.9%), and germacrene-4-ol (3.0–10.3%) were the major EO constituents. Monoterpenes represented 89.5–92.8% and sesquiterpenes were 6.7–7.1% of the EO. The EO yield was 0.61–3.8% in dried biomass, while the concentration of podophyllotoxin varied from undetected to 0.19%. Antioxidant activity was higher in EOs from female (F) plants in DPPH assay; in the FRAP assay, some EOs from male (M) plants collected in January, March, May, and July were the most active. Moreover, EO from F plants exhibited good activity on α -amylase and α -glucosidase enzymes. The tested EOs from both M and F plants at 5 μL, 10 μL, and 20 μL significantly reduced or completely suppressed the germination and sprout length of seeds of five weed species. Eight chemotypes of J. sabina were identified and the EO of these were tested for suppression of soft white winter wheat, SWWW (Triticum aestivum L.) germination and root and shoot growth. About half of the chemotypes suppressed wheat seed germination, root, and shoot growth. J. sabina EO could potentially be further explored for the development of biopesticides to be utilized for weed control in organic production systems and possibly for control of pre-harvest sprouting in wheat. [Display omitted] • Juniperus sabina contains essential oil and podophyllotoxin used for anticancer drugs. • 8 chemotypes based on sabinene, myrtenyl acetate, α -pinene, others, were identified. • Essential oil exhibited bioactivity against α -amylase and α -glucosidase enzymes. • The essential oil suppressed germination and growth of weed species and winter wheat. • Results showed the potential of J. sabina as biopesticide and podophyllotoxin source. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]