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Natural products are usually considered harmless; however, these substances need to be consumed with caution. Biological assays with plant models are a suitable alternative for prospective studies to assess natural product-initiated toxicity. The aim of this study was to examine the toxic potential of leaf and flower extracts derived from Tropaeolum majus L. a widely used plant in traditional medicine. Seeds of Lactuca sativa L. were exposed to T. majus extracts and based upon the seedling growth curve values, the 50% Inhibition Concentration (IC 50 ) was calculated and applied for cell cycle analysis exposure. Both extracts contained organic acids, proteins, amino acids, and terpene steroids. Sesquiterpene lactones and depside were detected in leaf extracts. The higher concentration tested exhibited a marked phytotoxic effect. The extracts induced clastogenic, aneugenic cytotoxic, and potential mutagenic effects. The possible relationships between the classes of compounds found in the extracts and effects on cells and DNA were determined.

The experiments were carried out to evaluate the Allelopathic effect of extracts of leaves and pods of mesquite (P. juliflora) on germination and early growth of Vachellia nilotica and Vachellia seyal. Seeds of both Vachellia species were soaked in the extracts of leaves or pods of mesquite at four weights 3, 6, 9, and 12 grams. Leaf or pod extracts at the weight of 9 and 12 grams showed a significant reduction in germinated seeds of V. seyal and emerged seedlings of the two Vachellia species compared to the control. The radical length of the two species was significantly affected with leaf extracts of all weights and with pod extracts of weights of 9 and 12 g. The lowest plumule length of V. seyal and V. nilotica were achieved with leaf extracts of weights of 6, 9, and 12 g and pod extracts of weights of 9 and 12 g compared to the control. Pod extracts of all weights significantly decreased the shoot height of both Vachellia species and root length of V. nilotica, and water contents of the shoot and root of V. seyal and V. nilotica compared to the control. Significant reduction in root length of V. nilotica and shoot and root water content of V. seyal and V. nilotica associated with leaf extracts of all weights. The study concluded that; mesquite's leaf and pod extracts harm the germination and early growth of V. nilotica and V. seyal. [ABSTRACT FROM AUTHOR]

Acmella radicans (Jacquin) R.K. Jansen is a new invasive species recorded in Yunnan Province, China, and little is known about its allelopathic potential and allelochemicals. In this study, the allelopathic effects of the essential oil (EO) of A. radicans on seed germination and seedling growth of four common plants, Brassica napus, Brassica rapa ssp. chinensis, Digitaria sanguinalis, and Lolium multiflorum, were explored. The results showed that the seed germination index, germination rate, root length, stem length, and biomass of B. napus and B. rapa ssp. chinensis were significantly inhibited at all EO concentrations of A. radicans, but there was a 'low-promotion and high-inhibition effect' on the root length of D. sanguinalis and L. multiflorum at low concentrations of 0.5 μL·mL−1 and 0.5–1.0 μL·mL−1, respectively. With increasing concentrations of EO, the inhibition rates of seed germination and seedling growth of four common plants gradually increased, and D. sanguinalis and L. multiflorum were the most inhibited, followed by B. rapa ssp. chinensis, and the least inhibited was B. napus. Thirty-two components were identified using GC–MS, representing 99.07% of the EO in A. radicans. The major components were 2-tridecanone (30.46%), caryophyllene oxide (19.18%), 4,8,11,11-tetramethylbicyclo[7.2.0]undec-3-en-5-ol (7.84%), β-caryophyllene (7.67%), and widdrol (4.7%). Among the compounds we identified, (E,E)-2,4-decadienal, 2-tridecanone, γ-cadinene, δ-cadinene, (E)-α-cadinol, spathulenol, caryophyllene oxide, and widdrol have been previously reported as having possible allelopathic effects. Our study was the first to show that A. radicans could potentially release allelochemicals to influence neighboring plants during its invasion and expansion. [ABSTRACT FROM AUTHOR]

A comparative study of volatiles, antioxidant activity, phytotoxic activity, as well as in silico molecular docking and ADMET study, was conducted for essential oils from three Vitex species, viz., V. agnus-castus, V. negundo, and V. trifolia. Essential oils (OEs) extracted by hydrodistillation were subjected to compositional analysis using GC-MS. A total number of 37, 45, and 43 components were identified in V. agnus-castus, V. negundo, and V. trifolia, respectively. The antioxidant activity of EOs, assessed using different radical-scavenging (DPPH, H2O2 and NO), reducing power, and metal chelating assays, were found to be significant as compared with those of the standards. The phytotoxic potential of the EOs was performed in the receptor species Raphanusraphanistrum (wild radish) and the EOs showed different levels of intensity of seed germination inhibition and root and shoot length inhibition. The molecular docking study was conducted to screen the antioxidant and phytotoxic activity of the major and potent compounds against human protein target, peroxiredoxin 5, and 4-hydroxyphenylpyruvate dioxygenase protein (HPPD). Results showed good binding affinities and attributed the strongest inhibitory activity to 13-epi-manoyl oxide for both the target proteins. [ABSTRACT FROM AUTHOR]

This study examined the phytotoxicity of the extract of Datura metel. It involved the planting of seeds of monocot, yellow maize (Zea mays) and a dicot, brown bean (Phaseolus vulgaris), growth and analysis of seedlings of the two plants. Seeds of Z. mays were collected at the Institute of Agricultural Research and Training (IAR&T), Ibadan and the seeds of P. vulgaris were collected at International Institute for Tropical Agriculture (IITA), Ibadan, Nigeria. The leaf of D. metel was collected. The plant was identified and authenticated (FHI 111862) at Forestry Research Institute of Nigeria (FRIN) Ibadan, Nigeria. The collected leaves were carefully washed under running tap water and air-dried at room temperature for four weeks. The dry leaves were milled into a fine powder and extracted. The phytotoxic potentials of the extract were evaluated using a standard method. At the end of the experiment, seedlings were harvested, stem and leaf were separately collected, and shoot length of seedlings was measured, and kept frozen for the estimation of total protein, soluble sugar, free amino acids, proline, and plant pigments. The findings revealed that different concentrations of aqueous extract of the leaf of D. metel retarded the rate of germination of seeds, significantly inhibited the shoot length of P. vulgaris and Z. mays and reduced concentrations of chlorophyll, free amino acids, protein, sugar, and proline. In conclusion, this study revealed that the extract exhibited a deleterious effect on germination, growth and biochemical parameters in seedlings of P. vulgaris and Z. mays. [ABSTRACT FROM AUTHOR]

The study was aimed to explore the phytotoxic potential of Sonchus oleraceus L. on the emergence and seedling growth of Echinocloa cruss-galli L. and quantification of allelochemicals present in leaves, stem and fruit of S. oleraceus weed. The experiment comprised of aqueous extracts of leaf, roots and fruits applied at 0.25, 0.5, 1, 2, 4 and 8% (w/v) along with a control (0%). Data regarding seed emergence, emergence index, emergence percentage, root length, shoot length and seedling dry weight were recorded. All the tested concentrations of all the parts of S. oleraceus significantly inhibited the seed emergence, emergence index, emergence percentage (%), growth and delayed mean emergence time and time taken to 50% emergence of E. cruss-galli. However, maximum mean emergence time (5.20 days) and time taken to 50% emergence (3.49 days), were noted at 8% concentration of fruit and leaf aqueous extracts, respectively. Fruit aqueous extract at 8% concentration caused the lowest germination index (1.70), germination percentage (40%), root length (0.09 cm), shoot length (0.45 cm) and dry weight (0.16 g) of E. cruss-galli. Results suggested that the extract of S. oleraceus weed at concentration (8%) can be used as potential bio-herbicide for the control of E. crussgalli weed. [ABSTRACT FROM AUTHOR]

During the course of screening for anti-seed germination phytochemicals, the methanol fraction of the Cedrus deodara fresh needles showed potent activity. Bioactivity-guided fractionation led to the isolation of thirty-eight phenolic compounds. Four ones were identified as previously undescribed including (7 S ,8 S)-3-methoxy-9′-acetoxy-3′,7-epoxy-8,4′-oxyneoligna-4,9-diol (7), (7 S ,8 R)-dihydro-3′-hydroxy-8-acetoxymethyl-7-(4-hydroxy-3-methoxy-phenyl)-1′-benzofuranpropanol (10), (8 S)-4,9,9′-trihydroxy-3,3′-dimethoxy-8,4′-oxyneolignan (11) and (7 S ,8 S)-4,7,9′-trihydroxy-3,3′-dimethoxy-9-acetoxy-8,4′-oxyneolignan (16), respectively. The potential phytotoxic effects of these compounds on the seed germination and root elongation of Arabidopsis thaliana were evaluated by the filter paper assay developed in our laboratory. Bioassay results indicated that caffeic acid (36) displayed most significant inhibitory activities against the seed germination and root elongation of A. thaliana , stronger than those of the commercial herbicides acetochlor and glyphosate at the same concentration of 200 μg/mL. Ditetrahydrofuran lignan (1), dihydrochalcone (25), and eight simple phenols (28 , 29 , 31 , 33 – 35, 37 and 38) completely inhibited the seed germination of A. thaliana at the concentration of 400 μg/mL, which were as active as acetochlor. Dihydroflavone (21) and the simple phenols 32 – 34 displayed stronger inhibitory effects on the root elongation of A. thaliana than that of glyphosate. The inhibitory effects of these active compounds on the seed germination and root elongation of Amaranthus tricolor and Lactuca sativa were evaluated as well. The phytotoxic activity of 11 , 16 , 22 , 25 , 31 , 34 , 37 and 38 were detected for the first time. In addition, the structure-activity relationships of the same class of these phytochemicals were discussed. Four undescribed neolignans were isolated, and seven phenolic allelochemicals displayed stronger inhibitory activity than that of glyphosate were detected in the fresh needle extract components of Cedrus deodara for the first time. [Display omitted] • Four new neolignans, and thirty-four phenols were isolated from the fresh needles of C. deodara. • The structure-activity relationships of the same class of the bioactive compounds were discussed. • This study shall provide a basis for the structural optimization of phenolic allelochemicals. [ABSTRACT FROM AUTHOR]

Due to increased risk attached with indiscriminate use of synthetic herbicides, researchers are looking for alternative weed control strategies. Allelopathy is a natural phenomenon that might be exploited for biological weed management in field crops. Allelopathic plant water extracts may provide selective growth inhibition of the weeds. The present studies were conducted to investigate the possible selective phytotoxic effect of Delonix regia aqueous, ethyl acetate and lyophilized leaf extract against field bindweed (Convolvulus arvensis L.) and wheat (Triticum aestivum L.). The results revealed that lower to medium aqueous (2.5 and 5%) and ethyl acetate (50, 500 and 1000 ppm) leaf extract concentrations inhibited filed bindweed germination, root length, shoot length and seedling dry biomass by 35-48%, 42-59%, 45-46% and 52-56% respectively, while no significant phytotoxic effect was observed on wheat at these concentrations. It is concluded that lower to medium concentrations of Delonix regia leaf extract might be safely utilized for natural control of field bindweed in wheat, reducing reliance upon synthetic herbicides. [ABSTRACT FROM AUTHOR]

Araucaria forest, named due to the high abundance of Araucaria angustifolia, occurs mainly in the southern Brazilian highlands, and the abundance of A. angustifolia in the forest is a current forest issue. The present study aimed at evaluating a potential allelopathic effect of A. angustifolia needle extracts that could mediate plant successional dynamics in the Araucaria forests. Senescent araucaria needles from A. angustifolia were evaluated for their allelopathic potential on Lactuca sativa through an in vitro study. The effect was evaluated by determining the germination of seeds, length of seedling and germination rate. The allelopathic potential of the A. angustifolia was confirmed for the highest doses tested (187.5 and 250 mg of the extracts). The potential allelochemical compounds identified were ent-kaurene and phyllocladene. In conclusion, A. angustifolia showed a potential allelophatic effect that may play an important role in successional dynamics of Araucaria forests. [ABSTRACT FROM AUTHOR]

Abstract: Repellent and insecticidal activities of essential oils extracted from leaves of Artemisia princeps Pamp and seeds of Cinnamomum camphora (L.) Presl. against storage pests Sitophillus oryzae L. and Bruchus rugimanus Bohem were investigated. Results showed that the two individual oils displayed good, but their mixture (1:1) exhibited much better repellent activities at concentrations from 250 to 1000μgg−1 and insecticidal actions at concentrations ⩾1000μgg−1 against the test beetles S. oryzae and B. rugimanus. Oils from A. princeps and C. camphora applied individually were significantly toxic to seed germination of wheat at 500μgml−1. However, no toxic effects were found when the two oils were mixed (1:1 w/w) at the same concentration. These observations indicated that the mixture of the two plant-derived oils had a synergic effect and could be used in the control of storage pests. [Copyright &y& Elsevier]

Medicinal and aromatic plants have the ability to transmit volatile allelochemicals and affect their surrounding organisms. In this regard, their interaction should also be considered. The inhibitory effects of 112 essential oils on lettuce seed and seedling were investigated by cotton swab method. Germination (G%), Mean germination time (MGT), Lethal of embryo (L%), dormancy (D%), radicle growth (R%), and hypocotyl growth (H%) were measured. Two methods were used for evaluating allelopathic interaction effects: the simplified modified dilution check-board technique (SMCT) and the isobologram. Thymus daenensis had the highest inhibitory effect on G% (IC50 = 2.9 ppm) and the most lethal effect on the embryo (LC50 = 7.2 ppm). Thymus transcaspicus, Dracocephalum moldavica, Artemisia sieberi and Amomum subulatum had the greatest effect on MGT. Ziziphora tenuior, Trachyspermum ammi and Pelargonium graveolens had the highest effect on D%. Origanum vulgare was the strongest growth inhibitor. The highest synergistic effect on G% was in A. subulatum + Mentha suaveolens, on H% was related to Perovskia abrotanoides + T. daenensis, and on R% was observed in Artemisia vulgaris + M. suaveolens. The results of this study can lead to identification of new phytotoxic compounds in EOs and control weeds more effectively. [ABSTRACT FROM AUTHOR]