Biostimulant effect of Cladophora glomerata extract on garden cress plant growth.

Biostimulants that improve agriculture's productivity and environmental responsibility are widely favored and used. Algae has emerged as a viable option for sustainable agriculture. In the present study, the effects of the Cladophora glomerata (L.) Kütz. aqueous extract in three concentrations (2.5, 5, and 10 mg extract per mL of tap water) was tested on the growth and productivity of garden cress (GCR) Lepidium sativum L., plants over 12 days, and the results were compared with those of the control group (irrigated only with tap water). The effect of the algae extract was studied by assessing the changes in phenolic compounds using HPLC-DAD and determining the chlorophyll content as well as the total antioxidant capacity of the GCR using DPPH and ABTS tests. Total phenolics, as well as total flavonoids, were measured. The potential role of algae extract in promoting cress plant growth was attained when compared to the control, mainly at a concentration of 2.5 mg/mL, which exhibited the highest yield growth after 12 days and presented the highest antioxidant capacity at 13.53 ± 1.16 mg Trolox equivalent (TE)/g dry weight (DW), compared to 10.44 ± 0.33 mgTE/g DW for the control. The total phenolic content significantly increased (p < 0.05) from 14.34 ± 0.84 mg gallic acid equivalent (GAE)/ g dry weight (DW) to 23.14 ± 0.55 mg GAE/g DW. Eleven phenolic compounds were identified in different tested samples of GCR, whether treated or not treated with algae extracts. Chrysin was only identified in the treated plants. Therefore, the use of algae (C. glomerata) presents promising potential as a biostimulant in agriculture, contributing to increased plant growth and improved resistance to environmental stress.

Physicochemical and ecotoxicological approaches for Moknine Continental Sebkha in Tunisia.

Degradation of water quality is an emerging issue in many developing countries. In this context, industrial and domestic effluents heavily contaminate the coast of Moknine Continental Sebkha in Tunisia. The present study aimed to biomonitor the seawater quality of the Moknine Continental Sebkha coast using physicochemical and ecotoxicological approaches. The ecotoxicological assessment was performed using three species representing different trophic levels, namely Vibrio fischeri, Selenastrum capricornutum, and Lepidium sativum. In the physicochemical analysis such as BOD (biochemical oxygen demand), COD (chemical oxygen demand), TSS (total suspended solids), TOC (total organic carbon), NO3- (nitrate), AOX (adsorbable organic halogen), the recorded levels of pH and total suspended solids did not comply with the Tunisian standard (NT.09.11/1983). The ecotoxicological data confirmed that the tested water samples displayed toxicity to two test indicators L. sativum and S. capricornutum. A targeted chemical screening of the Moknine Continental Sebkha coast previously performed revealed the presence of total mercury, four phthalate acid esters, and one non-phthalate plasticizer, a fact that could explain the observed ecotoxicological effects and therefore might harm the biotic area and the health of the surrounding population.

Ecotoxicological assessment of biomass-derived furan platform chemicals using aquatic and terrestrial bioassays.

An environmental toxicological assessment of fourteen furanic compounds serving as valuable building blocks produced from biomass was performed. The molecules selected included well studied compounds serving as control examples to compare the toxicity exerted against a variety of highly novel furans which have been additionally targeted as potential or current alternatives to biofuels, building blocks and polymer monomers. The impact of the furan platform chemicals targeted on widely applied ecotoxicity model organisms was determined employing the marine bioluminescent bacterium Aliivibrio fischeri and the freshwater green microalgae Raphidocelis subcapitata, while their ecotoxicity effects on plants were assessed using dicotyledonous plants Sinapis alba and Lepidium sativum. Regarding the specific endpoints evaluated, the furans tested were slightly toxic or practically nontoxic for A. fischeri following 5 and 15 min of exposure. Moreover, most of the building blocks did not affect the growth of L. sativum and S. alba at 150 mg L-1 for 72 h of exposure. Specifically, 9 and 11 out of the 14 furan platform chemicals tested were non-effective or stimulant for L. sativum and S. alba respectively. Given that furans comprise common inhibitors in biorefinery fermentations, the growth inhibition of the specific building blocks was studied using the industrial workhorse yeast Saccharomyces cerevisiae, demonstrating insignificant inhibition on eukaryotic cell growth following 6, 12 and 16 h of exposure at a concentration of 500 mg L-1. The study provides baseline information to unravel the ecotoxic effects and to confirm the green aspects of a range of versatile biobased platform molecules.

Three Active Phytotoxic Compounds from the Leaves of Albizia richardiana (Voigt.) King and Prain for the Development of Bioherbicides to Control Weeds.

The global population is increasing day by day. To meet the food demand for such a huge number of people, crop production must increase without damaging the environment, and to prevent synthetic chemical herbicides from polluting the environment, controlling weeds using bioherbicides is essential. Accordingly, using phytotoxic substances obtained from plants for biological weed management has attracted attention. The plant Albizia richardiana possesses phytotoxic compounds that have been previously recorded. Hence, we have conducted this research to characterize more phytotoxic compounds in Albizia richardiana. Aqueous methanolic extracts of Albizia richardiana plant significantly restricted the growth of the examined plants lettuce and Italian ryegrass in a species- and concentration-dependent manner. Three active phytotoxic compounds were isolated through various chromatographic methods and identified as compound 1, 2, and 3. Compound 3 exhibited stronger phytotoxic potentials than the other two compounds and significantly suppressed the growth of Lepidium sativum (cress). The concentration of the compounds required for 50% growth reduction (I50 value) of the Lepidium sativum seedlings ranged between 0.0827 to 0.4133 mg/mL. The results suggest that these three phytotoxic compounds might contribute to the allelopathic potential of Albizia richardiana.

Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes.

String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4'E)-4,4'-(ethane-1,2-diyldiazanylylidene)bis{7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)pyrrolidin-1-yl]-1-cyclopropyl-6-fluoro-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid} (GMFX-en) and its metal complexes were identified and confirmed by elemental analyses, FT-IR, UV/VIS, 1 H-NMR spectra, magnetic susceptibility, conductometric measurements and thermal analyses. The FT-IR spectral data showed the chelation behavior of GMFX-en toward the metal ions through oxygen of carboxylate group and nitrogen of azomethine group. In the light of all spectral data, these complexes presumably have octahedral geometry configurations. Thermal analysis specified that the decaying of the metal complexes exist in two or three steps with the final residue metal oxides. Antimicrobial activity of the new prepared metal complexes was screened against some common phytopathogens and their mode of action has been also discussed. The potential phytotoxic effectiveness of the new complexes was furthermore inspected on two commonly experimental plants. The complexes showed significant antimicrobial and phytotoxic effects against the majority of tested phytopathogens and the two tested plants, respectively. The potential antimicrobial activity of the complexes proved their possibility to be used successfully in agropharmacutical industry to control many serious phytopathogens. The phytotoxicity of the studied complexes also indicated their possibility as potential bio-based herbicides alternatives to weed control in crop fields.

Short-term physiological and biometrical responses of Lepidium sativum seedlings exposed to PET-made microplastics and acid rain.

Plastics enter in terrestrial natural system primarily by agricultural purposes, while acid rain is the result of anthropogenic activities. The synergistic effects of microplastics and acid rain on plant growth are not known. In this study, different sizes of polyethylene terephthalate (PET) and acid rain are tested on Lepidium sativum, in two separate experimental sets. In the first one we treated plants only with PET, in the second one we used PET and acid rain together. In both experimentations we analyzed: i) plant biometrical parameters (shoot height, leaf number, percentage inhibition of seed germination, fresh biomass), and ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione). Results carried out from our experiments highlighted that different sizes of polyethylene terephthalate are able to affect plant growth and physiological responses, with or without acid rain supplied during acute toxicity (6 days). SHORT DESCRIPTION: This study showed that different sizes of PET microplastics affect physiological and biometrical responses of Lepidum sativum seedlings, with or without acid rain; roots and leaves responded differently.

Ecotoxicity profile of heavily contaminated surface water of two rivers in Tunisia.

Persistent organic and inorganic contaminants generated by industrial effluent wastes poses a threat to the maintenance of aquatic ecosystems and public health. The Khniss and Hamdoun rivers, located in the central-east of Tunisia, receive regularly domestic and textile wastewater load. The present study aimed to survey the water quality of these rivers using physicochemical, analytical and toxicological approaches. In the physicochemical analysis, the recorded levels of COD and TSS in both samples exceed the Tunisian standards. Using the analytical approach, several metals and some textile dyes were detected. Indeed, 17 metals were detected in both samples in varying concentrations, which do not exceed the Tunisian standards. The sources of metals pollution can be of natural and anthropogenic origin. Three textile disperse dyes were detected with high levels compared to other studies: the disperse orange 37 was detected in the Khniss river with a concentration of 6.438 µg/L and the disperse red 1 and the disperse yellow 3 were detected in the Hamdoun river with concentrations of 3.873 µg/L and 1895 µg/L, respectively. Textile activities were the major sources of disperse dyes. For both samples, acute and chronic ecotoxicity was observed in all the studied organisms, however, no genotoxic activity was detected. The presence of metals and textile disperse dyes could be associated with the ecotoxicological effects observed in the river waters, in particular due to the industrial activity, a fact that could deteriorate the ecosystem and therefore threaten the human health of the population living in the study areas. Combining chemical and biological approaches, allowed the detection of water ecotoxicity in testing organisms and the identification of possible contributors to the toxicity observed in these multi-stressed water reservoirs.

Potential use of Schumannianthus dichotomus waste: the phytotoxic activity of the waste and its identified compounds.

The phytotoxic potential of the leaves and twigs of Schumannianthus dichotomus, discarded in the mat-making industry against four test plants (lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), foxtail fescue (Vulpia myuros (L.) C.C. Gmel.) and timothy (Phleum pratense L.)) was investigated and found strong phytotoxic activity. An assay-guided fractionation of S. dichotomus extarcts against cress (Lepidium sativum L.) through a series of column chromatography steps yielded two compounds, 8-(5-oxo-2,5-dihydrofuran-2-yl) octanoic acid (ODFO) and (E)-6-hydroxy-2,6-dimethylocta-2,7-dienoic acid (8-carboxylinalool). ODFO and 8-carboxylinalool showed strong phytotoxic activity against cress and timothy. The concentrations required for 50% growth inhibition (I50 value) of the seedlings of cress and timothy were 111.94-128.01 and 36.30-91.75 µM, respectively, for ODFO, but the values were much higher at 315.98-379.13 and 107.92-148.41 µM, respectively, for 8-carboxylinalool, indicating the stronger phytotoxic activity of ODFO. This study is the first to isolate ODFO and 8-carboxylinalool from S. dichotomus and their phytotoxic potential while ODFO is firstly encountered from any natural source. The growth inhibitory activity of the identified compounds may explain their role in the phytotoxic activity of S. dichotomus, which suggests the possible use of its leaves and twigs or its active constituents as natural bioherbicides.

Decomposition and organic amendments chemistry explain contrasting effects on plant growth promotion and suppression of Rhizoctonia solani damping off.

Organic Amendments (OAs) has been used in agroecosystems to promote plant growth and control diseases caused by soilborne pathogens. However, the role of OAs chemistry and decomposition time on plant growth promotion and disease suppression is still poorly explored. In this work, we studied the effect of 14 OAs at four decomposition ages (3, 30, 100, and 300 days) on the plant-pathogen system Lactuca sativa-Rhizoctonia solani. OAs chemistry was characterized via 13C-CPMAS NMR spectroscopy as well as for standard chemical (i.e. N content, pH, EC) and biological parameters (i.e. phytotoxicity and R. solani proliferation bioassay). OAs have shown variable effects, ranging from inhibition to stimulation of Lactuca sativa and Lepidium sativum growth. We recorded that N rich OAs with high decomposability were conducive in the short-term, while converting suppressive in the long term (300 days). On the other hand, cellulose-rich OAs with high C/N ratio impaired L. sativa growth but were more consistent in providing protection from damping-off, although this property has significantly shifted during decomposition time. These results, for the first time, highlight a consistent trade-off between plant growth promotion and disease control capability of OAs. Finally, we found that OAs effects on growth promotion and disease protection can be hardly predictable based on the chemical characteristic, although N content and some 13C CPMAS NMR regions (alkyl C, methoxyl C, and carbonyl C) showed some significant correlations. Therefore, further investigations are needed to identify the mechanism(s) behind the observed suppressive and conducive effects and to identify OAs types and application timing that optimize plant productivity and disease suppression in different agro-ecosystems.

Assessment of phytotoxicity of leachates from landfilled waste and dust from foundry.

The study assesses the contamination, classification and phytotoxicity of foundry waste. The presented results are a part of the research on the agrotechnical use of foundry waste. Landfilled foundry waste (LFW) and dust samples were taken from one of the Polish foundries. An analysis of the waste and its leachate composition was conducted. Phytotoxicity tests were carried out using Lepidium sativum. The aim of the phytotoxicity study was to evaluate germination and root growth after 72 h and the accumulation of heavy metals after 7 days. LFW was least contaminated with heavy metals and metalloids compared to dust. The composition of the foundry dusts depended on the unit of the foundry, from which it was collected. It was found that electric arc furnace dust (EAFD) was the most polluted by heavy metals among the dust samples. According to the requirements of Polish regulations most of tested waste were classified as non-hazardous, and EAFD as hazardous waste due to high Pb concentration in leachate. Phytotoxicity tests have shown a low phytotoxicity of the leachate from most of the tested waste. The results of the accumulation test showed that an excess of metal and metalloids in leachate was not directly related to its accumulation in plants. A negative correlation between EC, Cu, Co, Fe, Pb, Cr, K, Na, sulfate, fluoride, ammonia, phenol and formaldehyde concentration in leachate and GI was found. It was stated that the Fe, Mn, As and Se in plants was significantly correlated with concentrations in leachate.

An Oxygen Delivery Polymer Enhances Seed Germination in a Martian-like Environment.

Critical to the success of establishing a sustainable human presence on Mars is the ability to economically grow crop plants. Several environmental factors make it difficult to fully rely on local resources for agriculture. These include nutrient sparse regolith, low and fluctuating temperatures, a high amount of ultraviolet radiation, and water trapped locally in the form of ice or metal oxides. While the 96% CO2 martian atmosphere is ideal to support photosynthesis, high CO2 concentrations inhibit germination. An added difficulty is the fact that a vast majority of crop plants require oxygen for germination. Here, we report the production of a polymer-based oxygen delivery system that supports the germination and growth of cress seeds (Lepidium sativum) in a martian regolith simulant under a martian atmosphere at 101 kPa. The oxygen-donating system is based on a low-density lightly cross-linked polyacrylate that is foamed and converted into a dry powder. It is lightweight, added in low amounts to regolith simulant, and efficiently donates enough oxygen throughout the volume of hydrated regolith simulant to fully support seed germination and plant growth. Germination rates, plant development, and plant mass are nearly identical for L. sativum grown in 100% CO2 in the presence of the oxygen-donating lightly cross-linked polyacrylate compared with plants grown in air. The polymer system also serves to protect root structures and better anchors plants in the regolith simulant.

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

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

Characterization of heavy metal toxicity in some plants and microorganisms-A preliminary approach for environmental bioremediation.

In situ bioremediation processes are important for control of pollution and clean-up of contaminated sites. The study and implementation of such processes can be designed through investigations on natural mechanisms of absorption, biotransformation, bioaccumulation and toxicity of pollutants in plants and microorganisms. Here, the phytotoxic effects of Cr(VI) and Cd(II) on seed germination and plant growth of Lepidium sativum have been examined at various concentrations (30-300 mg/L) in single ion solutions. The studies also addressed the ecotoxicity of metal ions on Azotobacter chroococcum and Pichia sp. isolated from soil. Microbial growth was estimated by weighing the dry biomass and determining the enzymatic activities of dehydrogenase and catalase. The results showed that Cr(VI) and Cd(II) can inhibit L. sativum seed germination and root development, depending on the metal ion and its concentration. The phytotoxic effect of heavy metals was also confirmed by the reduced amounts of dried biomass. Toxicity assays demonstrated the adverse effect of Cr(VI) and Cd(II) on growth of Azotobacter sp. and Pichia sp., manifested by a biomass decrease of more than 50 % at heavy metal concentrations of 150-300 mg/L. The results confirmed close links between phytotoxicity of metals and their bioavailability for phytoextraction. Studies on the bioremediation potential of soils contaminated with Cr(VI) and Cd(II) using microbial strains focusing on Azotobacter sp. and Pichia sp. showed that the microbes can only tolerate heavy metal stress at low concentrations. These investigations on plants and microorganisms revealed their ability to withstand metal toxicity and develop tolerance to heavy metals.

Biotransformation and toxicity effect of monoanthraquinone dyes during Bjerkandera adusta CCBAS 930 cultures.

The aim of this study was to evaluate of possibility of biotransformation and toxicity effect of monoanthraquinone dyes in cultures of Bjerkandera adusta CCBAS 930. Phenolic compounds, free radicals, phytotoxicity (Lepidium sativum L.), ecotoxicity (Vibrio fischeri) and cytotoxicity effect were evaluated to determine the toxicity of anthraquinone dyes before and after the treatment with B. adusta CCBAS 930. More than 80% of ABBB and AB129 was removed by biodegradation (decolorization) and biosorption, but biodegradation using oxidoreductases was the main dye removing mechanism. Secondary products toxic to plants and bacteria were formed in B. adusta strain CCBAS 930 cultures, despite efficient decolorization. ABBB and AB129 metabolites increased reactive oxygen species (ROS) production in human fibroblasts, but did not increase LDH release, did not affect the resazurine reduction assay and did not change caspase-9 or caspase-3 activity.

Effect of inoculated azotobacteria and Phanerochaete chrysosporium on the composting of olive pomace: Microbial community dynamics and phenols evolution.

The effect of inoculated azotobacteria and basidiomycetes white-rot fungi on the population dynamics of bacteria and eumycetes during the co-composting of olive mill pomace and wheat straw was evaluated by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis combined with sequencing of rRNA gene amplicons from selected DGGE bands. The evolution of pH, temperature, phytotoxicity and water-soluble phenol content during co-composting was also monitored. In general, a similar evolution of microbial biodiversity was seen in both the inoculated and uninoculated (control) piles, which was in keeping with a similar evolution of phytotoxicity and water-soluble phenol content. Overall, under the conditions applied, data suggest a marginal influence of the inoculated starters on the physical, chemical and microbiological properties of compost piles, with the resident microbiota playing a major role.

Physicochemical and toxicological characterization of hazardous wastes from an old glasswork dump at southeastern part of Sweden.

More than 34 old glasswork sites in the southeastern part of Sweden pose a permanent threat to human and environmental health due to the presence of toxic trace elements in open dumps with glass waste. The possibility of leaching of trace elements from different fractions of the disposed waste needed to be assessed. In the present investigation, leachate from a mixture of soil and waste glass of particle sizes of less than 2 mm (given the name fine fraction) was characterized by analyzing the pH (7.3), total organic content (TOC < 2%), organic matter content (4.4%), moisture content (9.7%), chemical oxygen demand (COD, 163 mg/kg) and trace elements content, being the values in accordance to the Swedish guidelines for landfilling of inert materials. However, very high trace elements content was found in the fine fraction as well as in all colors of waste glass, whose values were compatible to hazardous waste landfill class. Tests with Lepidium sativum growing in the fine fraction as substrate revealed chronic toxicity expressed as inhibition of root biomass growth in 11 out of 15 samples. Additionally, leachate from fine fractions posed acute toxicity to genetically modified E. coli (Toxi-Chromotest). This study highlights the importance of combining physicochemical characterization with toxicity tests for both solid waste and leachate obtained from different waste fractions for proper hazardousness assessment supporting decision making on remediation demands.

Impact of ZnO and ZnS nanoparticles in sewage sludge-amended soil on bacteria, plant and invertebrates.

The effect of zinc oxide nanoparticles (ZnO NPs) and zinc sulfide nanoparticles (ZnS NPs) on the toxicity of sewage sludges in sewage sludge-amended soils was investigated with respect to plant- (Lepidium sativum) and soil- (Folsomia candida) species. The toxicity of porewater obtained from the tested soils towards Vibrio fischeri (Microtox®) was also investigated. Two sewage sludges (SSL1 and SSL2) with different organic matter content were amended with nanoparticles. Depending on the type of biotest and the type of sewage sludge, different effects of ZnO or ZnS NPs on the toxicity of sewage sludge-amended soil were observed. In general, ZnO and ZnS NPs stimulated root growth for SSL1 or reduced the harmful impact of SSL2 on the root growth of L. sativum roots. Greater stimulation or inhibition of root growth was observed for the ZnO than ZnS NPs. The unfavorable effect of ZnO/ZnS NPs on F. candida mortality and reproduction was observed at a concentration of ZnO/ZnS in sewage sludge ≥250 mg/kg. Generally, there were no significant differences between ZnO and ZnS NPs toxicity towards F. candida. Aging for 45 days of sewage sludge-amended soil containing NPs affected ZnO and ZnS NPs toxicity to all tested organisms. In the most cases, the toxicity decreased after 45 days of aging for plant (L. sativum) and invertebrates (F. candida). The toxicity of porewater to V. fischeri from sewage sludge-amended soil contains ZnO NPs did not change, while in the case of ZnS NPs, the toxicity increased after 45 days of aging.

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones and -benzo[ b][1,4]thiazinones: Synthesis and Investigation of Their Effects on Glycogen Phosphorylase and Plant Growth Inhibition.

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones were obtained via the corresponding 2-nitrophenyl glycosides obtained by two methods: (a) AgOTf-promoted glycosylation of 2-nitrophenol derivatives by O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate or (b) Mitsunobu-type reactions of O-perbenzoylated methyl (α-d-gluculopyranose)heptonate with bulky 2-nitrophenols in the presence of diethyl azodicarboxylate (DEAD) and PPh3. Catalytic hydrogenation (H2-Pd/C) or partial reduction (e.g., H2-Pd/C, pyridine) of the 2-nitro groups led to spiro-benzo[ b][1,4]oxazinones and spiro-benzo[ b][1,4]-4-hydroxyoxazinones by spontaneous ring closure of the intermediate 2-aminophenyl or 2-hydroxylamino glycosides, respectively. The analogous 2-aminophenyl thioglycosides, prepared by reactions of O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate with 2-aminothiophenols, were cyclized in m-xylene at reflux temperature to the corresponding spiro-benzo[ b][1,4]thiazinones. O-Debenzoylation was effected by Zemplén transesterification in both series. Spiro-configurations were determined by NMR and electronic circular dichroism time-dependent density functional theory (ECD-TDDFT) methods. Inhibition assays with rabbit muscle glycogen phosphorylase b showed (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} and (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]thiazin-3(4 H)-one} to be the most efficient inhibitors (27 and 28% inhibition at 625 µM, respectively). Plant growth tests with white mustard and garden cress indicated no effect except for (1' R)-4-hydroxyspiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} with the latter plant to show modest inhibition of germination (95% relative to control).

Microplastics accumulate on pores in seed capsule and delay germination and root growth of the terrestrial vascular plant Lepidium sativum.

The impacts of nano- and microplastics (<100 nm and <5 mm, respectively) on terrestrial systems is to the present largely unexplored. Plastic particles are likely to accumulate in these systems primarily by the application of sewage sludge. The aim of the current study was to investigate the effects of three sizes of plastic particles (50, 500, and 4800 nm) on a terrestrial plant (cress; Lepidium sativum), using a standardized 72 h bioassay. Cress seeds were exposed to five different concentrations of plastics, ranging from 103 to 107 particles mL-1. Germination rate was significantly reduced after 8 h of exposure for all three sizes of plastics, with increased adverse effect with increasing plastic sizes. Seeds exposed to 4800 nm microplastics showed a germination rate decline from 78% in control to 17% in the highest exposure. No difference in germination rate occurred after 24 h of exposure, regardless of the size of the plastic used. Significant differences in root growth were observed after 24 h, but not after 48 or 72 h of exposure. Impacts on germination are likely due to physical blockage of the pores in the seed capsule by microplastics as shown by confocal microscopy of fluorescent microplastics. In later stages, the microplastics particularly accumulated on the root hairs. This is the first detailed study on the effect of nano- and microplastics on a vascular, terrestrial plant, and our results indicate short-term and transient adverse effects.

Ecotoxicological effects of traffic-related pollutants in roadside soils of Moscow.

The objective of this research is to find correlations between traffic-related contaminants in the roadside soils and their ecotoxicity. The study was conducted in Moscow in the vicinity of a highway of 125 000 vehicles per day. The topsoils (0-3 cm depth) were sampled perpendicular to the road at 1-, 6-, 10-, 18- and 50-m distances from the roadbed. Total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAH), heavy metals (HM) in total and phyto-available forms, and deicing salts (DS) were determined. A battery of soil-contacting organisms was tested: phytotoxicity of rye (H. vulgare L.) and garden cress (L. sativum L.); E. foetida earthworm growth rate and mortality; basal and substrate-induced respiration activity, nitrogen fixation and the denitrification activity of the soil microbial complex. To determine the possible risk to aquatic ecosystems, the algal toxicity test (S. quadricauda) was provided. Correlations between "chemical" data and intensity of "biological" effects were analyzed. Concentrations of most contaminants declined to the background values with distance from the road increase. However, the toxicity of roadside soils was obtained for all examined organisms within the whole 50 m zone. Live organisms exhibited different sensitivities to roadside soils pollution. The intensity of inhibition effects decreased in order: higher plants > earthworms and microorganisms > algae. The risk for aquatic ecosystems was assessed as low. Higher plants toxicity correlated with TPH, PAH, some HM, and DS; earthworm toxicity correlated with TPH, some PAH, HM, and DS; microorganism toxicity correlated with TPH and DS; algae had no observed correlations with contaminants. TPH and DS were general ecotoxicants affecting all organisms. Higher plants may be considered the PAH indicators and earthworms as HM indicators. A set of higher plants and earthworms may be recommended as the reduced test-battery of relevant organisms for cost-effective assessment of the toxicity of roadside soils.