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Salt stress is one of the major limiting factors for plant production, and the quality of medicinal plants is also affected by soil salinity. Hyssop (Hyssopus officinalis L.) plants were cultivated for four weeks in perlite: sand and irrigated with Hoagland nutrient solution containing 0, 50, 100, 150, and 200 mM NaCl. Plants growth was decreased by salt stress while the leaf relative water content was not affected, and the chlorophyll content decreased only by the highest salt concentration (200 mM). Sodium was accumulated at small amounts, indicating a high ability of this species to exclude salt. Soluble sugars and proline were accumulated up to 1.6 and 4.5 fold, respectively. The antioxidant enzymes activity (peroxidase, catalase, ascorbate peroxidase) were increased by the salt treatments, particularly in the leaves. The levels of secondary metabolites (saponins, phenolics, flavonoids, anthocyanins, and iridoids) were all increased under salt stress, and the total antioxidant capacity of alcoholic extract of the leaves and roots was significantly higher in the salt-treated compared with control plants. Our results showed that hyssop is a salt-tolerant species, and the quality of this medicinal plant is improved when grown under saline conditions.

Green algae are dominant primary producers in aquatic environments. Thus, assessing the influences of pollutants such as nanoparticles on the algae is of high ecological significance. In the current study, cadmium selenide nanoparticles (CdSe NPs) were synthesized using the hydrothermal method and their characteristics were determined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FT-IR) techniques. Subsequently, the toxicity of synthesized nanoparticles on the green microalga Chlorella vulgaris was investigated. The observations by SEM confirmed that exposure to CdSe NPs had severe impacts on the algal morphology. Furthermore, the obtained results revealed the toxic effect of CdSe NPs by a decrease in the number of cells. Measurement of antioxidant enzymes activity showed an increase in the activity of catalase, and a decrease in the activity of superoxide dismutase (SOD) at high concentrations of CdSe NPs. The exposure of C. vulgaris to CdSe NPs resulted also in a change in algal pigments as well as total phenol content. Taken together, CdSe NPs appeared to have significant cytotoxic effects on C. vulgaris in the applied concentrations.

Polycyclic aromatic hydrocarbons (PAHs) have high risks for human and living organisms due to their mutagenic and carcinogenic properties. Here, the effect of different concentrations of fluorene as a persistent toxic PAH on growth parameters and antioxidant systems in the green microalga Chlorella vulgaris was investigated. Intriguingly, cell number as well as dry and fresh weight of the alga were raised at 2 ppm fluorene compared to the control sample. However, with the increasing levels of fluorene from 10 to 50 mg L−1, the growth parameters gradually decreased. Accordingly, cells of C. vulgaris were found to enhance the activity of ROS scavenging enzymes after 7 days of exposure to fluorene in a concentration-dependent manner. Exposure to 25 and 50 mg L−1 fluorene was led to a significant decrease at chlorophyll content, whereas the concentration of carotenoids was not changed. Total phenol and flavonoid contents were markedly raised in 50 mg L−1 of fluorene compared to the control. Although flow cytometry assessment showed no substantial reduction in the viability at 50 mg L−1 fluorene-treated samples for 24 h, chlorophyll fluorescence was noticeably reduced. The results of SEM analysis revealed that the 50 mg L−1 fluorene treatment clearly damaged the algal cells after 24 h. The ability of the alga for biodegradation of fluorene was assessed by GC-MS. Consequently, a number of produced intermediate compounds were identified. These findings displayed that C. vulgaris had not only notable resistance against fluorene but also noteworthy potential for its degradation.

The toxic impacts of CuO nanoparticles (NPs) on the marine phytoplankton Nannochloropsis oculata were evaluated by measuring a number of biological parameters. Exposure to different concentrations of CuO-NPs (5–200 mg/L) significantly decreased the growth and content of chlorophyll a of N. oculata. The results showed that CuO-NPs were toxic to this microalga with a half maximal effective concentration (EC50) of 116.981 mg/L. Exposure to CuO-NPs increased the hydrogen peroxide (H2O2) content and induced the membrane damages. Moreover, the concentration of phenolic compounds was increased, while the levels of carotenoids were markedly decreased in comparison to the control sample. The activity of catalase (CAT), ascorbate peroxidase (APX), polyphenol oxidase (PPO) and lactate dehydrogenase (LDH) enzymes significantly was increased in response to CuO-NPs treatments. These results indicated that CuO-NPs stimulated the antioxidant defense system in N. oculata to protect the cells against the oxidative damages. The Fourier-transform infrared spectroscopy (FTIR) analyses showed that the main functional groups (C=O and C–O–C) interacted with CuO-NPs. The images of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the cell membrane damage and the change of cell wall structure which may be contributed to the nanotoxicity. These findings may provide additional insights into the mechanisms of cytotoxicity induced by CuO-NPs.

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic pollutants effecting different aspects of plants physiology. To assess the physiological responses of plants to PAHs, maize (Zea mays) was treated with 25, 50, 75, and 100 ppm of pyrene and after 21 days, the activity of some antioxidant enzymes, malondialdehyde (MDA), total flavonoid, total anthocyanin, and soluble sugar contents were measured in shoots and roots of plants. Pyrene led to increase MDA content as well as CAT, POD, and SOD activities. Increase in pyrene concentration reduced all studied growth variables and significantly increased photosynthetic pigments contents of plants. Soluble sugar content was significantly higher in the shoot, while that was reduced in the roots through increasing of pyrene concentration (p < 0.05). Also, the increase of pyrene concentration decreased total flavonoid content compared to anthocyanin content. In conclusion, these findings supported the hypothesis that pyrene toxicity induces oxidative stress in the maize plant and it also increases the antioxidant systems in order to moderating stress condition. However, the antioxidant system of maize was not strong enough to eliminate all produced ROS at high concentrations, thus this caused oxidative damage to the plant and decreased its growth variables.

The growing demands for nanotechnology in the recent years have resulted in environmental release of nanomaterials. In the current study, reduced graphene oxide-silver nanocomposites (Ag-rGO) were synthesized by an easy method and their characteristics were determined using X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), energy dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) techniques. Subsequently, toxicity of Ag-rGO was examined on the marine microalga Chlorella vulgaris. After treatment of algal cells with different concentrations of Ag-rGO for 24 h, growth parameters have been significantly decreased. In addition, a considerable reduction in viability of the treated cells was designated. Further considerable effects of Ag-rGO treatments have been revealed by increments in the activities of a number of antioxidant enzymes and reductions in the photosynthetic pigment contents. Our results showed that the main toxic effects of Ag-rGO are associated with the presence of Ag nanoparticles in the structure of these nanocomposites.

Nanotechnology has quite a lot of applications in various fields of industrial sectors like food and agriculture. Although nanotechnology can improve the quality of life, its possible associated risks should be assessed. Here copper oxide nanoparticles (CuO NPs) were synthesized by chemical (polymer pyrolysis) and biological (green) methods with an average size of 30 and 44 nm, respectively. Afterwards, a cell biology approach was applied to evaluate the toxic effects of chemically and biologically synthesized CuO nanoparticles on tobacco cell suspension cultures. Both types of CuO nanoparticles significantly dropped the viability of the cells in a dose and time dependent manner. Accordingly, tobacco cells were found to increase the activity of antioxidant enzymes after 48 h of exposure to nanoparticles. The production of reactive oxygen species (ROS) and malondialdehyde (MDA) in a dose dependent manner was also observed. Assessment of the toxicity of CuO NPs revealed that chemically synthesized NPs were more toxic than biologically synthesized ones. It can be concluded that the organic components of the plant extract as capping agents that remain on the surface of green synthesized CuO NPs may reduce their toxicity effects.

Chemical constituents of the essential oil isolated from Salvia sahendica at different growth stages (vegetative, flowering and seeding (S-S) were identified. Among 50 identified oil constituents, ...

Plants are essential components of all ecosystems and play a critical role in environmental fate of nanoparticles. However, the toxicological impacts of nanoparticles on plants are not well documented. Titanium dioxide nanoparticles (TiO2-NPs) are produced worldwide in large quantities for a wide range of purposes. In the present study, the uptake of TiO2-NPs by the aquatic plant Spirodela polyrrhiza and the consequent effects on the plant were evaluated. Initially, structural and morphological characteristics of the used TiO2-NPs were determined using XRD, SEM, TEM and BET techniques. As a result, an anatase structure with the average crystalline size of 8nm was confirmed for the synthesized TiO2-NPs. Subsequently, entrance of TiO2-NPS to plant roots was verified by fluorescence microscopic images. Activity of a number of antioxidant enzymes, as well as, changes in growth parameters and photosynthetic pigment contents as physiological indices were assessed to investigate the effects of TiO2-NPs on S. polyrrhiza. The increasing concentration of TiO2-NPs led to the significant decrease in all of the growth parameters and changes in antioxidant enzyme activities. The activity of superoxide dismutase enhanced significantly by the increasing concentration of TiO2-NPs. Enhancement of superoxide dismutase activity could be explained as promoting antioxidant system to scavenging the reactive oxygen species. In contrast, the activity of peroxidase was notably decreased in the treated plants. Reduced peroxidase activity could be attributed to either direct effect of these particles on the molecular structure of the enzyme or plant defense system damage due to reactive oxygen species.

Nanoparticles have potential high risks for living organisms in the environment due to their specific qualities and their easy access. In the present study, selenium nanoparticles (Se NPs) with two different coatings (l-cysteine and tannic acid) were synthesized. The characteristics of particles were analyzed using XRD, FT-IR and SEM. The impact of the nanoparticles besides Se4+, on the aquatic higher plant Lemna minor was evaluated and compared. Entrance of l-cysteine and tannic acid capped Se NPs in the roots of Lemna minor was proved by TEM and fluorescence microscopy. Adverse effects of mentioned NPs and differences of these effects from those by sodium selenite as the ionic form were assessed by a range of biophysicochemical tests. Altogether, the results asserted that Lemna minor was notably poisoned by both capped Se NPs and Se4+. Thus, growth and photosynthetic pigments were decreased while lipid peroxidation along with total phenol and flavonoid contents were raised. Eventually some changes in enzymatic activities were presented. To sum up the consequences, it can be concluded that all changes occurred due to the plant defense system especially in order to remove reactive oxygen species (ROS) and possible phytotoxicity originated by l- cysteine and tannic acid capped Se NPs in addition to Se4+. The influence of tannic acid capped Se NPs after sodium selenite is stronger by the means of antioxidant enzymes activity in comparison with l-cysteine capped Se NPs.

The surface characteristics of nanoparticles cause their influx into the environment and lead to their interaction with fungi, algae, and plants. In the present study, the toxic effects of copper oxide nanoparticles were studied on the higher aquatic plant Spirodela polyrrhiza. Copper oxide nanoparticles were synthesized using green sonochemistry and their surface specifications were determined using XRD and SEM. The entrance and uptake of CuO nanoparticles in the roots of S. polyrrhiza was confirmed using fluorescence microscopy. The toxicity of CuO nanoparticles on S. polyrrhiza was investigated by measuring the growth rate (relative frond number), enzymatic activities (peroxidase, superoxide dismutase, and catalase) and content of photosynthetic pigments. In all experiments, the negative effects of CuO nanoparticles on the growth of S. polyrrhiza were confirmed by means of growth and enzymatic and pigment assays. Accordingly, significant changes in antioxidant enzyme activity were achieved. Catalase, peroxidase, and superoxide dismutase activity were increased due to the plant's defence system for scavenging the reactive oxygen species. In addition, relative frond number and chlorophyll content were reduced owing to possible phytotoxicity generated by CuO nanoparticles.

Cadmium selenide nanoparticles (CdSe NPs) were synthesized by an easy and simple method and their properties were assessed by XRD, TEM and SEM techniques. The effects of CdSe NPs as well as Cd2+ ions on Lemna minor plants were investigated. The absorption of CdSe NPs by the plants had some adverse consequences that were assessed by a range of biological analyses. The results revealed that both CdSe NPs and the ionic form of cadmium noticeably caused toxicity in L. minor. Morphological parameters as well as peroxidase (POD) activity were deteriorated. In contrast, the activities of some other antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) as well as the contents of total phenol and flavonoids went up. Taken all together, it could be implied that CdSe NPs as well as Cd2+ were highly toxic to plants and stimulated the plant defense system in order to scavenge produced reactive oxygen species (ROS).

Phytoremediation potential of the aquatic plant Spirodela polyrrhiza was examined for direct blue 129 (DB129) azo dye. The dye removal efficiency was optimized under the variable conditions of the operational parameters including removal time, initial dye concentration, pH, temperature and amount of plant. The study reflected the significantly enhanced dye removal efficiency of S. polyrrhiza by increasing the temperature, initial dye concentration and amount of plant. Intriguingly, artificial neural network (ANN) predicted the removal time as the most dominant parameter on DB129 removal efficiency. Furthermore, the effect of dye treatment on some physiologic indices of S. polyrrhiza including growth rate, photosynthetic pigments content, lipid peroxidation and antioxidant enzymes were studied. The results revealed a reduction in photosynthetic pigments content and in multiplication of fronds after exposure to dye solution. In contrast, malondialdehyde content as well as catalase (CAT) and peroxidase (POD) activities significantly increased that was probably due to the ability of plant to overcome oxidative stress. As a result of DB129 biodegradation, a number of intermediate compounds were identified by gas chromatography-mass spectroscopy (GC-MS) analysis. Accordingly, the probable degradation pathway of DB129 in S. polyrrhiza was postulated.

A clear consequence of the increasing application of nanotechnology is its adverse effect on the environment. Semiconductor nanoparticles are among engineered nanomaterials that have been considered recently for their specific characteristics. In the present work, zinc selenide nanoparticles (ZnSe NPs) were synthesized and characterized by XRD, TEM, DLS and SEM. Biological aspects related to the impact of nanoparticles and Zn2+ ions were analyzed on the aquatic higher plant Lemna minor. The localization of ZnSe NPs in the root cells of L. minor was determined by TEM and fluorescence microscopy. Then, the entrance of ZnSe NPs into the plant cells was evaluated by a range of biological tests. The outcomes revealed that both the NPs and the ionic forms noticeably poisoned L. minor. In one hand, growth parameters and physiological indices such as photosynthetic pigments content were decreased. On the other hand, the activities of some antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)), as well as the contents of nonenzymatic antioxidants (phenols and flavonoids) were elevated. Taken together, high concentration of ZnSe NPs and Zn2+ triggered phytotoxicity which in turn provoked the plants' defense system. The changes in antioxidant activities confirmed a higher toxicity by Zn2+ ions in comparison with ZnSe NPs. It means that the considered ions are more hazardous to the living organisms than the nanoparticles.

The present study was conducted to evaluate the potential of aquatic vascular plant, Nasturtium officinale, for degradation of C.I. Acid Blue 92 (AB92). The effect of operational parameters such as initial dye concentration, plant biomass, pH, and temperature on the efficiency of biological decolorization process was determined. The reusability of the plant in long term repetitive operations confirmed the biological degradation process. The by-products formed during biodegradation process were identified by GC-MS technique. The effects of the dye on several plant physiological responses such as photosynthetic pigments content and antioxidant enzymes activity were investigated. The content of chlorophyll and carotenoids was significantly reduced at 20 mg/L of the dye. The activities of superoxide dismutase and peroxidase were remarkably increased in the plant root verifying their importance in plant tolerance to the dye contamination.

The potential of pennywort (Hydrocotyle vulgaris) for phytoremediation of C.I. Acid Blue 92 (AB92) was evaluated. The effects of various experimental parameters including pH, temperature, dye concentration and plant weight on dye removal efficiency were investigated. The results showed that the optimal condition for dye removal were pH 3.5 and temperature 25 degree C. Moreover, the absolute dye removal enhanced with increase in the initial dye concentration and plant weight. Pennywort showed the same removal efficiency in repeated experiments (four runs) as that obtained from the first run (a 6-day period). Therefore, the ability of the plant in consecutive removal of AB92 confirmed the biodegradation process. Accordingly, a number of produced intermediate compounds were identified. The effect of treatment on photosynthesis and antioxidant defense system including superoxide dismutase, peroxidase and catalase in plant roots and leaves were evaluated. The results revealed a reduction in photosynthetic pigments content under dye treatments. Antioxidant enzyme responses showed marked variations with respect to the plant organ and dye concentration in the liquid medium. Overall, the increase in antioxidant enzyme activity under AB92 stress in the roots was much higher than that in the leaves. Nevertheless, no significant increase in malondialdehyde content was detected in roots or leaves, implying that the high efficiency of antioxidant system in the elimination of reactive oxygen species. Based on these results, pennywort was founded to be a capable species for phytoremediation of AB92-contaminated water, may be effective for phytoremediation dye-contaminated polluted aquatic ecosystems.

The potential of Hydrocotyle vulgaris as an aquatic plant species was evaluated for phytoremediation of C.I. Basic Red 46 (BR46) from nutrient solution. Under the optimized experimental conditions, BR46 was removed up to 95% from incubation medium by H. vulgaris. The ability of the plant in consecutive removal under long term repetitive experiments confirmed the biodegradation process. Accordingly, a number of produced intermediate compounds were identified. An artificial neural network (ANN) model was developed to predict the biodegradation efficiency. A predictive performance (R(2)=0.974) was obtained based on the network results. Interestingly, dye stress enhanced the activity of antioxidant enzymes including superoxide dismutase, peroxidase and catalase in H. vulgaris roots and leaves. Enzymatic responses found to be highly depended on the plant organ and dye concentration in the liquid medium. Overall, the increase in the activity of antioxidant enzymes was much higher in the roots than in the leaves. Nevertheless, no significant increase in the malondialdehyde (MDA) content was detected in both roots and leaves which reflects the high efficiency of antioxidant system in the elimination of reactive oxygen species.

This study was carried out to investigate the potential of duckweed (Lemna minor L.) for bioremediation of C.I. Basic Red 46 (BR46) solution. Our results revealed the notable ability of the plant species in biological degradation of BR46. The reusability of the plant in long-term repetitive operations was also confirmed. The decolorization efficiency was extremely dependent on different operational parameters such as initial dye concentration, pH, temperature, and amount of plant. Interestingly, activities of superoxide dismutase and peroxidase as antioxidant enzymes were increased in different concentrations of the dye. In contrast, catalase activity declined in duckweed plants exposed to the dye. An artificial neural network (ANN) model was developed to predict the biological decolorization efficiency. The obtained data indicated that ANN provide realistic predictive performance (R2 = 0.981). © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1082–1089, 2013

Plants play an important role in the fate of nanoparticles in the environment through their uptake, bioaccumulation, and transfer to trophic chains. However, the impacts of nanoparticles on plants as essential components of all ecosystems are not well documented. In the present study, the toxic effects of l-Cysteine-capped CdS nanoparticles on Spirodela polyrrhiza as an aquatic higher plant species were studied. l-Cysteine-capped CdS nanoparticles were synthesized using hydrothermal method and their characteristics were determined by XRD, SEM, HR-TEM, and FT-IR techniques. The diameter of majority of synthesized nanoparticles was about 15–20 nm. Subsequently, the uptake of l-Cysteine-capped CdS nanoparticles by the plant species was confirmed using epifluorescence microscopy. The activity of peroxidase and superoxide dismutase as antioxidant enzymes was assayed and the relative frond number was calculated in the presence of different concentrations of l-Cysteine-capped CdS nanoparticles. The obtained results revealed the toxic effects of the synthesized nanoparticles on S. polyrrhiza, leading to growth reduction and significant changes in antioxidant enzymes’ activity.

The potential of an aquatic fern, Azolla filiculoides, in phytoremediation of a mono azo dye solution, C.I. Acid Blue 92 (AB92), was studied. The effects of operational parameters such as reaction time, initial dye concentration, fern fresh weight, pH, temperature and reusability of the fern on biodegradation efficiency were investigated. The intermediate compounds produced by biodegradation process were analyzed using GC-MS analysis. An artificial neural network (ANN) model was developed to predict the biodegradation efficiency. The findings indicated that ANN provides reasonable predictive performance (R2 = 0.961). The effects of AB92 solutions (10 and 20 mg L(-1)) on growth, chlorophylls and carotenoids content, activity of antioxidant enzymes such as superoxide dismutase, peroxidase and catalase and formation of malondialdehyde were analyzed. AB92 generally showed inhibitory effects on the growth. Moreover, photosynthetic pigments in the fronds significantly decreased in the treatments. An increase was detected for lipid peroxidation and antioxidant enzymes activity, suggesting that AB92 caused reactive oxygen species production in Azolla fronds, which were scavenged by induced activities of antioxidant enzymes.

The genus Astragalus is a rich source of a variety of biologically active compounds including phenols, saponins, polysaccharides and essential oils. The present study was conducted to determine ontogenetic variation of the volatile organic compounds as well as total phenolic contents and antioxidant activity in leaves of A. compactus. The leaves of plant were harvested at vegetative, flowering and fructification stages and were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). Total phenolic content (TPC) was determined using the Folin-Ciocalteau reagent and the antioxidant capacity was evaluated with the 1,1- diphenyl-2-picrylhydrazyl (DPPH) test. Different classes of volatile compounds were identified including alcohols, esters, hydrocarbons, sterols and terpenoides. Significant variation of these compounds was found during phenological stages of development. Sterols and hydrocarbons were the main components of essential oils at the vegetative stage. The presence of terpenoides (phytol) and alcohols (docosanol) was significant at the flowering stage. Fructification phase was characterized by the high content of sterols and hydrocarbons and absence of phytol. The antioxidant activity and phenolic content were related to the physiological stage and the highest amount detected at fructification phase. The ontogenetic variations of phenolic contents and antioxidant properties are largely contributed by climatic factors such as temperature and solar radiation., EXCLI Journal ; Vol. 11, 2012