The Stimulatory Effect of Strontium Ions on Phytoestrogens Content in Glycine max (L.) Merr

Neuroprotective potential of formononetin, a naturally occurring isoflavone phytoestrogen

The increased prevalence of neurological illnesses is a burgeoning challenge to the public healthcare system and presents greater financial pressure. Formononetin, an O-methylated isoflavone, has gained a lot of attention due to its neuroprotective potential explored in several investigations. Formononetin is widely found in legumes and several types of clovers including Trifolium pratense L., Astragalus membranaceus, Sophora tomentosa, etc. Formononetin modulates various endogenous mediators to confer neuroprotection. It prevents RAGE activation that results in the inhibition of neuronal damage via downregulating the level of ROS and proinflammatory cytokines. Furthermore, formononetin also increases the expression of ADAM-10, which affects the pathology of neurodegenerative disease by lowering tau phosphorylation, maintaining synaptic plasticity, and boosting hippocampus neurogenesis. Besides these, formononetin also increases the expression of antioxidants, Nrf-2, PI3K, ApoJ, and LRP1. Whereas, reduces the expression of p65-NF-κB and proinflammatory cytokines. It also inhibits the deposition of Aβ and MAO-B activity. An inhibition of Aβ/RAGE-induced activation of MAPK and NOX governs the protection elicited by formononetin against inflammatory and oxidative stress-induced neuronal damage. Besides this, PI3K/Akt and ER-α-mediated activation of ADAM10, ApoJ/LRP1-mediated clearance of Aβ, and MAO-B inhibition-mediated preservation of dopaminergic neurons integrity are the major modulations produced by formononetin. This review covers the biosynthesis of formononetin and key molecular pathways modulated by formononetin to confer neuroprotection.

Extraction of Isoflavones, Alpha-Hydroxy Acids, and Allantoin from Soybean Leaves-Optimization by a Mixture Design of the Experimental Method

Soybeans are commonly known as a valuable source of biologically active compounds including isoflavones as well as allantoin and alpha-hydroxy acids. Since these compounds exhibit skin therapeutic effects, they are widely used in the cosmetic and pharmaceutical industries. The presented paper shows the optimization of three solvent systems (ethanol, water, and 1,3-propanediol) to increase the extraction efficiency of isoflavones (daidzin, genistin, 6″-O-malonyldaidzin, 6″-O-malonylglycitin, 6″-O-malonylgenistin), allantoin, and alpha-hydroxy acids (citric acid, malic acid) from soybean leaves. A simplex centroid mixture design for three solvents with interior points was applied for the experimental plan creation. Based on the obtained results of metabolite extraction yield in relation to solvent composition, polynomial regression models were developed. All models were significant, with predicted R-squared values between 0.77 and 0.99, while in all cases the model's lack of fit was not significant. The optimal mixture composition enabling the maximization of extraction efficiency was as follows: 32.9% ethanol, 53.9% water, and 13.3% propanediol (v/v/v). Such a mixture composition provided the extraction of 99%, 91%, 100%, 92%, 99%, 70%, 92%, and 69% of daidzin, genistin, 6″-O-malonyldaidzin, 6″-O-malonylglycitin, 6″-O-malonylgenistin, allantoin, citric acid, and malic acid, respectively. The solvent mixture composition developed provides a good extraction efficiency of the metabolites from soybean leaves and high antioxidant properties.

Transcriptome analysis revealed that jasmonic acid biosynthesis/signaling is involved in plant response to Strontium stress

Strontium (Sr) has become an increasing global threat for both environment and human health due to its radioactive isotope, Sr-90 which can be found in the nuclear-contaminated soils and water. Although excessive Sr has been known to be toxic to plant growth and development, the molecular mechanisms underlying plant response to Sr stress, especially on the transcription level, remains largely unknown. To date, there is no published genome-wide transcriptome data available for the plant responses to Sr toxicity. Therefore, we aimed to gain insight on the molecular events occurring in plants in Sr toxicity condition by comparing the genome-wide gene expression profiles between control and Sr-treated plants using RNA-seq analysis. A total of 842 differentially expressed genes (DEGs) were identified in response to Sr stress compared to the control. Based on the analysis of DEGs using Gene Ontology (GO), DEGs were significantly enriched in the GO terms of response to salicylic acid (SA), response to jasmonic acid (JA), and defense response to bacterium. In addition, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that DEGs were mainly involved in metabolic processes including phenylpropanoid biosynthesis and alpha-linolenic acid metabolism, which is known as a precursor of JA biosynthesis. Furthermore, MapMan analysis revealed that a number of genes related to the biotic stress such as pathogenesis-related protein (PR) genes were highly up-regulated under Sr stress. Taken together, this study revealed that JA biosynthesis and/or signaling might be associated with plant response to Sr stress, and play important roles to maintain proper growth and development under Sr stress.

Nitrogen modulates strontium uptake and toxicity in Hypericum perforatum plants

Strontium is an unavoidable element occurring in plants due to its abundance in the soil and similarity with calcium. To mimic natural conditions, impacts of additional inorganic (nitrate) or organic (urea and allantoin) nitrogen sources (1 mM of each N form in addition to 3.53 mM N in the basic cultivation solution) or N deficit on strontium-induced changes (100 µM Sr) in the widely used medicinal plant Hypericum perforatum L. were studied. Though various effects of Sr on primary (stimulation of amino acids but depression of most Krebs acids, ascorbic acid and thiols) and secondary metabolites (stimulation of phenols but no change of pseudo/hypericin) or mineral elements were observed (reduction of Ca amount in both shoots and roots), organic N forms often mitigated negative action of Sr or even combined stimulatory impact was observed. Organic N forms also elevated shoot accumulation of Sr while N deficit reduced it. Additional N forms, rather than Sr itself, modulated reactive oxygen species and nitric oxide formation in the root tissue. Germination experiment showed no toxicity of Sr to H. perforatum up to 1 mM Sr and even stimulated accumulation of amino acids and phenols, indicating similar ontogenetic-related responses.

The Impact of Long-and Short-Term Strontium Treatment on Metabolites and Minerals in Glycine max

The impact of long-term exposure to Sr2+ (LTE, four doses, 43.5 mg Sr2+ per pot, with a total of 174 mg Sr2+ per pot during the entire period of cultivation) and short-term exposure to Sr2+ (STE, one dose, 870 mg Sr2+ per pot four days before harvest) on the content of phytoestrogens and allantoin in soybeans were compared. Sr2+ accumulation, the effect on the concentration of macroelements, and basic physiology were also analyzed. LTE reduced the content of malonyldaidzin and malonylgenistin in the roots (58% and 50% compared to the control, respectively). STE increased the amount of all isoflavones in the stem and genistein in the leaves and decreased the content of malonyldaidzin and malonylgenistin in the leaves (55% and 48% compared to the control, respectively) and roots (69% and 62% of the control, respectively) as well as genistein and coumestrol in the roots (both 50% compared to the control). Sr2+ presence stimulated the accumulation of allantoin in the roots (three-fold higher than in the control), but only STE had similar effects on the shoots. In contrast to LTE, Sr2+ was transported extensively from the roots to the leaves under STE. In comparison to the control, LTE resulted in an increase in the Ca content in the stem by 36%, whereas Ca2+ accumulation in the leaves, stems, and roots increased by 60%, 80%, and 36%, respectively, under STE. Additionally, a significant accumulation of K was found only in the roots of the LTE group. The chlorophyll content did not differ between the treatments. Overall, the production of phytoestrogens and Sr accumulation were affected by both the applied dose and the duration of exposure to Sr.

Strontium in the environment: Review about reactions of plants towards stable and radioactive strontium isotopes

Radiostrontium is released to the environment from routine and accidental discharge and acts on living organisms either from external sources or after absorption. When incorporated by plants, it enters the food chain and causes primary threat to human health and the environment. Understanding the mechanisms of plants for strontium uptake and retention is therefore essential for decision making concerning agriculture: are uptake rates low enough so that plants can serve as food? Or is radiostrontium accumulated so that plants should not be eaten but could be probably used for extracting strontium from water and soil in hot spots of pollution? The review presents a summary of studies about the origin of stable and radioactive strontium in the environment and effects coming from both internal and external exposure of plants. Mobility and availability of strontium to plant roots in soil are controlled by external factors such as chemical composition of the soil and pH, temperature and agricultural soil cultivation as well as soil biological networks built by microbial communities. Plant surfaces may receive input of strontium from deposition induced by atmospheric pollution or by acquisition from water through the whole immersed surface. Cells have entry mechanisms for strontium such as plasma membrane transporters for calcium and potassium. Part of absorbed strontium can be lost via processes discussed in this review. We give examples on strontium transfer factors for 149 plants to estimate plant absorption capacity for strontium from soil, water and air. Uptake efficiency of terrestrial and aquatic plants is deciding about their remediation potential to either remove radiostrontium by accumulation and rhizofiltration or to retain it in roots or aerial parts. Data of strontium content in soils after fallout and edible plants from long-term monitoring support the evaluation of the potential hazards posed by strontium input to the food chain.

Effect of Long-Term Strontium Exposure on the Content of Phytoestrogens and Allantoin in Soybean

Abiotic stress, including metal excess, can modify plant metabolism. Here we investigated the influence of long-term strontium exposure (12 weeks, 0.5⁻4.0 mM Sr) on the content of phytoestrogens and allantoin as well as the mineral composition in soybean. Seven phytoestrogens were identified in the soybean: daidzin, glycitin, genistin, malonyldaidzin, malonylgenistin, daidzein, and coumestrol. The results showed that both malonyldaidzin and malonylgenistin were dominant phytoestrogens; however, the roots contained a relatively high amount of daidzein. It was found that strontium reduced the phytoestrogen content and decreased the antioxidant capacity. Strontium evoked depletion of the sum of all phytoestrogens by 40⁻70% in the leaves, 25⁻50% in the stems and in the seeds, depending on the strontium concentration. In the roots, 0.5 and 4.0 mM of strontium decreased the total phytoestrogen content by 25 and 55%, respectively, while 2.0 mM of strontium did not exert an effect on their accumulation. On the other hand, strontium ions induced allantoin accumulation mainly in the roots. Strontium was preferentially accumulated in the leaves, with a slight impact on macro- and micro-nutrients. Our research showed strontium-secondary metabolites interaction in the soybean, which can be useful for obtaining a natural pharmaceutical product containing both strontium and phytoestrogens for remediation of postmenopausal osteoporosis.

Radiostrontium transport in plants and phytoremediation

Radiostrontium is a common product of nuclear fission and was emitted into the environment in the course of nuclear weapon tests as well as from nuclear reactor accidents. The release of ⁹⁰Sr and ⁸⁹Sr into the environment can pose health threats due to their characteristics such as high specific activities and easy access in human body due to its chemical analogy to calcium. Radiostrontium enters the human food chain by the consumption of plants grown on sites comprising fission-derived radionuclides. For humans, Sr is not an essential element, but, due to solubility in water and homology with calcium, once interred in the body, it gets deposited in bones and in teeth. This concern has drawn the attention of researchers throughout the globe to develop sustainable treatment processes to remediate soil and water resources. Nowadays, phytoremediation has become a promising approach for the remediation of large extents of toxic heavy metals. Some of the plants have been reported to accumulate Sr inside their biomass but detailed mechanisms at genetic level are still to be uncovered. However, there is inadequate information offered to assess the possibility of this remediation approach. This review highlights phytoremediation approach for Sr and explains in detail the uptake mechanism inside plants.

Phenolic Acid Content and Antioxidant Properties of Extruded Corn Snacks Enriched with Kale

Prohealth food contains specific components which have positive influence on the health and well-being of the consumer. An important position among bioactive compounds occurs for polyphenols. Many results have indicated that an increased intake of phenolic compounds may reduce the risk of cardiovascular diseases and type 2 diabetes. The objective of the study was production of extruded corn snacks with addition (0, 2, 4, 6, and 8%) of kale (Brassica oleracea L. var. sabellica)-a polyphenol-rich plant. Afterwards, high-performance liquid chromatography-mass spectrometry (LC-ESI-MS/MS) and antioxidant activity analyses of snack extracts were performed. In the corn snacks enriched with kale, fifteen phenolic acids were indicated. These were protocatechuic, 4-OH-benzoic, vanillic, trans-caffeic, cis-caffeic, trans-p-coumaric, cis-p-coumaric, trans-ferulic, cis-ferulic, salicylic, gentisic, syringic, 3-OH-cinnamic, trans-sinapic, and cis-sinapic acids. Both the qualitative and quantitative content of polyphenols increased with the addition of B. oleracea. Data from spectrophotometric analyses of the samples showed high DPPH radical scavenging potential of snacks enriched with 4, 6, and 8% of kale. Snacks enriched with kale contain high level of phenolic acids and, therefore, have great potential to make a valuable source of natural antioxidants. High-temperature short-time extrusion-cooking process had no negative impact on polyphenol's activity.

Carlina vulgaris L. as a Source of Phytochemicals with Antioxidant Activity

The methanol extracts from three populations of Carlina vulgaris L. were examined for the chlorogenic acid content, mineral content, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity. Two populations originated from natural nonmetallicolous habitats (NN (populations from Nasiłów) and NP (populations from Pińczów)), and one metallicolous population (MB) was collected from Bolesław waste heap localized at the place of former open-cast mining of Ag-Pb and Zn-Pb ores dating back to the 13th century and 18th century, respectively. The level of Zn, Pb, Cd, Fe, Ni, and Mn was significantly higher in the root and leaves of MB plants as a result of soil contaminations compared to those of the NN and NP ones. The highest antioxidant potency has been showed by the plants growing in a nonmetallicolous habitat. The flower head extracts obtained from the nonmetallicolous populations also contained the largest amount of chlorogenic acid, whereas the lowest was determined in the roots (ca. 2–3.5 mg/g and 0.2–0.4 mg/g of air-dry weight, resp.). These studies provide important information on the influence of a habitat on the quality of herbal materials and the content of the biologically active primary and secondary metabolites.

Metabolomic tool to identify soybean [Glycine max (L.) Merrill] germplasms with a high level of shade tolerance at the seedling stage

The isoflavone profiles of seeds of various soybean genotypes with different levels of shade tolerance at the seedling stage were investigated. High-performance liquid chromatography (HPLC) was used to quantify 12 isoflavones, and the data were analyzed using a multivariate statistical analysis. Combined with field experimental data and an orthogonal partial least-squares discriminant analysis (OPLS-DA), several aglycones (genistein (GE), daidzein (DE), and glycitein (GLE)) were selected and identified as key compounds involved in the shade tolerance of soybean seedlings. Additional correlation analysis and laboratory shading stress experiments with soybean seedlings also confirmed the function of these selected isoflavones, especially GE, in the discrimination of soybean seedlings with different levels of shade tolerance. Furthermore, the structure-antioxidant activity relationships between a range of isoflavones and the plant shade-tolerance mechanism are discussed. Targeted metabolomic analyses of isoflavones could reveal the diversity of shade tolerance in soybean seedlings, thus contributing to the breeding of excellent soybean varieties.

Selected secondary metabolites in Echium vulgare L. populations from nonmetalliferous and metalliferous areas

The aim of this study was to evaluate the effect of severe environmental conditions prevailing on metalliferous waste heaps and heavy metal-contaminated growth substrates on accumulation of selected secondary metabolites, antioxidant capacity, and heavy metal concentration in two metallicolous (MC, MZ) and one nonmetallicolous (NM) populations of Echium vulgare L. The shoots and the roots of the three studied populations were collected from their natural habitats. Additionally, the plants were cultivated on different growth substrates, i.e. a contaminated substrate obtained from the areas of growth of the MZ and MC populations and an uncontaminated one from the NM population site. Several compounds, i.e. allantoin, rutin, rosmarinic acid, chlorogenic acid, and 4-hydroxybenzoic acid were identified in the shoots. Moreover, rosmarinic acid, allantoin, and shikonin were measured in the roots. The adverse environmental conditions contributed to a ca. 10- and 4-fold increase in the concentration of allantoin in the roots and shoots, respectively, as well as a ca. 4-fold and ca. 3-fold increase in the level of 4-hydroxybenzoic acid and shikonin, respectively, in comparison with the plants from the uncontaminated site. Similarly, a great impact of the contaminated substrate on the compounds was demonstrated in the soil experiment. Regardless of the populations, even ca. 20-fold higher levels of allantoin and shikonin were observed in plants grown on the MC and MZ substrates. In contrast, the chlorogenic acid concentration was lower in plants collected from the metalliferous areas and in all populations cultivated on the contaminated substrates in comparison with plants from the uncontaminated soil. Unambiguous results were obtained in the case of rutin, i.e. decreased accumulation in both metallicolous populations from the natural environment and increased accumulation in plants grown on the contaminated substrates. The high concentrations of heavy metals in the substrates contributed to high HM concentrations in plant tissues. However, some differences were observed between the metallicolous and nonmetallicolous populations - the accumulation of metals was lower in the shoots and higher in the roots of the NM population, compared with the MZ and MC populations.