Selenium species in the roots and shoots of chickpea plants treated with different concentrations of sodium selenite

Estimated daily intake and health risk assessment of total and organic selenium in crops across areas with different selenium levels

BACKGROUND

The health risk of Se has gained significant attention. Previous studies mainly focused on the health risk of total Se in high-Se area. Less attention has been paid to the health risk of organic selenium in areas with varying selenium levels.

METHODS

A total number of 109 crop samples (edible parts) were collected in Langao County, Shannxi Province, China from 2018 to 2020, including 42 corn, 18 rice, 9 sweet potato, 25 potato, 12 radish, and 3 eggplant samples. The hydride generation atomic fluorescence spectrometry (HG-AFS) method was used to determine the total and organic Se contents.

RESULT AND CONCLUSION

(1) Corn (2.82 mg/kg), rice (0.44 mg/kg), potato (6.56 mg/kg), and eggplant (0.77 mg/kg) in high-Se area, as well as sweet potato (1.07 mg/kg) and radish (4.28 mg/kg) in medium-Se area, exhibited the highest total Se content among all crops in this county, and 5-328 times higher than the values of Se-enriched standard (2) The average daily intake of total/organic Se of residents in high-Se area reached 676/449 μg/day, which was 1-4 times higher than levels observed in medium-Se area (419/257 μg/day) and low-Se area (196/128 μg/day). The organic Se daily intakes from dietary combinations of rice + radish and rice + eggplant in high-Se area lower than 400 μg/day, which could be safely consumed. The organic Se daily intakes from dietary combinations of sweet potato + radish and sweet + eggplant in medium-Se area higher than 400 μg/day, which could not be safely consumed. The total / organic Se daily intakes of all dietary combinations in low-Se area lower than 400 μg/day, which could be safely consumed. (3) The health risk associated with crops might be overestimated due to the higher non-carcinogenic risk attributed to total Se compared to organic Se. The present study demonstrated that daily intake and health risk of total and organic Se in crops across areas with different Se levels varied significantly.

Shelf-life extension of Fragaria × ananassa Duch. using selenium nanoparticles synthesized from Cassia fistula Linn. leaves

Fragaria × ananassa Duch. (Strawberry) fruit is susceptible to postharvest diseases, thus decrease in quality attributes, such as physiological and biochemical properties leads to decrease in shelf life. The objective of the present study was to check the effect of Selenium NP's and packaging conditions on the shelf life of strawberry (Fragaria × ananassa Duch) fruits. The shelf life was observed with 4 days intervals and examined for characteristics such as physiological weight loss, moisture content, percentage decay loss, peroxidase, catalase, and DPPH radical scavenging. The quality change of postharvest Fragaria × ananassa Duch. was monitored by the application of selenium nanoparticles (T1 plant extract in 10 mM salt solution, T2 plant extract in 30 mM salt solution, T3 plant extract in 40 mM salt solution, T4 distilled water; control) in different packaging materials (plastic bags, cardboard, and brown paper) at different storage conditions (6°C and 25°C). 10 mM, 20 mM, and 30 mM solution of sodium selenite salt, prepared from 1 M stock solution. Selenium nanoparticles were synthesized using Cassia fistula L. extract and sodium selenite salt solution. Polyvinyl alcohol (PVA) was used as a stabilizer. The nanoparticles were characterized through UV-visible spectroscopy and X-Ray diffractometer (XRD). It was observed that the strawberry Fragaria × ananassa Duch. Treated with T1 (CFE and 10 mM salt solution) stored in plastic packaging at ±6°C showed the best physiological parameters and hence the treatment is recommended for storage without affecting the quality of strawberry fruit up to 16 days.

Selenium in cereals: Insight into species of the element from total amount

Selenium (Se) is a trace mineral micronutrient essential for human health. The diet is the main source of Se intake. Se-deficiency is associated with many diseases, and up to 1 billion people suffer from Se-deficiency worldwide. Cereals are considered a good choice for Se intake due to their daily consumption as staple foods. Much attention has been paid to the contents of Se in cereals and other foods. Se-enriched cereals are produced by biofortification. Notably, the gap between the nutritional and toxic levels of Se is fairly narrow. The chemical structures of Se compounds, rather than their total contents, contribute to the bioavailability, bioactivity, and toxicity of Se. Organic Se species show better bioavailability, higher nutritional value, and less toxicity than inorganic species. In this paper, we reviewed the total content of Se in cereals, Se speciation methods, and the biological effects of Se species on human health. Selenomethionine (SeMet) is generally the most prevalent and important Se species in cereal grains. In conclusion, Se species should be considered in addition to the total Se content when evaluating the nutritional and toxic values of foods such as cereals.

Systematic study on the reduction efficiency of ascorbic acid and thiourea on selenate and selenite at high and trace concentrations

Selenate (Se(VI)) and selenite (Se(IV)) are common soluble wastewater pollutants in natural and anthropogenic systems. We evaluated the reduction efficiency and removal of low (0.02 and 2 mg/L) and high (20 and 200 mg/L) Se(IV)_(aq) and Se(VI)_(aq) concentrations to elemental (Se⁰) via the use of ascorbic acid (AA), thiourea (TH), and a 50-50% mixture. The reduction efficiency of AA with Se(IV)_(aq) to nano- and micro-crystalline Se⁰ was ≥ 95%, but ≤ 5% of Se(VI)_(aq) was reduced to Se(IV)_(aq) with no Se⁰. Thiourea was able to reduce ≤ 75% of Se(IV)_(aq) to bulk Se⁰ at lower concentrations but was more effective (≥ 90%) at higher concentrations. Reduction of Se(VI)_(aq)→Se (IV)_(aq) with TH was ≤ 75% at trace concentrations which steadily declined as the concentrations increased, and the products formed were elemental sulfur (S⁰) and S_nSe_8-n phases. The reduction efficiency of Se(IV)_(aq) to bulk Se⁰ upon the addition of AA+TH was ≤ 81% at low concentrations and ≥ 90% at higher concentrations. An inverse relation to what was observed with Se(IV)_(aq) was found upon the addition of AA+TH with Se(VI)_(aq). At low Se(VI)_(aq) concentrations, AA+TH was able to reduce more effectively (≤ 61%) Se(VI)_(aq)→Se(IV)_(aq)→Se⁰, while at higher concentrations, it was ineffective (≤ 11%) and Se⁰, S⁰, and S_nSe_8-n formed. This work helps to guide the removal, reduction effectiveness, and products formed from AA, TH, and a 50-50% mixture on Se(IV)_(aq) and Se(VI)_(aq) to Se⁰ under acidic conditions and environmentally relevant concentrations possibly found in acidic natural waters, hydrometallurgical chloride processing operations, and acid mine drainage/acid rock drainage tailings. Graphical Abstract ᅟ.

Is foliar enrichment of pea plants with iodine and selenium appropriate for production of functional food?

Pea (Pisum sativum L.) plants were sown in a field and foliar sprayed at blooming stage with solutions of different forms of iodine (I) - I- and IO3- and selenium (Se) - SeO32- and SeO42-. The possibility of enrichment of pea seeds to nutritionally important levels of both elements and their distribution through the plant parts were studied. To evaluate stress caused by application of I and Se, some morphological, physiological and biochemical characteristics were determined. The results showed elevated concentrations of both elements in all parts of pea plants. In seeds, I content was more than 6-fold higher, while Se content was up to 12-fold higher than in control plants. Although the plants were in good condition, some differences in pod characteristics and electron transport system activity were observed. Glutathione content was not affected by any treatment and only the I- + SeO42- combination decreased the amount of anthocyanins in plants.

Diet composition and serum levels of selenium species: A cross-sectional study

Selenium is a trace element of both nutritional and toxicological interest, depending on its dose and chemical form. Diet is the primary source of exposure for most individuals. We sought to investigate the influence of food intake on serum levels of selenium species. Among fifty subjects randomly selected from a Northern Italian population, we assessed dietary habits using a validated semi-quantitative food frequency questionnaire. We also measured circulating levels of selenium species in serum using high pressure liquid chromatography associated with inductively-coupled plasma dynamic reaction cell mass spectrometer. Circulating levels of inorganic selenium, the most toxic selenium species, were positively associated with intake of fish, legumes and dry fruits, and inversely associated with intake of dairy products and mushrooms. Concerning the organic selenium species, selenoproteinP-bound selenium was inversely associated with intake of fish, fresh fruits, vegetables, and legumes, while selenocysteine-bound selenium positively associated with intake of fresh fruit, potato, legume and mushroom. In the present study, intakes of different foods were correlated with different types of selenium species. These results have important public health implications when assessing the nutritional and toxicological potential of diet composition with reference to selenium exposure.

Alleviation of selenium toxicity in Brassica juncea L.: salicylic acid-mediated modulation in toxicity indicators, stress modulators, and sulfur-related gene transcripts

The present work reveals the response of different doses of selenium (Se) and alleviating effect of salicylic acid (SA) on Se-stressed Brassica juncea seedlings. Selenium, a micronutrient, is essential for both humans and animals but is toxic at higher doses. Its beneficial role for the survival of plants, however, is still debatable. On the other hand, SA, a phenolic compound, is known to have specific responses under environmental stresses. Experiments were conducted using leaves of hydroponically grown seedlings of Pusa bold (PB) variety of B. juncea, treated with different concentrations of Se (50, 150, 300 μM) for 24- and 96-h exposure times. Increasing Se concentrations inhibited growth and, caused lipid peroxidation, concomitantly increased stress modulators (proline, cysteine, SOD, CAT) along with sulfur-related gene transcripts (LAST, APS, APR, GR, OASL, MT-2, PCS) in Brassica seedlings. On the basis of the above studied parameters, maximum inhibition in growth was observed at 300 μM Se after 96-h exposure time. Further, co-application of SA along with 300 μM Se helped to mitigate Se stress, as shown by improved levels of growth parameters, toxicity indicators (chlorophyll, protein, MDA), stress modulators (proline, cysteine, SOD, and CAT), and expression of sulfur-related genes as compared to Se-treated seedlings alone. Altogether, this study revealed that Se + SA combinations improved seedling morphology and were effective in alleviation of Se stress in PB variety of B. juncea.