In Vitro Evaluation of the Inhibitory Activity of Different Selenium Chemical Forms on the Growth of a Fusarium proliferatum Strain Isolated from Rice Seedlings

In this study, the in vitro effects of different Se concentrations (5, 10, 15, 20, and 100 mg kg−1) from different Se forms (sodium selenite, sodium selenate, selenomethionine, and selenocystine) on the development of a Fusarium proliferatum strain isolated from rice were investigated. A concentration-dependent effect was detected. Se reduced fungal growth starting from 10 mg kg−1 and increasing the concentration (15, 20, and 100 mg kg−1) enhanced the inhibitory effect. Se bioactivity was also chemical form dependent. Selenocystine was found to be the most effective at the lowest concentration (5 mg kg−1). Complete growth inhibition was observed at 20 mg kg−1 of Se from selenite, selenomethionine, and selenocystine. Se speciation analysis revealed that fungus was able to change the Se speciation when the lowest Se concentration was applied. Scanning Electron Microscopy showed an alteration of the fungal morphology induced by Se. Considering that the inorganic forms have a higher solubility in water and are cheaper than organic forms, 20 mg kg−1 of Se from selenite can be suggested as the best combination suitable to inhibit F. proliferatum strain. The addition of low concentrations of Se from selenite to conventional fungicides may be a promising alternative approach for the control of Fusarium species.

Effect of Selenium Form and Salicylic Acid on the Accumulation of Selenium Speciation Forms in Hydroponically Grown Lettuce

Selenium (Se) uptake by plants depends on its form and salicylic acid (SA) can increase the efficiency of plant biofortification in Se. This study investigated the effects of selenite (Na2SeO3) and selenomethionine (SeMet) applied individually or together with SA on a total content of Se, Se speciation forms, yield and content of sugars and ascorbic acid of lettuce, as well as activity of selenocysteine methyltransferase (smt) and methionine methyltransferase (mmt) genes of the Se metabolic pathway. Lettuce was grown in the nutrient film technique (NFT) system. Se and SA were used at doses of 0.5 and 10.0 mg dm−3 of the nutrient solution, respectively. The treatments were: 1. control, 2. Na2SeO3, 3. Na2SeO3 + SA, 4. SeMet, 5. SeMet + SA, 6. SA. Se was accumulated more in the roots than the leaves. SeMet was more effective in biofortification than Na2SeO3. SA enhanced Se uptake, especially organic Se. Plants supplied with SeMet alone or SeMet + SA accumulated in their leaves mainly SeMet and methylselenocysteine (MeSeCys), while those treated with Na2SeO3 or Na2SeO3 + SA accumulated MeSeCys and selenite (SeO3−2). The roots showed no expression of smt, while the expression of two mmt genes was independent of either Se or SA. The leaves of plants supplied with Na2SeO3 demonstrated the strongest expression of mmt and smt.

XAS studies of Se speciation in selenite-fed rats

An investigation of selenium speciation in the tissues of selenite-fed rats by principal component analysis of X-ray absorption spectra.

Food-chain selenium and human health: spotlight on speciation

There is a growing appreciation that it is not just the total intake of dietary Se that is important to health but that the species of Se ingested may also be important. The present review attempts to catalogue what is known about Se species in foods and supplements and the health effects in which they are implicated. The biosynthetic pathways involved in Se assimilation by plants and the way in which Se species are metabolised in animals are presented in order to give an insight into the species likely to be present in plant and animal foods. Known data on the species of Se in the food chain and in food supplements are tabulated along with their concentrations and the analytical methodology used. The latter is important, since identification that is only based on retention-time matching with authentic standards must be considered as tentative: for evidence of structural confirmation, fragmentation of the molecular ion in addition to MS data is required. Bioavailability, as normally defined, is higher for organic Se species. Health effects, both beneficial and toxic, thought to be associated with specific Se species are described. Potent anti-tumour effects have been attributed to the low-molecular-weight species,Se-methyl-selenocysteine and its γ-glutamyl-derivative, found in a number of edible plants of theAlliumandBrassicafamilies. There remain considerable gaps in our knowledge of the forms of Se that naturally occur in foods. Without adequate knowledge of Se speciation, false conclusions may be drawn when assessing Se requirements for optimal health.

Trace element speciation in human milk

This paper summarizes speciation results in human milk samples. Information is presented about why these elements were speciated, which techniques were applied, and which speciation results were gained in human milk. We focus on a few selected elements, such as Zn, Se, I, and Mn. Each of these elements is regarded as an "essential" element and of specific importance for newborns. At the end of each element section, we attempt to extract the overall speciation information from the different literature sources. In short, for Zn it can be concluded that this element is bound predominantly to low-molecular-weight (LMW) compounds. Several papers identify the major Zn species as Zn-citrate. A few minor species are identified as well. The pattern of Se speciation seems to be dependent on the nutritional intake. Selenium speciation in milk from slightly Se-depleted regions shows Se bound in the LMW range, ligands were partly identified. In Se-rich regions, Se seems to be associated with proteins, e.g., glutathione peroxidase. The major I species in human milk is iodide, as found by several groups. Other I species, however, were seen as well. The results of Mn speciation from different groups agreed that Mn is to a considerable amount in the LMW fraction. Again, citrate seems to play an important role as ligand.