Stability of Se species in plant extracts rich in phenolic substances

Selenium Species and Fractions in the Rock-Soil-Plant Interface of Maize (Zea mays L.) Grown in a Natural Ultra-Rich Se Environment

Selenium (Se) enrichments or deficiency in maize (Zea mays L.), one of the world's most important staple foods and livestock feeds, can significantly affect many people's diets, as Se is essential though harmful in excess. In particular, Se-rich maize seems to have been one of the factors that led to an outbreak of selenosis in the 1980s in Naore Valley in Ziyang County, China. Thus, this region's geological and pedological enrichment offers some insight into the behavior of Se in naturally Se-rich crops. This study examined total Se and Se species in the grains, leaves, stalks, and roots of 11 maize plant samples, Se fractions of soils around the rhizosphere, and representative parent rock materials from Naore Valley. The results showed that total Se concentrations in the collected samples were observed in descending order of soil > leaf > root > grain > stalk. The predominant Se species detected in maize plants was SeMet. Inorganic Se forms, mainly Se(VI), decreased from root to grain, and were possibly assimilated into organic forms. Se(IV) was barely present. The natural increases of Se concentration in soils mainly affected leaf and root dry-weight biomasses of maize. In addition, Se distribution in soils markedly correlated with the weathered Se-rich bedrocks. The analyzed soils had lower Se bioavailability than rocks, with Se accumulated predominantly as recalcitrant residual Se. Thus, the maize plants grown in these natural Se-rich soils may uptake Se mainly from the oxidation and leaching of the remaining organic-sulfide-bound Se fractions. A viewpoint shift from natural Se-rich soils as menaces to possibilities for growing Se-rich agricultural products is also discussed in this study.

Stability of Tl(III) in the context of speciation analysis of thallium in plants

The paper presents both "good" and "bad" results obtained during speciation analysis of thallium in plant tissues of a hyperaccumulator of this metal. The object was white mustard - Sinapis alba L. In this plant there were found traces of trivalent thallium. The crucial point of this study (especially in the case of so unstable thallium form as Tl(III)) was to prove that the presence of Tl(III) was not caused by the procedure of sample preparation itself, and that the whole analytical method provides reliable results. Choice of the method for conservation of the initial speciation, extraction with the highest efficiency and proving the correctness of the obtained data were the most difficult parts of the presented study. It was found that: both freezing and drying cause significant changes in the speciation of thallium; quantitative analysis could be performed only with fresh tissues of mustard plants; only short-term storage of an extract from fresh plant tissues is possible; the methodology is not the source of thallium (III); only the presence of DTPA can greatly limit the reduction of TI(III) to TI(I) (up to 1-3%); the UV irradiation results in disintegration of TI(III)DTPA in the presence of plant matrix (reduction up to 90%).

Validation of a Stability-Indicating Method for Methylseleno-L-Cysteine (L-SeMC)

Methylseleno-L-cysteine (L-SeMC) is a naturally occurring amino acid analogue used as a general dietary supplement and is being explored as a chemopreventive agent. As a known dietary supplement, L-SeMC is not regulated as a pharmaceutical and there is a paucity of analytical methods available. To address the lack of methodology, a stability-indicating method was developed and validated to evaluate L-SeMC as both the bulk drug and formulated drug product (400 µg Se/capsule). The analytical approach presented is a simple, nonderivatization method that utilizes HPLC with ultraviolet detection at 220 nm. A C18 column with a volatile ion-pair agent and methanol mobile phase was used for the separation. The method accuracy was 99-100% from 0.05 to 0.15 mg/mL L-SeMC for the bulk drug, and 98-99% from 0.075 to 0.15 mg/mL L-SeMC for the drug product. Method precision was <1% for the bulk drug and was 3% for the drug product. The LOQ was 0.1 µg/mL L-SeMC or 0.002 µg L-SeMC on column.

Storage Effect on Phenols and on the Antioxidant Activity of Extracts fromAnemopsis californicaand Inhibition of Elastase Enzyme

The amount of total phenols and flavonoids and the antioxidant activity of leaf, stem, and rhizome methanolic extracts from a commonly consumedAnemopsis californicaunder different storage conditions were investigated. Storage conditions were at 50, 25, 4, and −20°C, protected or not from light, during 180 days. The inhibition of the elastase enzyme was also evaluated. The results demonstrated that leaf, stem, and rhizome methanolic extracts ofAnemopsis californicamaintain approximately up to 97 and 95% stability in phenolic content and antioxidant activity, respectively, when stored during 60 days at −20°C in the dark. Additionally, these extracts, principally from leaf and rhizome, showed an elastase inhibitory effect by 75 and 71.8%, respectively. Therefore, this study provides the basis for further research on the anti-inflammatory activity. On the other hand,Anemopsis californicacould comprise a good alternative of use as antioxidant in foods.

Selenium and its species in the aquatic moss Fontinalis antipyretica

The ability of the widely distributed aquatic moss Fontinalis antipyretica to take up Se from water was studied. Nine locations in the Notranjska region (Slovenia) with different land use in the catchment were sampled for water and moss in the year 2010 in spring, summer and autumn. The concentrations of Se in water at all locations did not exceed 0.2 ng mL(-1). F. antipyretica took up Se in the range between 345 and 2250 ng g(-1). All results for Se are expressed on dry matter basis. The Se content varied depending on the location and season. The highest concentration (2250 ± 170 ng g(-1)) of Se was found in the Žerovniščica stream that flows through an agricultural area with dairy farming. The fraction of insoluble Se compounds in the residue after enzymatic hydrolysis using protease (XIV) was around 75%. Soluble Se compounds in the enzymatic extract of F. antipyretica were separated and measured using HPLC coupled to ICP-MS. Se(IV) and Se(VI) were found but no organic Se compounds were detected, even at the highest concentration.

Dietary supply of selenium for adolescents in three residential care orphanages in Southern Ghana

Adolescents require optimum dietary supply of the essential trace mineral selenium (Se); however the absence of reliable and accurate data on the dietary supply of selenium for the adolescent population in Ghanaian residential care orphanages have made it difficult for public health nutritionists to assess the adequacy of the dietary supply. The dietary supply of selenium for adolescents (12-15 years) in three residential care orphanages, (Osu, Tutu-Akwapim and Teshie), in Southern Ghana have been evaluated by sampling their 24-h duplicate diets (including water) for 7-consecutive days using the duplicate diet sampling technique. The mass fraction of selenium in the blended lyophilized homogenates of duplicate diets was determined by radiochemical neutron activation analysis (RNAA). The validity of the RNAA method for selenium determination was checked by analyses of NIST SRM 1548a (Typical diet). The chemical yield of the radiochemical separation was determined by spectrophotometry. The average mass fractions of selenium in the blended lyophilized 24-hour duplicate diets for Osu, Tutu-Akwapim and Teshie were; 165±61 [117.2-285.2], 203±68 [110.5-304.9] and 250±92 [128.8-408.0]ng Seg(-1) lyophilized matter respectively. The average dietary supply of Se were, 57.6±17.3 [42.2-88.4], 82.0±30.7 [44.3-136.2] and 91.7±44.2 [46.0-153.4]μg Se day(-1) for Osu, Tutu-Akwapim and Teshie orphanages respectively. The data generated will help public health nutritionists in the provision of dietary advice and nutritional support for the studied orphanages, as well as other orphanages. The data will also help in the planning of institutional diets.