Iron Bioaccessibility and Speciation in Microalgae Used as a Dog Nutrition Supplement.

Chlorella vulgaris, Arthrospira platensis, Haematoccocus pluvialis, and Phaeodactylum tricornutum are species of interest for commercial purposes due to their valuable nutritional profile. The aim of this study was to investigate the iron content in these four microalgae, with emphasis on their iron bioaccessibility assessed using an in vitro digestion system to simulate the process which takes place in the stomach and small intestine of dogs, followed by iron quantification using atomic absorption spectrometry. Furthermore, the extraction of soluble proteins was carried out and size exclusion chromatography was applied to investigate iron speciation. Significant differences (p < 0.004) in iron content were found between C. vulgaris, which had the highest (1347 ± 93 µg g-1), and H. pluvialis, which had the lowest (216 ± 59 µg g-1) iron content. C. vulgaris, A. platensis, and H. pluvialis showed an iron bioaccessibility of 30, 31, and 30%, respectively, while P. tricornutum showed the lowest bioaccessibility (11%). The four species analysed presented soluble iron mainly bound to proteins with high molecular mass ranging from >75 to 40 kDa. C. vulgaris showed the highest iron content associated with good bioaccessibility; therefore, it could be considered to be an interesting natural source of organic iron in dog nutrition.

Iron Content, Iron Speciation and Phycocyanin in Commercial Samples of Arthrospira spp.

Cyanobacteria are characterized by high iron content. In this research, we collected ten commercial samples of Arthrospira spp. sold as food supplement to determine iron content and assess whether iron speciation showed variability among samples and changed respect to A. platensis grown in controlled conditions. Particular attention was also paid to phycocyanin, as an iron-binding protein. In six of the ten samples, 14 essential and non-essential trace elements were analysed using ICP-MS. Iron content measured in samples using atomic absorption spectrometry (AAS) varied from 353 (sample S5) to 1459 (sample S7) µg g-1 dry weight and was in the range of those reported by other authors in commercial supplements. Iron speciation was studied using size exclusion chromatography followed by the analysis of the collected fraction for the determination of iron by AAS and for protein separation using SDS-PAGE. Overlapping chromatographic profiles were obtained for total proteins, phycocyanin and iron, although quantitative differences were evidenced among the samples analysed. In most samples, iron was mainly bound to ligands with high molecular mass; however, in four samples iron was also bound to ligands with low molecular mass. In fractions containing the most relevant iron burden, the principal protein was phycocyanin, confirming its role as an iron-binding protein in commercial samples.

Supplementation of Boswellia serrata and Salix alba Extracts during the Early Laying Phase: Effects on Serum and Albumen Proteins, Trace Elements, and Yolk Cholesterol.

Extracts from Boswellia serrata (Bs) and Salix alba (Sa) are used as supplements in poultry feed. The aims of this research were to study the possible effects of dietary supplementation with Bs and Sa extracts on serum and albumen proteins, zinc and iron, and yolk cholesterol content in Leghorn hens during the critical phase of the onset of laying. A total of 120 pullets, 17 weeks of age, were assigned to two groups (control (C) and treated (T), n = 60 each). The T group received a supplement containing Bs (5%) and Sa (5%) for 12 weeks. The study lasted 19 weeks. Serum proteins were fractionated using agarose gel electrophoresis (AGE) and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Trace elements were determined in serum using atomic absorption spectrometry, and yolk cholesterol was determined using a colorimetric test. No significant differences were observed between control and supplemented hens for the analyzed biochemical indices. Moreover, the supplementation with phytoextracts did not negatively affect the physiological variations in serum proteins; therefore, it can be safely used as a treatment to prevent inflammatory states at onset and during the early laying phase.

Iron Speciation and Iron Binding Proteins in Arthrospira platensis Grown in Media Containing Different Iron Concentrations

Cyanobacteria are characterized by high iron content. This study investigated the effects of varying iron concentrations (1, 5, and 10 mg L-1) in the culture media on the biochemical composition and the iron bioaccumulation and speciation in Arthrospira platensis F&M-C256. Iron content measured in biomasses varied from 0.35 to 2.34 mg g-1 dry weight depending on the iron concentration in the culture media. These biomasses can be considered of interest for the production of spirulina-based supplements with low and high iron content. Iron speciation was studied using size exclusion chromatography followed by atomic absorption spectrometry and proteomic analysis. The role of C-phycocyanin as an iron binding protein was also investigated. Overall, the present results provide a better understanding of iron metabolism in cyanobacteria and a foundation for further studies.