Magnetic nanoparticles coated with carboxylate-terminated carbosilane dendrons as a reusable and green approach to extract/purify proteins

Extraction/purification of proteins, at both analytical and industrial levels, is a limiting step that usually requires the use of organic solvents and involves tedious work and a high cost. This work proposes a more sustainable alternative based on the use of magnetic nanoparticles (MNPs) coated with carboxylate-terminated carbosilane dendrons. MNPs coated with first- and second-generation carbosilane dendrons and bare MNPs were employed for the extraction of proteins with different molecular weights and charges. Interaction of proteins with MNPs significantly varied with the pH, the protein, and the dendron generation (different sizes and number of charges in the periphery). Optimal dendron:protein molar ratios and suitable conditions for disrupting interactions after protein extraction were also researched. Second-generation dendron-coated MNPs showed 100% retention capability for all proteins when using acidic conditions. They were reused without losing magnetism or interaction capacity after a disruption of protein-dendron interactions with 0.2% SDS at 100 °C for 10 min. The capacity of dendron-coated MNPs was successfully applied to the recovery/purification of proteins from two food by-products, olive seeds and cheese whey. Graphical abstract

Gas chromatography-mass spectrometry analysis and in vitro biological studies on fixed oil isolated from the waste pits of two varieties of Olea europaea L.

Olive oil isolated from the fruits of the Olea europaea L. is an important part of Mediterranean diet. It is known for its diverse biological actions. Furthermore, a little amount of fixed oil and other bioactive components can also be extracted from the olive seeds which are considered as byproduct of olive oil extraction. Therefore, this study was designed to analyze the fatty acid composition and to perform in vitro biological studies on fixed oil isolated from olive seeds. The fixed oil was isolated from the olive seeds of Syrian and Greek black olive fruits by using Soxhlet apparatus. The purity was checked by measuring its refractive index. Composition of two isolated oils and a commercially available virgin olive oil was determined by preparing their Methyl esters (FAME) followed by GC-MS analysis. Various in vitro assay methods were used to investigate activities such as antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), cytotoxic activity by using Brine shrimps lethality bioassay and antimicrobial activity against two bacterial strains; Staphylococcus aureus and Escherichia coli by agar well diffusion method. GC-MS analysis revealed that the two isolated oils differ quantitatively in chemical composition with oleic acid identified as the major chemical constituent (62.6% and 73.56%). Both the fixed seed oils showed a concentration dependent DPPH radical scavenging activity ranging from 8 to 76% inhibition. The oils also exhibited excellent cytotoxic activity but no antimicrobial activity was observed. The chemical composition of the isolated fixed olive seed oil is found to be almost similar to the commercially available fruit olive oil. The fixed oil from the seeds of olive fruits possesses useful biological actions. Further studies are needed to isolate and quantify their bioactive constituents.

Antioxidant activity of Phaseolus L. species seeds with different coat colour

The aim of the research was to screen the antioxidant activity of mature seeds of related bean species using the collection samples of the National Center for Plant Genetic Resources of Ukraine: Phaseolus vulgaris L., P. multiflorus Lam., P. lunatus L. and P. acutifolius A. Grey which have different colouration of their seed shell. The determination of antioxidant activity was carried out using the improved method of the stable radical DPPH•: methyl alcohol in the eluting solution was replaced by non-toxic ethyl alcohol. The results of the analysis are presented as the equivalent of a standard antioxidant (chlorogenic acid), expressed in mg of the standard per 1 g of a sample, taking into account dilutions according to the calibration schedule. As a result of the Phaseolus L. collection screening, it was found that the antioxidant activity of bean seeds depended on the colour of the seed coat. Regardless of the bean type, white seeds had the lowest indicator (equivalent to chlorogenic acid is 0.82–0.96 mg g–1 of seed). Painted seeds have different antioxidant activity. In P. vulgaris L., olive seeds have the highest index (4.21–5.07 mg g–1 of seeds), it is 2.36–3.60 mg g–1 in wine red seeds and 2.72–3.21 mg g–1 in pink ones. And the tendency of the influence of drawing colour and the area of a seed coat is noticed. In P. lunatus L., the antioxidant activity of white seeds with a motley wine-red pattern (2.27 mg g–1 of seeds) is more than twice as high as of white seeds without a pattern (0.94 mg g–1 of seeds). In P. multiflorus Lam., all the coloured seeds had a very high antioxidant activity regardless of the seed coat colour and its pattern (6.09–6.16 mg g–1 of seeds). In P. acutifolius A. Gray, the change in this parameter, depending on the seed coat colour, was small (1.27–1.62 mg g–1 of seeds). It was found that the antioxidant activity of beans depended on the environmental conditions: the stress of plants because drought leads to its increase.