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A synthesis of new enantiomerically enriched derivatives of (S)-α-aminopropionic acid, containing in the β-position 1,2,3-triazole groups coupled with a o-, m- and p-substituted phenyl residue, was developed based on Cu(I) catalyzed [3 + 2] cycloaddition of azides with alkynes. As the starting materials was used the square-planar Ni(II)complex of the Schiff base of propargylglycine with the chiral auxiliary BPB (Benzylprolylbenzophenone) and 1,4-substituted phenyl azides. The assignment of the (S)-absolute configuration of the α-carbon atom of the amino acid residue of the main diastereomeric complexes of the cycloaddition products was carried out on the basis of positive Cotton effects in the region of 480–580 nm of the circular dichroism spectra. The target amino acids were isolated from acid hydrolysates of diastereomeric complexes using ion-exchange demineralization and crystallization from aqueous ethanol. Additional confirmation of the absolute configuration and determination of the enantiomeric purity of the target amino acids were carried out by chiral HPLC analysis. As a result, seven new non-proteinogenic (S)-α-amino acids, containing in the β-position a 1,2,3-triazole moiety, were synthesized. [ABSTRACT FROM AUTHOR]

Summary: In recent years, natural pigments in living organisms have attracted increased interest as an excellent biological material for the development of new biotechnological approaches. Melanin, a large polymeric pigment, has important functions in cells, including free radical scavenging and radiation protection, making this molecule attractive for medical and nutritional purposes. The variety of forms of melanin in organisms requires the use of various approaches to its purification. In this study, we have developed a simple yet unique and effective method for extracting melanin from six plant sources. The melanin yield was in the range of 6.7–21.5% for the plant sources used. The advantage of using grape skin waste as a raw material is shown, which is of great importance for obtaining cheap and functional melanin. The activity of purified melanin in scavenging 2, 2‐diphenyl‐1‐picrylhydrazyl radical is IC50 3.2–99.0 mg L−1. This remarkable feature highlights the attractiveness of grape melanin for further use as a natural antioxidant in medicine. The ability of grape melanin to adsorb heavy metal ions highlights its attractiveness for the food industry and for the development of other biotechnological applications. Smoke, after passing through a cigarette filter charged with melanin, is significantly enriched with reducing agents, which is a phenomenon for the health of smokers. [ABSTRACT FROM AUTHOR]