Biologically active fraction of plant melanin, process of its preparation and use

摘要

A fraction of vegetable melanin, consisting of monomeric units of vegetable flavonoids, especially of catechins and leucoanthocyanidins, having a summary empirical formula of the H-form [C34-59O14-23H32-44N6-8]n, where n=6 to 8, molecular weight (5±1).103 Da, the amount of -OH groups 4.02 to 4.05% by weight, the amount of =O groups 1.04 to 1.06% by weight, the content of individual elements (% by weight) C 49.44 to 49.52; H 5.10 to 5.73; N 1.15 to 1.24; O 41.20 to 42.10; concentration of unpaired electrons (spin/g) 1018 to 1022 and bright spectral lines in the regions 3433, 1620, 1400 and 1200 to 1100 cm-1. A Process for production of vegetable melanin consists in that a vegetable raw material which contains native polymer and/or basic building units, such as catechins and lecoantocyanidines, is treated with 0.05 to 0.3 M aqueous solution of an alkali metal hydroxide at a temperature of 15 to 75° C., pH of the extract is adjusted to 1 to 2 by adding an inorganic acid, based on chlorine, wherein the excluded sediment is purified and subsequently dried at 100 to 110° C.