Allomelanins

Melanins are complex polymeric structures, which are usually mixtures of macromolecules. Melanins are classified as eumelanins, phaeomelanins and allomelanins. ... 

Allomelanins — These are structurally different compounds containing little or no nitrogen. They are considered polymers of phenolic compounds like catechol. Fnngi prodnce melanin pigments, predominantly dihydroxyphenylalanine (DOPA)-melanin and dihydroxynaphthalene (DHN)-melanin. ... 

Kamei, H. et al.. Suppression of growth of cultured malignant cells by allomelanins, plant-produced melanins. Cancer Biother. Radiopharm., 12, 47, 1997. 

Melanins are classified according to their chemical structure into the insoluble black eumelanins (poly-5,6-indole quinones) and the alkali-soluble red phaeomelanins (polydihydrobenzothiazines). Nicolaus (5) includes another group, the homoaromatic phenolic allomelanins (per-... 

Gel permeation chromatography has been used in studies of water-soluble melanins. Several fractions were separated from allomelanin from Aspergillus niger on Sephadex G gels (Ref. 7, p. 131). Similarly, humic acids were separated into three fractions on Sephadex G-75 (297). 

A. sativum, 3664, 3665, 3678 Allodynia, 1374 Allograft rejection, 1834 Allomelanins, 1564 Allophylus edulis, 4094 All-/rans- 3-carotene, 3588 Ahnazolone (ALM), 29 ALM E, 29 Almeidea, 731 ALM Z, 29 Alnus, 1553 Aloe-emodin, 1554 Alpha-cypermethrin, 4070 Alpha-fetoprotein, 2208 Alpha-ionol, 4095 Alpha-pinene, 4098 Alpha-secietase, 3714 Alteromonas, 788 Alumina, 3331, 3332 Aluminium, 3645 Aluminium oxide, 692 Alyosia triphylla, 2982... 

Humic earth results from the decomposition of organic matter, particularly cellulose from dead plants. The organic phase contains humic acids, allomelanins with complex phenolic macro-molecular structure. Humic substances fall between plants and geological materials (coals and petroleum). Degraded organic matter when released into the environment will form relatively soluble fulvic acids which will condense to form humic acids and then humins with lower solubilties. Humic earths are transitional between the low grade coal lignite (. v.) and peaty soils. 

This ketone was shown to occur in natural huntic acids and fulvic acids by hydrolysis with 2 N sodium hydroxide at 170° [2392], Allomelanins found in soils, coals and peat, resulting from the decomposition of organic matter, particularly dead plants [2393],... 

In soils and clays the most generally present biopolymers that naturally occur in the adsorbed state on mineral and clay particles are humic substances , or humic acids these are decomposition products of lignin, whidi is the major non-cellulosic polymer in wood and other plant debris. Humic acids (also called allomelanins (Merck Index, 1989)) are for the greater part polyphenolic compounds, usueJly anionic polyelectrolytes, which can complex metal ions, and are surface active and thus capable, upon adsorption onto mineral particles, to enhance their suspension stability in aqueous media (Chheda and Grasso, 1994). 

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