Spinochrome B

Spinochrome B (2,3,5,7-tetrahydroxynaphthoquinone) is an organic compound with formula , formally derived from 1,4-naphthoquinone through the replacement of four hydrogen atoms by hydroxyl (OH) groups.

Spinochrome B occurs naturally as pigment in the shell and spines of sea urchins such as the Japanese dull red species aka-uni (Pseudocentrotus depressus), the greenish-black murasaki-uni (Heliocidaris crassispina), and the brown bafun-uni (Strongylocentrotus pulcherrimus).Chika KURODA and Masae OKAJIMA (1958), Studies on the Derivatives of Naphthoquinones, XIV. The pigments of sea urchins, IX. Proc. Japan Acad., volume 34, pages 616--618. Online version accessed on 2010-02-01. Pigment M2 is drawn as 2,3,6,8-thNQ but that is the same as 2,3,5,7-thNQ. The genus Heliocedaris should be Heliocidaris and the species purcherrmus should be pulcherrimus.Chika KURODA and Masae OKAJIMA (1967), Studies on the Derivatives of Naphthoquinones, XVIII. The pigments of sea urchins, XIII. Proc. Japan Acad., volume 43, pages 41--44. Online version accessed on 2010-02-01. It is soluble in methanol and crystallizes as bright red needles that sublime above 200 °C.

The compound gives a greenish yellow solution when treated with sodium hydroxide, a green solution with ferric chloride, and a green precipitate with lead acetate. It forms a fourfold acetate ester, ()4, that crystallizes from methanol as yellow needles that melt at 157 °C.

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