Spinochrome D (2,3,5,6,8-pentahydroxy-1,4-naphthoquinone) is an organic compound with formula , formally derived from 1,4-naphthoquinone through the replacement of five hydrogen atoms by hydroxyl (OH) groups.
Spinochrome D occurs naturally as a brownish red pigment in the shell and spines of sea urchins such as the Japanese aka-uni (Pseudocentrotus depressus). It is soluble in diethyl ether and crystallizes as brownish red needles that sublime at 285âÂÂ295 ðC.
The compound gives a yellowish brown solution when treated with sodium hydroxide, a bluish green solution with ferric chloride, and a violet precipitate with lead acetate. It forms a five-fold acetate ester, ()<sub>5</sub>, that crystallizes from methanol as yellow needles that melt at 185âÂÂ186 ðC.