Hexahydroxy 1,4 naphthalenedione

2,3,5,6,7,8-Hexahydroxy-1,4-naphthalenedione, also called hexahydroxynaphthoquinone or spinochrome E, is an organic compound with formula C
10H
6O
8. It is formally derived from naphthoquinone (1,4-naphtalenedione) through replacement of all six hydrogen atoms by hydroxyl (OH) groups. The numerical prefixes "2,3,5,6,7,8" are superfluous, since there is no other hexahydroxy derivative of 1,4-naphthoquinone.

The substance forms red micro-needles which do not melt below 300 °C, and can be sublimed in vacuum at about 265 °C.

The compound occurs in the shell ("test") and spines of the sea urchins Paracentrotus lividus and Psammechinus miliaris.

The compound can be produced by condensation of 3,4,5,6-tetramethoxyphthalaldehyde with glyoxal.