Chemical composition of shells from red (Strongylocentrotus franciscanus) and green (Strongylocentrotus droebachiensis) sea urchin

The shells from red and green sea urchins accounted for 47.9 and 40.7% of their body weights, respectively. The red and green sea urchin shells contained 91.08 and 90.77% minerals and 4.06 and 4.99% proteins, respectively. The shells did not contain any chitin. Sea urchin shells had a relatively large amount of naphthoquinone pigments, 121 mg per 100 g in red and 163 mg per 100 g in green species. The small quantities of glucosamine detected (20 mg/g in red and 25 mg/g in green sea urchins) originated from mucopolysaccharides present in a layer of connective tissues attached to the shells. Using EI–MS spinochromes A, B, C, and D were found in fractions of naphthoquinone pigments separated from shells of green sea urchin by Sephadex LH-20 column chromatography. The presence of the molecular ion of spinochrome D in its mass spectrum of well separated fractions V–VII may suggest that this compound can appear as a complex with organic compounds and could be a derivative of benzene dicarboxylic acid.