Optimization of (Poly)Hydroxynaphthoquinone Extraction from Shells of Strongylocentrotus Droebachiensis Sea Urchins

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Extraction of lipophilic substances from shells and spines of green sea urchins (Strongylocentrotus droebachiensis) was studied. It was found that the extraction time had the greatest influence on the yield of lipophilic substances whereas temperature and extraction modulus had insignificant effects. Ethanol (95%) was chosen as the extractant affording the maximum amount of lipophilic substances. Optimization of the defatting step established that the maximum yield of lipophilic substances (1.2%) was attained after extraction for 3 h at 55°C with a 1:8 raw-material—extractant ratio. Free fatty acids (57%), phospholipids (~7%), diglycerides, sterols, triglycerides, and hydrocarbons were detected in the lipophilic extract. Phospholipids in the lipophilic extract were represented mainly by phosphatidylcholine. Lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidylinositol, and phosphatidylethanolamine were detected in trace quantities. The (poly)hydroxynaphthoquinone pigment content after purifying the raw material of lipophilic substances was 98.5% according to HPLC.