Extraction and antioxidant property of polyhydroxylated naphthoquinone pigments from spines of purple sea urchin Strongylocentrotus nudus

► A polyhydroxylated 1,4-naphthoquinone (PHNQ) pigment concentrate was extracted from Strongylocentrotus nudus spines. ► Eight PHNQ in the concentrate were indentified tentatively. ► The pigment concentrate had significant antioxidant properties.