https://www.britannica.com/science/naphthoquinone
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Naphthoquinones are encountered in some bacteria and in the leaves, seeds, and woody parts of higher plants. They can be recovered as yellow, orange, red, or purple crystals. They are soluble in organic solvents and have been used extensively as dyes for fabrics. Among the naphthoquinones of biochemical and physiological importance are the K vitamins. Another series within the naphthoquinone class manifests conspicuous red, purple, or sometimes green colours in a few animal types. These are the spinochromes, so named because they are conspicuous in tissues and in the calcareous tests (shells) of echinoids, or sea urchins.
