Any of a group of red-brown pigments derived from porphobilinogen.

Any of the group of ommochromes characterized by weaker colours, lower stability to alkalis, and lower molecular weights than ommins.

Any of the group of sulphur-containing ommochromes characterized by stronger colours, greater stability to alkalis, and higher molecular weights…

Any of a group of invertebrate (chiefly arthropod) pigments derived by condensation reactions from kynurenine and giving yellow, red, and…