Tyrian Purple from marine muricids, especially from Plicopurpura pansa (Gould, 1853)

A review of the literature discloses that most marine snails of the family Muricidae produce in the hypobranchial gland a viscous secretion containing, besides mucus and biologically active compounds, minute amounts of chromogens. These chromogens develop enzymatically and under the influence of light and oxygen into a purple pigment known as "Tyrian Purple", "Royal Purple" or shellfish purple. In the hypobranchial gland the enzyme purpurase is kept apart from the chromogens, so that no pigments are formed under normal conditions. Different species of muricids produce different pigments, depending on the number and concentration of different chromogens and on the varying light intensity and oxygen availability during pigment formation. The main pigments obtained from the hypobranchial gland from muricids are indigoids. The pigment of P. pansa is mainly 6,6′-dibromindigo with smaller amounts of 6-bromoindigo and 6,6′-dibromoindirubin, similar to that of Murex brandaris.