Pigment first found in wings of butterflies. Widely distributed in insects and in animals. Has been separated from urine and from the crab. Isoln and structure: Schpf, Becker, Ann. 507, 266 (1933); 524, 55, 126 (1936); Schpf, Kottler, Ann. 539, 128 (1939); Wieland, Purrmann, Ann. 544, 163 (1940). See also Fukushima, Shiota, J. Biol. Chem. 247, 4549 (1972). Synthesis: Purrmann, Ann. 546, 98 (1940); 548, 284 (1941); Koschara, Z. Physiol. Chem. 277, 159 (1943); Totter, J. Biol. Chem. 154, 105 (1944); Elion et al., J. Am. Chem. Soc. 71, 741 (1949); Koschara, DE 859471 (1952 to Bayer), C.A. 52, 10222f (1958); Stuart, Wood, J. Chem. Soc. 1963, 4186. Facile synthesis: Taylor, Jacobi, J. Am. Chem. Soc. 95, 4455 (1973); Taylor et al., J. Org. Chem. 40, 2341 (1975). Exhibits tumor inhibitory properties.