Über Leukopterin, das Flügelpigment der Kohlweißlinge (Pieriden). II

The Chemistry of the Pteridines.

“…Virtually all the pteridines have well-developed acidic properties and are soluble in both alkalies and ammonia (13,23,24,48,49,105,108). Quantitative data are available for only two compounds, 2-amino-6-hydroxypteridinej whose pK, is 8.0, and 2-amino-6-hydroxy-8-pteridinecarboxylic acid, whose pK,'s are 3.9 and 7.7, respectively, for the first and second dissociations (2).…”

“…It is attacked by alkaline ferricyanide (105), but in contrast to uric acid is unaffected by molecular oxygen in the presence of manganese dioxide (105).…”

“…In methanol, the hydrochloride (XXIII) of leucopterin glycol dimethyl ether results, although this substance has not been obtained pure because of its ready loss of one methyl group by hydrolysis. The corresponding free base can be obtained from the hydrochloride by the action of pyridine in methanol (105). In water, the hydrochloride (XXII) of leucopterin glycol itself is obtained, along with a small amount of oxalylguanidine, the yield of which can be increased by working at 60-70°C.…”

“…Leucopterin glycol is stable to boiling water (103) but on energetic hydrolysis with dilute acids it yields carbon dioxide, acid ammonium oxalate, and guanidine, isolated as its chloroaurate (105). Apparently the pyrimidine ring is in part altered before the liberation of guanidine, since only about one third of a mole of guanidine, which is stable under these conditions, is isolable (105).…”

Genetic Research in the Lepidoptera: Being the Galton Lecture of London University, Delivered August 1939, to the Seventh International Congress of Genetics

“…In the groups Pharmacophagus and Papilio (sensu stricto), in which flavones do not occur, these colours appear to be due solely to "pterins" like the white leukopterin (Clg~HlgO~N15) isolated by Wieland et al (1933) Pierine butterflies, see below). They are manufactured by the insects themselves, being of the same general type as uric acid.…”