Les ptérines des Pieridae et leur biosynthèse: IV — Métabolisme de la ptérine, de la xanthoptérine et de leurs dérivés hydrogénés chez Colias croceus

Abstract

Summary The metabolism of simple pterin components is studied by injection of 2-14C labelled compounds: pterin, di- and tetra-hydropterin, xanthopterin, dihydroxanthopterin, in pupae of the Pierid butterfly Colias croceus, during the phase of pigment formation. The compounds deposited in the scales of the adult wings are investigated by paper, thin layer and ion-exchange column chromatography. The results show that pterin is mainly oxidised to isoxanthopterin and that xanthopterin is partly deposited in the scales without modification, partly oxidised to leucopterin, owing to its state of covalent hydration, partly transformed into erythropterin through nucleophilic addition or into 2 unknown compounds, the already described croceopterin being amongst them. Hydrogenated pterin produces labelling of the pterin series, but also of the xanthopterin series and appears to be the precursor of both types of pigments. Hydrogenated xanthopterin gives results which differ only quantitatively by from xanthopterin, owing to the proportions of hydrogenated, hydrated or anhydrous forms. A biosynthesis scheme is proposed and the role of the various factors directing this synthesis and leading to pigment polymorphism is discussed.