When grown in a medium rich in glucose but poor in nitrogen. the algae C/dure/lr protorhecoides excrete a red pigment the structure of which has been proven to correspond IO a product of osydative ring cleavage of the chlorophyll-u chromophore at the C4-C5 methine bridge.Chlorophyll-cr catabolism: l9-Formyl-1[2lH. 22Hlbilinon derivative

The structure of a new red pigment produced during the “bleaching” of Chlorella protorhecoides cells has been elucidated by analytical methods as well as by in vitro isomerization into the new compound of a synthetic sample of a previously characteriLed chlorophyll a catabolite.