Fig. 2. Coloured Chl-catabolites (yellow and pink coloured YCCs and PiCCs) result from ‘biological’ and from ‘chemical’ oxidation of the colourless ‘non-fluorescent’ Chl-catabolites (NCCs): NCC 1 is thus oxidized to the yellow YCC 2. The latter is further oxidized to the PiCC 3 via the blue Zn-complex Zn-3.