Absorption Coefficients of Chlorophyll Derivatives

Methods are described for the isolation of chlorophylls a and b, and for the preparation of 12 chlorophyll derivatives, including crystalline pheophorbide a, from these starting compounds. Laboratory cultures of Chlorella were fed C 14 O 2 . After 9 days growth the cells were heat-killed, their pigments extracted, and chlorophylls a and b isolated chromatographically. The following C 14 -labelled compounds were prepared: chlorophyll a, allomerized chlorophyll a, chlorophyllide a, pheophytin a, allomerized pheophytin a, pheophorbide a, methyl pheophorbide a, chlorophyll b, chlorophyllide b, methyl chlorophyllide b, allomerized chlorophyllide b, allomerized methyl chlorophyllide b, pheophorbide b, and allomerized pheophorbide b. Assuming uniform distribution of carbon-14 label in the parent chlorophyll molecules, specific and molar absorption coefficients were calculated from the specific radioactivities of these derivatives.