Reduction of the Formyl Group of Zinc Pheophorbide b in vitro and in vivo: a Model for the Chlorophyll b to a Transformation

Abstract

Abstract The chemical reduction of the formyl group of pheophorbide b with sodium cyanoborohy­ dride in methanol leads to 7 1 -methoxy-and 7 1 -hydroxy-pheophorbide a. The same reaction with zinc pheophorbide b yields in addition zinc pheophorbide a. This was characterized by mass and 1 H -NMR spectroscopy. Infiltration of zinc pheophorbides a and b and of zinc 7 1 -hydroxy-pheophorbide a into etiolated oat leaves yielded phytylated products. The best yield in the esterification was obtained with 7 1 -hydroxy-pheophorbide a. Analysis of the products revealed the formation of zinc pheophytin a from all infiltrated compounds. The significance for the transformation of chlorophyll b into chlorophyll a is discussed.