REDUCTION OF CHLOROPHYLL A, A' AND B BY SODIUM-BOROHYDRIDE - SEPARATION OF DIASTEREOISOMERIC DESOXO-CHLOROPHYLL ALCOHOLS ON A SUCROSE COLUMN

Chlorophyll a, a′ and b were reduced with sodium borohydride in pyridine and the desoxo-chlorophyll alchohols (DOCA) produced were separated on a sucrose column. Reduction of chlorophyll a (Chl a) for 15 min resulted in one principal product, the 9(R) 10(R) DOCA a. Similar treatment of Chl a′ yielded as the principal reduction product a different diastereomer, presumably the 9(S) 10(S) DOCA a. More unreduced Chl remained also in the latter instance. This was interpreted as an indication of the steric hindrance of the 9-oxo group by the methoxycarbonyl group in Chl a′. Reduction of Chl a for 30 min resulted in three diastereomeric DOCA as evidenced by the separtion on a sucrose column. These were presumably the 9(S) 10(S), 9(R) 10(R) and 9(S) 10(R) forms of DOCA a. The 9(R) 10(R) form was, however, the principal reduction product also in this instance. When Chl a′ was reduced for 30 min, the separation on sucrose yielded possibly four diastereomeric DOCA which were thought to possess the 9(S) 10(S), 9(R) 10(S), 9(R) 10(R) and 9(S) 10(R) configurations. The 9(S) 10(S) form was still the principal reduction product. Chl a′ also yielded appreciable amounts of magnesium-free pigments, which was interpreted as further evidence for the higher pheophytinization tendency of Chl a′ in comparison with that of Chl a′. The separation of the products from the reduction of Chl b for 30 min yielded five components. Two of them were 10-epimers of Chl b-3-methanol and the three others, different diastereomers of DOCA b-3-methanol. © 1979.