In vitro conversion of phytol to phytanic acid in rat liver: subcellular distribution of activity and chemical characterization of intermediates using a new bromination technique.

The enzymatic conversion of phytol to phytanic acid has been demonstrated in vitro in rat liver. Subcellular fractionation indicated that the mitochondrial fraction possessed the highest activity. Substantial activity was also present in the microsomal fraction. A new bromination-thin-layer chromatography procedure was developed to separate the phytol-dihydrophytol mixture and this procedure was applied to identify, characterize and quantitate the metabolites of phytol-phytanate conversion, i.e., phytanic acid, phytenic acid and dihydrophytol. Phytanic and phytenic acids were formed in the ratio 100:7.4. The conversion of phytol to phytenic acid was in the range 2-3%. No dihydrophytol was detected over boiled, acidified, or no-enzyme controls. The presence of phytenic acid and the absence of dihydrophytol in the incubation mixture confirm the previous in vivo studies and suggest that phytenic acid may be an intermediate in phytol-phytanate conversion.