TOBACCO POLYPHENOLS: III. THE ROLE OF FERULIC ACID IN THE BIOSYNTHESIS OF CHLOROGENIC ACID

Abstract

C14-labelled ferulic acid (3-methoxy-4-hydroxycinnamic acid) is actively metabolized by leaf tissues of Nicotiana tabacum with the formation of its glucoside and glucose ester, and the coumarin glucoside, scopolin (6-methoxy-7-O-β-D-glucosido-coumarin). There is considerably less utilization in quinic acid ester formation. The only quinic acid esters which become labelled following the administration of labelled ferulic acid in the light yield ferulic acid on hydrolysis. One of these is 3-O-feruloyl-quinic acid. In the dark, the principal quinic acid esters synthesized again contain ferulic acid, but a low incorporation of activity into chlorogenic acid (3-O-caffeoyl-quinic acid) can be demonstrated. These findings are discussed in relation to reports of the utilization of ferulic acid in chlorogenic acid biosynthesis in other higher plant tissues.