METABOLISM OF [U–¹⁴C]–(+)–CATECHIN IN THE PLANT UNCARIA GAMBIR

Abstract

Chromatographie analysis of fresh leafy shoots of Uncaria gambir Roxb. revealed that (+)-catechin and (–)–epicatechin are the major flavonoids present together with trace amounts of three unidentified polyphenols. Administration of [U– ¹⁴ C]–(+)–catechin to young leafy shoots showed that about 92.9 %, 88.4 % and 80.8 % of dose radioactivity were detected in the 24 h, 48 h and 12 h leafy shoots respectively as extractable compounds. High levels of ¹⁴C incorporation was found in (+)-catechin, (–)–epicatechin and one unidentified polyphenol. In addition, small amounts of radioactivity was detected in two other unidentified polyphenols. It is suggested that [U– ¹⁴ C]–(+)–catechin may be converted to a component of the unidentified polyphenols. The low production of ¹⁴ CO ₂ (ranging from 0.2–2 % of dose) over the period of 24–72 h indicate that (+)–catechin is not significantly utilized as a substrate for respiratory processes in the plant. It is suggested that (+)-catechin is an end product of biosynthesis in the plant U. gambir.