Intrinsic isotopic 13C labelling of polyphenols

Abstract

The intrinsic isotopic labelling of plants with (13)CO2 is an effective method to generate highly labelled compounds using photosynthesis and avoiding labour-intensive complex organic syntheses. In this study, the intrinsic isotopic labelling of polyphenols in parsley, spinach and peppermint is shown for the first time. The plants were grown in an atmosphere where (12)CO2 was replaced by (13)CO2, in order to generate highly labelled compounds. The total content of (13)C as well as the individual polyphenols were analysed by Isotopic Ratio-MS and HPLC-Iontrap-MS(n). After 34 days of plant growth under (13)CO2, degree of labelling was found to be higher than 90 atom% (13)C for most polyphenols, predominantly consisting of highly and fully labelled isotopomers; the total plant material contained more than 88 atom% (13)C. Such highly labelled compounds can be used in future studies to dissect both metabolism and bioavailability of polyphenols in humans.

Keywords: Isotope labelling; Natural products; Phytochemistry; Polyphenols; Stable isotope.