Plant cell culture strategies to increase 13C‐enrichment of lycopene for human metabolic tracing studies

Abstract

The red tomato carotenoid lycopene (LYC) and/or its metabolites may contribute to anti‐cancer bioactivity. However, little is known regarding LYC metabolites that are endogenously‐produced or absorbed from foods. To better understand LYC metabolism, tracer LYC was 13C‐biolabeled using tomato cell cultures grown in 13C‐glucose‐ containing media. Biolabeling produces a mixture of 13C‐mass isotopomers. The goal of this work was to shift the enrichment of LYC (C40H56) toward the uniformly labeled ([U]‐13C‐LYC) isotopomer, in order to provide a strong signal for metabolite detection. ‘Ailsa Craig’ hp‐1 cell cultures were grown in 13C‐glucose‐containing media for 1, 2, or 3 serial growth cycles and mass isotopomeric distribution was quantitated by tandem high pressure liquid chromatography (HPLC)‐mass spectrometry. Serially culturing cells for 1, 2, or 3 growth cycles led to [U]‐13CLYC yields of 10, 38, 46 %, respectively, with no deleterious effect on total LYC yield (~5 mg LYC/L culture for each cycle). To optimize harvest timing, HPLC evaluation of media glucose utilization during the labeling cycle indicated 99% of media glucose was incorporated by day 12 of the growth period. These approaches greatly enhance production efficiency of highly enriched a 13C‐LYC tracer for human carotenoid metabolism research.Grant Funding Source : Pelotonia Postdoctoral Fellowship at OSU and NIH/NCCAM 5R21AT005166‐02