Engelmann, Nancy J., Adam Reppert, Gad Yousef, Randy Rogers and Mary Ann Lila. 2009. In vitro production of radiolabeled red clover (Trifoliumpratense) isoflavones. Plant Cell Tissue & Organ Culture 98: 147-156.
Red clover isoflavones are increasingly used in dietary supplements for their purported estrogenic effects. However, little is known about their metabolism in animals due to a lack of commercially available isotopically-labeled tracers. The goal of this research was to establish red clover cell culturing methodology for (14)C-biolabeling of isoflavones. When root, leaf, and petiole-derived suspension cultures were grown in darkness or light, dark-grown, petiole-derived solution cultures produced the highest concentrations of the two major red clover isoflavones, formononetin (0.67 mg/g FM inoculum) and biochanin A (0.13 mg/g FM inoculum). Varying levels and timing of copper chloride elicitor did not significantly affect isoflavone accumulation. Approximately 38% of the (14)C-sucrose dose accumulated in the cells. Eighteen percent of the initial labeled dose was detected in the isoflavone-rich methanolic extract and of that, 22% accumulated in isoflavones.