Biotransformation of cardenolides by plant cell cultures1

A culture of DAUCUS CAROTA cell line Ca68, previously shown to specifically hydroxylate digitoxigenin at the C-5 position, has been shown also to convert gitoxigenin and oleandrigenin to their corresponding 5beta-hydroxy derivatives. These two products have not been identified previously. 5beta-Hydroxygitoxigenin has been identified by physico-chemical methods and data on its mass spectrum and (13)C-NMR spectrum are reported. 5beta-Hydroxyoleandrigenin was identified from its high resolution mass spectrum. Addition of gitoxigenin at 72 hrs after inoculation resulted in a two fold increase in the rate of bioconversion compared to addition at 0 hr. The results are discussed in relation to other biotransformation reactions and with respect to improving the yields of plant products and the formation of novel compounds.