Biotransformation of hydroxycoumarins by the cultured cells of Nicotiana tabacum

Administration of hydroxycoumarins to the cultured cells of Nicotiana tabacum caused the ladder fragmentation of genomic DNA of the cells and the secretion of the intracellular phytoalexin, scopoletin, into the culture medium, and also the exogenous hydroxycoumarins were transformed into their corresponding β-d-glucosides. The glucosylation seems to be a defense reaction of the cells for detoxification of toxic hydroxycoumarins, because their glucosides did not cause the DNA fragmentation.