| A critical factor for the bioactivity of small molecules in vivo is their level of absorption, metabolism and excretion. To survey these facets of small molecule biology in Arabidopsis, I characterized 412 biologically active and inactive drug-like molecules. My results show that bioactive compounds are more likely to show uptake into plants. 23% of compounds show evidence of metabolites and 15% of compounds show evidence of extracellular metabolites. Four compounds with extracellular metabolites were characterized further; seedling transfer experiments after drug-loading suggest that 3 of the 4 metabolites were excreted from the root, possibly in an ATP dependent manner. Mass spectrometry of the extracellular metabolites identified them as either chlorinated, reduced, glycosylated, or potentially lysine-conjugated metabolites of the parent compounds. My results provide a foundation for future elucidation of the mechanisms involved in xenobiotic exudation in Arabidopsis and suggest the existence of a previously unrecognized xenobiotic-metabolite efflux system in plants. |
