Ribosides and Ribotide of a Fairy Chemical, Imidazole-4-carboxamide, as Its Metabolites in Rice.

The metabolism of imidazole-4-carboxamide (ICA) in plants has been unknown. Two metabolites ( 1 and 2 ) were isolated from ICA-treated rice, and their structures were determined by spectroscopic analysis including the single-crystal X-ray diffraction technique and synthesis. The ribotide of ICA ( 3 ), whose existence was predicted, was also synthesized and detected from the treated rice by LC-MS/MS. These results indicated that rice might interconvert ICA, 1 , and 3 to regulate the biological activity.