Metabolism of 2,5-dimethyl-4-hydroxy-3(2H)-furanone in detached ripening strawberry fruits

The transformation of S-[methyl-C-14]adenosyl-L-methionine (C-14-SAM) and [2-(or 5-)methyl-C-14]-2,5-dimethyl-4-hydroxy-3(2H)-furanone (C-14-1) was investigated in detached ripening strawberry fruits over a three-day period. Radiochemical analysis of the different fruit parts revealed that 46% and 51% of the applied C-14 remained in the stems for C-14-SAM and C-14-1, respectively. In samples obtained by solid phase extraction, 1, 2,5-dimethyl-4-methoxy-3(2H)-furanone (2), and glycosidically bound 1 were analyzed by reversed-phase high-performance liquid chromatography. Incorporation of C-14-SAM and C-14-1 into 2 was observed with transformation rates of 0.4% and 0.3% of the applied C-14, respectively. In addition, 0.7% of the applied C-14-1 was recovered as glycosidically bound 1. The data support the conclusions that C-14-SAM is the source of the methyl group in the 4-methoxy compound 2 and that 1 is the precursor of 2 and the glycosides studied.