Radiotracer Studies on the Formation of 2,5-Dimethyl-4-hydroxy-3(2H)-furanone in Detached Ripening Strawberry Fruits

The transformation of 12 radioactively labeled compounds into 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF), glycosidically bound DMHF, and 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMMF) was investigated in detached ripening strawberry fruits (Fragaria x ananassa) over a 3-day period. Radiochemical analysis of the different fruit parts revealed that major portions of the applied radioactivity (up to 66%) remained in the stems and calyx. Incorporation levels of [2- 14 C]-dihydroxyacetone, D-[1- 3 H]glucose, D-[U- 14 C]-glucose, D-[U- 14 C]glucose 6-phosphate, D-[U- 14 C]fructose, and D-[U- 14 C]fructose 1,6-bisphosphate into the total amount of furanone derivatives were 0.022, 0.032, 0.035, 0.147, 0.202, and 0.289% of the radioactivity entering the fruits, respectively. Minor amounts of radioactivity ( <0.001%) were detected in the furanone structures after the administration of[1- 14 C]acetate and [3- 14 C]pyruvpye. L-[1- 14 C]Fucose, L-[6- 3 H]fucose, L-[1- 3 H]rhamnose, L-[U- 14 C]-threonine, L-[U- 14 C]lactaldehyde, and [2- 14 C]malonic acid were not transformed into DMHF or a derivative thereof.