Stability of naturally occurring 2,5-dimthyl-4-hydroxy-3[2H]-furanone derivatives

The stability, in aqueous buffer solutions at different pH values (pH 2.0-8.0, interval: 1.5 pH units), of 2,5-dimethyl-4-hydroxy-3[2H]-furanone (Furaneol, DMHF, 1), its methoxy derivative 2,5-dimethyl-4-methoxy-3 [2H]-furanone (methoxyfuraneol, mesifurane, DMMF, 2 and the glycosidically bound forms DMHF P-D-glucopyranoside 3 and DMHF 6'-O-malonyl-beta-D-glucopyranoside 4 was investigated over a period of 32 days at 23 degrees C. Only slight decomposition of 2 and 3 was observed, whereas 1 and 4 were found to be unstable at all pH values. In addition, 3 and 4 were subjected to enzymatic hydrolysis. In contrast to the rapid hydrolysis of 3, the malonylated glycoside, 4, remained unaffected by enzymatic treatment with beta-glucosidase (Emulsin). Using a pectinolytic enzyme preparation (Rohapect D5L; Rohm, Darmstadt, Germany) with esterase activities, hydrolysis of 4 was achieved.