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Generation of ( E )-1-(2,3,6-Trimethylphenyl)buta-1,3-diene from C 13 -Norisoprenoid Precursors

2005; American Chemical Society; Volume: 53; Issue: 17 Linguagem: Inglês

10.1021/jf051039w

1520-5118

Agnieszka Cox, George K. Skouroumounis, Gordon M. Elsey, Michael V. Perkins, Mark A. Sefton,

Food Quality and Safety Studies

Three C13-norisoprenoid compounds, 3,6,9-trihydroxymegastigma-4,7-diene (6), 3,4,9-trihydroxymegastigma-5,7-diene (4), and the actinidols (8), have all been synthesized and subjected to acid hydrolysis. All three were shown to generate (E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene (1) under wine conservation conditions. At 45 °C, approximately 4000−5000 ng/L of 1 was formed from 1.0 mg/L of precursor, after 173 days, while at 25 °C more wine-like amounts (200−600 ng/L) were observed. A glucoside, 4,5-dihydrovomifoliol-C9-β-d-glucopyranoside (9b), was isolated from grapevine leaves by multilayer coil countercurrent chromatography (MLCCC), and its stereochemistry was deduced as being (5R, 6S, 9R) by NMR and CD spectroscopy. Hydrolysis of this glucoside produced 1, but in quantities insufficient to account for the levels observed in wine. Keywords: TPB; SIDA; polyphenols; grapes; precursors; C13-norisoprenoids; MLCCC.