Transformation of 3,5-dimethoxy,4-hydroxy cinnamic acid by polyphenol oxidase from the fungus Trametes versicolor: product elucidation studies.
Sinapic acid (SA), 3,5-dimethoxy,4-hydroxy cinnamic acid, was incubated with a crude polyphenol oxidase from the fungus Trametes versicolor. Some products of this transformation were isolated and their structures identified using mass spectrometry, nuclear magnetic resonance and Fourier transform infrared spectroscopy, and X-ray crystallography. It was found that the enzymatic oxidation of SA includes two distinct phases. In the initial phase SA is enzymatically transformed to r-1H-2c,6c-bis-(4'-hydroxy-3', 5'-dimethoxyphenyl)-3,7-dioxabicyclo-[3,3,0]-octane-4,8-dione, dehydrodisinapic acid dilactone. The mechanism of this reaction may involve coupling of two phenoxy radicals by the beta-beta mode and subsequent intramolecular nucleophilic attack. In the second phase dehydrodisinapic acid dilactone is transformed by polyphenol oxidase into several intermediate products, including 4-(4-(3, 5-dimethoxy-4-oxo-2,5-cyclohexadienyliden)-1, 4-dihydroxy-(E)-2-butenylidene)-2,6-dimethoxy-2, 5-cyclohexadien-1-one. The final product of the overall transformation of SA is 2,6-dimethoxy-p-benzoquinone. The obtained results were used to propose a part of the transformation pathway for the enzymatic oxidation of SA by polyphenol oxidase.
Lacki
K
K
Department of Chemical Engineering, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
Duvnjak
Z
Z
D001487:Basidiomycota / Q000201:enzymology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000378:metabolism; D004156:Catechol Oxidase / Q000737:chemistry / Q000378:metabolism*; D002794:Choline / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000737:chemistry* / Q000378:metabolism*; D007783:Lactones / Q000737:chemistry / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods
D019086:Bridged Bicyclo Compounds, Heterocyclic; D003373:Coumaric Acids; D007783:Lactones; C118604:dehydrodisinapic acid dilactone; C005685:sinapine; C073734:sinapinic acid; D004156:Catechol Oxidase; D002794:Choline