Crude onion peroxidase extract: novel application in the synthesis of natural products Case: oxidative dimerization of coniferyl alcohol
2012
Kessi, O.
The objective of this study was to investigate the influence of the onion production period on enzymatic activity and protein quantity of a crude onion peroxidase extract, as well as the enzymatic activity of the latter on the oxidative coupling of coniferyl alcohol (CAL) into the corresponding (E) coniferyl alcohol dimer in two different systems (monophasic and biphasic system made of water/ water-immiscible organic solvents, using THF and EtOAc as organic solvents), and therefore the antioxidant activity of the resultant product. First, the onion production period seems to have no influence on the activity nor the protein quantity of the enzyme during the four months of experimentation. The oxidative coupling of coniferyl alcohol in the biphasic system with the use of AcOEt gave one major product, eluting at around 12 min. This major product obtained with these conditions (EtOAc, pH 3, 10eq H2O2, overnight) displayed an ion peak at m/z 374 (ESIMS) referring to a dimer of (E)-coniferol and corresponding to C21H26O6. A study of antioxidant activity by interaction with DPPH of the resulting products from the oxidative coupling of coniferyl alcohol obtained under: THF, pH 3, 2 mM CAL and 3mM H2O2 (10 eq) overnight conditions, indicated that the resulting compounds are good DPPH radical scavengers, comparable to the reference compound CA.
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