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Fractionation of phenolic compounds from a purple corn extract and evaluation of antioxidant and antimutagenic activities
Abstract
Qualitative and quantitative analysis of anthocyanins and other phenolic
compounds from a purple corn extract was performed. The purple corn extract had
cyanidin-3-glucoside, pelargonidin-3-glucoside, peonidin-3-glucoside and its respective
acylated anthocyanin-glucosides. Cyadinin-3glucoside was the main constituent (44.4 ??
4.7%) followed by the acylated cyanidin-3-glucoside (26.9 ?? 8.0%). Other phenolic
compounds present in the purple corn corresponded to protocatechuic acid, vanillic acid,
and p-coumaric acid. In addition, quercetin derivatives, a hesperitin derivative and pcoumaric
and ferulic acid derivatives were found.
Fractionation of phenolic compounds yielded two main fractions, an
anthocyanin-rich water fraction (WF) and an ethyl acetate fraction (EAF). Evaluation of
antimutagenic activity in both fractions revealed higher antimutagenic activity in the
ethyl acetate fraction compared to the anthocyanin-rich fraction. On the other hand,
antioxidant activity of the anthocyanin-rich fraction was higher compared to the ethyl
acetate fraction.
Further fractionation of the anthocyanin-rich fraction in a Toyopearl HW40 gel
permeation column yielded five sub-fractions which showed no difference in
antimutagenic activity except for the water sub-fraction WF-V. All the sub-fractions
were active as antimutagens and antioxidants. Further fractionation of the ethyl acetate
fraction yielded four sub-fractions that showed to be active as antimutagens and
antioxidants. Ethyl acetate sub-fraction EAF-IV was the most active as an antimutagen.
HPLC-DAD characterization of that sub-fraction revealed mainly the presence of a
quercetin derivative with UV-visible spectral characteristics similar to rutin but with a
little longer retention time.
The mechanism of antimutagenic action by the phenolic compounds present
either in the anthocyanin-rich fraction or the ethyl acetate fraction and sub-fraction EAFIV
seems to be a contribution of a direct action on the enzymes involved in the
activation of the mutagen and to the scavenging activity of the mutagen nucleophiles, as
demonstrated by our assays.
Citation
Pedreschi, Romina Paola (2005). Fractionation of phenolic compounds from a purple corn extract and evaluation of antioxidant and antimutagenic activities. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /2343.