E. Nunezdelicado et al., CYCLODEXTRINS AS SECONDARY ANTIOXIDANTS - SYNERGISM WITH ASCORBIC-ACID, Journal of agricultural and food chemistry, 45(8), 1997, pp. 2830-2835
The preservation of the antioxidant capacity of ascorbic acid by 2-hyd
roxypropyl-beta-cyclodextrins has been studied. For this, a model syst
em consisting of ascorbic acid, H2O2, a phenolic compound, 2,2,5,7,8-p
entamethylchroman-6-ol (PMC), and commercial soybean lipoxygenase was
used. In this system, ascorbic acid was oxidized by PMC radicals gener
ated by the hydroperoxidative activity of lipoxygenase, giving rise to
a biphasic curve, in which the inflection point represents the time a
t which all the ascorbic acid has been consumed (t .(ip)). This t .(ip
) depends on the enzyme, ascorbic acid, and PMC concentration. When 2-
hydroxypropyl-beta-cyclodextrins were included in the system, the t .(
ip), increased, indicating that these cyclodextrins were acting as sec
ondary antioxidants, so preserving the antioxidant capacity of the sys
tem. A mathematical model to explain the effect of cyclodextrins on as
corbic acid oxidation in this experimental system is described, giving
a constant, K-c, which represents the preservation capacity of a part
icular antioxidant system produced by cyclodextrins.