Multiple combinations of phenolic compounds in
oranges tend to increase antioxidant capacity, suggests recent study.
In a recent study published in the Journal of Food Science, researchers
sought to analyze the antioxidant activity and interactions of multiple
phenolic compounds in navel oranges (Citrus sinensis).Freeman
et al., cite other research findings in the literature noting that while
individual phenolic compounds have a high antioxidant capacity, the antioxidant
activity of whole fruit has been observed to be higher than any one individual
compound at concentrations found in fruit.The difference, they note, may be due to
the total influence of multiple compounds in fruit at low concentrations,
unidentified compounds or “synergistic
interactions between phenolic compounds.”
Freeman, et al., write that the potential additive or
synergistic pharmacological influence of multiple compounds within a food is
described in the literature as “endointeractions,”
while “exointeractions” are
interactions among unrelated plant components (i.e. food compounds from
different foods) and/or drugs.In this
study they hypothesized that “by starting
with the individual phenolic antioxidants at the concentration found in a
specific fruit, synergism could be demonstrated using only endointeractions.”
Freeman et al., prepared mixtures of 2, 3 and 4
phenolic compounds found in navel oranges; these included
chlorogenic acid, hesperidin, luteolin,myricetin, naringenin, p-coumaric
acid, and quercetin. They quantified the antioxidant capacities of each mixture
using the Oxygen Radical Absorbance Capacity (ORAC) assay.
Overall, it was observed that several combinations of
2, 3 and 4 compounds yielded a significantly higher antioxidant capacity when
compared to individual compounds.Notably, despite predictions, any combination past 3 did not progressively increase
total antioxidant capacity.In all, the
synergism of 5 combinations of 3 compounds increased the total ORAC, as did all
but one combination of 2 compounds; one combination of 2 compounds actually
diminished antioxidant capacity.
Freeman
et al., presented a multifaceted model to best explain their results which
focused, in part, on the presence or absence of functional catechol groups in
phenolic compounds.Despite the
soundness of their model to explain their findings they acknowledged several
limitations of their study, such as the fact that only a few compounds from
oranges were studied (there are hundreds more), no direct comparison was made
to the orange as a whole and only one assay was employed.However, proving their hypothesis of
synergism among phenolic compounds to be true, Freeman et al., assert that further study in this area is
warranted.
Study: Freeman, B.L., Journal of Food Science, Vol. 75, Nr. 6, (2010)
