Phenolic Synergy in Oranges - Fascinating New Research!

Friday, January 21, 2011

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)

posted by Innate Response at

9:36 AM

Phenolic Synergy in Oranges - Fascinating New Research!

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