Abstract
The risk of pharmacokinetic polyphenols-trace elements interaction may undesirable therapeutic outcomes. We evaluate the long-term use of silibinin, epigallocatechin (ECGC), quercetin and rutin on the absorption and tissue distribution of zinc, copper and iron after single oral doses in rats. Five groups of rats were either with olive oil as control or with one of the polyphenols silibinin, EPGC, quercetin or rutin, administered orally as oily solutions for 30 days. At day 30, a solution contains sulphate salt of zinc, copper and iron was administered orally; 3 hrs later blood samples, tissues of brain, kidney and liver were obtained for evaluation of the elements levels. The results showed that the polyphenols increased both serum and tissue levels of these elements compared with controls. This effect was relatively varied according to the structural differences among flavonoids. In conclusion, long-term use of supraphysiological doses of flavonoids increase absorption of Zn, Cu and Fe and their tissue availability in brain, kidney and liver; this effect seems to be different with variations in structural features.
Highlights
Flavonoids are one of the bioactive compounds widely available in fruits and vegetables [1]
Concerning long-term effects of the tested flavonoids on the absorption of Cu, all of them produced significant increase (P < 0.05) in serum Cu levels compared to the values reported in controls; only Silibinin dihemisuccinate (SDH) and quercetin demonstrated significantly different effects in this respect, when the effects of the four flavonoids compared with each others (Figure 2)
The most prominent effect for the studied flavonoids in this respect was reported on iron tissue availability, where Epigallocatechin gallate (EGCG) produced consistent increase in the three targeted organs while rutin showed the lowest effect in this respect compared to others
Summary
Flavonoids (polyphenolic compounds) are one of the bioactive compounds widely available in fruits and vegetables [1]. Many peoples are motivated by scientific research that is widely carried in the news media, which indicated these flavonoids and polyphenols could prevent cancer, ageing, and cardiovascular diseases [3,4]. These researches are often carried out in animals and their effects in humans remain uncertain [5]. There is currently an extensive range of flavonoid supplements on the market [7]. Suppliers of such supplements recommend daily flavonoid intakes in amounts that are many times higher than those doses which can normally be achieved from a flavonoid-rich diet.
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