Complexation of Bioelements and Toxic Metals by Polyphenolic Compounds - Implications for Health

Abstract

Nowadays, growing interest in the possibility of prophylactic and therapeutic use of plant products rich in biologically active compounds has been observed. Among them, special interest has been focused on polyphenol-rich products. Owing to the multidirectional favourable action of polyphenols, products rich in these compounds are recommended as functional food in the case of civilization diseases. Moreover, data from studies in animal models show that polyphenols may be a promising preventive/therapeutic strategy for xenobiotics, including toxic heavy metals. The protective impact of polyphenols against metal toxicity may be explained by the presence of many hydroxyl groups in the structure of these compounds, which are capable of forming complexes with metals preventing as a result from their gastrointestinal absorption and accelerating their elimination from the body with urine. However, it should be taken into account that polyphenols may bind not only ions of toxic metals, but also bioelements, what makes a risk of their shortage in the organism. This review provides an overview of implications for humans' and animals' health of complexation of bioelements and toxic metals by polyphenols present in the popular foodstuffs, including phenolic acids, cyanidin derivatives, delphinidin, quercetin, kaempferol, morin, epigallocatechin-3-gallate, and curcumin. Polyphenolic compounds capable of binding both necessary and toxic metals occur in commonly consumed products such as green tea, and some fruit and vegetables, including chokeberries, bilberries, and black currant fruit, grapes, and apples, as well as onion. The mechanisms of complexation of essential and toxic metals by polyphenols and possible implications of these for health are discussed.

Extract from <em>Aronia melanocarpa </em>L. Berries Prevents Cadmium-induced Oxidative Stress in the Liver: a Study in a Rat Model of Low-level and Moderate Lifetime Human Exposure to this Toxic Metal

“…The favourable effect of AE on the oxidative/antioxidative status of the liver under treatment with Cd may be explained by a direct effect of the extract resulting from its strong antioxidative potential [4,25] and from an indirect effect related to interactions between ingredients of the extract and this toxic element. Both the direct and indirect effects might be due to first of all the high abundance of polyphenolic compounds, characterized by strong antioxidative properties and the ability to chelate Cd 2+ [4,26,27,32,33]. The polyphenolic profile of aronia berries includes mainly anthocyanins (cyanidin 3-O-α-arabinoside, cyanidin 3-O-β-galactoside, cyanidin 3-O-β-glucoside, cyanidin-3-xyloside, pelargonidin-3-galactoside, pelargonidin-3-arabinoside), proanthocyanidins (oligomeric and polymeric catechins), flavonols (quercetin, quercetin-3-galactoside, quercetin-3glucoside, quercetin-3-rutinoside, quercetin-3-vicianoside, quercetin-3-robinobioside, and kaempferol) as well as chlorogenic acid and neochlorogenic acid [4,25,27].…”

“…Aronia berries (chokeberries) are a rich source of polyphenolic compounds, which are one of the most powerful and widespread groups of natural antioxidants [4,31]. Owing to the large number of hydroxyl groups (-OH groups), these compounds are capable of chelating metal ions, including Cd ions (Cd 2+ ) [31][32][33]. Apart from polyphenols, chokeberry is also abundant in other ingredients characterized by an ability to detoxify FR and ROS, such as vitamins, essential bioelements, carotenoids, phytosterols, and triterpenes [4].…”

Review of polyphenol‐rich products as potential protective and therapeutic factors against cadmium hepatotoxicity

“…According to their structure, molecular weight and hydroxylation patterns, polyphenols are divided into five major classes: phenolic acids, phenolic alcohols, flavonoids, stilbenes and lignans (Quideau et al, ). A wide spectrum and diversity of polyphenolic compounds action (Figures and ) refers to the presence of ‐OH groups capable of chelating metals and detoxifying FR (Borowska et al, ; Brzóska, Gałażyn‐Sidorczuk, et al, ; Dai et al, ; Okoye, Chukwuneke, Ekere, & Ihedioha, ; Quideau et al, ; Ravichandran et al, ).…”

“…Data from the literature show that if consumption is reasonable, there are no negative side effects and possibility of overdose of polyphenolic compounds (Chang et al, ; Kelley et al, ; Pezeshki et al, ; Tresserra‐Rimbau et al, ). However, due to the ability of polyphenols to chelate metals (Borowska et al, ; Horniblow et al, ; Primikyri et al, ), it should be taken under consideration that some deficiencies of essential bioelements may occur during the very high and prolonged consumption of these compounds (Zijp, Korver, & Tijburg, ); however, this aspect needs more attention to evaluate fully the interaction between polyphenols and essential elements in the human body.…”

“…As the liver is one of the target organs for Cd and disturbances in the proper functioning of this organ have serious consequences for health (Brea et al, ; Chang et al, ; Targher et al, ), in the present review our attention has been focused on polyphenol‐rich food products as a possible effective strategy in the protection from Cd hepatotoxicity and treatment of this heavy metal‐induced liver damage. Owing to the ability of polyphenols to bind ions of divalent metals, including toxic metals (Borowska, Brzóska, & Tomczyk, ; Brzóska, Gałażyn‐Sidorczuk, et al, ; Dai, Dong, & Ma, ; Horniblow, Henesy, Iqbal, & Tselepis, ; Jayanta & Shukla, ; Primikyri et al, ; Ravichandran, Rajendran, & Devapiriam, ), and strong antioxidative potential of these compounds (Brzóska, Borowska, & Tomczyk, , Brzóska, Rogalska, et al, ), as well as their abundance in dietary products (Brzóska, Borowska, & Tomczyk, ; Brzóska, Rogalska, et al, ; Quideau, Deffieux, Douat‐Casassus, & Pouységu, ), it seems to be of high importance to consider the possibility of using polyphenols as potential preventive and therapeutic agents against Cd hepatotoxicity. As the knowledge on the mechanisms of this xenobiotic‐induced liver damage is imperative when looking for possible factors effective in the protection from Cd hepatotoxicity, the pathways of this organ injury by Cd are also presented in the current paper.…”