Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies

Polyphenols are secondary metabolites of plants and are generally involved in defense against ultraviolet radiation or aggression by pathogens. In the last decade, there has been much interest in the potential health benefits of dietary plant polyphenols as antioxidant. Epidemiological studies and associated meta-analyses strongly suggest that long term consumption of diets rich in plant polyphenols offer protection against development of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases. Here we present knowledge about the biological effects of plant polyphenols in the context of relevance to human health.

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Plant Polyphenols as Dietary Antioxidants in Human Health and Disease

Anthocyanins are flavonoids in fruits and vegetables that render them vivid red to blue. To date, there have been more than 635 anthocyanins identified in nature, featuring six common aglycones and various types of glycosylations and acylations. Dietary consumption of anthocyanins is high compared to other flavonoids, owing to their wide distribution in plant materials. Based upon many cell-line studies, animal models, and human clinical trials, it has been suggested that anthocyanins possess anti-inflammatory and anti-carcinogenic activity, cardiovascular disease prevention, obesity control, and diabetes alleviation properties, all of which are more or less associated with their potent antioxidant property. Evidence suggests that absorption of anthocyanins occurs in the stomach and small intestine. Epithelial tissue uptake seems to be highly efficient, yet transportation into circulation, tissue distribution, and urine excretion are very limited. The bioactivity of bioavailable anthocyanins should be a f...

Anthocyanins: Natural Colorants with Health-Promoting Properties

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.

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Techniques for analysis of plant phenolic compounds.

Anthocyanins and betalains play important roles both in plant physiology, visual attraction for pollinators and seed dispersers, but also in food mainly defining its aesthetic value. Since anthocyanin and betalain structures allow to predict only part of their appearance, additional chemical and anatomical functions are required to modulate the appearance of plants and coloured food. Physiological effects that the same pigments exert in plants are supposedly similar to those which they show in humans following ingestion of coloured food. Therefore, anthocyanins and betalains both in fresh and also processed fruit and vegetables serve two functions: They improve the overall appearance, but also contribute to consumers' health and well-being.

Functional properties of anthocyanins and betalains in plants, food, and in human nutrition

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/S0014-5793%2803%2900504-0

The stomach as a site for anthocyanins absorption from food1

Anthocyanins represent the main flavonoid pigments in red grape and wine, in red berries, and in many other fruits and vegetables and are widespread in the human diet. After ingestion, these complex, hydrophilic compounds quickly appear as intact molecules in the plasma. This study investigated their presence in the brain of anesthetized rats that received 8 mg/kg of body weight of a pure anthocyanin mixture extracted from Vitis vinifera grapes. The mixture was maintained in the stomach for 10 min. After this time, intact anthocyanins were detected by HPLC-DAD-MS not only in the plasma (176.4 +/- 50.5 ng/mL, mean +/- SEM) but also in the brain (192.2 +/- 57.5 ng/g). These results demonstrate for the first time that grape pigments can reach the mammalian brain within minutes from their introduction into the stomach.

Fast access of some grape pigments to the brain.

Fruits and vegetables are rich in flavonoids, and ample epidemiological data show that diets rich in fruits and vegetables confer protection against cardiovascular, neurodegenerative and inflammatory diseases, and cancer. However, flavonoid bioavailability is reportedly very low in mammals and the molecular mechanisms of their action are still poorly known. This review focuses on membrane transport of flavonoids, a critical determinant of their bioavailability. Cellular influx and efflux transporters are reviewed for their involvement in the absorption of flavonoids from the gastro-intestinal tract and their subsequent tissue distribution. A focus on the mammalian bilirubin transporter bilitranslocase (TCDB 2.A.65.1.1) provides further insight into flavonoid bioavailability and its relationship with plasma bilirubin (an endogenous antioxidant). The general function of bilitranslocase as a flavonoid membrane transporter is further demonstrated by the occurrence of a plant homologue in organs (petals, berries) where flavonoid biosynthesis is most active. Bilitranslocase appears associated with sub-cellular membrane compartments and operates as a flavonoid membrane transporter.

Bioavailability of flavonoids: a review of their membrane transport and the function of bilitranslocase in animal and plant organisms.

Phenolics from bilberries ( Vaccinium myrtillus L.) sampled from seven different locations and highbush blueberries ( Vaccinium corymbosum L.) from one location in Slovenia were analyzed. In samples of both species 15 anthocyanins were identified by LC-MS/MS. Their contents were expressed as cyanidin 3-glucoside equivalents (C3GE); bilberries contained 1210.3 ± 111.5 mg C3GE/100 g fw and blueberries 212.4 ± 14.1 mg C3GE/100 g fw. Glycosides of delphinidin and cyanidin were predominant (488.5 vs 363.6 mg C3GE/100 g fw) in the bilberries and glycosides of malvidin (108.0 vs 100.8 mg C3GE/100 g fw) in the blueberries, whereas the contents of peonidin were lowest (74.5 vs 4.8 mg C3GE/100 g fw) in both berries. The contents of flavanols, flavonols, phenolic acids, and stilbenes were determined by LC-MS. For the first time, rutin was identified (bilberries, 0.2 ± 0.0 mg/100 g fw; blueberries, 3.1 ± 0.1 mg/100 g fw). Chlorogenic acid (as 3-caffeoylquinic acid) was the most abundant among the phenolic acids (23.1 ± 1.0 mg/100 g fw in bilberries and 70.0 ± 3.4 mg/100 g fw in blueberries). Statistical analysis shows that the content of 27 individual flavonoids, phenolic acids, and stilbenes can be used to identify the picking region of these Slovenian bilberries.

Andreja Vanzo

Papers

The stomach as a site for anthocyanins absorption from food1

Fast access of some grape pigments to the brain.

Bioavailability of flavonoids: a review of their membrane transport and the function of bilitranslocase in animal and plant organisms.

Phenolics in Slovenian Bilberries (Vaccinium myrtillus L.) and Blueberries (Vaccinium corymbosum L.)

Bilberry and blueberry anthocyanins act as powerful intracellular antioxidants in mammalian cells