Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

Tannins are a unique group of phenolic metabolites with molecular weights between 500 and 30 000 Da, which are widely distributed in almost all plant foods and beverages. Proanthocyanidins and hydrolysable tannins are the two major groups of these bioactive compounds, but complex tannins containing structural elements of both groups and specific tannins in marine brown algae have also been described. Most literature data on food tannins refer only to oligomeric compounds that are extracted with aqueous-organic solvents, but a significant number of non-extractable tannins are usually not mentioned in the literature. The biological effects of tannins usually depend on their grade of polymerisation and solubility. Highly polymerised tannins exhibit low bioaccessibility in the small intestine and low fermentability by colonic microflora. This review summarises a new approach to analysis of extractable and non-extractable tannins, major food sources, and effects of storage and processing on tannin content and bioavailability. Biological properties such as antioxidant, antimicrobial and antiviral effects are also described. In addition, the role of tannins in diabetes mellitus has been discussed.

Tannins: current knowledge of food sources, intake, bioavailability and biological effects.

Phenolic compounds constitute a group of secondary metabolites which have important functions in plants. Besides the beneficial effects on the plant host, phenolic metabolites (polyphenols) exhibit a series of biological properties that influence the human in a health-promoting manner. Evidence suggests that people can benefit from plant phenolics obtained either by the diet or through skin application, because they can alleviate symptoms and inhibit the development of various skin disorders. Due to their natural origin and low toxicity, phenolic compounds are a promising tool in eliminating the causes and effects of skin aging, skin diseases, and skin damage, including wounds and burns. Polyphenols also act protectively and help prevent or attenuate the progression of certain skin disorders, both embarrassing minor problems (e.g., wrinkles, acne) or serious, potentially life-threatening diseases such as cancer. This paper reviews the latest reports on the potential therapy of skin disorders through treatment with phenolic compounds, considering mostly a single specific compound or a combination of compounds in a plant extract.

The Potential of Plant Phenolics in Prevention and Therapy of Skin Disorders

Catechin, epicatechin, quercetin, rutin and resveratrol in red grape: Content, in vitro antioxidant activity and interactions

Grape is one of the oldest fruit crops domesticated by humans. The numerous uses of grape in making wine, beverages, jelly, and other products, has made it one of the most economically important plants worldwide. The complex phytochemistry of the berry is characterized by a wide variety of compounds, most of which have been demonstrated to have therapeutic or health promoting properties. Among them, flavonoids are the most abundant and widely studied, and have enjoyed greater attention among grape researchers in the last century. Recent studies have shown that the beneficial health effects promoted by consumption of grape and grape products are attributed to the unique mix of polyphenolic compounds. As the largest group of grape polyphenols, flavonoids are the main candidates considered to have biological properties, including but not limited to antioxidant, anti-inflammatory, anti-cancer, antimicrobial, antiviral, cardioprotective, neuroprotective, and hepatoprotective activities. Here, we discuss the recent scientific advances supporting the beneficial health qualities of grape and grape-derived products, mechanisms of their biological activity, bioavailability, and their uses as nutraceuticals. The advantages of modern plant cell based biotechnology as an alternative method for production of grape nutraceuticals and improvement of their health qualities are also discussed.

Recent advances and uses of grape flavonoids as nutraceuticals.

Stilbenes: Quantitative extraction from grape skins, contribution of grape solids to wine and variation during wine maturation

Differentiation of red winemaking technologies by phenolic and volatile composition

Isolation and purification of dimeric and trimeric procyanidins from grape seeds

Fractionation of red wine polyphenols by solid-phase extraction and liquid chromatography.

A simple and reproducible HPLC method permitting simultaneous determination of phenolic acids (gallic, vanillic, syringic, and ferulic), phenolic aldehydes (vanillin, syringaldehyde, coniferaldehyde, and sinapaldehyde), and furanic derivatives (furfural, 5-hydroxymethylfurfural, and 5-methylfurfural) in brandies was developed and validated. A considerable advantage of this method is the good separation and quantification of the compounds of interest without sample preparation. The method exhibited good linearity, high precision, high sensitivity, and suitable selectivity and specificity over a wide range of concentrations as well as low analytical limits. It can therefore be of a great interest either for scientific research or for routine analysis of brandies, namely in quality control. The analysis of four-year-aged brandies shows the real applicability of the method to distinguishing brandies according to the botanical species of the wooden barrel.

High‐performance liquid chromatography method for analysis of phenolic acids, phenolic aldehydes, and furanic derivatives in brandies. Development and validation

M. Isabel Spranger

Papers

Stilbenes: Quantitative extraction from grape skins, contribution of grape solids to wine and variation during wine maturation

Differentiation of red winemaking technologies by phenolic and volatile composition

Isolation and purification of dimeric and trimeric procyanidins from grape seeds

Fractionation of red wine polyphenols by solid-phase extraction and liquid chromatography.

High‐performance liquid chromatography method for analysis of phenolic acids, phenolic aldehydes, and furanic derivatives in brandies. Development and validation