Polyphenols groups

Flavones and flavonols are relevant phytochemicals in food products, spices and medicinal plants. They are secondary metabolites belonging to the polyphenols group, and have in common the general structure of two aromatic rings and often more than three phenolic hydroxyls. Flavones and flavonols often show high antioxidant activity in vitro, and they complex metal ions and scavenge free radicals. They have a planar structure that allows intermolecular interactions and stacking in... 

The Cu ion is used as an example of a metal that complexes with a high degree of selectivity on polyphenolic groups of soil organic matter. One of these groups is the biphenol (catechol) type, which dissociates to form the ligand... 

The most numerous complexing sites on humus, carboxylate groups, bond Cu " much less selectively, and are unlikely to compete with polyphenolic groups for Cu retention except at low pH or at high Cu levels that saturate the polyphenolic complexing sites. 

Michailov, M.K. Flavonoids of polyphenol group of tobacco Studies by methods of paper chromatography Doklady Akadernii Nauk SSSR 108 (1956) 511-514. 

Nonalcoholic and strong drinks (tea, wine) contain a number of aromatic substances with amino and hydroxyl groups (first of all, there are polyphenolic compounds and alkaloids) which defined sort and quality of drinks. 

Oxidation of monophenols to polyphenols or oxidation of aromatic methyl groups by persulfates (Caro s acxJ)... 

Males et al. [103] used aqueous mobile phase with formic acid for the separation of flavonoids and phenolic acids in the extract of Sambuci flos. In a cited paper, authors listed ten mobile phases with addition of acids used by other investigators for chromatography of polyphenolic material. For micropreparative separation and isolation of antraquinone derivatives (aloine and aloeemodine) from the hardened sap of aloe (Liliaceae family), Wawrzynowicz et al. used 0.5-mm silica precoated plates and isopropanol-methanol-acetic acid as the mobile phase [104]. The addition of small amounts of acid to the mobile phase suppressed the dissociation of acidic groups (phenolic, carboxylic) and thus prevented band diffusions. 

Amrhein, N. Hollander-Czytko, H. Leifeld, J. Schulz, A. Steinriicken, H.-C. Topp, H. Proc. Internationales d etudes et assemblies du Groupe Polyphenols, 1982, pp. 21-30. 

Infrared Spectra. Limited effort has been made to identify the major chemical group components of the extract. Infrared spectra (Perkin-Elmer 913) of the evaporated extracts from two lakes were similar in having peaks at the following frequencies 3,000-3,100, 3,200-3,600, 1,500-1,650, and 1,690-1,760 cm-l. These preliminary data would suggest the presence of polyphenolic compounds in the extract which may be related to humic materials occurring in nature (16). 

Tea leaf, in common with all plant leaf matter, contains the full complement of genetic material, enzymes, biochemical intermediates, carbohydrates, protein, lipids, and structural elements normally associated with plant growth and photosynthesis. In addition, tea leaf is distinguished by its remarkable content of methylxathines and polyphenols. These two groups of compounds are predominantly responsible for those unique properties of tea that account for its popularity as a beverage. It must be noted that the chemical composition of tea leaf varies with climatic condi-... 

As indicated in Table 2, the polyphenols constitute the most abundant group of compounds in tea leaf. Of these, the epi- form of the catechin group of fiavanois predominate. Their structure is shown in Figure 2. 

There is also another group of polyphenolic compounds, thus far only known through their biological activity as thrombogenic haptens.69... 

Inhibitors of non-haem iron absorption include polyphenols and phytates. The former, secondary plant metabolites rich in phenolic hydroxyl groups, are found... 

In recent years, numerous papers have been published about one of the most important groups of phytochemicals, the polyphenols (Manach and others 2004). These compounds, which possess an array of healthy properties, but also some disadvantages that will be discussed in this chapter, are present in a variety of plants used in both human and animal diets. However, the structure of this type of compound means that they can be oxidized by several pro-oxidant agents. The objective of this chapter is to describe the main enzymatic agents responsible for the degradation of polyphenols. In order to understand the mechanisms of degradation that will be described in the following sections, a brief summary of the main properties of the polyphenols is required. 

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