Phenolic compounds anthocyanins

Perez-Vicente, A., Gil-Izquierdo, A., and Garcia-Viguera, C., In vitro gastrointestinal digestion study of pomegrate juice phenolic compounds, anthocyanins, and vitamin C, J. Agric. Food Chem., 50, 2308, 2002. 

Phenolic compounds, anthocyanins and tannins, are considered among the most important substances extracted from the grape pomace. 

Some of the most common fruits and vegetables containing four specific families of phenolic compounds, anthocyanins, flavanones, flavonols, and hydroxycinnamates, are characterized for their individual major components and compared with reports from the leading literature of Macheix and coworkers [32] and other researchers. 

Cornus species fruits are significantly rich in phenolic compounds, anthocyanins, flavonoids, and ascorbic acid. Therefore, they could be considered as a valuable source of natural antioxidants. The evaluation of the antioxidant activity of their extracts demonstrated elevated levels, but also great variations among species and genotypes. The presence of these natural antioxidants provide protection against harmful free-radicals and therefore against caneer and heart diseases. 

The passage of pomace constituents, particularly phenolic compounds (anthocyanins and tannins), into fermenting juice depends on various elemental factors. The results constitute overall maceration kinetics. The phenomena involved are complex and do not cause a regular increase in extracted substances. In fact, among these various factors, some tend to increase phenolic compounds, while others lower concentrations. Moreover, they do not necessarily always act in the same manner on the various constituents of this group. 

In a fermentor undergoing carbonic maceration, the grape berry is transformed by anaerobic metabolism reactions of its own cells. These reactions are independent of any yeast involvement and have been covered in the preceding section. Tissue degradation favors the maceration phenomena involved. Phenolic compounds, anthocyanins, nitrogen compounds and other components of the solid parts of the berry are diffused in the juice of the pulp. 

Table 14.2. Phenolic compounds, anthocyanins and color of different types of French ros6 wines (Rib6reau-Gayon et al, 1976)...

Hong, V. and Wrolstad, R.E., Use of HPLC separation/photodiode array detection for characterization of anthocyanins, J. Agric. Food Chem., 38, 708, 1990. Osmianski, J. and Lee, C.Y., Isolation and HPLC determination of phenolic compounds in red grapes. Am. J. Enol. Vitic., 41, 204, 1990. 

Many herbicides and other chemicals have been reported to influence levels of various phenolic compounds in higher plants by unknown mechanisms. It is unlikely that more than a few of these compounds have a primary influence on secondary phenolic compound synthesis. For instance, in our survey of the effects of 17 herbicides on anthocyanin accumulation, only glyphosate appeared to directly influence accumulation (31). The effects of several compounds on secondary phenolic compound production for which the mechanism of influence is unknown are summarized in Table II. A much longer list could be derived from the literature. Unfortunately, many of these compounds are phytotoxic or are known to have effects other than on secondary aromatic compound production. In most cases the effects on these compounds correlate well with extractable PAL activity (31, 71, 72, 73, 74) (Figure 5), even though they do not directly affect the enzyme. 

Ishikura, N. (1976). Seasonal changes in contents of phenolic compounds and sugar in Rhus, Euonymus and Acer leaves with special reference to anthocyanin formation in autumn. Botanical Magazine, Tokyo 89 251-257. 

Food and plant phenolics are commonly detected using DAD detectors (Tan and others 2008). Photodiode array detection allows collection of the entire UV spectrum during the elution of a chromatographic peak, which makes it possible to identify a phenolic compound by its spectra. Simple phenols, phenolic acids, flavanones, benzophenones, isoflavones, and flavan-3-ols have maximum absorbance at 280 nm, hydroxycinnamic acids at 320 nm, flavonols, flavones, and dihydroflavonols at 365 nm, and anthocyanins at 520 nm (Ibern-G6mez and others 2002 Merken Hand Beecher 2000). Hydrolyzable tannins show a characteristic shoulder at 300 nm, suitable for identifying them (Arapitsas and others 2007). For stilbenes, maximum absorbance of trans-forms are at 306 nm and at 285 nm for cA-forms (Lamuela-Raventos and others 1995). 

Phenolic compounds are far more stable than vitamin C, showing retention/recovery values of 86-140% of this group, anthocyanins showed the lowest recovery rates. Phenolic compounds are also retained during storage. Odriozola-Serrano and others... 

Tiburzy (22,31) obtained similar results by application of the PAL inhibitor aminooxyacetic acid (AOA). However, AOA does not specifically inhibit PAL (99), and PAL is not only involved in lignin biosynthesis (100). Thus, AOA and the related inhibitor aminooxyphenyl propionic acid (AOPP) (101,102) inhibit the biosynthesis of lignin (103,104), anthocyanins (105), other flavonoids (106), and conjugates of cinnamic acids (107) via PAL, as well as ethylene (108-110) via a pyridoxal phosphate dependent enzyme (110,111). In view of the possible function of phenolic compounds as phytoalexins (21,112,113) and the well documented role of ethylene in some resistance reactions (114-116), the above cited experiments with AOA (22,... 

Reactions of anthocyanins and flavanols take place much faster in the presence of acetaldehyde that is present in wine as a result of yeast metabolism and can also be produced through ethanol oxidation, especially in the presence of phenolic compounds, or introduced by addition of spirit in Port wine technology. The third mechanism proposed involves nucleophilic addition of the flavanol onto protonated acetaldehyde, followed by protonation and dehydration of the resulting adduct and nucleophilic addition of a second flavonoid onto the carbocation thus formed. The resulting products are anthocyanin flavanol adducts in which the flavonoid units are linked in C6 or C8 position through a methyl-methine bond, often incorrectly called ethyl-link in the literature. 

Timberlake, C.F. and Bridle, P., Interactions between anthocyanins, phenolic compounds, and acetaldehyde and their significance in red wines. Am. J. Enol. Vitic. 27, 97, 1976. 

The anthocyanins, in contrast to certain other phenolic compounds (see Section 8.3.4), are not toxic to higher animal species. For the invertebrates, too, anthocyanin toxicity seems... 

Analysis and Biological Activities of Potato Clycoalkaloids, Calystegine Alkaloids, Phenolic Compounds, and Anthocyanins... 

This limited overview on the analysis of four classes of the following secondary potato metabolites is, except for anthocyanins, largely limited to our own studies of glycoalkaloids, calystegine alkaloids, and phenolic compounds. Because interest in these potato constituents arises from potential health benefits and occasional toxicity, we also include in this overview a brief discussion of these aspects that relate to composition and a description of experimental methods. The interested reader should consult the cited references for an entry into the extensive worldwide literature on the diverse analytical and biological aspects for these metabolites. 

A major group of citrus compounds interacting with drugs are phenolics, which include hydroxycinnamic acids, flavonoids such as flavanones, fla-vones, and flavonols, and anthocyanins, as well as coumarins (Table 1, Fig. 1) (30). Many of these phenolic compounds have been shown to have antioxidant and anticancer properties that may play an important role in cancer prevention, but also in prevention of other chronic diseases such as coronary heart disease, gout, and arthritis (58 60). 

The first method uses the fact that in acid media anthocyanins exist in a colored and a colorless form (9 and 10) in equilibrium, with the position of the equilibrium depending on pH. Consequently, the difference in color intensity between the two pH values (0.6 and 3.5 for example) is proportional to the pigment concentration. Since the phenol function is not affected by this variation, other phenolic compounds, especially tannins, do not interfere since their absorption at 550 nm is the same at both pH values. 

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