Dietary phenolic compounds

Morton, L.W. et al.. Chemistry and biological effects of dietary phenolic compounds relevance to cardiovascular disease, Clin. Exp. Pharmacol. Physiol, 27, 152, 2000. 

Welsch, C.A., Lachance, P.A., and Wasserman, B.P., Dietary phenolic compounds inhibition of Na -dependent o-glucose uptake in rat intestinal brush border membrane vesicles, J. Nutr., 119, 1698, 1989. 

Vieira O, Escargueil-Blanc I, Meilhac O, Basile JP, Laranjinha J, Alemeida L, Salvayre R, Negre-Salvayre A. 1998. Effect of dietary phenolic compounds on apoptosis of... 

The main classes of phenolic compounds found in fruits are (1) phenolic acids, (2) stilbenes, (3) lignans, (4) flavonoids, and (5) tannins or proanthocyanidins. These classes are the most abundantly occurring phenolic compounds which are also an integral part of everyday dietary antioxidants in populations worldwide [7]. The most abundant phenolic compounds in the diet are phenolic acids (benzoic and cinnamic acid derivatives) and flavonoids which account for 60% and 30%, respectively, of total dietary phenolic compounds [7]. These phenolic compounds may be associated with various carbohydrates and organic acids and with one another (Figure 2 Table 1). 

Dietary Phenolic Compounds Experimental Condition Actions References... 

TABLE 5 Regulation of Cell-Cycle Progression by Dietary Phenolic Compounds—Cont d... 

MicroRNAs have recently been discovered as key regulators of gene expression. Dietary phenolic compounds can also modulate gene expression... 

The biological role of all phenolic compounds is not completely well understood but several have important roles in plant growth and development. They act as cell wall support materials (Wallace and Fry 1994) and they are also important in the defense mechanisms of plants under different environmental stress conditions such as wounding, infection, and excessive light or UV irradiation (Dixon and Paiva 1995 Bennett et al. 1994). Dietary phenolic compounds from plants have generally been considered as non-nutrients and their possible benefit to human health has only recently been established. 

The consumption of a mixture of phenolic compounds presented in apple or purple grape juice inhibited mammary carcinogenesis in 7,12-dimethylbenzo[a]anthracene (DMBA) treated rats (Liu and others 2005 Jung and others 2006). However, the individual antioxidants of these foods studied in clinical trials, including (3-carotene, vitamin C, and vitamin E, do not appear to have consistent preventive effects comparable to the observed health benefits of diets rich in fruits and vegetables, suggesting that natural phytochemicals in fresh fruits and vegetables could be more effective than a dietary supplement. 

Harnly JM, Bhagwat S and Lin LZ. 2007. Profiling methods for the determination of phenolic compounds in foods and dietary supplements. Anal Bioanal Chem 389(1 ) 47—61. 

Table 8.3. Dietary fiber content and phenolic compounds associated with insoluble dietary fiber (% on dry basis mean values SD n > 4)...

This method is also used to measure ex vivo low-density lipoprotein (LDL) oxidation. LDL is isolated fresh from blood samples, oxidation is initiated by Cu(II) or AAPH, and peroxidation of the lipid components is followed at 234 nm for conjugated dienes (Prior and others 2005). In this specific case the procedure can be used to assess the interaction of certain antioxidant compounds, such as vitamin E, carotenoids, and retinyl stearate, exerting a protective effect on LDL (Esterbauer and others 1989). Hence, Viana and others (1996) studied the in vitro antioxidative effects of an extract rich in flavonoids. Similarly, Pearson and others (1999) assessed the ability of compounds in apple juices and extracts from fresh apple to protect LDL. Wang and Goodman (1999) examined the antioxidant properties of 26 common dietary phenolic agents in an ex vivo LDL oxidation model. Salleh and others (2002) screened 12 edible plant extracts rich in polyphenols for their potential to inhibit oxidation of LDL in vitro. Gongalves and others (2004) observed that phenolic extracts from cherry inhibited LDL oxidation in vitro in a dose-dependent manner. Yildirin and others (2007) demonstrated that grapes inhibited oxidation of human LDL at a level comparable to wine. Coinu and others (2007) studied the antioxidant properties of extracts obtained from artichoke leaves and outer bracts measured on human oxidized LDL. Milde and others (2007) showed that many phenolics, as well as carotenoids, enhance resistance to LDL oxidation. 

Lamuela-Raventos, R.M., Covas, M.I., Fito, M., Marrugat, J., and de la Torre-Boronat, M.C., Detection of dietary antioxidant phenolic compounds in human LDL, Clin. Chem., 45, 1870, 1999. 

Various excellent reviews are available on phenolic compounds, their chemistry and analysis, content in foods and nutritional significance (Bravo, 1998 Dykes and Rooney, 2006 Manach et al., 2004 Naczk and Shahidi, 2006 Robbins, 2003). From a nutritional perspective, phenolic compoimds (especially tannins) are regarded as antinutritional factors due to their ability to form complexes with dietary proteins and minerals and digestive enzymes (Bravo, 1998). However, lately there has been increasing focus on the positive aspects of phenolics due to their ability to act as antioxidants which may offer potential health benefits such as prevention of diseases such as cancer and cardiovascular disease. 

Nonflavonoid Phenolic Compounds—Structure and Their Dietary Occurrence 21... 

There is growing evidence from human feeding studies that the absorption and bioavailability and thus bioactivity of phenolic compounds and flavonoids are very much dependent on the nature of their chemical structure. Their chemical classification and dietary occurrence is briefly discussed in the following section. 

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