Phenolic antioxidants health benefits

There is a health benefit associated with hindering hydrogen bonding. Alkylphenols as a class are generally regarded as corrosive health hazards, but this corrosivity is eliminated when the hydroxyl group is flanked by bulky substituents in the ortho positions. In fact, hindered phenols as a class of compounds are utilized as antioxidants in plastics with FDA approval for indirect food contact. 

Among the plant phenols, the flavonoids and the anthocyanidins, belonging to the 1,3-diphenylpropans, have been studied in most detail, mainly because of their potential health benefits. With more than 4,000 different flavonoids known, systematic studies of the effects of variation in molecular structure on physico-chemical properties of importance for antioxidative effects have also been possible (Jovanovic et al, 1994 Seeram and Nair, 2002). Flavonoids were originally found not to behave as efficiently as the classic phenolic antioxidants like a-tocopherol and synthetic phenolic antioxidants in donating... 

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. 

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. 

In association with well-known health benefits related to the consumption of fruit- and vegetable-rich diets, research on the protective effects of plant-derived phenolic compounds (polyphenols) has developed notably in recent years. In particular, their antioxidant properties have been the objective of extensive research. However these phenolics are the target of an array of chemical reactions that, if confirmed to occur in vivo, would contribute to their health promoting effects. It is now emerging that both parent compounds and their metabolites produced after ingestion can regulate cell and tissue functions by both antioxidant and nonantioxidant mechanisms. This volume provides the latest evidence supporting these concepts. 

The health benefits explain the growth in interest concerning the characterization and evaluation of phenolics and antioxidant capacity in food-related products. The chemical structures of the main polyphenols found in Madeira table wines are summarized in Fig. 7.13. 

Extensive reviews of analytical methods for anthocyanins (Francis, 1982 Jackman et al., 1987b Strack and Wray, 1994) and other flavonoids (Williams and Harbome, 1994) as well as phenolic acids (Herrmann, 1989) have been published. In these reviews, extraction procedures, methods for fractionation of groups of polyphenols and the identification and quantification of individual components are presented. Here, a brief presentation of more recently published methods for grape and berry polyphenolic analyses is given with respect to their relationship to antioxidant activity and health benefits. 

Some studies have concluded that organic production methods would mean increased nutrient content, particularly organic acids and poly-phenolic compounds. Although many of these substances are considered to have potential human health benefits as antioxidants, their impact on human health when consuming greater levels of organic acids and poly-phenolics has not yet been determined (Winter and Davis, 2006). 

Research into food safety, both microbial and chemical food safety, has been accompanied by a parallel effort to identify, test, and optimize healthy constituents of foods. The interest in chemicals in foods extends beyond traditional areas - vitamins, essential minerals, etc. - to secondary chemicals sometimes termed phytonutrients or neutraceuticals which have positive health benefits including prevention or alleviation of diabetes, heart disease, Alzheimer s disease, cancer, arthritis, and many other diseases. Food producers use this information as a marketing tool. Compounds of interest include phenols/polyphenols, flavonoids, carotenoids, anthocyanins, and several other classes that function as antioxidants,... 

Almond is a nutrition-dense food providing a spectrum of macro- and micronutrients. Moreover, it is an excellent source of bioavailable phytochemicals that are believed to possess health promotion potentials. Among these phenolic compounds, including phenolic acids and flavonoids, which are the major antioxidant active substances in almond. Other components such as tocopherols and terpenoids also make contribution to the antioxidant activity of almond. The health benefits of almond have been explored. Almond appears to be effective in reducing the risk of heart disease and cancer prevention, and consumption of ahnond is reconunended by FDA for better health conditions. 

Although antioxidant activity and phenolic constituents of hazelnut (hazelnut kernel) [4,26-28] and some of its by-products [29-31,100] have been reported, little is known about phenolic phytochemicals and their potential health benefits in hazelnut and hazelnut by-products. Therefore, this chapter provides detailed information on nutraceuticals, phytochonicals, and health aspects of hazelnut and hazelnut by-products and evaluates their antioxidant activities by a number of indicators. Taxanes present in hazelnut by-products are discussed in detail. Where possible, the health benefits of relevant phytochemicals are described. 

Wine phenols are commonly referred to as polyphenols , due as may be seen in Figure 2, to the presence of multiple phenolic groups in their structures, which confer on these compounds various properties linked to health benefits, specifically the antioxidant properties attributed to the consumption of moderate amounts of red wine. Much has been published on this subject and the area and references to reviews may be found in Further reading section. 

Phenolic compounds in grains, fruits and vegetables act as antioxidants and may have health benefits. Total free phenolics, primarily chlorogenic acid, decreased significantly due to extrusion in potato peels produced by steam or abrasion peeling (unpublished data). We suspect that the lost phenolics react with themselves or with other compounds to form larger insoluble materials. 

Phenolic compounds, primarily flavonoids, have antioxidant properties which may contribute to health benefits of wine consumption (Kanner et ai, 1994 Frankel, 1994). Wine consumption has a possible cardioprotective effect and may prevent thrombosis (Frankel, 1994). Epicatechin and quercetin are more effective in preventing LDL (low density lipoprotein) oxidation than a-tocopherol (vitamin E) (Frankel, 1994). Quercetin is found at an average concentration of 25 mg/L in red wine. Catechin and epicatechins are among the most abundant phenolics in wine and are present at about 150 mg/ L in red wine and about 15 mg/ L in white wine. Resveratrol is thought to be of major importance as a dietary antioxidant in red wines, but levels are much lower than catechin/epicatechin (Frankel, 1994). 

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