Antioxidants Compounds that prevent phenols

As we will learn in Section 15.12, many antioxidants-compounds that prevent unwanted radical oxidation reactions from occurring—are phenols, compounds that contain an CH group bonded directly to a benzene ring. 

The occurrence in the olive pomace of unique oleuropein oligomers (14) with a degree of polymerization of up to five oleuropein monomers was reported by Cardoso et al. [27]. Their bioactivities have, however, not yet been studied. In fact, besides the evidence that olive phenolic compounds can have antioxidant, cardioprotective, antimicrobial, antihypertensive, anti-inflammatory, and chemo-preventive properties [26], the majority of the studies have focused on hydroxytyrosol (15). This compound has revealed remarkable pharmacological and antioxidant activities and thus has been further studied for its bioavaUability and metabolism in humans in order to establish its health-beneficial effects [29-31]. 

Antioxidants Substances that at low concentrations than those of an oxidizable biochemical substrate markedly delay or prevent oxidation of this substrate [67]. Their behavior could be ascribed to scavenging reactive radicals and chelation of redox-active metals, particularly iron and copper. The most active and evaluated dietary antioxidants belong to the family of phenolic and polyphenolic compounds. 

MIXXIM AO-30 ia broadly approved by the FDA for uae aa an antioxidant in products that are in contact with food. It is a non-staining, high nolecular weight, hindered phenolic compound which prevents thermal and oxidative degradation. 

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. 

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). 

Oxidation of phenols is one of the most important aspects of these compounds to the biologist. Oxidation of phenolic compounds can result in the browning of tissues. Well-known examples are the browning of lfuits after they have been cut. Oxidation can also result in the formation of metabolites that are toxic to animals and plants, and that can account for spoilage of foods in processing. On the other hand, toxic compounds formed from the oxidation of phenolics can inhibit pathogenic microorganisms. Certain phenols are used as retardants or antioxidants to prevent the oxidation of fatty acids. 

Non-discoloring, sulfur containing phenolic antioxidant and stabilizer that provides long-term heat stability by preventing thermo-oxidative degradation. Used for the process stabilization of polyethylene wire and cable resins for polyethylene during extruder compounding. Can also be applied in styrenic polymers, polypropylene, elastomers such as EPDM and SBR and for carboxylated SBR latex, polybutadiene rubber and polyisopropene rubber. 

---