Prooxidant property

Young, A.J. and Lowe, G.M., Antioxidant and prooxidant properties of carotenoids. Arch. Biochem. Biophys., 385, 20, 2001. 

In vitro antioxidant and prooxidant properties of ascorbic acid have been clearly demonstrated. It is understandable that the competition between antioxidant and prooxidant activities of ascorbic acid depends on the rates of Reactions (11) and (12). 

Therefore, depending on their structures, flavonoids may reduce the ascorbate radical or oxidize ascorbate, exhibiting antioxidant or prooxidant properties in the systems containing flavonoids and ascorbate together. 

FIGURE 29.7 Structures of flavonoids possessing different antioxidant and prooxidant properties. 

A comparison with its different derivatives shows that 4 -OH is not a sole reactive group responsible for the antioxidant activity of resveratrol, while the trans-conformation is absolutely necessary for the inhibition of cell proliferation [187], However, similar to flavonoids resveratrol may exhibit prooxidant properties, for example to promote DNA fragmentation, although its prooxidant activity seems to be unimportant under physiological conditions [188],... 

Donaldson J, LaBella F. 1983. Prooxidant properties of vanadate in vitro on catecholamines and on lipid peroxidation by mouse and rat tissues. J Toxicol Environ Health 12 119-126. 

It is well established that Q is a component of the respiratory chain and plays a critical role in respiration and oxidative phosphorylation. It was thought that the presence of (X was confined exclusively to the inner mitochondrial membrane and its sole function was to serve as the redox component of the respiratory chain. However, this belief has been modified as it has been shown that Q is present in all cellular membranes examined. The major part of Q is present in the reduced form in human and animal tissues, and serves as an important antioxidant. In fact, it has been shown that QH2-IO, the reduced form of Q IO, efficiently scavenges free radicals and it is as effective as ct-tocopherol in preventing peroxidative damage to lipids, considered the best lipid-soluble antioxidant in humans. The antioxidant and prooxidant properties of mitochondrial ubiquinone have recently been reviewed. ... 

Antioxidant and prooxidant properties of carotenoids have recently been reviewed [50,51]. Carotenoids serve as efficient quenchers of single oxygen. Their assumed function as antioxidants in vivo is largely based on model experiments. 

Good antioxidant, but also prooxidant properties p,(3-carotene (1) > lycopene (24) > zeaxanthin (15). 

Strong antioxidants with no prooxidant properties canthaxanthin (16) astaxanthin (17) > actinioerythrol (26). 

Azam S, Hadi N, Khan NU, Hadi SM (2004) Prooxidant property of green tea polyphenols epicatechin and epigallocatechin-3-gallate implications for anticancer properties. Toxicol In Vitro 18 555-561... 

Ascorbic acid can block a variety of membrane-bound receptor proteins, the mechanisms of which are primarily explained by its antioxidant/prooxidant properties, rather than its direct binding to the receptors. 

Nerin et al. (2008) developed and evaluated AO coated polypropylene (PP) film containing rosemary extract It was found that 4.0% w/w rosemary extract coated PP film inhibited the oxidation extent up to 30.1% when compared to the eontrol film at 15 days for iron (11) and 42.2% in comparison with additive-free PP film at 20 days for fatty acids from flax seed oil. Ascorbic acid has proven to be not adequate for antioxidant quantitative purposes owing to its prooxidant properties. 

In addition to the use of alkyl gallates as food and cosmetic additives, the multifunctional action of these compounds and their potential application for other purposes has been widely investigated, as described below. Some of these applications, which are discussed below, involve their use as enzymatic inhibitors, as anticancer, antifungal and antimicrobial agents, and as additives in nonfood and noncosmetic industries (Figure 14.2). These applications are mainly based on the antioxidant and prooxidant properties of these compounds, which, together with their potential toxicity, are also discussed below. 

The study of the toxicity of several polyphenolic antioxidants, including alkyl gal-lates, toward human promyelocytic leukemia cells (HL-60) has shown that the polyphenol cytotoxicity may be related to their prooxidant properties since, as indicated above, the same polyphenol compounds could behave as both antioxidants and prooxidants, depending on concentration and free radical source [39]. Polyphenols may act as substrates for peroxidases and other metalloenzymes, yielding quinone- or quinomethide-type prooxidant and/or alkylating products. Another characteristic of the action of polyphenols is that their cytotoxicity increases upon an increase in their lipophilicity. Thus, the concentration of gallic acid, BG and OG for 50% survival of HL-60 cells (IC50) is 750, 110, and 30 pM, respectively. 

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