Pro-oxidant activities

MAHGOUB s E o and HUDSON B J F (1985) Inhibition of the pro-oxidant activity of copper by primary antioxidants in lard, Food Chem, 16, 97-101. 

Thus the question arises as to what forms of haem proteins and transition metals are available in vivo that are capable of mediating the formation of damaging initiating or propagating species, since the majority of the iron and haem proteins in the human body are protected in vivo from exerting pro-oxidant activities by their compart-mentalization within their functional locations in the haem and non-haem iron-containing proteins and enzymes. 

Treatment with iron chelators and a-tocopherol protect against lipid p>eroxidation and hepatocellular injury in iron-overloaded rats (Sharma etal., 1990). When hepatocytes are isolated from rats, which have been pretreated with a-tocopherol, there is a significant reduction in iron-induced lipid peroxidation and improvement in cell viability in vitro (Poli et al., 1985). Similar effects were seen when hepatocytes were incubated with iron chelators (Bacon and Britton, 1990). Treatment of moderately, but not heavily, iron-loaded rats with desferrioxamine in vivo inhibits the pro-oxidant activity of hepatic ultrafiltrates (Britton et al., 1990b). 

Detoxification of pro-oxidatively active molecules (radicals, peroxides) is ensured by enzymatic and nonenzymafic compounds. 

In the cell-free system (phosphate-buffered saline, pH 7.4) the C60/PVP complex (C60 0.66%, PVP with molecular mass 25,000) under illumination increased the fluorescence level significantly compared to control values (pure PVP at the same concentration), which indicates the presence of pro-oxidant activity in C60 under the given conditions. This effect augmented significantly at increasing time of illumination, which could be judged as another evidence in favor of pro-oxidant activity of the C60/PVP complex (Fig. 7.1). 

Carotenoids are isoprenoid compounds that are biosynthesized only by plants and microorganisms. Some carotenoids (a- and p-carotene, p-cryptoxanthine) can be cleaved into vitamin A (retinol) by an enzyme in the small intestine. Carotenoids have been reported to present some effects in the prevention of cardiovascular diseases [410] and in the prevention of some kind of cancers [411]. Furthermore, antioxidant activity has been widely reported [411-414] but a switch to pro-oxidant activity can occur as a function of oxygen concentration [415,416]. 

Progesterone synthesis inhibition. Fresh root, on the perfused ovaries of rabbits fed a carrot-rich diet, was active . Pro-oxidant activity. The root, at a concentration of 1%, was active at 120° F on peanut oil . 

Gazzani, G. Anti- and pro-oxidant activity of some vegetables in the Mediterranean diet. Riv Sci Aliment 1994 23(3) 413-420. 

The above-described observations indicate that chlorogenic and caffeic acids switch from anti- to pro-oxidant activity, depending on their concentration, on the presence of free transition metal ions, or on their... 

Kristensen, L. and Andersen, H.J. 1997. Effect of heat denaturation on the pro-oxidative activity of metmyoglobin in linoleic acid emulsions. J. Agric. Food Chem. 45 7-13. 

Lee-Hilz YY, Boerboom AM, Westphal AH, Berkel WJ, Aarts JM, Rietjens IM. 2006. Pro-oxidant activity of flavonoids induces EpRE-mediated gene expression. Chem Res Toxicol 19 1499-1505. 

Evidence is now accumulating to show that reactions involving metals might be the common denominator underlying AD and PD. In these disorders, an abnormal reaction between a protein and a redox-active metal ion (copper or iron) promotes the formation of ROS. It is especially intriguing how the antioxidant Cu/Zn-SOD activity can convert into a pro-oxidant activity, a theme echoed in the recent proposal that Ap and PrP, the proteins respectively involved in AD and prion diseases, possess similar redox properties [Bush, 2002],... 

Under OS vitamin E can generate pro-oxidant activity that is already in the gut and is directed against those structure such as chilomicrons, used to transport vitamin E. 

To counteract OS one should not use only one antioxidant at high dosages because the pro-oxidant activity may prevail over the antioxidant one. 

Since the crocin-bleaching method is based on competition kinetics, it can also be used to detect pro-oxidant activity (POA), for example, of early MRPs the DPPH method cannot. In fact, in the presence of antioxidants, the crocin-bleaching rate [reaction (1)] is slowed down, because the antioxidant reacts with the radical first and the antioxidant radical formed [reaction (2)] reacts only slowly with the crocin [reaction (3) ]. On the contrary, the pro-oxidant competes with the radical for the crocin [reaction (4)], thus increasing the extent of crocin bleaching 446... 

L. Manzocco, S. Calligaris, and M. C. Nicoli, Assessment of pro-oxidant activity of foods by kinetic analysis of crocin bleaching, J. Agric. Food Chem., 2002, 50, 2767-2771. 

Calligaris et al. (2004) studied changes in antioxidant and pro-oxidant activity in milk subjected to different heat treatments. Their results indicated that short heat treatments can be potentially responsible for a depletion in the overall antioxidant properties of milk. Only the application of severe heat treatments, associated with the formation of brown melanoidins, allowed a recovery and even a possible increase in the antioxidant properties of milk. 

Calligaris, S., Manzocco, L., Anese, M., Nicoli, M.C. 2004. Effect of heat-treatment on the antioxidant and pro-oxidant activity of milk. Int. Dairy J. 14, 421 127. 

Although glutathione is specifically decreased in kwashiorkor, blood levels of selenium-dependent glutathione peroxidase (a scavenger of peroxides) and vitamins A, C, and E (all members of the antioxidant machinery) are lower in both kwashiorkor and marasmus (Ashour et al., 1999). Why then are marasmic children, also deficient in some antioxidants, spared the oxidative stress Does a weakened antioxidant defense manifest as a serious threat only in the presence of pro-oxidant activities of the type encountered in kwashiorkor What is a possible trigger for the increase in free radicals, and how might this account for some of the phenotypic alterations in kwashiorkor ... 

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