Antioxidant radical scavenger

The stabilizers chosen for evaluation include different types of heat and light stabilizers selected to represent different mechanisms of action as well as chemical compositions (ArJi). Types of stabilizers evaluated include benzotriazole and benzophenone light stabilizers [ultraviolet (UV) light absorbers], hindered amine light stabilizers (HALS, catalytic radical scavengers), hindered phenol heat stabilizers (antioxidant radical scavengers), and thioester heat stabilizers (antioxidant hydroperoxide decomposers). 

Carbon black PE. PB Peroxides Antioxidant, radical scavenger, peroxide decomposition 59... 

P physocatyx Ijmiide Cancer chemoprcventivc Antioxidant (radical scavenging against DPPH) Inactive [47]... 

Primary antioxidant radical scavengers in a compound, otherwise useful as heat stabilizas, can suppress the desired crosslinking mechanism. 

Unsaturated fats (high iodine value >4) are sensitive to oxidation by peroxides becoming rancid. Adding antioxidants (radical scavengers, examples butylhydrox-yanisole and butyl hydroxy toluene, see Sect. 23.9) will prevent this. 

The base additive packages required for the stabilization of polyolefins usually comprise combinations of phenolic antioxidants (primary antioxidants, radical scavengers), phosphites or phosphonites (secondary antioxidants) and acid scavengers. The co-operative performance of such an additive combination is certainly influenced by the proper choice and concentration of all individual components. Even acid scavengers can play an important role in melt viscosity retention during processing as well as in the long term stability of the final polymer article. 

Others. Fo-ti (type not specified) is reported to be nonmutagenic per the Ames Salmonella/microsome assay the hyd-xoxyanthraquinones in its aqueous extract (decoction) had antimutagenic effects. The same effect was also demonstrated by the root extract in a Tradescantia micronucleus assay. The authors attributed the antimutagenic effect to a possible combination of antioxidant, radical scavenging, and DNA repair activity of fo-ti. Raw fo-ti has cathartic activities. 

There are, indeed, many biological implications that have been triggered by the advent of fullerenes. They range from potential inhibition of HIV-1 protease, synthesis of dmgs for photodynamic therapy and free radical scavenging (antioxidants), to participation in photo-induced DNA scission processes [156, 157, 158, 159, 160, 161, 162 and 163]. These examples unequivocally demonstrate the particular importance of water-soluble fullerenes and are summarized in a few excellent reviews [141, 1751. 

Vitamin E can also act as an antioxidant (qv) in animals and humans alone or in combination with vitamin C (qv). Both are good free-radical scavengers with the vitamin C acting to preserve the levels of vitamin E (35). Vitamin E in turn can preserve the levels of vitamin A in animals (13). It has been shown that vitamin E reduces the incidence of cardiovascular disease (36—39). This most likely results from the antioxidant property of the vitamin which inhibits the oxidation of low density Hpoproteins (LDLs) (40—42). The formation of the oxidized LDLs is considered important in decreasing the incidence of cardiovascular disease (43). 

Radical Scavengers Hydrogen-donating antioxidants (AH), such as hindered phenols and secondary aromatic amines, inhibit oxidation by competing with the organic substrate (RH) for peroxy radicals. This shortens the kinetic chain length of the propagation reactions. 

Aromatic Amines. Antioxidants derived from -phenylenediarnine and diphenylamine are highly effective peroxy radical scavengers. They are more effective than phenoHc antioxidants for the stabilization of easily oxidized organic materials, such as unsaturated elastomers. Because of their intense staining effect, derivatives of -phenylenediamine are used primarily for elastomers containing carbon black (qv). 

In 1922, Evans and Bishop named the animal nutritional factor essential of reproduction Vitamin E . In the 1960s, vitamin E was associated with antioxidant function. Twenty-five years later, vitamin E has been found to possess functions that are independent of its antioxidant and free radical scavenging ability. a-Tocopherol specific molecular mechanisms were discovered which are still under investigation. 

Besides all the sensory and texturizing properties, GA has interesting antioxidant properties such as an efficient capacity for deactivation of excited electronic states and moderated radical scavenging capacity. There is increasing experimental evidence that associate the antioxidant function with its protein fraction, mainly by amino acid residues such as histidine, tyrosine and lysine, which are generally considered as antioxidants molecules (Marcuse, 1960,1962 Park et al., 2005). 

BORS w, HELLER w, MICHEL c and SARAN M (1990) Flavouoids as antioxidants determination of radical-scavenging efficiency Methods in Enzymology 186, 343-55. 

As strong antioxidants and scavengers of superoxide, hydroxyl and peroxyl radicals, tea flavonoids can suppress radical chain reactions and terminate lipid peroxidation (Kumamoto and Sonda, 1998, Yang and Wang, 1993). 

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