S. M. SIEGEL 

 and 



F. PORTO 



Union Carbide Research Institute 



Oxidants, Antioxidants, and Growth 



Regulation 



The re-establishment of interest in oxygen toxicity (6,8,9, 10, 11,25) 

 has provided a new orientation in oxygen biochemistry. Recognition 

 of the dual role of oxygen in life process opens the way to a more 

 fundamental understanding of interrelationships involving the phys- 

 ical organic chemistry of oxidation, the metabolic machinery of the 

 cell, and processes of growth and differentiation. 



Interest in oxygen poisoning has led to the discovery that many 

 radiation protectant-reducing compounds often active in catalytic 

 quantities also provide a biological defense against oxygen (8, 11, 25). 

 Such an overlap of protective agents is a logical consequence of the 

 well-established interdependence between oxygen and ionizing radia- 

 tion in inflicting cellular damage (8, 16). It has been suggested that 

 damage produced by these agents is no more than an intensification 

 of activity along already-existing radical-mediated (that is, one- 

 electron) pathways of oxidation-reduction (25, 28), and that deterior- 

 ative changes so effected, even by oxygen alone, differ little from the 

 terminal processes of senescence as they ordinarily take place. Thus, 

 it has been concluded (29) that "The life-shortening action of radia- 

 tion involves the induction of ... . degenerative changes and stimu- 

 lates in many respects acceleration of the natural aging process." 

 The demonstration in the early 1950's of oxygen and antioxidant 

 effects in heat damage led similarly to a concept linking tissue damage 

 and accelerated aging processes (2). 



These and other considerations, together with the recognition of 

 antioxidant activity as a function of electron mobility (26, 27), have 

 led to the formulation of the Regulator-Antioxidant Hypothesis, 

 which seeks to relate regulation of growth, development, and aging 



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