title: Human plasma paraoxonase 1 (PON1) arylesterase activity during aging: correlation with susceptibility of LDL oxidation.
abstract: OBJECTIVE
  The role of free radicals has long been proposed as a cause for the aging process. Oxidative stress is considered a major factor for altering many physiological processes and enzymatic activities during aging and is also known to play a major role in the development of several age-dependent diseases. Paraoxonase 1 (PON1) is an anti-atherosclerotic enzyme that mainly prevents accumulation of lipoperoxides and inhibits the lipid oxidation in low-density lipoproteins (LDL). This study was undertaken to investigate the antioxidant behavior of PON1 by measuring its arylesterase activity. The susceptibility of LDL for oxidation and the radical scavenging activity of plasma were also measured during aging in humans.
  
  
  METHODS
  Arylesterase activity of PON1 was measured in plasma of human subjects between 20 and 81 years of age of both genders. The susceptibility of LDL for oxidation and radical scavenging activity were measured in plasma.
  
  
  RESULTS
  Decrease in plasma arylesterase activity of PON1, increase in susceptibility of LDL for oxidation and decrease in plasma radical scavenging activity were observed as a function of human age.
  
  
  CONCLUSIONS
  The study provides evidence of a relationship between PON1 activity, LDL oxidation and free radical scavenging activity of plasma. The present results emphasize the dependency of PON1 activity to prevailing oxidative stress during human aging. Our findings assume significance in view of the possible categorization of PON1 as a longevity gene.
authors.affiliation: Department of Biochemistry, University of Allahabad, Allahabad, Uttar Pradesh 211002, India.
authors.forename: Mohammad Murtaza
authors.initials: MM
authors.lastname: Mehdi
authors.forename: Syed Ibrahim
authors.initials: SI
authors.lastname: Rizvi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D043303:Aryldialkylphosphatase / Q000097:blood*; D002265:Carboxylic Ester Hydrolases / Q000097:blood*; D005260:Female; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D018384:Oxidative Stress
chemical_list: D008077:Lipoproteins, LDL; D002265:Carboxylic Ester Hydrolases; C019734:arylesterase; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human