Variability of Oxygen Radical Absorbance Capacity (ORAC) in Different Animal Species

Free Radic Res. 1998 Nov;29(5):399-408. doi: 10.1080/10715769800300441.


The oxygen radical absorbance capacity (ORAC) was measured both in whole (ORAC-T) and deproteinized (ORAC-AS) plasma samples of human, pig, cow, rabbit, dog, cat, sheep, horse, dolphin, turkey, guinea-hen and chicken. In the 12 species, ORAC-T data, expressed as micromoles of peroxyl radicals trapped by 11 of sample, were found scattered between 8,600 and 23,000 micromol/l. The species with the highest ORAC-T values were cat among mammals and chicken among avies. ORAC-AS values ranged between 600 and 2000 micromol/l, with the highest values found in dolphin and sheep among mammals, while chicken was first among avies. In the 12 species, the relative contribution of ORAC-AS in relation to ORAC-T ranged from 5% to 20%. Protein SH-groups and uric acid were measured in plasma of all species, but no significant correlation was found between thiols and ORAC-T values or between uric acid and ORAC-AS values. Our results show that: (1) the ORAC method is reproducible and sensitive enough to be used in the comparison of the peroxyl-radical absorbance capacity of protein and non-protein plasma components in different animal species; (2) both in mammals and in avies, there is a deep intra-class heterogeneity of ORAC-T and ORAC-AS values; (3) by considering most species, plasma proteins and lipoproteins account for about 85-90% of the overall peroxyl-radical trapping capacity. In the dolphin only, the protein contribution decreases to 80%; (4) uric acid accounts for about one-half of the ORAC-AS value in human, guinea-hen and for about one-third in chicken, while it provides a very limited contribution in other species. We conclude that species with the highest ORAC-T, like cat and chicken, or with the highest ORAC-AS, like dolphin, are interesting models to study the reasons of such a marked antioxidant defense in the plasma.

MeSH terms

  • Absorption
  • Animals
  • Antioxidants / metabolism*
  • Birds
  • Cats
  • Cattle
  • Chickens
  • Dogs
  • Dolphins
  • Free Radicals
  • Half-Life
  • Horses
  • Humans
  • Peroxides / blood*
  • Rabbits
  • Sheep
  • Spectrometry, Fluorescence
  • Swine
  • Turkeys
  • Uric Acid / blood


  • Antioxidants
  • Free Radicals
  • Peroxides
  • Uric Acid
  • perhydroxyl radical