Photochemiluminescent detection of antiradical activity: II. Testing of nonenzymic water-soluble antioxidants.

A method for testing and quantification of nonenzymic antioxidants, such as ascorbic acid and uric acid, and of polycomponent systems, e.g., blood plasma, is described. This method is based on a photo-induced, chemiluminescence-accompanied, and antioxidant-inhibitable autoxidation of luminol. The sensitivity of the assay lies in a region of nanomolar quantities of substances. The interassay variability of the method is lower than 5%, the intraassay variability is 2%. The mean values of an integral antioxidant capacity (AC) of human blood plasma, measured with this method as a duration of the chemiluminescence inhibition, were between 10 and 20 arbitrary Units (10 arb.U. = 1 min) per 1 microliter, and showed the age-dependent patterns with maximal values (+/- SD) with newborns (n = 7): 20.8 +/- 4.1 arb.U. and aged persons (46 +/- 9.4 years old, n = 16): 15.4 +/- 5.2 arb.U., and minimal with children (7.3 +/- 3 years old, n = 10): 9.9 +/- 2.6 arb.U. AC of young people (28.7 +/- 6.5 years old, n = 22) was 12.1 +/- 2.7 arb.U. AC of six tested animal species was lower as that of humans, with maximal values with guinea pigs: 8.5 arb.U. (mean value) and spontaneously hypertensive rats: 8.6 arb.U. The lowest values were registered with minipigs: 1.4 arb.U. Mice (strain 17) showed 3.8, Lewis and Wistar rats accordingly 4.6 and 6.2 arb.U.