title: Enhanced chemiluminescence assay vs colorimetric assay for measurement of the total antioxidant capacity of human seminal plasma.
abstract: Although the enhanced chemiluminescence assay is commonly used to measure the nonenzymatic total antioxidant capacity (TAC) of the human seminal plasma, it is cumbersome, expensive, and time-consuming. We describe herein an alternate method to measure TAC that is based on the ability of antioxidants in seminal plasma to interfere with a reaction between 2,2'-azino-di-[3-ethylbenzthiazoline sulphonate] and metmyoglobin with H(2)O(2). This reaction produces a relatively stable blue-green color with absorbance maxima at 600 nm. We compared this colorimetric assay with our established chemiluminescence method and assessed quality control parameters (ie, intra-assay and interassay variabilities) in addition to intraobserver and interobserver differences. Our results show that the colorimetric assay was fairly predictive of antioxidant capacity similar to the chemiluminescence assay (P <.001). Furthermore, there was a high level of agreement between the duplicate measures by the same observer (intraobserver) and intra-assay variability, with a concordance correlation coefficient of 0.99. The interassay coefficient of variation was 4.7% (overall). The mean +/- SD of the difference between the 2 observers was 2.98% +/- 4.1%. In conclusion, we found that the colorimetric assay is a reliable and accurate method to evaluate seminal TAC, and it could be used as a simpler, rapid, and cheaper alternative to the chemiluminescence assay.
authors.affiliation: Center for Advanced Research in Human Reproduction, Infertility and Sexual Function, Glickman Urological Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.
authors.forename: Tamer M
authors.initials: TM
authors.lastname: Said
authors.forename: Namita
authors.initials: N
authors.lastname: Kattal
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Sharma
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Sikka
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Thomas
authors.forename: Edward
authors.initials: E
authors.lastname: Mascha
authors.forename: Ashok
authors.initials: A
authors.lastname: Agarwal
mesh_terms: D000975:Antioxidants; D002624:Chemistry, Clinical / Q000379:methods* / Q000592:standards; D002839:Chromans; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D015588:Observer Variation; D017382:Reactive Oxygen Species / Q000378:metabolism; D015203:Reproducibility of Results; D012661:Semen / Q000378:metabolism*; D013053:Spectrophotometry / Q000379:methods* / Q000592:standards
chemical_list: D000975:Antioxidants; D002839:Chromans; D017382:Reactive Oxygen Species; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid