Aerobic metabolism requires a complex antioxidative system to balance reactive oxygen species (ROS). When in excess, ROS disrupt cellular activities and molecular structures. Owing to the variety of ROS, there are different antioxidative activities that require various tests for their detection. The so-called 'total antioxidative capacity' inhibition assay presented in this paper can be used to quantify the overall activity of low-molecular-weight antioxidants (AOs) in biological samples. The assay is based on enhanced horseradish peroxidase-catalyzed luminol chemiluminescence. It can be fine-tuned so that the biological samples meet the requirements of the light detector. A detailed protocol describing all relevant parameters is provided. The procedure is quick, inexpensive and reproducible. The assay can be used with diverse biological materials such as plant extracts and blood plasma. Hence, it is applicable to fields as diverse as crop breeding, medical diagnostics or food sciences. The time needed for the assay depends on the number of samples and their AO content. The protocol takes one working day to complete when five samples with five replicates are measured sequentially.
