Antioxidant Assays
Measure antioxidant defence at every level: total antioxidant capacity, glutathione and thiols, antioxidant enzymes, and vitamins C and E.
ABTS and FRAP methods, plus total antioxidant status, give one functional read-out for the whole sample.
Reduced glutathione, GSH/GSSG, total thiols, glutathione peroxidase (including GPX4) and GST activity.
Catalase, peroxidase, MPO and xanthine oxidase activity, vitamins C and E, and NAD(P)H.
Both measure total antioxidant capacity but by different chemistry. The ABTS method measures the ability of a sample to quench a coloured radical, and responds to both water- and lipid-soluble antioxidants. The FRAP method measures the ability to reduce ferric iron, and reports reducing power. Results from the two methods are not interchangeable, so keep to one method within a study.
The combined ability of all antioxidants in a sample to counter oxidation. It is a functional measure rather than the level of one molecule.
Glutathione is oxidised to GSSG as it neutralises oxidants. A falling GSH/GSSG ratio is a sensitive indicator of oxidative stress.
Some kits are validated for plant tissue. See plant and environmental stress assays and check the product page.