Xanthine Assay

Xanthine is a purine base found in most human body tissues and fluids. A number of stimulants are derived from xanthine, including caffeine, aminophylline, IBMX, paraxanthine, pentoxifylline, theobromine, and theophylline, which can stimulate heart rate, force of contraction, cardiac arrhythmias at high concentrations. Therefore, detection of Xanthine alteration in biological samples is important for disease diagnosis and therapy monitoring.

Amplite^® Xanthine Assay Kits (Cat# 13842 & 13843) provide a quick and ultrasensitive method for the measurement of xanthine. The assay can be performed in a convenient 96-well or 384-well microtiter-plate format. Xanthine is oxidized to uric acid in the presence of xanthine oxidase to release hydrogen peroxide, which can be specifically measured with Amplite^® Red by an absorbanceµ microplate reader at 576±5 nm or by a fluorescence microplate reader at Ex/Em = 540 nm/590 nm. With Amplite^® Colorimetric Xanthine Assay Kit (Cat# 13842), as low as 1.2 µM xanthine was detected in a 100 µL reaction volume. With Amplite^® Fluorimetric Xanthine Assay Kit (Cat# 13843), as low as 0.4 µM xanthine was detected in a 100 µL reaction volume.



Xanthine oxidase (XO) is an enzyme that catalyzes the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. It plays an important role in the catabolism of purines. Xanthine oxidase is normally found in liver and jejunum. During severe liver damage, xanthine oxidase is released into blood, so a blood assay for XO is a way to determine if liver damage has happened. Xanthinuria is a rare genetic disorder where the lack of xanthine oxidase leads to high concentration of xanthine in blood and can cause health problems, such as renal failure.

Amplite^® Fluorimetric Xanthine Oxidase Assay Kit (Cat# 11304) provides a quick and ultrasensitive method for the measurement of xanthine oxidase activities. In the assay, xanthine oxidase catalyzes the oxidation of purine bases, hypoxanthine or xanthine to uric acid and superoxide, which spontaneously degrades to hydrogen peroxide (H₂O₂). The kit uses our Amplite^® Red substrate which enables a dual recordable mode. The fluorescent signal can be easily read by either a fluorescence microplate reader at Ex/Em = 540/590 nm or an absorbance microplate reader at ~576 nm. With Amplite^® Xanthine Oxidase Assay Kit, as low as 0.15 mU/mL xanthine oxidase was detected in a 100 µL reaction volume.