Cell experiment:

Human colon carcinoma cells (Caco-2) are used and grown in Eagle’s minimum essential medium supplemented with 10% FBS, 1% non-essential amino acid mixture, and 1% Pen-Strep at 37℃ in a humidified atmosphere with 5% CO2. Caco-2 cells are incubated with indomethacin in the presence or absence of Uric acid for 24 or 48 hours[1].

Animal experiment:

To evaluate the effect of oral administration of Uric acid on NSAID-induced enteropathy, mice are given Uric acid (2.5, 10, 25, 100, or 250 mg/kg body weight) suspended in 0.5% carboxymethyl cellulose orally at 30 minutes before, and 12 hours after indomethacin or vehicle treatment. To evaluate the effect of intraperitoneal administration of inosinic acid plus potassium oxonate on NSAID-induced enteropathy, mice are given inosinic acid (500 mg/kg body weight) plus potassium oxonate (250 mg/kg body weight) 24 intraperitoneally at 30 minutes before, and 12 hours after indomethacin or vehicle treatment[1].

Uric acid is an endogenous antioxidant that scavenges reactive oxygen species (ROS) including singlet oxygen, oxygen radicals, and peroxynitrite.

Uric acid is an endogenous antioxidant that scavenges reactive oxygen species (ROS) including singlet oxygen, oxygen radicals, and peroxynitrite. Incubation with indomethacin significantly increases malondialdehyde (MDA) levels in Caco-2 cells compare to those not treated indomethacin. Incubation with both indomethacin and Uric acid significantly decreases MDA levels compare to those grown in the presence of indomethacin alone. Co-treatment of cells with indomethacin and Uric acid significantly decreases ROS levels compare to those in cells incubated with indomethacin alone. Cell viability in Caco-2 cells treated with both indomethacin and Uric acid is higher than that in cells treated with indomethacin alone. Uric acid has a protective effect on indomethacin-induced intestinal cell changes through its antioxidant activity[1].

When mice treated with indomethacin are concurrently administered Uric acid orally, ulcer areas are significantly reduced, in a Uric acid dose-dependent manner. Indomethacin increases the ratio of crypt depth to villous height in the ileum, while the ratio is significantly lower when mice are concurrently administered Uric acid orally. Administration of indomethacin also increases the histopathological score of tissue damage in the small intestine, while mice concurrently administered Uric acid orally has a significantly lower histopathological score. The ileal levels of malondialdehyde (MDA) in indomethacin-induced enteropathy model mice orally administered Uric acid are also significantly lower than the levels in mice administered indomethacin alone[1].

[1]. Yasutake Y, et al. Uric acid ameliorates indomethacin-induced enteropathy in mice through its antioxidant activity. J Gastroenterol Hepatol. 2017 Nov;32(11):1839-1845.