Citric acid-d4-1 is a deuterium-labeled variant of citric acid. Citric acid functions as a preservative and food additive. It induces apoptosis in HaCaT cells, causing cell cycle arrest at the G2/M and S phases. Additionally, citric acid leads to hepatic oxidative damage by reducing antioxidant enzyme activity and exhibits nephrotoxicity in mice.

Administered intraperitoneally, citric acid at doses of 120, 240, and 480 mg/kg significantly reduces GSH-Px activity and elevates MDA (malonyldialdehyde) levels in the livers of mice. This dosage range also induces apoptosis by enhancing caspase-3 activity in mouse hepatocytes in a dose-dependent manner. Additionally, weekly administration of these doses over three weeks results in renal toxicity in mice.