Citric acid (77-92-9) is a small molecule primarily acting as an intermediate in the tricarboxylic acid (TCA) cycle contributing to mitochondrial energy production Citric acid exerts its biological effects in part by acidifying the local environment and chelating calcium In cell-based studies citric acid induces apoptosis in HaCaT cells and causes cell cycle arrest at the G2/M and S phases It also reduces antioxidant enzyme activity resulting in hepatic oxidative injury and exhibits nephrotoxicity in mouse models No IC50 value has been reported for citric acid Based on these pharmacological activities citric acid is of interest for research on cell death oxidative stress and as an excipient or anticoagulant in pharmaceutical and biochemical applications