Curcumin is the major active component of turmeric and widely used as a spice and coloring agent in food. However, its safety evaluation has been little investigated. To evaluate the 90-day subchronic toxicity of curcumin in rats, its general observation, clinical biochemistry, pathology, and metabolomics were evaluated. The results showed that curcumin induced liver injury through the generation of the overexpression of reactive oxygen species (ROS) and pro-inflammatory cytokines IL-6 and the decreases of the levels of antioxidant enzyme SOD and detoxified enzyme GST. Meanwhile, for the self-protection of rats, curcumin treatment activated the transcription of Nrf-2 and elevated the expression of HO-1 to reduce tissue damage. Furthermore, curcumin significantly increased key mRNA levels of HK2, PKM2, LDHA, CES, Cpt1, Cpt2, FASN, and ATP5b and decreased levels of GLUT2 and ACC1 to enhance glycolysis and inhibit lipid metabolism and TCA cycle. Therefore, overdose or long-term intake of curcumin could initiate the unbalanced state of bodies through oxidative stress, inflammation, and metabolic disorders, which induces liver injury. Intermittent administration of curcumin is necessary in our daily lives.
Keywords: curcumin; metabolomics; oxidative stress; self-protection; subchronic toxicity.