Quercetin is an abundant flavonoid that has been isolated from a variety of fruits and vegetables and has diverse biological activities, including antioxidant, anticancer, and anti-inflammatory properties. Quercetin (5-100 mg/kg) reduces autophagy, decreases the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) content, and increases total antioxidant capacity in the kidney in a mouse model of cadmium-induced autophagy. It reduces tumor growth, induces apoptosis, and halts the cell cycle at the G phase in an HL60 mouse xenograft model when administered at a dose of 120 mg/kg every four days. Quercetin (30 µM) also inhibits histamine release from antigen-stimulated RBL-2H3 cells and decreases the expression of TNF-α, IL-1β, IL-6, and IL-8 induced by PMACI in HMC-1 cells.