Quercetin (QC)

Quercetin is a ubiquitous dietary flavonol and a prominent member of the flavonoid class of polyphenols, found in high concentrations in foods such as onions, apples, and berries [1, 15]. Although often termed a "target" in popular literature, it is fundamentally a bioactive small molecule that exerts pleiotropic effects by binding to and modulating numerous proteins, including kinases, enzymes, and transporters [1, 17]. Its biological roles are diverse, characterized by potent antioxidant activity via free radical scavenging and anti-inflammatory properties through the inhibition of pro-inflammatory cytokines and pathways like NF-κB and cyclooxygenase (COX) [4, 11]. In therapeutic research, quercetin is extensively investigated for its potential in managing chronic conditions such as cancer, diabetes, and cardiovascular diseases [3, 7]. It is particularly noted for its "senolytic" properties, often used in combination with drugs like dasatinib to selectively eliminate senescent cells to combat aging-related pathologies [10]. Despite its broad pharmacological profile and interaction with key survival pathways like PI3K/Akt/mTOR, quercetin's transition to clinical practice is hampered by its poor water solubility, rapid metabolism, and low systemic bioavailability [6, 19].

Other names

3,3',4',5,7-PentahydroxyflavoneSophoretinMeletinXanthaurineQuercetolQuercitinFlavin meletin

Quercetin acts as a multi-target modulator that inhibits various signaling pathways including PI3K/Akt/mTOR and NF-κB, scavenges reactive oxygen species (ROS), and inhibits multiple protein kinases such as Aurora kinase and Hck. It also modulates the activity of ABC transporters like P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP), and regulates transcription factors such as Nrf2 to enhance antioxidant defenses.