Abstract
Quercetin, an abundant flavonoid in various foods and plants, exhibits diverse therapeutic potential due to its antioxidant, anti-inflammatory, and anticancer properties. This review explores its biological and pharmacological activities, mechanisms of action, formulations, absorption, bioavailability, adverse effects, and potential therapeutic applications.Initially isolated in the 1800s as a dye and in 1936 as a polyphenol, quercetin has garnered attention for its antioxidant capabilities, particularly in preventing oxidative damage from low-density lipoprotein (LDL) cholesterol, reducing the risk of cardiovascular disease (CVD). Studies also suggest its efficacy in lowering blood glucose levels, improving insulin sensitivity, and inhibiting viral infections, including COVID-19.Despite its promising benefits, quercetin’s bioavailability is limited by factors such as poor water solubility and rapid metabolism. Researchers have explored various formulations and delivery systems, including quercetin glycosides, nano-formulations, and phytosomes, to enhance quercetin’s absorption and effectiveness.While generally considered safe, high doses of quercetin supplements may lead to gastrointestinal disturbances, headache, and tingling sensation. Furthermore, its interaction with other medications warrants further investigation.Quercetin has therapeutic advantages in CVDs, metabolic syndrome, neurodegenerative disorders, respiratory conditions, skeletal conditions, bacterial and fungal infections, cancer, diabetes, iron-induced toxicity, oxidative stress, and viral infections. However, research in humans is limited, and optimal dosage and formulations remain to be established.Quercetin’s diverse pharmacological activities make it a promising therapeutic agent for various conditions, disorders, and diseases. Future research should focus on standardizing formulations, investigating long-term safety, elucidating mechanisms of action, and clarifying interactions with other medications to optimize quercetin’s therapeutic use.