Quercetin is a flavonoid with significant pharmacological properties, found in various plants and foods. It has potent antioxidant activity, capable of scavenging reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive chlorine species (ROC), which helps in reducing oxidative stress. Quercetin also exhibits anti-inflammatory, antiviral, antihypertensive, and anti-cancer properties. It protects low-density lipoprotein (LDL) from oxidation and inhibits angiogenesis. Quercetin is commonly found in foods like onions, grapes, apples, and berries, and is often present in glycosidic form. Its aglycone form is less common but has limited bioavailability. Quercetin's bioavailability is influenced by its chemical structure, origin, and interactions with other compounds. It is metabolized in the gastrointestinal tract and liver, with metabolites such as quercetin-3-glucuronide and quercetin-30-sulfate being excreted in urine and bile. Quercetin has been shown to have beneficial effects on cardiovascular health, including reducing blood pressure and protecting against vascular damage. It also exhibits anti-inflammatory and neuroprotective properties, potentially beneficial in Alzheimer's disease. Quercetin has antiviral activity against viruses such as HIV, hepatitis B, and SARS-CoV-2. It has hepatoprotective effects and can reduce oxidative stress and inflammation. Quercetin also shows potential in treating diabetes, arthritis, and cancer by inducing apoptosis and inhibiting cell proliferation. Its synergistic effects with other drugs, such as doxorubicin, resveratrol, and epigallocatechin gallate, enhance its therapeutic potential in various diseases. Overall, quercetin's diverse pharmacological properties make it a promising candidate for various therapeutic applications.Quercetin is a flavonoid with significant pharmacological properties, found in various plants and foods. It has potent antioxidant activity, capable of scavenging reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive chlorine species (ROC), which helps in reducing oxidative stress. Quercetin also exhibits anti-inflammatory, antiviral, antihypertensive, and anti-cancer properties. It protects low-density lipoprotein (LDL) from oxidation and inhibits angiogenesis. Quercetin is commonly found in foods like onions, grapes, apples, and berries, and is often present in glycosidic form. Its aglycone form is less common but has limited bioavailability. Quercetin's bioavailability is influenced by its chemical structure, origin, and interactions with other compounds. It is metabolized in the gastrointestinal tract and liver, with metabolites such as quercetin-3-glucuronide and quercetin-30-sulfate being excreted in urine and bile. Quercetin has been shown to have beneficial effects on cardiovascular health, including reducing blood pressure and protecting against vascular damage. It also exhibits anti-inflammatory and neuroprotective properties, potentially beneficial in Alzheimer's disease. Quercetin has antiviral activity against viruses such as HIV, hepatitis B, and SARS-CoV-2. It has hepatoprotective effects and can reduce oxidative stress and inflammation. Quercetin also shows potential in treating diabetes, arthritis, and cancer by inducing apoptosis and inhibiting cell proliferation. Its synergistic effects with other drugs, such as doxorubicin, resveratrol, and epigallocatechin gallate, enhance its therapeutic potential in various diseases. Overall, quercetin's diverse pharmacological properties make it a promising candidate for various therapeutic applications.