Biomarkers

Target: Quercetin

Quercetin is a flavonoid, a type of polyphenolic compound, widely found in various fruits, vegetables, and beverages such as apples, onions, berries, and tea. Its chemical structure consists of a 3,5,7-trihydroxyflavone backbone with additional hydroxyl groups at the 3', 4', and 5' positions, making it a pentahydroxyflavone. This structure contributes to its potent antioxidant properties, allowing it to neutralize free radicals and reduce oxidative stress in biological systems​​​​. Quercetin is primarily recognized for its antioxidant activity, which plays a crucial role in protecting cells from damage caused by reactive oxygen species (ROS). This antioxidative capacity is beneficial for reducing inflammation and potentially lowering the risk of chronic diseases such as cardiovascular disease and certain cancers. Quercetin belongs to the larger group of chemicals known as flavonols, which are a subclass of flavonoids widely distributed in the plant kingdom​​. This biomarker is naturally produced by plants as part of their defense mechanism against pathogens, UV radiation, and herbivores. It is commonly found in the outer layers of many fruits and vegetables, contributing to their color and health benefits. Quercetin's medicinal uses are extensive; it has been studied for its potential to alleviate allergy symptoms, reduce blood pressure, improve endurance, and enhance overall cardiovascular health. Additionally, it is being explored for its anti-carcinogenic properties and its ability to modulate immune function​​. In industrial applications, quercetin is utilized as a dietary supplement and in functional foods due to its health-promoting properties. The presence of quercetin in human biological samples, such as plasma and urine, serves as an indicator of dietary intake of flavonoid-rich foods. Elevated levels of quercetin in the human body are associated with a diet high in fruits and vegetables, reflecting a potentially lower risk of oxidative stress-related diseases​​. (PMID: 9925128)