red onion extract

Red onion extract is derived from the bulbs of the red onion (*Allium cepa L.*), and is commonly used as a dietary supplement or traditional remedy. Its main active constituents are flavonoids such as **quercetin** and catechin, along with other phytochemicals, which exert significant **antioxidant**, **anti-inflammatory**, **antihyperglycemic**, and **hypolipidemic** effects. Mechanistically, red onion extract acts through: - **Antioxidant activity**: scavenging free radicals, decreasing lipid peroxidation, upregulating endogenous antioxidant systems (e.g., glutathione), and normalizing red cell plasma membrane redox systems[1][3][4]. - **Anti-inflammatory action**: inhibiting cytokines (IL-4, IL-5, IL-10, IL-13, IFN-γ, TNF-α), cyclooxygenase-2 (COX-2), leukotriene and thromboxane biosynthesis, and histamine release—resulting in attenuation of allergic and inflammatory symptoms[2][3][4]. - **Metabolic modulation**: lowering cholesterol and glucose via effects on key enzymes, upregulating LDL receptor and cholesterol 7 alpha-hydroxylase, inhibition of α-glucosidase and α-amylase, and enhancing insulin secretion and sensitivity[3][4]. Preclinical and limited clinical studies have demonstrated benefits for redox balance, allergic rhinitis, dyslipidemia, type 2 diabetes, and cardiovascular risk factors, but large-scale clinical trials are lacking[1][2][3][4][5]. Red onion extract is usually administered orally or topically and is commercially available as a supplement, though not standardized as a pharmaceutical drug.

Other names

Allium cepa L. extractonion extractred onion juicered onion dietary supplement