Quercetin supplements
Organic quercetin powder and its derivatives are flavonoids widely distributed in the plant kingdom and have various biological activities. It exists in many plants' flowers, leaves, and fruits, mainly in the form of glycosides, such as rutin, quercetin, serine, etc. Quercetin can be obtained by acid hydrolysis. The content of quercetin in onion is the highest, so quercetin is also called onion. It has various biological properties, including antioxidant and free radical scavenging, anti-fibrosis, anti-viral, analgesic, and protective cardiovascular system, which form the basis for maintaining overall health and disease resistance.
What are the biological and medicinal properties of quercetin
1. Quercetin has a direct scavenging effect on superoxide anion, hydroxyl radical, and lipid peroxidation free radical
Free radical damage can cause or even exacerbate diseases such as bad cells, stroke, and heart disease and is closely related to aging. Free radicals are produced in the body at all times. Once the balance between oxidation and anti-oxidation is out of balance, cells will be damaged due to oxidative stress, eventually leading to diseases.
Flavonoids' free radical scavenging ability is partly attributed to the OH group on the antioxidant active group-phenol in the molecular structure. Quercetin and its derivatives, which belong to flavonoids, are superoxide anion radical scavengers. It has 4 OH groups on the chroman ring of polyphenols and the 4-position and 3' of the B ring. The hydroxyl group at the 4' position and the unsaturated double bond at the 2.3 positions endow quercetin with a potent antioxidant capacity. The antioxidant properties of quercetin are not only based on capturing oxygen free radicals but also based on its ability to bind transition metals with redox oxidation to form metal chelates, thereby deactivating transition metals such as iron and copper. Quercetin can complex iron ions to form an inactive iron ion complex, preventing iron ions from participating in the biochemical reactions of many free radicals, such as the Fenton reaction. In contrast, the iron ion complex still maintains the activity of a free radical scavenger. At the same time, quercetin can also inhibit aldose reductase, and reduce NADPH consumption, thereby improving the body's antioxidant capacity.
2. Quercetin acts as a protein kinase inhibitor and modulates protein kinase signaling pathways
Pure quercetin is a natural protein kinase inhibitor contained in plant-based foods. It can competitively bind to the ATP-binding site on protein kinases such as PI3K, changing the kinase's phosphorylation state, and making it inactive. The competitive binding ability of quercetin to these protein domains determines its inhibitory effect on protein kinases. Quercetin can specifically inhibit CK2, AMPK, PI3K, and other protein kinases, and the inhibition rate reaches about 20%. The inhibition of quercetin protein kinase may show protective effects and disease prevention effects on cells, and of course, it may be the opposite. 10-30 μM quercetin induces caspase three activations by inhibiting Akt and ERK phosphorylation, leading to primary neuronal cell death. However, even after people eat foods rich in quercetin, the concentration in the blood is far from reaching the above level.
3. Quercetin acts as a signaling molecule to regulate gene expression
Flavonoids such as quercetin can not only alter the phosphorylation status of target molecules by selectively interacting with different components of many protein kinases and lipid kinase signaling cascades, inhibit or activate these signaling pathways to affect cell function, but also Strengthens cellular endogenous antioxidant defenses by modulating gene expression. Quercetin and the like regulate the expression of genes downstream of the sequence through direct or indirect regulation of specific DNA sequences.
Nuclear factor kappa B and activator protein-1
NF-KB is a critical nuclear transcription factor in eukaryotic cells. It plays a regulatory role in the transcription of genes related to immune and inflammatory responses, growth, development, and death. It plays a vital role in the pathogenesis of diseases due to the participation of cytokines, inflammatory mediators, and proteases. However, the overactivation of NF-KB is, at the same time, one of the primary causes of many diseases-. Quercetin and green tea extract can regulate the overactivation of NF-KB, which may have a potential symptom-improving effect on conditions affected by the overactivation of NF-KB. In addition, quercetin can also control the expression of AP-I. AP-I transcription factor mainly exists in cells in the form of the c-Fos/c-Jun heterodimer and c-Jun/c-Jun homodimer. It plays a vital role in regulating various gene expressions, activating a series of oxidative stress response groups, and regulating gene expression related to cell growth and stress.
Xenobiotic responsive elements
The promoter regions of CYP450 enzyme family genes contain XRE, which can be partially regulated by the aryl hydrocarbon receptor AhR. Quercetin acts as a natural ligand, directly binds to AhR, and induces the transcription of XRE-related genes. Because AhR plays an essential role in the transcriptional activation of CYP450 enzymes, dietary intake of quercetin may increase the levels of cell phase I and phase II detoxification enzymes and better resist the toxic damage that the body may suffer.
4. Quercetin acts as a topoisomerase inhibitor to prevent viral replication
DNA topoisomerases control the maintenance of DNA topology. Quercetin is a potent inhibitor of type I and types II topoisomerases, and it can compete with the ATP-binding domain of topozyme and significantly inhibit DNA unwinding. Correspondingly, quercetin can disrupt viral replication by altering the topology of viral DNA. Quercetin can inhibit the pose of the human immunodeficiency virus, thereby exerting an anti-HIV effect.
After metabolizing quercetin in the body, metabolic modifications alter its antioxidant properties. Although the metabolites of quercetin (such as glucuronide, methylated form, and quercetin-GSH conjugated form) still have the reducing ability to provide hydrogen ions, their effectiveness in scavenging active oxygen is greater than that of their parent aglycone. Weak. In addition, the concentrations of quercetin and its metabolized forms in the blood and organs are lower than those of small molecule antioxidants such as vitamin C and vitamin E. Indicating that the dose of quercetin can produce biological activity in vitro is significantly higher than that in vivo the peak concentration. Despite this, quercetin's in vivo protective effect is stronger than the above-mentioned small molecule antioxidants.
How to take quercetin
You can buy quercetin powder or capsules online from Xi'an Sonwu as a dietary supplement. Quercetin is found in many commonly eaten foods and is available as a dietary supplement. Recommended dosage range from 500–1,000 mg per day. Quercetin has low bioavailability, which means your body absorbs it poorly. Accessories may include other compounds such as vitamin C or the digestive enzyme bromelain, as they may increase absorption.
Additionally, quercetin has synergistic effects when combined with other supplements such as resveratrol, genistein, and catechins.
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