Clinical studies of Myricetin have shown that it has potential therapeutic value in many aspects. In the field of metabolic diseases, phase I clinical trials have shown that Myricetin can help improve glucose tolerance in patients with type 2 diabetes mellitus and show potential to regulate lipid metabolism. Its antioxidant and anti-inflammatory properties have shown symptom-relieving effects in chronic inflammatory diseases such as arthritis. Preliminary studies also suggest that it may have neuroprotective effects against neurodegenerative diseases and may improve vascular endothelial function. At present, myricetin is mainly used in the form of dietary supplements (common dose 250-500mg/day), and products have been marketed in the fields of antioxidant and anti-aging. However, its clinical application still faces challenges such as low bioavailability, and the phase III clinical data need to be improved.

Pharmacological action

-Antioxidant

Myricetin is a flavonoid widely distributed in nature, which can scavenge a variety of free radicals and has significantly better antioxidant capacity than common antioxidants such as vitamin C. In addition, Myricetin can also inhibit lipid peroxidation reactions and protect cell membranes and DNA from oxidative damage, making it potentially valuable in the prevention and treatment of oxidative stress-related diseases. Studies have shown that Myricetin improves the inhibition of LPS-induced oxidative stress damage by inhibiting reactive oxygen species (ROS) and increasing glutathione peroxidase (GPx), and ultimately exerts significant antioxidant activity.

Figure 1 Effect of Myricetin on LPS-induced ROS levels and GPx activity.

-Anti-inflammatory

Myricetin, an active component of flavonol plants, has significant anti-inflammatory effects, can reduce pathological damage in a variety of inflammatory models, reduce the level of pro-inflammatory factors, and effectively inhibit tissue oedema and inflammatory cell infiltration, and has shown good effects in skin inflammation and arthritis models. It was found that Myricetin effectively inhibited the expression of pro-inflammatory factors interleukin-6 (IL-6) and interleukin-8 (IL-8) in A549 cells stimulated by tumour necrosis factor-α (TNF-α).

Figure 2 Regulatory effect of myricetin on TNF-α-induced intracellular pro-inflammatory factor in A549. (A) IL-6 and (B) IL-8 mRNA expression levels.

-Hypoglycaemic effect

As a flavonoid, Myricetin can effectively reduce fasting blood glucose levels and improve glucose tolerance in diabetic model animals, and it also has an ameliorating effect on diabetes-related oxidative stress and chronic inflammatory states. Studies have shown that Myricetin can significantly reduce blood glucose levels in experimental diabetic model animals, while enhancing glucose-stimulated insulin secretion, thereby exerting a significant hypoglycemic effect.

Figure 3 Effect of Myricetin on blood glucose balance in diabetic model mice.

-Liver protection

The active flavonoid Myricetin isolated from plants can reduce chemical liver injury, inhibit the process of liver fibrosis, improve liver pathological damage, and its hepatoprotective effect is comparable to that of silymarin, and show an improvement effect on both alcoholic and non-alcoholic fatty liver disease. Studies have shown that Myricetin can improve the survival rate of mice, and play hepatoprotective functions such as reducing serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, which in turn plays a protective role against lipopolysaccharide (LPS)/D-aminogalactose (D-GalN)-induced fulminant hepatitis in mice.

Figure 4 Effect of Myricetin on serum ALT (A) and AST (B) levels 6 hours after LPS/D-GalN administration.

-Anti-hyperuricaemia

As a typical dietary flavonoid, Myricetin can effectively improve hyperuricemia, mainly by inhibiting uric acid production and promoting uric acid excretion, and the uric acid-lowering effect of myricetin is comparable to that of the clinical first-line drug allopurinol, which provides an important basis for the development of new uric acid-lowering drugs. Myricetin could significantly reduce the serum uric acid concentration in hyperuricemia model rats, and its uric acid lowering effect showed a significant dose-response relationship.

Figure 5 Effect of Myricetin on uric acid level in hyperuricemia model rats.

-Anticancer

Myricetin is a natural flavonoid, which can directly kill tumour cells by inhibiting cancer cell proliferation and inducing apoptosis, and at the same time block tumour angiogenesis, thereby limiting the nutrient supply and metastasis of cancer cells. In addition, Myricetin's powerful antioxidant capacity can neutralise free radicals and reduce oxidative stress damage, while its anti-inflammatory properties help improve the tumour microenvironment. These multiple mechanisms of action make them show good application prospects in the field of cancer prevention and adjuvant therapy. Studies have shown that Myricetin significantly inhibits the proliferation of human hepatocellular carcinoma SNU-790 cells in a concentration-dependent manner.

Figure 6 SUN-790 cells were treated with different concentrations of Myricetin for 24 hours.

-Other effects

Myricetin is a natural flavonoid with multi-target pharmacological activity, which not only has a significant antibacterial effect and inhibits a variety of pathogenic bacteria, but also can effectively protect the nervous system and improve the symptoms related to neurodegeneration. Previous studies have shown that Myricetin can also reduce myocardial damage and improve heart function. In addition, Myricetin also has outstanding anti-osteoporotic activity, which can promote bone formation and inhibit bone resorption, and these pleiotropic pharmacological properties make it show important development value in the prevention and treatment of infectious diseases, neurodegenerative diseases, cardiovascular diseases, osteoporosis and metabolic diseases.

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