Quercetin is a widely distributed flavonoid alcohol compound with a variety of biological activities in the plant world. It is found in a variety of vegetables and fruits, such as Brazilian berries, broccoli and apples, as well as in tea, red wine, olive oil, chemicalbook and propolis. Among them, it is high in Sophora japonica, buckwheat stems and leaves, seabuckthorn, hawthorn and onion. Quercetin mainly comes from coniferous cherry, tea, red onion, raspberry, blueberry and other plants.
Quercetin is the best studied of all bioflavonoids. But it’s not actually a good supplement. However, it’s an interesting research topic. It works synergistically with other bioflavonoids and increases the absorption of resveratrol and green tea catechins.
Quercetin is a bioflavonoid found in fruits and vegetables, but the content is the highest in apples and onions.
Like many other bioflavonoids, quercetin has antioxidant, anti arteriosclerosis and anti carcinogenic properties. Quercetin also has neural activity and has some of the same abilities as caffeine, but its efficacy is weak.
There is a difference between the effects observed by quercetin in vitro (cell culture) and in vivo (in vivo) studies, mainly due to the low oral bioavailability of quercetin (a low percentage of compounds are absorbed and put into use).
Many studies have also pointed out that there are significant differences between people who consume the same amount of quercetin, suggesting that there may be a large degree of variation in supplements.
In vitro studies of 25-100 um showed that quercetin could protect PC-12 neurons from the induction and inhibition of toxins and peroxides induced by oxidative stress β- The formation of amyloid pigmentation. It is reported that quercetin-3-glucuronide has a protective effect on some reactive oxygen species as low as 0.5um.
Quercetin can inhibit the release of nitric oxide by increasing the expression of heme oxygenase-1, thus playing an anti-inflammatory role in the brain (thus protecting the body from Alzheimer’s disease and Parkinson’s disease).
On the other hand, quercetin may be a potential neurotoxic substance at a supraphysiological level. It has been noted in some studies that quercetin initially protects neurons, but it was later found to act as a toxin in vitro studies. In pure in vitro neuronal cultures, quercetin seems to induce toxicity at a concentration of 1-10um, but its toxicity is reduced to a certain extent in vivo due to its protection by the metabolism of peripheral glial cells.
Quercetin supplement, 20mg / kg, can prevent the damage of dioxin to testis, so as to prevent the decline of testosterone level; The mechanism seems to be achieved through the presence of antioxidants in the testis, because based on the same mechanism, quercetin can also protect the kidney from dioxins. Quercetin prevents physical injury, as demonstrated by rotating the rat testicles 720 degrees clockwise.
Using onion juice as a good source of quercetin, the testosterone level of rats increased after 20 days of 4g / kg body weight per day.
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