The Difference Between Quercetin and Isoquercetin

Quercetin and isoquercetin are two common types of natural active products. They have relatively similar names, but they have different functions and effects, and their uses are also quite different. What are the differences between the two types of products with similar names?

Ⅰ. What is quercetin?

Quercetin is a kind of flavonol, which can be found in many kinds of vegetables and herbs. It contains many beneficial biological activities, which can help healthy cell proliferation and cardiovascular immunity. And quercetin has antioxidant properties, can scavenge free radicals, help cell regulation, and promote DNA integrity. In addition, quercetin can help the body maintain sufficient glutathione levels during oxidative stress and support immune regulation. For this, many people would like to buy high quality quercetin.

Quercetin is the basic structure of many flavonoids, such as rutin and isoquercitrin. At the same time, the quercetin ring structure will also exist as part of a larger flavonoid molecule, such as the high sugar in hypericum and the flavonoid glycoside in ginkgo. Because it is easier to extract from rutin, quercetin is often added to supplements. However, quercetin rarely exists directly in nature and is not easily absorbed on the absorption surface of the small intestine. Its absorption occurs in a slower and less efficient passive diffusion process.

Quercetin mainly exists in the form of glucoside in nature, usually at the 3'or 4'position of the glucoside chain. Apples and onions are one of the most abundant food sources of quercetin glucoside, especially quercetin-3-glucoside, isoquercitrin and isoquercetin.

Ⅱ. The molecules of rutin and isoquercetin are very similar in structure

Rutin and isoquercetin are two terms that can be used interchangeably, even in the eyes of experts, because their molecules are very similar in structure. 

Functionally, these two molecules are almost indistinguishable. There is almost no difference between rutin uses and benefits and isoquercetin uses and benefits. Studies have shown that isoquercetin has higher bioavailability than quercetin or rutin.

1. Chemical structure

From the chemical point of view, isoquercetin is a glycoside, and quercetin is aglycone, which is commonly known as glycoside. Quercetin and isoquercetin have the same skeleton. From the perspective of chemical synthesis, isoquercetin is the addition of a glucose to the skeleton.

2. Water solubility

In terms of water solubility, quercetin is completely insoluble in water while isoquercetin is soluble in water.

3. Bioavailability

Isoquercetin, has been proven to have higher bioavailability and faster absorption rate than quercetin or rutin, and its rate is about twice that of quercetin, but more than rutin is ten times higher. The glucose part of isoquercetin accelerates the uptake of molecules and the conversion to quercetin. The above are isoquercetin benefits. Chengdu Kindarco Company, as a plant extract manufacturer, offers high quality isoquercetin for customers.

The enzyme and activity transport mechanism of cells in the small intestine interacts with the glucose component in the isoquercetin molecule to accelerate their uptake and conversion to quercetin. If there is no glucose component, the absorption of quercetin in the small intestine will be completed through a slower and less efficient passive diffusion process. Therefore, isoquercetin is a more bioavailable form of quercetin. Comparing the bioavailability of quercetin and isoquercetin in animal research models: the bioavailability of quercetin is 2%, and that of isoquercetin is 12%.