Is Blueberry Extract Anthocyanin an Antioxidant?

Blueberry (Vaccinium corymbosum L.), of the family Ericaceae, is a perennial shrub in the genus Vaccinium. There are more than 400 species in the genus, with more than 90 species distributed in China, mainly in the southwestern, southern and northeastern regions [1]. Blueberries are rich in chemical components, containing trace elements such as potassium, zinc, iron, and manganese, as well as amino acids (15 to 17 types), vitamins, proteins, lipids, and superoxide dismutase [2-3]. They also contain anthocyanins, chlorogenic acid, polysaccharides, quercetin and its derivatives, and kaempferol and its derivatives. Blueberries have a variety of health benefits, including antioxidant, anti-hypertension, and hyperlipidemia, as well as liver protection. With the improvement of people's health awareness and the recognition of the health benefits of blueberries, blueberries have become popular, and the development of the blueberry industry has also been very rapid.

1 Main active ingredients of blueberries

In recent years, as research on blueberries has continued to deepen, a variety of active ingredients have been isolated and extracted from blueberries, including anthocyanins, chlorogenic acid, polysaccharides, quercetin and its derivatives, kaempferol and its derivatives, etc.

1.1 Anthocyanins

Anthocyanins are abundant in blueberries and come in a variety of types. They are a very important type of bioactive ingredient in blueberries, mostly existing in the form of glycosides. Relevant scholars at home and abroad have also conducted a lot of research on anthocyanins in blueberries. TIAN et al. [ 2] used high performance liquid chromatography to analyze and conclude that highbush blueberries contain five anthocyanins: peony pigment, cornflower pigment, delphinium pigment, morning glory pigment and mallow pigment.

1.2 Flavonols and their glycosides

Flavonols are also a major active substance in blueberries. They can be found in both free and bound form, and mostly in the form of glycosides [4]. Flavonols currently isolated from blueberries include rutin, hyperoside, isoquercitrin, quercitrin, kaempferol-3-O-glucoside, hyperin, isohyperin, myricetin-3-O arabinoside, quercetin-3-O-glucoside, quercetin-3-O-galactoside and quercetin-3-O-arabinoside [5-7].

1.3 Phenolic acids

Phenolic acids are phenolic substances. The phenolic acids known in blueberries include ferulic acid, p-coumaric acid, caffeic acid, gallic acid, gentisic acid, protocatechuic acid, vanillic acid, vanillic acid, sinapic acid, and syringic acid [8-9].

1.4 Polysaccharides

Blueberries are rich in polysaccharides. Infrared spectroscopy and high-performance liquid chromatography analysis showed that the polysaccharides in blueberry leaves are mainly composed of galacturonic acid, arabinose, xylose, fucose and galactose [10].

2 Health benefits of blueberries

2.1 Antioxidant effect

Liu Xiaoli et al. [11] conducted an antioxidant study on blueberry leaves and concluded that they have the ability to resist lipid oxidation. FERLEMI et al. [12] concluded that chlorogenic acid and quercetin contained in blueberry leaves have strong antioxidant effects. Hao Meng [13] found that the polyphenol components in blueberry leaves can scavenge free radicals and have very strong antioxidant activity, and can be used in the preparation of natural antioxidants, medicines and health products. Li Yingchang et al. [14] found that the total flavonoids in blueberry leaves have a significant inhibitory effect on peroxidation.

2.2 Hepatoprotective effect

A study by Hua Yuwei et al. [15] showed that administering blueberry leaf polyphenols to high-fat mice can significantly reduce the levels of alanine aminotransferase and aspartate aminotransferase in the liver, indicating that blueberry leaf polyphenols have a protective effect on the liver.

2.3 Lipid-lowering effect

Zhang Qingfeng et al. [16] gave high cholesterol rats an oral dose of blueberry leaf total flavonoids. The study showed that the rats' serum total cholesterol, AST, LDL, ALT, and triglyceride levels were significantly reduced, while HDL levels were significantly increased. There was a clear dose-response relationship between the total flavonoid concentration and the effect, indicating that blueberry leaf total flavonoids have a certain hypolipidemic effect [17].

2.4 Antiviral

TAKESHITA et al. [18] and ISHIDA et al. [19] applied blueberry leaf extract to hepatitis C virus and found that oligomeric proanthocyanidins in blueberry leaves can affect the expression of hepatitis C virus RNA and have a good inhibitory effect.

2.5 Prevention of cardiovascular disease

Anthocyanins in blueberries have a certain regulatory effect on the contraction of blood vessels in the human body, and have a significant effect on maintaining blood pressure stability. They also improve the blood circulation system, reduce the stickiness of platelets in the blood, prevent the formation of blood clots, and reduce the incidence of cardiovascular diseases [20].

2.6 Anti-tumor

ICHIKAWA et al. [21] found that blueberry leaf extract can inhibit the proliferation of T cells in leukemia by degrading JAK proteins. In addition, RIBERA-FONSECA et al. [22] found that blueberry leaf extract can significantly reduce cancer cell migration and the expression of gastric cancer-related proteins, showing strong inhibitory activity against cancer cells. ROLLE et al. [23] showed that the active ingredient anthocyanin in blueberries has anti-tumor proliferation effects. SUN Xiyun [24] concluded through experiments that blueberry polysaccharides have certain anti-tumor effects.

3 Conclusion

Blueberries are rich in active ingredients and have a variety of health benefits, which has led to increasing interest in them and promoted the rapid development of the blueberry industry. At present, there has been a lot of research on the isolation of crude blueberry extracts. The next step could be to increase research on the isolation and purification of blueberry compounds to lay the foundation for the development of pharmaceutical or health products, as well as to evaluate the quality of blueberries from different varieties, origins and seasons.

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