Extraction and identification of anthocyanins

The use of organic solvents such as methanol and ethanol to extract anthocyanin pigments causes a toxicity issue.

 Although ethanol is considered as a generally safe extraction medium, isolation of anthocyanins using water-based extraction is consider a greener way.

  This extraction technique uses acidified water (0.01% HCl, pH ~2.3) that is subjected to high temperatures between 110–160°C under a constant pressure of 40 bars

  This increases the solubility of anthocyanins from the plant during extraction with water.

Anthocyanins are extracted from plants as a crude mixture. For that reason, separation or isolation of specific type of anthocyanin is needed for a specific purpose. 

 These include thin layer chromatography, high speed countercurrent chromatography, high-performance liquid chromatography, cellulose column chromatography, and reversed-phase ion-pair chromatography, as well as gas chromatography.

 In addition to separation and identification of anthocyanins, quantification of these compounds is commonly done by various chromatographic methods. High-performance liquid chromatography is the most used method in quantification of anthocyanins. 

Anthrocyanin and its types

Anthocyanins are blue, red, or purple pigments found in plants, especially flowers, fruits, and tubers. In acidic condition, anthocyanin appears as red pigment while blue pigment anthocyanin exists in alkaline conditions. Anthocyanin is considered as one of the flavonoids although it has a positive charge at the oxygen atom of the C-ring of basic flavonoid structure. It is also called the flavylium (2-phenylchromenylium) ion.

anthocyanidins and anthocyanins possess antioxidative and antimicrobial activities, improve visual and neurological health, and protect against various non-communicable diseases. These studies confer the health effects of anthocyanidins and anthocyanins, which are due to their potent antioxidant properties.

Different mechanisms and pathways are involved in the protective effects, including free-radical scavenging pathway, cyclooxygenase pathway, mitogen-activated protein kinase pathway, and inflammatory cytokines signaling. 

Anthocyanin is one of the subclasses of phenolic phytochemicals. Anthocyanin is in the form of glycoside while anthocyanidin is known as the aglycone.

Anthocyanidins are grouped into 3-hydroxyanthocyanidins, 3-deoxyanthocyanidins, and O-methylated anthocyanidins, while anthocyanins are in the forms of anthocyanidin glycosides and acylated anthocyanins. The most common types of anthocyanidins are cyanidin, delphinidin, pelargonidin, peonidin, petunidin, and malvidin. 

Anthocyanin is derived from flavonol, and it has the basic structure of flavylium ion, that is a lack of a ketone oxygen at the 4-position

Different mechanisms and pathways are involved in the protective effects, including free-radical scavenging pathway, cyclooxygenase pathway, mitogen-activated protein kinase pathway, and inflammatory cytokines signaling