Key Properties and Benefits of Anthocyanins Explained
Anthocyanin Definition
Anthocyanins are also known as Anthocyanins. These are water-soluble pigments present in plants, especially in fruits and vegetables. The red, blue, purple, pigments in fruits, vegetables and tubers are due to Anthocyanins. These pigments belonging to the phenol group are in glycosylated forms. When it comes to anthocyanin meaning, the word ‘Anthocyanins’ came from the combination of ‘Anthos’ and ‘Kyanous’. The former implies flowers whereas the latter signifies dark blue colour.
Most of the red, blue, purple flowers contain Anthocyanins. For example, red hibiscus, red roses, pink blossom, blue rosemary, blue chicory, purple sage, purple mint, lavender are edible. Some of these are commonly used as food, colourants and as folk medicine too.
What Is Anthocyanin?
Anthocyanin is a sub-division of phenolic phytochemicals. It is mostly found in the fruits and flowers, particularly their epidermal tissues’ vacuolar sap. Since Anthocyanin is available as a glycoside, you can call it as a glycone. They are a subclass of flavonoids. Thus, they are polyphenols which give the unique colour of the plants or parts of the plants. Apart from normal anthocyanins, Acylated Anthocyanins are also present in plants.
Properties of Anthocyanins
They are responsible for the red, blue or purple colours of vegetable petals, cereals like eggplants, onions, black rice, berries. Along with carotenoids, the autumn leaf colour is partially dependent on the presence of anthocyanins.
Based on their anthocyanin chemistry, they can be classified into two groups, flavonoids and phenolics. These plant pigments are soluble in water.
It has been used as an appetite stimulant, choleric agent and to prevent other diseases as well. Since this is a bioactive component, the bioavailability is the crucial factor for maintaining good health and healing several illnesses.
Source of Anthocyanins
The fruits, vegetables, grains containing anthocyanins are delicious as well as nutritious. Some of the foods that contain Anthocyanins in high amounts are blackberries, purple asparagus, concord grapes, pomegranates, eggplant, raspberries, purple corn, red cabbage, black rice. Still, Anthocyanins are present in fruits and vegetables; they are available in compound forms, not independently. And it is found that the effects are much better when they are consumed in combination with other compounds rather than in isolation. More research is still required to explore different aspects of Anthocyanins.
Uses of Anthocyanins
Anthocyanins have a vast area of applications.
The red, blue or purple pigments extracted from the plants are widely used as dye or food colourant. For instance, Anthocyanin extracted from grape skin is heavily used for adding attractive colours to fruit jams, beverages, or confectionaries.
Several anthocyanin-rich flowers and fruits are used as medicines for treating different ailments. They possess various properties like anti-microbial, anti-cancer, anti-inflammatory, anti-diabetic, as well as anti-obesity. They are also highly effective for the prevention of cardiovascular disease (CVDs). Hence Anthocyanins are potential pharmaceutical ingredients having great medicinal values.
Since people are now concerned about the toxic effects of synthetic food pigment, the demand for plant-based colourants like Anthocyanins is increasing rapidly in the food industry.
The Basic Anthocyanin Structure and Anthocyanin Formula
(Image to be added soon)
This picture depicts the structure of anthocyanins.
The structure of anthocyanin has come from flavylium ion and its basic formula is C15H11O+..
Therapeutic Effects
Anthocyanins are known for their therapeutic effects in different diseases.
Anticancer: Anthocyanins have been studied extensively for treating cancer as well as antiangiogenesis. Antiangiogenesis is a method that stops new blood cell formation that sends oxygen to the tumour cells. It helps in developing cancerous cells. The study for particularly these diseases is based on models of animals along with in-vitro and cell structure.
Anti-diabetic: Anthocyanins are widely used for treating diabetes as in many research, it is seen that anthocyanin-rich Cornus fruits work fantastic in diabetes treatment. For this reason, consumption of Cornus fruits has been prescribed in traditional diabetes treatment in China since ancient times. In studies, noticeable improvement has been seen due to the consumption of anthocyanin-rich fruits for eight weeks at one go.
Anti-obesity: Anthocyanins have potential to fight against obesity. According to a study, the inclusion of purple corn in a regular diet for 12 weeks helps to reduce body weight as well as the weight of white and brown adipose tissues also decreases.
FAQs on What Are Anthocyanins? Meaning, Structure & Significance
1. What are anthocyanins and where are they found in nature?
Anthocyanins are a class of water-soluble pigments belonging to the flavonoid group. They are responsible for the vibrant red, purple, and blue colours observed in many flowers, fruits, and vegetables. They are found in the cell vacuoles of various plant tissues, contributing to the colour of plants like blueberries, red cabbage, cherries, and eggplant skin.
2. What is the basic chemical structure of an anthocyanin?
The fundamental structure of an anthocyanin consists of two parts: an anthocyanidin (the aglycone or non-sugar part) and one or more sugar molecules (glycones) attached to it. The core of the anthocyanidin is the flavylium cation, which has a C6-C3-C6 skeleton, meaning two benzene rings (A and B) are linked by a three-carbon chain that forms a heterocyclic C-ring containing oxygen.
3. What is the significance of anthocyanins in plants?
In plants, the significance of anthocyanins extends beyond just providing colour. Their primary functions include:
Attracting Pollinators: Their bright colours attract insects and animals, aiding in pollination and seed dispersal.
Protection from UV Radiation: They act as a natural sunscreen, absorbing harmful UV light that could damage the plant's DNA.
Antioxidant Activity: They protect plant cells from oxidative stress caused by environmental factors like drought, cold, and high light intensity.
4. Which common foods are rich sources of anthocyanins?
Many commonly consumed fruits and vegetables are excellent sources of anthocyanins. These include:
Berries: Blueberries, blackberries, raspberries, strawberries, and cranberries.
Fruits: Grapes (especially red and black varieties), cherries, plums, and pomegranates.
Vegetables: Red cabbage, eggplant (skin), radishes, and red onions.
Grains: Black rice and purple corn.
5. How do anthocyanins benefit human health?
Anthocyanins are powerful antioxidants that offer several health benefits. They help neutralize harmful free radicals in the body, which can reduce the risk of chronic diseases. Key benefits include strong anti-inflammatory properties, improved vision, enhanced brain function, and support for cardiovascular health by helping to lower blood pressure and prevent arterial plaque formation.
6. Why do anthocyanins change colour with varying pH levels?
The colour of anthocyanins is directly linked to their chemical structure, which is sensitive to pH. In acidic conditions (low pH), the flavylium cation structure is stable, appearing red. As the pH increases towards neutral, the molecule loses a proton, forming a purple quinonoidal base. In alkaline conditions (high pH), it can transform further into a blue or even colourless chalcone form. This is why red cabbage juice can be used as a natural pH indicator.
7. What is the key difference between an anthocyanin and an anthocyanidin?
The primary difference lies in the presence of sugar molecules. An anthocyanidin is the basic, non-sugar part of the structure, known as the aglycone. An anthocyanin is a glycoside, meaning it is an anthocyanidin that has one or more sugar molecules (like glucose or galactose) chemically bonded to it. This attachment of sugars makes anthocyanins more water-soluble and generally more stable than their anthocyanidin counterparts.
8. How does the molecular structure of an anthocyanin influence its specific shade of colour?
The exact shade of red, purple, or blue is determined by modifications to the basic anthocyanidin structure. Key factors include the number and position of hydroxyl (-OH) and methoxyl (-OCH3) groups on the B-ring. For instance, an increasing number of hydroxyl groups tends to shift the colour from orange-red towards blue. The type of sugar attached and the presence of other molecules through copigmentation also play a significant role in stabilizing and modifying the final colour seen in the plant.
