Flavonoid

Flavonoid

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Structure of flavonoids

Flavonoids are a class of polyphenolic compounds found in many plants. They are known for their diverse beneficial biological activities in humans and are a significant part of the human diet.

Structure

Flavonoids are characterized by their 15-carbon skeleton, which consists of two phenyl rings (A and B) and a heterocyclic ring (C). This structure can be abbreviated as C6-C3-C6.

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Flavone skeleton

The basic structure of flavonoids can be modified in various ways, leading to different subclasses such as flavones, flavonols, isoflavones, and others.

Subclasses

Flavones

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Flavone structure

Flavones are characterized by a double bond between C2 and C3 and a ketone at C4. They are commonly found in parsley, celery, and chamomile.

Flavonols

Flavonol structure

Flavonols have a hydroxyl group at C3 in addition to the structure of flavones. They are abundant in onions, kale, and broccoli.

Isoflavones

Isoflavone structure

Isoflavones have a different arrangement of the B ring, which is attached at C3 of the C ring. They are primarily found in soybeans and other legumes.

Flavanones

Flavanones are similar to flavones but lack the double bond between C2 and C3. They are found in citrus fruits like oranges and grapefruits.

Anthocyanins

Anthocyanins are pigments responsible for the red, purple, and blue colors in many fruits and vegetables. They are water-soluble and found in berries, grapes, and red cabbage.

Chalcones

Chalcones are open-chain flavonoids that serve as precursors to other flavonoid classes. They are found in licorice and hops.

Biological Functions

Flavonoids are known for their antioxidant properties, which help in neutralizing free radicals and reducing oxidative stress. They also exhibit anti-inflammatory, antiviral, and anticancer activities.

Biochemical pathways of flavonoids

Flavonoids can modulate cell signaling pathways and influence the activity of various enzymes. They are also involved in the regulation of gene expression.

Dietary Sources

Flavonoids are widely distributed in the plant kingdom and are present in a variety of foods and beverages. Common sources include:

• Fruits: apples, berries, grapes
• Vegetables: onions, kale, broccoli
• Beverages: tea, red wine, citrus juices

Related Pages

• Polyphenol
• Antioxidant
• Plant secondary metabolism