Flavonoid biosynthesis

Flavonoid biosynthesis is a biological process that involves the production of flavonoids, a diverse group of phytonutrients (plant chemicals) found in almost all fruits and vegetables. Flavonoids are known for their beneficial effects on health, including their potential antioxidant, anti-inflammatory, anti-allergic, and anti-cancer properties.

Overview

Flavonoid biosynthesis is a subset of the larger phenylpropanoid pathway, which is responsible for the synthesis of a wide range of secondary metabolites in plants. The process begins with the amino acid phenylalanine, which is converted into cinnamic acid through the action of the enzyme phenylalanine ammonia-lyase (PAL). Cinnamic acid is then converted into p-coumaric acid by the enzyme cinnamate 4-hydroxylase (C4H).

Flavonoid Classes

The p-coumaric acid is then used as a substrate for the synthesis of various classes of flavonoids, including flavones, flavonols, flavanones, anthocyanins, and isoflavones. Each class of flavonoids is synthesized through a specific branch of the flavonoid biosynthesis pathway, involving different sets of enzymes.

Enzymes Involved

Key enzymes involved in flavonoid biosynthesis include chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), flavonol synthase (FLS), and anthocyanidin synthase (ANS). These enzymes catalyze the conversion of p-coumaric acid into the various classes of flavonoids.

Regulation

The flavonoid biosynthesis pathway is regulated at multiple levels, including transcriptional, post-transcriptional, and post-translational regulation. Key regulatory factors include MYB transcription factors, bHLH transcription factors, and WD40 repeat proteins, which form a complex known as the MBW complex that regulates the expression of genes involved in flavonoid biosynthesis.

Health Benefits

Flavonoids synthesized through this pathway have been associated with a range of health benefits, including protection against cardiovascular disease, cancer, and neurodegenerative diseases. They also play important roles in plant defense against pathogens and in plant-pollinator interactions.

See Also

• Phenylpropanoid pathway
• Secondary metabolites
• Phenylalanine ammonia-lyase
• Chalcone synthase
• Flavonoids