Phenylpropanoid

Phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. They play key roles in plant physiology, including defense against pathogens and UV radiation, and are responsible for the color and aroma of many fruits and flowers.

Biosynthesis

The biosynthesis of phenylpropanoids begins with the amino acids phenylalanine and tyrosine. These are converted into cinnamic acid and p-coumaric acid, respectively, by the action of the enzyme phenylalanine ammonia-lyase (PAL). These acids are then converted into their corresponding CoA esters by 4-coumarate:CoA ligase (4CL). The CoA esters are the precursors for the synthesis of a wide variety of phenylpropanoids.

Types of Phenylpropanoids

Phenylpropanoids can be classified into several major groups based on their chemical structures:

• Flavonoids: These are the most diverse group of phenylpropanoids, with over 6,000 known structures. They include anthocyanins, which give color to many fruits and flowers, and flavonols, which are important antioxidants.

• Lignans and Neolignans: These are derived from the dimerization of two phenylpropanoid units. They have a wide range of biological activities, including anti-cancer, anti-viral, and anti-inflammatory effects.

• Coumarins: These are derived from the cyclization of cinnamic acid derivatives. They have a wide range of biological activities, including anti-coagulant, anti-cancer, and anti-inflammatory effects.

• Phenolic acids: These include hydroxycinnamic acids and their derivatives, which are important antioxidants.

• Tannins: These are high molecular weight phenylpropanoids that are known for their ability to precipitate proteins.

Role in Plants

Phenylpropanoids play key roles in plant physiology. They are involved in the defense against pathogens and UV radiation, and contribute to the color and aroma of many fruits and flowers. They also play a role in plant growth and development, and in the response to environmental stress.

Health Benefits

Many phenylpropanoids have been shown to have health benefits. For example, flavonoids have antioxidant, anti-inflammatory, and anti-cancer properties. Lignans have been shown to have anti-cancer and heart health benefits. Coumarins have anti-coagulant and anti-cancer effects.