Natural phenols

Natural phenols are a class of chemical compounds consisting of a phenol unit with a structure that includes a hydroxyl group (-OH) attached to an aromatic hydrocarbon group. They are widely distributed in the plant kingdom and are often responsible for the color, flavor, and antioxidant properties of fruits, vegetables, and other plant-based foods. Natural phenols play a crucial role in plant defense against herbivores and pathogens, and they have been extensively studied for their potential health benefits in humans, including anti-inflammatory, anti-carcinogenic, and cardio-protective effects.

Classification

Natural phenols can be classified into several categories based on their chemical structure:

• Flavonoids, which include flavones, flavonols, flavanones, isoflavones, and anthocyanins.
• Phenolic acids, divided into hydroxybenzoic and hydroxycinnamic acids.
• Stilbenes, compounds that include resveratrol.
• Lignans, which are formed by the dimerization of phenolic compounds.
• Tannins, which are polyphenolic compounds that can bind to and precipitate proteins.

Biosynthesis

The biosynthesis of natural phenols in plants involves the shikimic acid pathway and the phenylpropanoid pathway. These metabolic pathways convert simple carbohydrate precursors into phenolic compounds. The key enzyme in the phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), catalyzes the first step in the conversion of phenylalanine to cinnamic acid, which is a precursor to many other phenolic compounds.

Functions in Plants

In plants, natural phenols serve several functions:

• They act as antioxidants, neutralizing harmful free radicals.
• They contribute to the structural integrity of plants by cross-linking with other molecular components.
• They play a role in plant pigmentation, attracting pollinators and deterring herbivores.
• They have antimicrobial properties, protecting plants against pathogens.

Health Benefits

Numerous studies have suggested that diets rich in natural phenols are associated with a reduced risk of chronic diseases such as heart disease, diabetes, and cancer. The antioxidant activity of phenols can help reduce oxidative stress, which is linked to the pathogenesis of these diseases. However, the bioavailability and metabolism of dietary phenols can vary greatly, influencing their health effects.

Research and Applications

Research on natural phenols continues to explore their potential applications in food preservation, pharmaceuticals, and cosmetics. Their antioxidant and antimicrobial properties make them attractive as natural additives to extend the shelf life of food products and as active ingredients in skincare products.

See Also

• Antioxidant
• Polyphenol
• Phytochemical
• Nutraceutical