Properties and applications of phenolic acids

Właściwości i zastosowanie kwasów fenolowych

Phenolic acids (phenol acids) are a group of compounds that are widely used in the cosmetic and pharmaceutical industries. Thanks to their diverse structure and biological action, they are valued remedies in the treatment and prevention of many diseases. What are the properties and uses of phenolic acids?

Phenolic acids – what are they?

Phenolic acids, also known as phenol acids, are phenol derivatives whose structure contains a hydroxyl group and a carboxyl group. Next to flavonoids, they are the second most important group of natural biologically active substances found in plants. They are characterized by great structural diversity – they can be both simple compounds as well as large and very complex molecules.

The most common phenolic acids comprise derivatives of hydroxybenzoic acid (including gallic acid, protocatechuic acid, vanillic acid, syringic acid) as well as derivatives of hydroxycinnamic acid (including caffeic acid, ferulic acid, coumaric acid, rosmarinic acid). In plant ingredients, they occur primarily in the form of combinations – glycosides and esters.

Examples of the directions of action of phenolic acids

Thanks to the presence of numerous hydroxyl groups, phenolic acids are primarily associated with antioxidant activity – they have the ability to scavenge/recapture free radicals and reactive forms of oxygen, and to modulate the expression of antioxidant enzymes. However, these are not the only health-promoting properties of phenol acids. They can also show:

  • cholepoietic and cholagogue action (thanks to caffeic acid, ferulic acid, chlorogenic acid, syringic acid, 3,4-dimethoxycinnamic acid);
  • antimicrobial action (thanks to caffeic acid, vanillic acid, p-coumaric acid, and p-hydroxybenzoic acid);
  • antiseptic, astringent and antiperspirant action (gallic acid);
  • hemostatic action (ellagic acid);

Research also indicates the potential of certain plant extracts rich in complex phenolic acid molecules in the prevention of atherosclerosis, diabetes, liver damage or certain cancers. Thanks to their multidirectional action, these compounds are the main active substances of some plant extracts used in the pharmaceutical industry and natural medicine.

Importance of phenolic acids in cosmetics and nutrition

Phenolic acids are also used in the cosmetic industry. Thanks to their strong antioxidant action, as well as their photoprotective, antibacterial and anti-inflammatory properties, they also find use in anti-acne and anti-aging products, as well as in cosmetics targeting skin discoloration. Furthermore, some phenolic acids (such as the somewhat controversial parabens – esters of 4-hydroxybenzoic acid) are used as preservatives.

The health-promoting properties of phenolic acids and their wide use in food products (spices, cereals, vegetables, fruits, teas) are also appreciated in the foodstuffs industry. They are the primary compounds that endow numerous spices with their digestion-enhancing properties. Phenolic acids and their derivatives are used as fortifying ingredients, precursors of substances that form or improve flavor and aroma, and as biologically active compounds that improve quality and nutritional value of food.

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