Hydroxycinnamic acids (HCCs) are a type of complex compounds. They have a multilateral effect on the human body. Thanks to these substances released from plants, valuable broad-spectrum drugs have been obtained. Despite their active use in medicine, the antioxidant mechanism of phenolic compounds is not yet fully understood. This is due to the presence of a large number of their derivatives and the complexity of the natural complexes in which they are included.
General information
Hydroxycinnamic acids are one of the types of biologically active substances that are most common in the plant world. They belong to phenols and are found in almost all higher plants.
These acids in the plant world are found both in free form and in various combinations, as well as in the composition of esters and glycosides. Glycosides are ether-like substances consisting of 2 components - saccharides (glucose, fructose, maltose) and aglycones (steroids, aldehydes, terpenes and others). The latter type of compounds is the most valuable part of herbal preparations based on glycosides, since the main therapeutic effect depends on them.
What are phenols?
The chemical structure of phenols includes hydroxyl groups OH linked to carbon atoms in the aromatic ring. The phenolic group is contained in tyrosine, an amino acid that is found in the protein molecules of all living organisms, and also plays a huge role in the production and activation of enzymes. Animals mostly get this type of substance with food. Phenols are produced by plants to protect against infectious diseases and damage by insect pests.
In its free form, phenol used in industry is a toxic environmental pollutant. However, phenolic compounds, and especially polyphenols, have valuable pharmacological properties. The simplest and most illustrative example is salicylic acid. Its derivative is known in medicine as aspirin. For the first time, salicylic acid was isolated from willow bark, and when it is heated, the carbon dioxide molecule is split off and phenol is formed.
Pharmacological properties
Phenols have the following pronounced pharmacological effects:
- anti-inflammatory;
- neuroprotective;
- antiseptic;
- antispasmodic;
- immunostimulating;
- antioxidant;
- antiviral.
One of the most important functions of these substances is participation in oxidation-reduction processes, as well as in the mechanism of neutralization of active oxygen (antioxidant effect).
Typical representatives
GKK are derivatives of caffeic acid. The most prominent representatives of this class of substances are the following acids:
- coumaric (n-hydroxycinnamic);
- chlorogenic (including its isomers);
- Coffee
- kaftar;
- ferulic, feruloylquinine and its isomers;
- chicory;
- synapic.
Structural formulas of some of them are shown in the figure below.
Prevalence
The largest amount of hydroxycinnamic acids was found in the following parts of plants:
- leaves of ordinary tobacco;
- unripe coffee beans (green);
- apples
- green parts of oilseeds;
- blueberry leaves.
By the type of acids contained in a significant amount, the following medicinal and edible plants can be distinguished:
- chlorogenic - dandelion;
- kaftar, chicory - grapes, echinacea purpurea, chicory;
- transferulova - perennial cereal (bluegrass) herbs, the family of cinnamon (beets, spinach, quinoa and other plants);
- Kumar, coffee, ferulic, synapic - echinacea, hawthorn fruit, burdock root, rhubarb, mountain arnica, chamomile;
- a complex of coffee, ferulic and coumaric acids - red and black currants and other types of berries.
The highest distribution of hydroxycinnamic acids in higher plants was obtained with 3,4-dioxicoric acid (the second name is coffee), which often forms more complex molecules with quinic, tartaric and shikimic acids, cellulose, proteins, lignin.
The value of phenols in the plant world
These substances have a double effect on the biosynthesis in plants. They have the ability to form spatial isomers, which differ greatly in physiological effects. Cis isomers, in which the substituents are located on one side of the plane of the aromatic ring, enhance plant growth, while trans isomers, on the contrary.
Hydroxycinnamic acids play an important role in resistance to pests and adverse environmental factors. They affect the biosynthesis of flavonoid glycosides. So, with a decrease in temperature and a decrease in illumination, the active production of anthocyanin begins, which leads to reddening of the leaves. Thus, plants adapt to stressful conditions. In the damaged parts, a decrease in phenolic and steroid substances is also noted. These compounds are involved in the process of photosynthesis and respiration of plants, in the metabolism of carbohydrates and lipids.
Medical use
Hydroxycinnamic acids are promising compounds for the development of effective drugs. In this regard, in the pharmaceutical industry there is a need to create new methods for the analysis and extraction of these substances from plant materials.
It was established that GCC can have the following effects on the human body:
- ferulic, caffeic, 1,4-dicofeylquinic acid - choleretic effect, increased renal function, stimulation of the liver in relation to the neutralization of toxins;
- coumaric acid - tuberculostatic effect (suppression of the multiplication of tuberculin bacillus);
- caffeic, chicory acid - a strong antimicrobial effect;
- ferulic acid - weakening the harmful effects of ionizing radiation; antihypoxic, antioxidant effect, reduced formation of pro-inflammatory factors, accelerated DNA synthesis, antiarrhythmic effect.
Experiments on animals showed that ferulic and caffeic acids significantly increase blood flow in the brain and reduce the risk of tissue edema of this organ with ischemic damage.