Hydroxycinnamic acids (HCA) are one of the types of complex compounds. They have a multifaceted effect on the human body. Thanks to these substances isolated from plants, valuable drugs with a wide spectrum of action 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 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, m altose) and aglycones (steroids, aldehydes, terpenes, and others). The last type of connection is the mosta valuable part of phytopreparations based on glycosides, since the main therapeutic effect depends on them.
What are phenols?
The chemical structure of phenols includes hydroxyl groups OH connected to carbon atoms in the aromatic ring. The phenolic group is found in tyrosine, an amino acid that is present in the protein molecules of all living organisms, and also plays a huge role in the production and activation of enzymes. Animals mainly receive this type of substances with food. Phenols are produced by plants to protect against infectious diseases and damage by insect pests.
In the 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 obvious 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, a molecule of carbon dioxide is cleaved off and phenol is formed.
Pharmacological properties
Phenols have the following pronounced pharmacological effects:
- anti-inflammatory;
- neuroprotective;
- antiseptic;
- antispasmodic;
- immunostimulatory;
- antioxidant;
- antiviral.
One of the most important functions of these substances is participation in the oxidativerecovery processes, as well as in the mechanism of neutralization of active oxygen (antioxidant action).
Typical Representatives
HCA are derivatives of caffeic acid. The most prominent representatives of this class of substances are the following acids:
- coumaric (n-hydroxycinnamon);
- chlorogenic (including its isomers);
- coffee;
- kaftar;
- ferulic, feruloylquinic and its isomers;
- chicory;
- sinapovaya.
The structural formulas of some of them are shown in the figure below.
Prevalence
Hydroxycinnamic acids are highest in the following plant parts:
- tobacco leaves;
- immature coffee beans (green);
- apples;
- green parts of oilseeds;
- blueberry leaves.
According to 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;
- transferula - perennial cereal (bluegrass) herbs, haze family (beets, spinach, quinoa and other plants);
- coumaric, coffee, ferulic, synapic - echinacea, hawthorn fruit, burdock root, rhubarb, mountain arnica, chamomile;
- complex from a coffee shop,ferulic and coumaric acids - red and black currants and other types of berries.
The most widespread of hydroxycinnamic acids in higher plants is 3,4-dioxycinnamic acid (the second name is coffee), which often forms more complex molecules with quinic, tartaric and shikimic acids, cellulose, proteins, lignin.
The importance of phenols in the plant kingdom
These substances have a dual effect on the processes of biosynthesis in plants. They have the ability to form spatial isomers that differ greatly in physiological effects. Cis-isomers, in which substituents are located on one side of the plane of the aromatic ring, enhance plant growth, and trans-isomers, on the contrary.
Hydroxycinnamic acids play an important role in pest and environmental resistance. They affect the biosynthesis of flavonoid glycosides. So, with a decrease in temperature and a decrease in illumination, an active production of anthocyanin begins, which leads to reddening of the leaves. Thus, plants adapt to stressful conditions. In the damaged parts, there is also a decrease in phenolic and steroid substances. These compounds are involved in the process of photosynthesis and respiration of plants, in the metabolism of carbohydrates and lipids.
Medical applications
Hydroxycinnamic acids are promising compounds for the development of effective drugs. In this regard, the pharmaceutical industry has maturedthe need to create new methods for the analysis and extraction of these substances from plant materials.
It has been established that HCC can have the following effects on the human body:
- ferulic, caffeic, 1,4-dicofeylquinic acid - choleretic effect, increased kidney function, stimulating the liver to neutralize toxins;
- coumaric acid - tuberculostatic effect (suppression of tuberculin bacillus reproduction);
- coffee, chicory acid – strong antimicrobial effect;
- ferulic acid - weakening the harmful effects of ionizing radiation; antihypoxic, antioxidant effect, decrease in the formation of pro-inflammatory factors, acceleration of DNA synthesis, antiarrhythmic effect.
Experiments on animals have shown that ferulic and caffeic acids significantly increase blood flow in the brain and reduce the risk of swelling of the tissues of this organ in ischemic damage.
