Pharmacological Properties of Creeping Thyme

Many studies have been carried out on the chemical composition and yield of essential oils from plants belonging to the genus Thyme, including the Thyme sp. It is believed that the chemical composition and yield of creeping thyme essential oil depend on the geographic region, plant development stage, harvest season, habitat and climatic conditions.

Thus, its content fluctuates from 0.1 to 0.8% and is occasionally fixed up to 1.2%. Analysis of the yield of essential oil of thyme in Estonia, its content is from 0.6 to 4.4 ml/kg. Only in one locality, it was 3 ml/kg, which corresponds to the standards of the European Pharmacopoeia. Similarly, the content of wild thyme essential oils from 5 regions of Armenia ranged from 4.5 to 7.4 ml/kg. Wild thyme samples from Pakistan achieved a yield of 0.48%, or 29 g/kg. In Serbia, the yield of essential oil from samples of this species growing in the mountains was 3 ml/kg (~ 0.3%) and 4.1 g/kg (~ 0.1%).

Over the past two decades, more and more studies have studied the chemical composition of Thyme Creeping essential oil, a summary table of the chemical composition of thyme is given below. It has been established that plant species of the thyme genus are characterized by chemical polymorphism, which means the existence of several chemotypes (geraniol, germacrene D, citral, linalool, (E)-caryophyllene, α-terpinyl acetate, carvacrol and thymol). According to PDR for Herbal Medicines, the main component of thyme essential oil is carvacrol, and it also contains borneol, isobutyl acetate, caryophyllene, 1,8-cineol, citral, citronellal, citronellol, paracymene, geraniol. , linalool, α-pinene, γ-terpinene, α-terpineol, terpinyl acetate and thymol in relatively high concentrations. Carvacrol and thymol are isomers, belonging to the group of monoterpene phenols with powerful antiseptic properties. They are very quickly absorbed after application and are rapidly metabolized since they do not undergo the first phase of biotransformation; instead, they are directly conjugated with sulfuric and glucuronic acids. They are excreted in the urine within 24 hours, mainly in the form of conjugates, and to a lesser extent unchanged.

According to the European Pharmacopoeia, creeping thyme herb should contain up to 1.2% essential oil, in which the total content of carvacrol and thymol is 40% or higher. In addition to the essential oil, thyme also contains flavonoids, phenol carboxylic acids and their derivatives, triterpenes and tannins. In addition to carvacrol and thymol, γ-terpinene and p-cymene were found in the composition. However, studies of the composition and concentration of compounds in the essential oil of thyme repens in different regions of the world revealed significant differences. For example, the content of essential oil in the populations of wild thyme in the Altai Mountains is 0.5-1%, but its chemical composition varies significantly depending on the height. In the village of Kolyvani, Kurya region (150 m above sea level), the main components of the oil are β-myrcene (4.0%), p-cymol (3.8%), 1.8-cineol (14.0%), cis -β-terpineol (8.2%), camphor (4.0%), and trans-nerolidol (29.8%), while in the same region, but also in the villages of Mendur-Sokkon (500-750 m above sea level) were identified as the main components: α-cymol (14.5%), 1,8-cineole (5.6%), γ-terpinene (17.2%) and carvacrol (29.6%). The essential oil from both areas contained less than 2% thymol.

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In addition, the presence of thymol and carvacrol in the essential oil of thyme, which grows wild in Lithuania, has not been established at all. Although thymol and carvacrol are noted in the literature as the dominant components, they are also not the main components of wild thyme essential oil in Estonia.

Differences in the chemical composition of essential oils have been established elsewhere: the main components of the essential oils of wild thyme from the mountain. Kopaonik (Serbia) are trans-caryophyllene (27.7%), γ-muurolene (10.5%) and α-humulene (7.5%), and already in the southern part of Serbia, the dominant components of the essential oil are trans-nerolidol ( 24.2%), germacrene D (16.0%), thymol (7.3%), δ-cadinene (3.7%) and β-bisabolene (3.3%). The essential oil of Thyme of Pakistani origin contains mainly thymol (53.3%) and carvacrol (10.4%).

The list of where thyme studies were carried out does not end here, and oil sucking differs significantly everywhere.

Due to the large variability in the content of the same components in thyme, the composition of the essential oil cannot be used as a reliable chemotaxonomic marker. However, its composition is of great importance when it comes to medical and cosmetic applications, as well as in industries where essential oils are used as raw materials, such as the food industry.

The pleasant aroma of wild thyme essential oil is mainly due to the phenolic monoterpenoids thymol and carvacrol, which inhibit lipid peroxidation and show powerful antimicrobial properties against various types of microorganisms. Numerous compounds in essential oils are natural antioxidants that act as a metabolic response to the endogenous production of free radicals and other types of oxidants.

Antioxidant Activity

The number of published works devoted to the study of the antioxidant activity thymus serpyllum, is relatively small, but some have evaluated it and compared it with other species. For example, some scientists noted that T. serpyllum essential oils showed better radical scavenging activity (IC50: 34.8 mg/mL) than Thyme Dubiansky and Thyme ovoid essential oils (IC50: 42.9 mg/mL). In terms of inhibition of linoleic acid peroxidation, thyme essential oil again showed better antioxidant activity than other species. They also found that thymol, the main component of the essential oil of most species, showed better antioxidant activity than the whole essential oil, while carvacrol, the main component of the essential oil that is made from creeping thyme, showed weaker antioxidant activity than the oil itself.

The antioxidant capacity of wild thyme essential oil, in terms of its ability to neutralize free radicals DPPH (1,1-diphenyl-2-picrylhydrazyl), i.e. the ability of essential oil components to donate hydrogen atoms and convert DPPH to its reduced form DPPH-H, has been proven to be superior. existing synthetic antioxidants such as hydroxyanisole (BHA) and in particular hydroxytoluene (BHT).

A study on the antioxidant capacity of the essential oil of T. serpyllum, native to Croatia, showed that it showed a lower ability to neutralize DPPH radicals than BHA, BHT, tocopherol, ascorbic acid, and thyme essential oil.

Estonian scientists have proven the pronounced antioxidant activity of wild thyme aqueous extracts containing phenols and flavonoids in terms of their high antioxidant capacity and potential antihypertensive effect in spontaneously hypertensive and normotensive rats. They showed that rapid injections of this extract (100 mg/kg body weight) reduced systolic and diastolic blood pressure and total peripheral resistance in the first case, without affecting these parameters in the second. The predominant phenolic compounds were rosmarinic and caffeic acids.

Causes of Antioxidant Activity

The antioxidant activity of the tested essential oils justifies the traditional use of wild thyme. The antioxidant potential is developed, to a greater extent due to the phenolic components of the essential oil. The chemoprotective effectiveness of the oil against disorders caused by oxidative processes in the body is mainly due to its ability to scavenge free radicals and the chelating properties of the herb.

However, the antioxidant activity of thyme essential oil is not due to the mere presence of certain dominant components, but results from the synergy of a larger number of components, including some that are only present in small amounts (trans-nerolidol, germakrene D, δ-cadinene, and β-bisabolene.

Antimicrobial Activity

Many scientists attribute the antimicrobial activity of Thyme species to the high concentration of carvacrol in its essential oil. This organic compound belongs to the class of monoterpenes and has biocidal properties, which leads to the disruption of the bacterial membrane. Moreover, it can cross cell membranes, reaching the inside of the cell and interacting with intracellular sites vital for bacteria. The biological precursor of carvacrol and another important component of plant extracts, p-cymol, has very weak antibacterial properties, but most likely it acts in synergy with carvacrol, expanding the membrane and causing its destabilization.

Antimicrobial analysis showed that alcoholic and aqueous extracts of creeping thyme showed inhibitory activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa test organisms. A comparative analysis of the effect of essential oils of oregano herb, common thyme and creeping thyme on the growth of bacteria Proteus mirabilis, Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus and Enterococcus faecalis showed that oregano essential oil demonstrated the highest antimicrobial activity while creeping thyme essential oil had the least inhibitory effect on the growth of these microorganisms.

There is an extensive study that proves that thyme has a bactericidal effect on a huge number of bacteria such as E. coli, salmonella, typhoid fever, cholera, and Staphylococcus aureus. This study found that the antimicrobial activity of wild thyme essential oil may be related to the effect of its phenolic compounds on growth suppression and mycotoxin production.

The inhibitory activity of essential oils depends on the conditions and duration of incubation, so a greater inhibitory effect is achieved due to the synergistic and cumulative effect of other components of the essential oil. Some scientists have found a positive correlation between the antimicrobial activity of essential oils from different thyme species, indicating that the activity can be attributed to the phenolic compound thymol, since it is present in high amounts in these oils. This confirms earlier findings that thymol is a good antimicrobial agent.

However, although thyme essential oil had the lowest thymol content, it showed the highest antimicrobial activity, confirming the importance of the synergistic effect of the other components.

Antitumor and Cytotoxic Activity

One of the main components of thyme essential oil, carvacrol has an important cytotoxic effect on tumor cells. Experiments confirmed that carvacrol exhibits significant cytotoxic activity against P388 murine leukemia and Hep-2. However, timonol, which is also one of the main components of essential oils obtained from most types of thyme, can be involved in stimulating the active proliferation of pulp fibroblasts. Comparing the antitumor activity of the essential oils of the most common types of thyme in relation to the growth of four human tumor cells, it was proved that the essential oil of creeping thyme exhibits the highest antitumor activity.

In 2014, a serious study was conducted in which, out of 21 isolated compounds, including carvacrol, thymol and thymoquinone, which are the main components of the extract of creeping thyme essential oil, it was proved that this hexane extract of this is cytotoxic for 6 types of cancer cells (MDA-MB-231, MCF-7, HepG2, HCT-116, PC3 and A549). It showed the best antitumor activity with HepG2 (liver carcinomas), followed by HCT-116 (colon cancer), MCF-7 and MDA-MB-231 (breast cancer), PC3. (prostate cancer) and A549 (lung carcinoma).

Conclusions

creeping thyme has a centuries-old tradition of use in ethnomedicine as an aromatic, analgesic, antiseptic, diaphoretic, anthelmintic, expectorant, diuretic, antispasmodic, carminative, sedative, stimulant and tonic. The aerial part of the plant has traditionally been most commonly used in the treatment of diseases and problems related to the respiratory, digestive and genitourinary tracts. However, the use of essential oil as one of the important products of this type of plant origin in modern medicine is growing due to its pharmacological properties. The chemical composition and yield of essential oil are considered to be influenced by geographic region, plant development stage, harvest season, habitat and climatic conditions. Therefore, its composition is of great importance,

New studies have revealed the pronounced antioxidant and antibacterial properties of the essential oil, based on the synergistic and cumulative action of its components. At the same time, the essential oils of creeping thyme showed better overall antioxidant activity compared to other types of thyme due to the better antioxidant activity of its main component in the essential oil, thymol.

Future studies should try to find out to what extent thymol or carvacrol are individually responsible for the cytotoxicity and to what extent this is the result of the combination with other constituents of the essential oil. Regarding its antitumor and cytotoxic activity, we believe that further research is needed on the effects of thyme extracts, aimed at improving the cytotoxic effect of this herb on oncology, in particular on liver cancer, on the basis of which new drugs can be created.

Due to its pharmacological characteristics, wild thyme essential oil represents an important natural resource for the pharmaceutical industry. In addition, it is a source of natural antioxidants, nutritional supplements, or functional food components in the food industry.

For the food and tea industry, thyme will also remain one of the most valuable products, but its taste will always be different, since its composition, strongly depends on the place of its collection.

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