1. Introduction
Teucrium polium L. (Lamiaceae) is found in Europe, North Africa, and Asia. The following medicinal claims are attributed to it: treatment of inflammatory diseases, gastrointestinal disorders, diabetes, rheumatism, indigestion, abdominal pain, colds, and urogenital diseases [
1,
2].
Chemical studies conducted on
T. polium oil have identified compounds belonging to the following classes: sesquiterpenes (α- and τ-cadinols), (E)-β-caryophyllene and its oxide forms, neoclerodane diterpenoids, and monoterpenes. The proportions of these chemical constituents vary according to the collection site [
2,
3], and possibly factors such as the time of plant collection, the part used for oil extraction, among others.
The following compounds have already been identified in
T. polium oil and listed as major components in at least one study: β-caryophyllene [
4,
5,
6,
7,
8], germacrene D [
5], limonene [
5,
9], p-cymene, 2,4-di-tert-butylphenol [
9], α-pinene [
6,
10], α-thujene, terpinen-4-ol [
10], ledol oxide (II), linalyl acetate, β-eudesmol [
11], α-cardinol, caryophyllene oxide, epi-α-muurolol, cadalene, longiverbenone, carvacrol [
6], 11-acetoxyeudesman-4-α-ol, α-bisabolol [
7], β-pinene, α-muurolol, α-cadinol, α-muurolol, α-cardinol, α-cardinol [
8], caryophyllene, γ-muurolene, cadinol, α-gurjunene, rosifoliol, 3-carene, γ-muurolene, α-phellandrene [
12], carvacrol, torreyol [
13], lycopersen, dodecane, 1,5-dimethyl decahydro naphthalene, tridecane [
14], myrcene, menthofuran, ocimene, pulegone [
15], β-eudesmol [
16], β-pinene, limonene, α-phellandrene, linalool, terpinen-4-ol, γ- and δ-cadinenes, cedrol, cedrenol, guaiol. In summary, more than 80 molecules have been identified in
T. polium oils [
17].
The essential oil of
T. polium, with α-pinene, linalool, and caryophyllene oxide as its major components, demonstrated activity against Gram-positive bacteria (Staphylococcus
aureus and Staphylococcus
epidermidis) and Gram-negative bacteria [
18]. Essential oils obtained from subspecies also showed activity against Acinetobacter baumannii and Staphylococcus
aureus [
18]
T. polium is known for its antidiabetic effects through various mechanisms, such as increasing insulin secretion and levels, inducing the regeneration of pancreatic β-cells, reducing oxidative damage, promoting glucose uptake in muscle tissues, inhibiting α-amylase activity, and enhancing GLUT-4 translocation [
2]. The antidiabetic effect was also observed in male Wistar rats induced with diabetes by STZ injection (60 mg/kg, i.p.) and treated with Teucrium
polium extract (100, 200, and 400 mg/kg) via daily gavage for 6 weeks. The results showed that the group treated with the extract exhibited reductions in glucose, triglycerides, and serum cholesterol, in addition to attenuating oxidative stress in aortic and cardiac tissues [
19]
Due to its antimicrobial and antidiabetic potential, as well as the variation in chemical composition, it is crucial to identify the possible pharmacological markers of the species and their potential mechanisms of action, toxicity, and other aspects. In this context, in silico studies prove to be an important tool for predicting molecular structures and potential mechanisms of action of such compounds, as this type of study allows for the computational simulation of compounds from databases to predict various parameters such as physicochemical, pharmacokinetic, and toxicological properties [
20]
This work is based on the analysis of the essential oil (EO) extracted from T. polium, with the major molecules selected for investigations related to physicochemical, pharmacokinetic, toxicological predictions, biological activities, and potential targets of action. Subsequently, molecular modeling of the selected compounds was performed.
3. Discussion
The essential oil obtained from
T. polium was subjected to GC-MS analysis, revealing the major constituents as Fenchone (31.25%), 3-Carene (15.77%), Limonene oxide, cis- (9.77%), and Myrcene (9.15%). When comparing these results to other studies, it is observed that other metabolites such as β-caryophyllene [
3], limonene [
10], ledene oxide II [
11], α-cardinol [
21], carvacrol [
6], and β-pinene were the major constituents [
22]. Studies on the environmental impact on the composition of T. polium oil are still scarce; however, it is known that factors such as altitude, water availability, macro and micronutrients in the soil, relative air temperature, and soil pH directly affect the chemical profile of plants [
23]
Myrcene was reported in previous studies as the major component of the essential oil of
T. polium [
24,
25,
26,
27,
28]. Myrcene was found to be the major compound in our study, too. However, the main constituents of the essential oils of the aerial parts were oxygenated monoterpenes and monoterpene hydrocarbons, which were in good agreement with the previous reports [
24,
29,
30,
31,
32].
On the other hand, Germacrene D was detected as major compound in the essential oils of
T. polium samples from different regions [
28,
30,
33,
34,
35]. Similarly, Germacrene D was detected as the main compound in our study. While Fenchone, 3-Carene and Limonene oxide, cis- were found to be the main compounds in our study, they were minor or absent in essential oils of Teucrium [
10,
33,
36]. Therefore, environmental factors, the plant part used in the extraction process, and the collection time can influence the chemical composition of the essential oil.
All selected molecules adhered to Lipinski’s rule and appear to exhibit high intestinal absorption. However, only molecules 2, 4, 5, 6, 8-14 distribute into the CNS. Adhering to Lipinski’s rule is crucial for drug candidates as it indicates that the drug will be well absorbed in the gastrointestinal tract and adequately distributed throughout the body, allowing for oral administration [
37,
38,
39]
All molecules seem to be metabolized by CYP3A4, but they inhibit CYP and sometimes more than one CYP. Molecules that inhibit CYP can interfere with the metabolism of other drugs, necessitating dose adjustments. Another evaluated parameter was toxicity, with 8, 10, 11, 12, 13 not being mutagenic, while 7, 9, and 14 were not carcinogenic. Unfortunately, no compound was devoid of toxicity; however, all compounds had an LD50 > 1400 mg/kg. Therefore, repeated-dose toxicity studies, in vivo genotoxicity, and in vivo carcinogenicity studies are important for understanding toxic effects and potential mechanisms.
After analyzing the pharmacokinetic studies and toxicities, molecules without carcinogenic potential were selected (7 - Myrtenal; 9 - Myrtenol; 14 - Verbenol). Myrtenal exhibited antihyperglycemic effects, reducing blood glucose levels and hemoglobin A1C, and aiding in weight recovery [
40].Derivatives of Myrtenal have shown activity against various cell lines[
40,
41,
42,
43]
Other activities related to Myrtenal derivatives include: anxiolytic [
44]; antiviral [
44]; antifungal [
45]; and analgesic [
46]. Another selected molecule was Myrtenol, which inhibits biofilm formation and virulence in drug-resistant Acinetobacter
baumannii. Myrtenol improved the susceptibility of BP-AB to the antibiotic’s amikacin, piperacillin/tazobactam, cefoperazone/sulbactam, and ceftazidime. This molecule regulates the expression of biofilm-associated genes in the BP-AB strain, and qPCR analysis reduced the expression levels of bfmR, bap, csuA/B, and ompA in groups D, E, and F compared to groups A, B, and C. A non-significant reduction in bfmR, bap, csuA/B, and ompA levels was also found in groups A, B, and C. The genes bfmR, bap, csuA/B, and ompA are key regulators of the transition from biofilm formation to maturation in the BP-AB strain [
47]. Myrtenol protects against myocardial ischemia-reperfusion injury through antioxidant and anti-apoptotic mechanisms [
48]Verbenol exhibited anti-ischemic and anti-inflammatory properties [
49]
To identify the potential target involved in the biological activity of Myrtenal, Myrtenol, and Verbenol, prediction studies were conducted, suggesting that all three bind to Nuclear Factor NF-kappa-B, a family of transcription factors involved in inflammation, immunity, cell proliferation, differentiation, and survival [
50]In recent years, the presence and activation of Nuclear Factor NF-kappa-B in different types of cancer has been highlighted, as well as the importance of developing inhibitors that act directly on Nuclear Factor NF-kappa-B [
51]. The possibility of therapeutically targeting this factor allows for a significant advance in tumor destruction during treatment, thereby enhancing antitumor activity[
52]
It is worth highlighting the medicinal importance of Teucrium species, which have been used since ancient times in the Mediterranean region for treating gastrointestinal issues and maintaining healthy endocrine gland function, as well as for treating malaria and severe dermatological disorders. However, studies evaluating their activity are scarce. Evaluations of the essential oils and ethanolic extracts of Teucrium
polium and Teucrium
parviflorum have shown that the extracts exhibited antioxidant, anti-butyrylcholinesterase, anti-tyrosinase, and anti-urease activities through in vitro and in silico assays[
53]It is noteworthy that T.
polium oil demonstrated moderate antioxidant potential [
54]
An in vivo study with the ethanolic extract of T.
polium demonstrated the plant’s anti-inflammatory potential at concentrations of 50 mg/kg, 100 mg/kg, and 150 mg/kg, leading to a reduction in paw edema in rats [
55]. When correlating this result with prediction studies, the regulation of NF-κB activity is crucial to prevent chronic inflammation, meaning that substances with anti-inflammatory activity can suppress NF-κB activation or interfere with its translocation to the nucleus, reducing the expression of inflammatory genes [
51] In addition to its involvement in the inflammatory process, NF-kappa-B (NF-κB) is involved in cell proliferation, apoptosis (programmed cell death), stress response, and other aspects relevant to cancer development and progression [
52].
It should be noted that the chronic inflammation process favors mutations, uncontrolled cell proliferation, and resistance to apoptosis, all of which are processes that can facilitate carcinogenesis [
56].Furthermore, NF-κB induces the production of vascular endothelial growth factor (VEGF) and regulates molecules involved in cell mobility and tissue invasion, such as matrix metalloproteinases (MMPs) [
57,
58]Considering this, it can be suggested that these molecules hold promise as antitumor and anti-inflammatory agents, and in vitro and in vivo studies are necessary to determine the best therapeutic use of these molecules.