Chemical Composition and Future Perspectives of Essential Oil Obtained from a Wild Population of Stachys germanica L. Distributed in the Balkan Mountains in Bulgaria.

Stachys germanica L. (Lamiaceae) is a plant associated with a rich history in the traditional medicine of Iran, Turkey, and Serbia. However, researchers have not fully investigated the pharmacological potential of the herb, and scientific data on this plant species are limited. The aim of the current study was to evaluate the chemical composition of the essential oil (EO) obtained from the aerial parts of S. germanica L. growing wild in Bulgaria and to perform a comparative analysis of the chemical composition of EOs obtained from the same plant species from other geographical regions. For the evaluation of the chemical profile of the isolated EO, gas chromatographic analysis with mass spectrometry was performed. The most abundant terpene class was oxygenated monoterpenes, which accounted for 59.30% of the total EO composition. The bicyclic monoterpene camphor, as a compound of this class, was identified as the major constituent in the EO, accounting for 52.96% of the total oil composition. The chemical profile of Bulgarian EO is quite different compared to that of EOs from other regions. It is the only one to contain more than 50% camphor. In addition, EO contains significant amounts of the diterpene geranyl p-cymene (10.49%). This is the first study describing the chemical composition of EO from Bulgarian Stachys germanica L., and our results reveal some future perspectives for the evaluation of the biological activity of EO from the studied plant species as a new therapeutic agent or natural remedy targeting different medical conditions. The EO has a promising potential to be used as a biopesticide and repellent as well, an environmentally friendly and safer alternative to standard pesticides.

A Study of the Chemical Composition, Antioxidant Potential, and Acute Toxicity of Bulgarian Tanacetum vulgare L. Essential Oil.

Common tansy (Tanacetum vulgare L.) is a plant with medicinal properties that has traditionally been used in folk medicine for its anthelmintic, antispasmodic, and choleretic effects, for the treatment of diarrhea and digestive problems, and externally, as an insecticide in veterinary practices. In the current study, we investigated, for the first time, the chemical profile and antioxidant activity of essential oil from a wild population of T. vulgare L. growing in Bulgaria. Common tansy essential oil (EO), which is rich in bicyclic monoterpenes, was obtained using hydrodistillation and characterized by using gas chromatography-mass spectrometry (GC-MS). Thirty-seven compounds were identified in Bulgarian tansy EO. Among the major constituents were oxygenated monoterpenes, including compounds such as camphor (25.24%), trans-chrysantenyl acetate (18.35%), cis-verbenol (10.58%), thujone (6.06%), eucaliptol (5.99%), and α-campholenal (5.98%). The analysis results identified the essential oil from T. vulgare L. grown in the western Rhodope Mountains of Bulgaria as the camphor chemotype. Furthermore, its antioxidant activity was analyzed using the oxygen radical absorbance capacity (ORAC) method and was found to be 605.4 ± 49.3 µmol TE/mL. The essential oil was also tested for single-dose acute toxicity on Wistar rats and was found to be non-toxic by oral administration. The mean lethal dose by intraperitoneal administration was LD50 i.p. = 14.9 g/kg body weight. The results of the conducted study can serve as a basis for the evaluation and subsequent exploration of other pharmacotherapeutic effects of the essential oil obtained from the inflorescences of the Bulgarian species T. vulgare L.

Echinophora tenuifolia subsp. sibthorpiana-Study of the Histochemical Localization of Essential Oil.

BACKGROUND: Echinophora tenuifolia L. subsp. sibthorpiana is a perennial, aromatic plant used in traditional folk medicine and cuisine of the Mediterranean and the Middle East. However, scholars have not fully studied the pharmacological potential of the herb, and the scientific data on this plant species are limited. This study aimed to evaluate the chemical composition of the essential oil (EO) obtained from the aerial parts of E. tenuifolia subsp. sibthorpiana growing wild in Bulgaria and to perform histochemical analysis. METHODS: A microscopic histochemical analysis and gas chromatography with mass spectrometry were performed. RESULTS: The histochemical analysis confirmed the presence of terpenes in the stem and leaf of E. tenuifolia subsp. sibthorpiana. The phenylpropanoid methyleugenol was identified as the main compound in the EO, representing 48.13% of the total oil composition. There were also found considerable amounts of monoterpene hydrocarbons, representing 41.68% of the total EO. Alpha-phellandrene, o-cymene, and ß-phellandrene were the most abundant monoterpene hydrocarbons. CONCLUSION: This is the first histochemical analysis performed on E. tenuifolia subsp. sibthorpiana. This is the first report of the EO composition from Bulgarian E. tenuifolia subsp. sibthorpiana, and our results indicate some future possibilities for evaluating of the biological activity of the EO of E. tenuifolia subsp. sibthorpiana and highlight the potential future use of the EO of this plant species. E. tenuifolia L. subsp. sibthorpiana EO possesses a good potential for use as a biopesticide and repellent an environmentally friendly alternative of synthetic pesticides.

Comparison between the Chemical Composition of Essential Oil from Commercial Products and Biocultivated Lavandula angustifolia Mill.

The main aim of this study was to assess the differences in the chemical composition of essential oil from biocultivated Lavandula angustifolia in the Thracian Lowland floristic region, Bulgaria, and commercially available products from Bulgarian markets. Following the analytical results conducted with gas chromatography-mass spectrometry, we have established some differences in the chemical composition of the tested samples. The essential oil of biocultivated lavender contained 35 compounds, which represent 94.13% of the total oil. Samples from commercial products contained 28-42 compounds that represent 93.03-98.69% of the total oil. All the examined samples were rich in monoterpene hydrocarbons (1.68-12.77%), oxygenated monoterpenes (70.42-87.96%), sesquiterpene hydrocarbons (4.03-13.78%), and oxygenated sesquiterpenes (0.14-0.76%). The dominant components in all examined samples were linalool (20.0-45.0%) and linalyl acetate (20.79-39.91%). All the examined commercial samples contained linalool and linalyl acetate as was described in the European Pharmacopoeia, but in one of the samples, the quality of linalyl acetate is lower than that recommended in the European Pharmacopoeia.

Chemical Composition and Histochemical Localization of Essential Oil from Wild and Cultivated Rhaponticum carthamoides Roots and Rhizomes.

Rhaponticum carthamoides (Willd.) Iljin is not only a source of phytosteroids and flavonoids, but is also source of essential oil (EO). This study evaluated the volatile metabolic constituents and histochemical localization of root and rhizome essential oils (EOs) from R. carthamoides populations wild-grown in Russia and cultivated in Bulgaria. The performed histochemical analysis confirmed the presence of lipophilic substances in the secretory ducts of the examined roots and rhizomes. Both EOs were obtained by hydrodistillation and further analyzed by gas chromatography with mass detection. The results showed differences between the chemical compositions of both EOs. Forty-six components were tentatively identified in R. carthamoides oil from the wild population, with ß-selinene (4.77%), estragole (6.32%), D-carvone (6.37%), cyperene (8.78%), and ledene oxide (11.52%) being the major constituents. In the EO isolated from cultivated R. carthamoides, twenty-three compounds were tentatively identified, with humulene (7.68%), ß-elemene (10.76%), humulene-1,2-epoxide (11.55%), ledene oxide (13.50%), and δ-elemene (19.08%) predominating. This is the first report describing the histolocalization and chemical profile of EO from R. carthamoides cultivated in Bulgaria. Further research on the cultivation of R. carthamoides in Bulgaria would affect the relationship between its chemical composition and pharmacological effects.

A study of flavonoid composition and antimicrobial activity of Scutellaria altissima L. from different floristic regions of Bulgaria.

INTRODUCTION: Scutellaria extracts and its constituents, especially the characteristic flavonoids such as baicalein and its glycoside baicalin, exhibit significant antimicrobial activity. AIM: To perform a comparative analysis of flavonoid composition and antimicrobial activity of extracts obtained from aerial parts and roots of Scutellaria altissima from the regions of Mezek and Bachkovo, Bulgaria. MATERIALS AND METHODS: 70% ethanol and aqueous extracts of aerial parts and roots of S. altissima were used. HPLC analysis of S. altissima extracts was performed. Microbiological tests were done on clinical isolates of Streptococcus mitis, Staphylococcus aureus, Escherichia coli, and Candida albicans. Minimal bactericidal and minimal bacteriostatic concentrations of S. altissima extracts were determined by the agar method. RESULTS: The ethanol extracts contain flavonoids approximately twice as much in comparison with the aqueous extracts. The baicalin content in the aerial parts of S. altissima from the region of Mezek is 5 times higher than that in the roots. S. altissima extracts have effective antimicrobial activity against S. mitis only. The minimal bactericidal concentration of ethanol extracts of S. altissima aerial parts and S. altissima roots is 2000 µg/ml and 8000 µg/ml at 24 hours, respectively. The bactericidal effect of aqueous extracts occurs at 48 hours at minimal bactericidal concentration of S. altissima aerial parts - 2000 µg/ml and of S. altissima roots - 6000 µg/ml. CONCLUSIONS: The finding that extracts of Bulgarian S. altissima possess effective antimicrobial properties against S. mitis suggests that it can be used as a potential source for the development of natural antimicrobial agents to suppress oral pathogens and prevent some oral infections.

Metabolite Profile and Antioxidant Activity of Some Species of Genus Scutellaria Growing in Bulgaria.

Until now, the interest to plants from genus Scutellaria in Bulgaria has been focused mainly on the terpenes in them. The purpose of this study is to enrich the information on the composition of the Bulgarian Scutellaria species in terms of both polyphenolic content as well as primary metabolites such as mono-, oligosaccharides and organic acids. An aerial part of three Scutellaria species growing in four low mountain regions of Southern Bulgaria was used. The flavonoids scutellarin, baicalin, baicalein, wogonin, wogonoside, luteolin, chrysin and a caffeoyl phenylethanoid glycoside-verbascoside have been identified via HPLC in different extracts from Scutellaria altissima, Scutellaria albida and Scutellaria galericulata. The antioxidant activity of the extracts has been evaluated. The Scutellaria altissima from Mezek and Scutellaria galericulata from Parvenets we studied, which are the richest in flavonoids (represented mainly by baicalin, scutellarin and wogonoside), show the highest Oxygen Radical Absorption Capacity. Hydroxyl Radical Averting Capacity of Scutellaria albida from Mezek and Scutellaria altissima from Bachkovo is the most pronounced, probably due to the content of scutellarin and luteolin and chrysin, respectively. Antioxidant activity of aqueous, methanolic and 70% and 96% ethanol extracts were also determined by the electrochemical method.

Antifeedant Activity of Neo-clerodane Diterpenoids from Scutellaria altissima against Colorado Potato Beetle Larvae.

Fourteen neo-clerodane diterpenoids isolated from Scutellaria altissima (Lamiaceae) were tested for insect antifeedant activity against Leptinotarsa decemlineata Say. Potato leaf disks treated with small amounts of the compounds (concentration 1000, 100, 10 ppm) resulted in good to very good antifeedant activity. Clerodin (1), scutecyprin (11) and 11-epi-scutecolumnin C (12) showed strong feeding inhibition at 1000 ppm and exhibited significant antifeedant activity at a concentration of 100 ppm. Activity was established by calculating the feeding ratio (FR) between the consumed areas of treated disks (CTD) and control disks (CCD). For comparison, FR50 values were determined as the FR at a CCD of 50%. Structural features of the compounds associated with the changes in activity and structure-antifeedant activity relationships are discussed. For the first time the anti-feedant activity has been evaluated of neo-clerodane diterpenoids with an unusual R-configuration of the carbon atom C-I 1.