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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 LD 50 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.

In this study, the essential oil composition of five Thymus species, belonging to Sect. Hyphodromi (A. Kerner) Halácsy - Thymus atticus Čelak., T. leucotrichus Halácsy, T. striatus Vahl, T. zygioides Griseb. and T. perinicus (Velen.) Jalas. was studied by GC/MS/FID. T. atticus, T. leucotrichus, and T. striatus were characterized by high amounts of sesquiterpenoids (57.7, 78.9 and 79.7 %, respectively) with β-caryophyllene and caryophyllene oxide as the main constituents. Aromatic compounds (61.2 %) were the most abundant group in T. zygioides essential oil, with thymol (51.2 %) as the principal component. The essential oil from the endemic species T. perinicus contained almost equal amounts of monoterpenoids (37.8 %) and aromatic compounds (36.0 %) with borneol (17.9 %) and thymol (20.9 %) as the major components. The obtained results revealed the existence of new chemotypes of T. atticus (caryophyllene oxide/β-caryophyllene), T. leucotrichus (β-caryophyllene/elemol/germacrene D) and T. striatus (β-caryophyllene/germacrene D/caryophyllene oxide). The essential oil content of endemic T. perinicus is reported for the first time. Principal component analysis (PCA) and cluster analysis (CA) were used to investigate the variations in the essential oils of different Thymus species from Sect. Hyphodromi (A. Kerner) Halácsy., (© 2021 Wiley-VHCA AG, Zurich, Switzerland.)

Bulgaria and North Macedonia have a long history of the production and use of honey; however, there is an obvious lack of systematic and in-depth research on honey from both countries. The oak honeydew honey is of particular interest, as it is highly valued by consumers because of its health benefits. The aim of this study was to characterize honeydew and floral honeys from Bulgaria and North Macedonia based on their NMR profiles. The 1D and 2D 1 H and 13 C-NMR spectra were measured of 16 North Macedonian and 22 Bulgarian honey samples. A total of 25 individual substances were identified, including quinovose, which was found for the first time in honey. Chemometric methods (PCA-principal component analysis, PLS-DA-partial least squares discriminant analysis, ANOVA-analysis of variance) were used to detect similarities and differences between samples, as well as to determine their botanical and geographical origin. Semiquantitative data on individual sugars and some other constituents were obtained, which allowed for the reliable classification of honey samples by botanical and geographical origin, based on chemometric approaches. The results enabled us to distinguish oak honeydew honey from other honey types, and to determine the country of origin. NMR was a rapid and convenient method, avoiding the need for other more time-consuming analytical techniques.

The Balkans endemic species Alkanna primuliflora Griseb., A. stribrnyi Velen., and A. graeca Boiss. & Spruner have limited distribution in the Balkan Peninsula and a large variation in the morphological characteristics. The populations of the three Alkanna species in the Bulgarian flora are small and fragmented. There are no previous reports on the chemical profile or on the embryology of these species. The hypothesis was that the limited distribution of A. primuliflora, A. stribrnyi, and A. graeca was due to their reproductive capacity and genetic diversity. Furthermore, we hypothesized that the three species will contain pyrrolizidine alkaloids (PAs), as other species of the genus Alkanna (Boraginaceae), but they would have differential alkaloids composition. The population genetic structure and differentiation showed a clear distinction between species and revealed average levels of genetic diversity among the natural populations of the three Alkanna species. The embryological investigation observed stability of the processes in the male and female generative spheres and high viability of mature pollen and embryo of the three species. The normal formation of male and female gametophytes without deviations or degenerative processes, and observed levels of genetic diversity between Alkanna individuals are important in maintaining the size and resilience of the Alkanna populations. Eight alkaloids were identified by GC-MS in A. primuliflora and A. graeca and six alkaloids in A. stribrnyi. The main pyrrolizidine alkaloids (PAs) in all investigated species was triangularine. A. primuliflora and A. graeca showed similar chemical composition that comprised 9-angeloylretronecine, 7-tigloylretronecine, 9-tigloylretronecine, triangularicine, dihydroxytriangularine, dihydroxytriangularicine, whereas, in A. stribrnyi 9-tigloylretronecine, triangularicine and dihydroxytriangularicine were not found. This is the first report on the presence of PAs in A. primuliflora, A. stribrnyi and A. graeca. Besides, this is the first report on the embryology of these endemic species. The results contribute to the knowledge of the three endemic Alkanna species and will facilitate policy-making and defining new strategies for their conservation., Competing Interests: NO authors have competing interests.

Chlorogenic (5-CQA), 1,5-, 3,5-, 4,5- and 3,4-dicaffeoylquinic (DCQA) acids were identified and quantified in the methanol extracts of Inula oculus-christi L., I. bifrons L., I. aschersoniana Janka var. aschersoniana, I. ensifolia L., I. conyza (Griess.) DC. and I. germanica L. by HPLC analysis. The amount of 5-CQA varied from 5.48 to 28.44 mg/g DE and the highest content was detected in I. ensifolia. 1,5-DCQA (4.05-55.25 mg/g DE) was the most abundant dicaffeoyl ester of quinic acid followed by 3,5-DCQA, 4,5-DCQA and 3,4-DCQA. The extract of I. ensifolia showed the highest total phenolic content (119.92±0.95 mg GAE/g DE) and exhibited the strongest DPPH radical scavenging activity (69.41±0.55 %). I. bifrons extract was found to be the most active sample against ABTS .+ (TEAC 0.257±0.012 mg/mL) and the best tyrosinase inhibitor. The studied extracts demonstrated a low inhibitory effect towards acetylcholinesterase and possessed low cytotoxicity in concentration range from 10 to 300 μg/mL toward non-cancer (MDCK II) and cancer (A 549) cells., (© 2020 Wiley-VHCA AG, Zurich, Switzerland.)

Raman spectroscopy, being able to provide rich information about the chemical composition of the sample, is gaining an increasing interest in the applications of food. Raman spectroscopy was used to analyze a set of wine samples (red and white) sourced from rarely studied traditional Bulgarian wines. One of the objectives of this study was to attempt the fast classification of Bulgarian wines according to variety and geographic origin. In addition, calibration models between phenolic compounds and Raman spectroscopy were developed using partial least squares (PLS) regression using cross-validation. Good calibration statistics were obtained for total phenolic compounds (by the Folin-Ciocalteu method) and total phenolic compounds and phenolic acids (spectrophotometrically at 280 nm) where the coefficient of determination (R 2 ) and the standard error in the cross-validation (SECV) were 0.81 (474.2 mg/dm 3 gallic acid), 0.87 (526.6 mg/dm 3 catechin equivalents), and 0.81 (44.8 mg/dm 3 caffeic equivalents), respectively. This study has demonstrated that Raman spectroscopy can be suitable for measuring phenolic compounds in both red and white wines.

The separately distilled flowers (F) and leaves' (L) essential oils of Inula britannica L. were investigated using capillary gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). A total of 83 constituents, representing 96.91% (F) and 96.73% (L) of the total oils, were registered. The oils were rich in terpenoids (57.85% and 77.28%), of which sesquiterpenoids dominated. The main constituents of the essential oils were viridiflorol (7.17%-8.20%) and himachalol (3.45%-8.71%) followed by 6,10,14-trimethyl-2-pentadecanone (5.43%-2.95%), 13-tetradecanolide (3.93%-4.87%) and 3-methyl-4-propyl-2,5-furandione (4.06%-0.29%).

The essential-oil composition of six native populations of Sideritis scardica from Bulgaria was studied by GC-FID and GC/MS analyses. Altogether, 37 components, representing 73.1 to 79.2% of the total oil content were identified. Among them, α-pinene (4.4-25.1%), β-pinene (2.8-18.0%), oct-1-en-3-ol (2.3-8.0%), phenylacetaldehyde (0.5-9.5%), β-bisabolene (1.3-11.0%), benzyl benzoate (1.1-14.3%), and m-camphorene (1; 0.3-12.4%) were the main compounds. All samples were characterized by low contents of oxygenated mono- and sesquiterpenes (≤1.6 and 2.3%, resp.). Principal component analysis (PCA) and cluster analysis (CA) showed a significant variability in the chemical composition of the studied samples as well as a correlation between the oil profiles and the ecological conditions of the natural habitats of S. scardica., (Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.)

Twelve steroidal alkaloids were isolated from four populations of Veratrum lobelianum Bernh. and Veratrum nigrum L. Full NMR data for veralosinine (1), and extensive 1H NMR data for veralosine (3) and teinemine (5) are presented here for the first time. (+/-)-15-O-(2-Methylbutyroyl)germine (10) is undescribed up to now. The antiproliferative activities of veranigrine, veralosinine, and neogermitrine have shown that they are a perspective for further studies.

The essential oil compositon of Achillea clusiana Tausch from Bulgaria has been studied by GC and GC/MS. Fifty-four components were registered, representing 92.5% of the oil. The oil was characterized by the presence of oxygenated mono- and sesquiterpenoids. The main components were beta-thujone (17.2%), 1,8-cineole (11.2%), camphor (11.1%) and alpha-thujone (7.8%). Farnesol (3.1%), nerolidol (2.7%) and oxygenated nerolidol derivatives (cabreuva oxides A-D, isohumbertiols A-D, bejarol and 7-hydroxy-6,7-dihydro-5,6E-dehydronerolidol) were the main sesquiterpenoids in the oil.

The chemical composition of fresh flowers from Allium ursinum (ramsons, bear's garlic, wild garlic) growing in Bulgaria has been studied. Thymidine (1), adenosine (2), astragalin (kaempferol-3-O-beta-D-glucopyranoside (3), kaempferol-3-O-beta-D-glucopyranosyl-7-O-beta-D-glucopyranoside (4), kaempferol-3-O-beta-D-neohesperoside (5), and kaempferol-3-O-beta-D-neohesperoside-7-O-beta-D-glucopyranoside (6) were isolated from the n-butanol extract and identified by different spectroscopic and spectrometric methods. Thymine (7), uridine (8), uracil (9) and 5-chloro-uridine (10) were detected in the same extract by GC-MS. This is the first report of the occurrence of 1, 2, 4, 7 - 10 in the flowers of A. ursinum. GC-MS of the volatile components of fresh flowers and leaves from the same plant revealed a high content of sulfur compounds, some of which are reported for the first time for A. ursinum. The antimicrobial activities of extracts from fresh flowers and leaves of A. ursinum have been tested; some extracts exhibited moderate antifungal properties.

Four groups of metabolites from the halophyte plant Stachys maritima Gouan, family Lamiaceae, were investigated: lipids, sterols, volatiles and polar compounds. Most of the metabolites have been previously reported to possess biological activity. Two of the main substances in the volatile fraction--phenidone and naphthalene, unusual for plants--were products of environmental contamination. This is a typical example of how marine pollutants could transfer and threaten terrestrial organisms via the trophic chain. The n-butanol extract possessed a relatively high antibacterial activity against S. aureus and Candida albicans, but was not active against Escherichia coli.

The essential oils of two species of Sideritis growing spontaneously in Bulgaria and Macedonia are reported, Sideritis scardica and Sideritis raeseri. The oils of S. scardica from different locations differed significantly: in the Macedonian sample alpha-cadinol (20%) predominated, while in the oil of Bulgarian samples the main components were diterpenic compounds and octadecenol (over 20%). This is the first report of ditrpenoids in essential oil of S. scardica. The oil of S. raeseri demonstrated a distinct chemical profile with its high concentration of sesquiterpenes, main components being germacrone (25%) and elemol acetate (15.9%). The observed qualitative variability of the oil composition of S. scardica of different geographic origin could be a result of different ecologic conditions but might also reflect the well-known tendency of some Sideritis species to hybridize.

The sterol composition of five Black Sea red algae: Callithamnion granulatum, Ceramium rubrum, Ceramium elegans, Laurencia papillosa and Laurencia coronopus was obtained. Monohydroxy sterols and their oxidized derivatives have been identified. The results obtained were compared with some recent data for the composition of sterols in other Black Sea red algae, which occupy different evolutionary positions. On the basis of their composition, some conclusions about the chemotaxonomy and chemoevolution of the species investigated have been proposed.

The aerial parts of Anthemis austriaca Jacq. afforded five new sesquiterpene lactones (two of which are dimeric guaianolides) and three new guaiane type sesquiterpene acids In addition, seven known terpenoids were also found in the studied species. Their structures were elucidated by spectral methods.

The volatiles of fresh flowers from nine natural populations of four Lamium species and Lamiastrum galeobdolon were analyzed by GC/MS. 49 compounds, 43 of them new for Lamium and Lamiastrum, were identified. The studied samples showed similarity of the volatile profiles and dependence of the oil-composition on the collection site. Significant amounts of squalene were found in all samples. The presence of homological series of straight chain alkanes from C12 to C31 was shown. Phenethyl alcohol was found only in L. maculatum f. alba.

Twenty-seven pyrrolizidine alkaloids were identified by a detailed phytochemical study and GC/MS analysis on twelve Bulgarian species from genus Senecio. Twenty of them are new for the corresponding species. Other six structures remain tentatively identified.

Four new eudesmanolides and two new guaianolides were isolated from the aerial parts of Anthemis carpatica Willd. and their structures elucidated by spectral methods. In addition, seven known sesquiterpene lactones were identified.

The known furostanol saponins methylprotodioscin and protodioscin and two new sulfated saponins, sodium salt of 26-O-beta-glucopyranosyl-22alpha-methoxy-(25R)-furost-5-ene-3beta,26-diol-3-O-alpha-rhamnopyranosyl-(1-->2)-beta-4-O-sulfo-glucopyranoside (methylprototribestin) and sodium salt of 26-O-beta-glucopyranosyl-22alpha-hydroxy-(25R)-furost-5-ene-3beta,26-diol-3-O-alpha-rhamnopyranosyl-(1-->2)-beta-4-O-sulfo-glucopyranoside (prototribestin) have been isolated from the aerial parts of Tribulus terrestris L. growing in Bulgaria. The structures of the new compounds were elucidated on the basis of 1D and 2D (DQF-COSY, TOCSY, HSQC-TOCSY, HSQC, HMBC, ROESY) NMR data, ESI mass spectra and chemical transformation.

Chemical investigation of the Bulgarian species Tanacetum. parthenium, T. millefolium, T. achilleifolium, T. corymbosum and T. macrophyllum afforded in addition to 24 known sesquiterpene lactones a new 12, 8-eudesmanolide 22. Besides, four known highly oxigenated terpenoids and a new keto-diol 30 of the rare iphionane skeleton were also isolated. The structures were elucidated on the basis of their spectral properties. The accumulation of the different sesquiterpene lactones in the studied species and there classification is discussed.

The aerial parts of Achillea setacea afforded, in addition of a rare monoterpene triol and 12 known sesquiterpene lactones, a new guaianolide containing an endoperoxide ring. Its structure was elucidated by spectral methods.

The chemical composition of propolis from Bulgaria, Turkey, Greece and Algeria was investigated by GC-MS. All of them contained mainly flavonoids and esters of caffeic and ferulic acids, which indicated that their main source are buds of poplars of the taxonomic section Aegieros. Some Turkish samples contained a low percent of diterpenic acids, while in Algerian samples significant amounts of a hydroxyditerpenic acid (M=322, its structure not determined by its MS) were found. All samples showed significant antibacterial and weak to moderate antifungal activity.

Leaf exudates from 39 species, belonging to 26 genera of Lamiaceae, have been isolated and their antibacterial and antiviral activity investigated. Some of the active compounds (ursolic acid, siderol and nepetalactone) were isolated and identified, most of them for the first time in the investigated plants. Some chemotaxonomic conclusions were drawn.