Essential oils of seven Stachys taxa from Croatia

Stachys durandiana Coss., an endemic plant of Morocco: chemical composition of its aerial parts essential oil

The genus Stachys L. (Lamiaceae) comprises more than 300 species as annual or perennial herbs or small shrubs, spread in temperate regions of Mediterranean, Asia, America, and Southern Africa and several species have been used in the traditional medicine of many countries. Section Stachys, one of nineteen sections of genus Stachys, is divided in two subsections: Sylvaticae and Circinatae. In the present study the chemical composition of the essential oil from aerial parts of Stachys durandiana Coss., endemic of Morocco, and belonging to subsection Circinatae, was analysed by GC-MS. No report has been previously published on this species. The result showed the presence of large quantity of monoterpene hydrocarbons (73.3%), being α-pinene (38.0%) β-pinene (14.8%), and limonene (11.1%) the principal constituents. Furthermore, a complete review on the chemical composition and biological properties of all the other Stachys taxa, belonging to section Stachys, studied so far, was carried out.

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.

The chemical composition of the aerial parts essential oil of Stachys ocymastrum L. Briq. (Lamiaceae) growing in Sicily (Italy)

The genus Stachys L. (Lamiaceae) comprises more than 300 species as annual or perennial herbs or small shrubs, spread in temperate regions of Mediterranean, Asia, America, and Southern Africa. Several species have been used in the traditional medicine to treat stress, skin inflammations, gastrointestinal disorders, asthma, and genital tumours. In the present study the chemical composition of the essential oil from aerial parts of Stachys ocymastrum L. Briq., belonging to section Olisia, endemic of the Western Mediterranean and Greece and collected in Sicily, was analysed by GC-MS. No one report has been previously published on any European accession of this species. The result showed the presence of large quantity of the diterpenoid phytol (23.80%). Other metabolites present in high quantity were β-caryophyllene (17.95%), geranyl-α-terpinene (13.26%) and trans-chrysanthenyl acetate (9.85%). Chemical considerations with respect all the other oils of Stachys taxa, belonging to section Olisia studied so far, were carried out.

Phytochemical Analysis and Biological Activity of Three Stachys Species (Lamiaceae) from Romania

Three species of Stachys genus (S. byzantina, S. officinalis, S. sylvatica) were investigated in the present study in terms of aromatic profile and total polyphenol content, as well as antibacterial activity and antioxidant capacity. Gas chromatography coupled with flame ionization detection (GC/FID) was used for exploration of the herbal alcoholic extracts. Using statistical analysis, volatile organic compounds (VOCs) and total phenolic chemical fingerprints were compared in order to describe differences and identify putative signature traits of the three Stachys species. The results showed that the analyzed Stachys extracts have a total polyphenol content being between 197 ± 0.27 mg GAE/g for S. sylvatica and 232 ± 43 mg GAE/g for S. officinalis. The antioxidant activity was between 444 ± 58 mM Trolox/g (S. sylvatica) and 602 ± 75 mM Trolox/g (S. officinalis). The volatile compounds identified were mostly sesquiterpenes, followed by monoterpenes and secondary compounds. The most abundant in all three species was germacrene D (21.9% 28–25.2%). The multivariate analysis demonstrated the potential of using plant tissue VOC profiles to discriminate between different Stachy species, with a total of 31 VOCs being identified from all three species. Although there were strong similarities among the three species’ VOC profiles, distinctions can be made using chemometric analysis. The microbiological results showed an antimicrobial capacity of all three extracts, especially on Gram-positive bacteria. In addition to increasing consumers’ understanding regarding the health benefits of these Stachy species, this investigation contributes to defining and preserving a precious genetic and cultural-historical biodiversity.

Shoot Multiplication and Callus Induction of Labisia pumila var. alata as Influenced by Different Plant Growth Regulators Treatments and Its Polyphenolic Activities Compared with the Wild Plant

This study aims to investigate whether the in vitro-cultured L. pumila var. alata has higher antioxidant activity than its wild plant. An 8-week-old L. pumila var. alata nodal segment and leaf explants were cultured onto Murashige and Skoog (MS) medium supplemented with various cytokinins (zeatin, kinetin, and 6-benzylaminopurine (BAP)) for shoot multiplication and auxins (2,4-dichlorophenoxyacetic acid (2,4-D) and picloram) for callus induction, respectively. The results showed that 2 mg/L zeatin produced the optimal results for shoot and leaf development, and 0.5 mg/L 2,4-D produced the highest callus induction results (60%). After this, 0.5 mg/L 2,4-D was combined with 0.25 mg/L cytokinins and supplemented to the MS medium. The optimal results for callus induction (100%) with yellowish to greenish and compact texture were obtained using 0.5 mg/L 2,4-D combined with 0.25 mg/L zeatin. Leaves obtained from in vitro plantlets and wild plants as well as callus were extracted and analyzed for their antioxidant activities (DPPH and FRAP methods) and polyphenolic properties (total flavonoid and total phenolic content). When compared with leaf extracts of in vitro plantlets and wild plants of L. pumila var. alata, the callus extract displayed significantly higher antioxidant activities and total phenolic and flavonoid content. Hence, callus culture potentially can be adapted for antioxidant and polyphenolic production to satisfy pharmaceutical and nutraceutical needs while conserving wild L. pumila var. alata.

Phytochemical and Biological Traits of Endemic Betonica bulgarica (Lamiaceae)

Betonica bulgarica is an endemic species distributed in Bulgaria. The chemical composition of the essential oil analysed by GC–MS (Gas chromatography–mass spectrometry) and the content of trace elements analysed by ICP–MS (Inductively coupled plasma mass spectrometry) were determined. Additionally, a study on the types and distribution of trichomes was done using a microscope with a camera. The essential oil was characterized using a high concentration of sesquiterpene hydrocarbons, whose major compounds are β-caryophyllene (17.4%), germacrene D (9.9%), and β-bourbonene (6.7%). The contents of manganese (177.2 µg/g) and strontium (156.8 µg/g) were highest among the investigated micronutrients. Two types of trichomes were identified on the adaxial and abaxial epidermises of the leaves of B. bulgarica—covering and glandular. Peltate stacked glandular trichomes with a four-celled head of type B were observed on the leaf surface.

LC-ESI/LTQOrbitrap/MS/MS and GC-MS profiling of Stachys parviflora L. and evaluation of its biological activities

The use of some Stachys genus as herbal remedies is known and the aerial parts have a pharmaceutical interest, being used in Anatolia and Iran as wild tea. In this study, chemical composition, antimicrobial, antioxidant, and antiproliferative activities of the methanolic extract and essential oil (EO) of Stachys parviflora L. (S. parviflora) were evaluated. Qualitative analysis of metabolites of S. parviflora methanolic extract was studied using liquid chromatography coupled to high resolution mass spectrometry (LC-ESI/LTQOrbitrap/MS), evidencing the presence of phenolic acids and flavonoids derivatives. The EO was analyzed using gas chromatography coupled to mass spectrometry (GC/MS). Eighty-seven compounds were characterized in the EO of S. parviflora, of which α-terpenyl acetate (23.6%), β-caryophyllene (16.8%), bicyclogermacrene (9.3%), spathulenol (4.9%) and α-pinene (4.2%) were found to be the major components. The highest antimicrobial effect of EO was found to S. aureus and B. cereus (MIC = 0.01 μg/ml), while the highest activity of extract was against B. cereus (MIC = 125 μg/ml). The methanolic extract exhibited strong antioxidant activity in DPPH (IC₅₀ = 76.87 μg/ml) and β-carotene/linoleic acid assay (BCB, IC₅₀ = 188.47 μg/ml) methods. Furthermore, in vitro cytotoxicity evaluation against three cell lines namely human ovarian carcinoma (A2780), human colon carcinoma (HCT), and mouse melanoma cell line (B16F10), showed an anti-proliferative activity of the EO ranging from IC₅₀ value 30.95 μg/ml to 16.55 μg/ml. The results from this study have demonstrated the promising cytotoxic, antibacterial, and antifungal properties of S. parviflora, which could have wide potential applications in food and pharmaceutical industries.

Taxonomical and Phytochemical Characterisation of 10 Stachys Taxa Recorded in the Balkan Peninsula Flora: A Review

The genus Stachys is one of the largest genera of the Lamiaceae, and it comprises about 300 species. Some species are highly polymorphic, with a number of infraspecific taxa. The aim of the present review is to summarise the available knowledge on 10 taxa belonging to the Balkan Peninsula flora (S. alpina L., S. germanica L., S. menthifolia Vis., S. obliqua Waldst. Et Kit., S. officinalis (L.) Trevis., S. palustris L., S. recta L. subsp. recta, S. recta L. subsp. subcrenata (Vis.) Briq., S. salviifolia Ten., and S. sylvatica L.) in order to enable insight into the identified biologically active substances and their possible application in intrageneric differentiation.

Identification of Insecticidal Constituents from the Essential Oil from the Aerial Parts Stachys riederi var. japonica

The essential oil of Stachys riederi var. japonica (Family: Lamiaceae) was extracted by hydrodistillation and determined by GC and GC-MS. A total of 40 components were identified, representing 96.01% of the total oil composition. The major compounds in the essential oil were acetanisole (15.43%), anisole (9.43%), 1,8-cineole (8.07%), geraniol (7.89%), eugenol (4.54%), caryophyllene oxide (4.47%), caryophyllene (4.21%) and linalool (4.07%). Five active constituents (acetanisole, anisole, 1,8-cineole, eugenol and geraniol) were identified by bioactivity-directed fractionation. The essential oil possessed fumigant toxicity against maize weevils (Sitophilus zeamais) and booklice (Liposcelis bostrychophila), with LC₅₀ values of 15.0 mg/L and 0.7 mg/L, respectively. Eugenol and anisole exhibited stronger fumigant toxicity than the oil against booklice. 1,8-Cineole showed stronger toxicity, and anisole as well as eugenol exhibited the same level of fumigant toxicity as the essential oil against maize weevils. The essential oil also exhibited contact toxicity against S. zeamais adults and L. bostrychophila, with LC₅₀ values of 21.8 µg/adult and 287.0 µg/cm², respectively. The results indicated that the essential oil of S. riederi var. japonica and its isolates show potential as fumigants, and for their contact toxicity against grain storage insects.

Polar Constituents, Essential Oil and Antioxidant Activity of Marsh Woundwort (Stachys palustris L.)

Stachys palustris, well-known as marsh woundwort, is a perennial herb growing in wet environments of Europe. Its tubers, leaves and seeds are eaten raw or cooked. Alike other Stachys species, the plant is also used as a traditional remedy. Despite S. palustris has been consumed for centuries, little is known about its chemical constituents. In this work the main secondary metabolites of S. palustris from Hungary and France have been analysed. From the plant ethanolic extracts, ethanoid glucosides, isoscutellarein derivatives, caffeoyl-quinic acids and iridoids have been isolated and structurally characterized by NMR. The essential oils were analysed by GC/MS and showed (E)-phytol, fatty acids and carbonylic compounds as the most abundant compounds. The radical scavenging capacity of plant ethanolic extracts, as evaluated by the DPPH assay, was noteworthy, with IC₅₀ values of 92.08 - 105.42 μg/ml.

Secretory structures and essential oil composition in Stachys officinalis (L.) Trevisan subsp. officinalis (Lamiaceae) from Italy

The secretory structures and the volatile fraction of Stachys officinalis (L.) Trevisan subsp. officinalis (Lamiaceae) from Italy were studied for the first time. Peltate and small capitate trichomes were observed on the whole plant (leaves and inflorescences). In the peltate trichomes, an unusual polyphenols content was evidenced by the histochemical methods. The volatile fraction was obtained by a solvent extract from the distillation water of leaves and inflorescences and analysed by GC-MS. Forty-four constituents for leaves, representing 94.1% of the total volatiles, and 57 compounds for flowers, accounting for 90.1% of the total volatiles, were identified. (E)-caryophyllene (20.1%), (E)-nerolidol (14.3%), caryophyllene oxide (6.1%) and γ-cadinene (5.7%) were recognised as the main constituents for the leaf volatile fraction, while caryophyllene oxide (16.5%), (E)-nerolidol (15.4%), humulene epoxide II (9.2%) and α-pinene (7.0%) were the main compounds for the flower volatile fraction.

Phytochemical and biological studies of Stachys species in relation to chemotaxonomy: a review

The genus Stachys is comprised of about 300 species spread throughout the world, hence representing one of the largest genera of the Lamiaceae. Several Stachys species have been exploited in traditional medicine as astringent, wound-healing, anti-diarrhoeal, anti-nephritic and anti-inflammatory agents. Moreover, antimicrobial, antioxidant and cytotoxic activities of some Stachys species are documented. Iridoids, flavonoids, phenolic acids and diterpenoids are reported as secondary metabolites of different species of this genus. The aim of the present review is to summarize and to highlight the recent advances in current knowledge on Stachys species and to compile reports of chemical constituents isolated from the genus Stachys over the past decades, together with their structural features, biological activities, and structure-activity relationships. Diversity of chemical constituents is discussed in relationship with current Stachys infrageneric taxonomy, classification and relationships with systematically close genera.

Variability of essential oils of Betonica officinalis (Lamiaceae) from different wild populations in Kosovo

The aerial parts and roots of Betonica officinalis were collected from three localities characterized by different ecological conditions to study the natural variability of the chemical composition of the essential oils in this plant. The leaves and inflorescences were collected during the flowering time, whereas the roots were collected at the end of the vegetative period. The plant material was dried at room temperature. The essential oils were obtained by micro-steam hydrodistillation and analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Overall, 69 constituents were identified in all localities and plant parts. The main compositions of the leaves in all localities were alpha-pinene, 1-octen-3-ol, beta-bourbonene, (E)-caryophyllene and germacrene D. The essential oil of the inflorescences was characterized by these main constituents: alpha-pinene, (E)-caryophyllene and trans-beta-farnesene. In all localities, the percentages of alpha-pinene and (E)-caryophyllene were higher in the inflorescences than in the leaves, whereas nonane was the main constituent in the roots.

Chemical composition of the essential oil of Stachys menthifolia Vis

Stachys menthifolia Vis. (Lamiaceae) is an endemic species from the Balkan Peninsula spread throughout Albania, Greece, Montenegro, and Croatia. This article presents the first investigation of the essential oil composition of this species from Croatia. Aerial parts of the plant were collected from three different natural habitats in the region of Biokovo Mountain. The studied populations showed similarity in qualitative, but not in quantitative, composition of their essential oils. Hydrodistilled volatile oil obtained from the plant material of S. menthifolia was subjected to gas chromatographic analysis coupled to mass spectrometry. More than 100 compounds were identified in the three samples, representing 86.8-90.8% of the total oil. The terpene profile of S. menthifolia is characterized by a high content of oxygenated sesquiterpenes (48.4-58.9%) and diterpene hydrocarbons (3.5-25.2%), with 8-alpha-acetoxyelemol (6.9-21.3%), abietatriene (3.5-21.1%), and 4'-methoxyacetophenone (4.5-17.0%) as the main constituents.

Composition of Essential Oils from Leaves and Flowers of Stachys Germanica Subsp. Salviifolia (Ten.) Gams (Labiatae) and Related Secretory Structures

The essential oils from both leaves (L) and flowers (F) of Stachys germanica subsp. salviifolia (Ten.) Gams (Labiatae/Lamiaceae) from Italy were analyzed by GC-MS for the first time. The distribution, morphology and histochemistry of the different types of glandular trichomes present on the epidermal surface were also determined. Twenty-nine constituents, representing 89.4% of the total leaf oil, and forty-one compounds, forming 97.8% of the total flower oil, were identified. Germacrene D (39.4%), phytol (10.2%), β-bourbonene (3.5%) and β-ylangene (3.3%) were recognized as the main constituents of the leaf essential oil, while limonene (24.1%), β-pinene (18.7%), germacrene D (12.8%) and ( E)-nerolidol (6.6%) were the main compounds of the flower essential oil.

Ab initio analysis of the Cope rearrangement of germacrane sesquiterpenoids

The energetics of the Cope rearrangement of 17 germacrane sesquiterpenoids to their respective elemane forms have been calculated using both density functional theory (B3LYP/6-31G*) and post Hartee-Fock (MP2/6-31G**) ab initio methods. The calculations are in qualitative agreement with experimentally observed Cope rearrangements, but the two methods give slightly different results. MP2 calculations generally show more favorable elemene energies compared to the respective germacrenes (by around 3-4 kcal mol(-1)) and smaller activation energies (by 2-3 kcal mol(-1)). Additionally, neither method is accurate enough to consistently reproduce the germacrene/elemene equilibrium. Apparently, the generally small energy differences between the two forms in these sesquiterpenoids cannot be adequately reproduced at these levels of calculation.