No abstract

In this study the quantity of the main nutritional and bioactive compounds, as well as the antioxidant activity (DPPH, FRAP and ABTS methods) and essential oil composition of Monarda fistulosa L. and Monarda citriodora subsp. austromontana Cerv. ex Lag. ‘Bees’ Favourite’ flowers were investigated. The field experiment was carried out for three years (2014–2016) and the laboratory analyses in the years 2015–2016. The obtained results showed that M. citriodora flowers were characterized by a dry matter (22.42%), total ash (1.86% FW), crude fibre (4.89% FW), sucrose (0.31% FW), total flavonoids (0.795% DW) and antioxidant activity in FRAP test (7.96 mg TE g–1 FW), while M. fistulosa showed the highest values of total sugars/titratable acidity ratio (4.05), antioxidant activity in DPPH test (7.35 mg TE g–1 FW) and contents of reducing sugars (1.46% FW), total chlorophyll (401.10 μg g–1 FW), chlorophyll a (271.74 μg g–1 FW) and b (92.07 μg g–1 FW), L-ascorbic acid (48.99 mg 100 g–1 FW) and total polyphenols (7.64 mg GAE g–1 FW). The essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The main compounds of M. fistulosa oil were carvacrol (28.16 and 23.66% in 2015, and 2016, respectively), p-cymene (20.10 and 17.94%), thymoquinone (12.60 and 16.30%) and γ-terpinene (8.72 and 4.07%), whereas linalool (34.86 and 26.96%), thymol (17.83 and 37.34%), β-thujene (6.12 and 2.00%) and camphene (5.80 and 5.64%) were the major constituents of M. citriodora Cerv. ex Lag. ssp. austromontana ‘Bees’ Favourite’ oil.

The aim of this study was to determine how the addition of gold and silver nanoparticles to culture media affects the composition of essential oils extracted from Lavandula angustifolia propagated on MS media with the addition of 10 and 50 mg·dm−3 of gold (24.2 ± 2.4 nm) and silver (27.5 ± 4.8 nm) nanocolloids. The oil extracted from the lavender tissues propagated on the medium with 10 mg·dm−3 AgNPs (silver nanoparticles) differed the most with respect to the control; oil-10 compounds were not found at all, and 13 others were detected which were not present in the control oil. The addition of AuNPs (gold nanoparticles) and AgNPs to the media resulted in a decrease of lower molecular weight compounds (e.g., α- and β-pinene, camphene, δ-3-carene, p-cymene, 1,8-cineole, trans-pinocarveol, camphoriborneol), which were replaced by those of a higher molecular weight (τ- and α-cadinol 9-cedranone, cadalene, α-bisabolol, cis-14-nor-muurol-5-en-4-one, (E,E)-farnesol).

The chemical composition of the essential oils obtained by hydrodistillation from the aerial parts of Thymus serpyllum and Thymus serpyllum‘Aureus’ has been investigated by gas chromatography-mass spectrometry (GC-MS). Forty-seven compounds (99.67% of the total oil) wereidentified in the essential oil of T. serpyllum. The main components found in the oil were carvacrol (37.49%), -terpinene (10.79%), -caryophyllene (6.51%), p-cymene (6.06%), (E)--ocimene (4.63%) and -bisabolene (4.51%). Similarly, carvacrol (44.93%), -terpinene(10.08%), p-cymene (7.39%) and -caryophyllene (6.77%) dominated in the oil of T. serpyllum ‘Aureus’. A total of forty three compounds wereidentified in this oil, representing 99.49% of the total oil content. On the basis of the obtained data it was proved that the content of 1-octen-3-ol,eucalyptol, (Z)--ocimene, (E)--ocimene, -terpinene, carvacrol methyl ether, germacrene D and -bisabolene was significantly higher for T.serpyllum while T. serpyllum ‘Aureus’ was characterized by a significantly higher content of 3-octanone, 3-octanol, p-cymene, borneol andcarvacrol. The isolated essential oils were evaluated for their antimicrobial activity against nine reference strains (Escherichia coli, Staphylococcusaureus, Staphylococcus epidermidis, Streptococcus agalactiae, Enterococcus faecalis, Bacillus cereus, Micrococcus luteus, Proteus vulgaris and Candidaalbicans) by the microdilution technique. Based on this test, the minimum inhibitory concentrations (MIC) of essential oil were calculated. Thevolatile oil obtained from T. serpyllum showed the highest antimicrobial activity relative to the strain of E. coli (MIC=0.025 μL/mL) and to theyeast C. albicans (MIC=0.05 μL/mL). Similarly, a significant antimicrobial activity exhibited T. serpyllum ‘Aureus’ essential oil, although the MICvalues obtained in that case for E. coli and C. albicans strains were twice as high and were respectively 0.05 μL/mL and 0.1 μL/mL.

Thymus vulgaris L. is an important aromatic plant, because of the synthesis and production of its essential oils for the pharmaceutical and cosmetic industries. In this study, we developed a micropropagation protocol for T. vulgaris ‘Słoneczko’ and evaluated the potential of micropropagated plants for essential oil production with industrial application. The seeds were soaked for 10 min in 10% sodium hypochlorite (NaOCl) solution. Then, each seed was put into a 20 ml test tube filled with 5ml of Murashige and Skoog (MS) medium. Half of the cultures were subjected to light intensity which was maintained at 40 µEm−2s−1, and the other half was cultured in the dark. Shoot explants were multiplied in vitro using MS medium supplemented with BAP, 2iP or KIN. The results obtained indicate that the cytokinin which had the most positive impact on plant development at the multiplication stage was 5 mg dm−3 2iP. Single-node fragments of shoots cultured on MS medium without plant growth regulators were transferred to MS medium supplemented with IAA, IBA and NAA at concentrations of 0.2, 0.5, 1 and 2 mgdm−3. The best rooting of shoots was obtained on MS medium supplemented with 2 mgdm−3 IBA. The essential oils obtained by hydrodistillation in Deryng and Clevenger apparatus from in vitro shoot cultures of T. vulgaris L. were analysed using gas chromatography-mass spectrometry (GC-MS). Analysis revealed the presence of 54 components represented mainly by oxygenated monoterpenes (56.81-57.28%) and monoterpene hydrocarbons (31.90-33.72%). Among identified constituents, the most abundant were thymol (33.37-34.05%), γ-terpinene (11.62-11.91%), p-cymene (9.81-10.07%), carvacrol (5.63-5.96%), carvacrol methyl ether (3.86-3.87%) and linalool (3.16-3.36%).