Antimicrobial activities of methanol extracts and essential oils of Rosmarinus officinalis, depending on location and seasonal variations

Rosmarinus officinalis is widely found in the lands of Aegean and Mediterranean regions of Turkey. The goal of this work was to test the antimicrobial activity of the essential oils and methanolic extracts of R. officinalis collected from three different regions at four different time intervals of the year against Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumonia, Enterococcus feacalis, Escherichia coli, Staphylococcus epidermidis, Bacillus subtilis and Candida albicans. Essential oils were obtained from the aerial parts of the plant by using a Clevenger apparatus, for 4 h. After distillation, the distillates were filtered, air-dried and then extracted by using a Soxhlet apparatus for 9 h to obtain the methanolic extracts. The antimicrobial activities of the methanolic extracts were tested by the disc diffusion technique. The antimicrobial activities of the essential oils obtained from R. officinalis were determined by minimum inhibitory concentration (MIC).The results indicated that the tested bacteria were sensitive to the essential oils and partially to the methanolic extracts. The antimicrobial activities of the essential oils against the tested bacteria differed, depending on location and seasonal variations.     

Chemical and biological characteristics of Cuminum cyminum and Rosmarinus officinalis essential oils

Essential oils extracted by hydrodistillation from Cuminum cyminum and Rosmarinus officinalis were characterized by means of GC and GC–MS. C. cyminum and R. officinalis contained α-pinene (29.1%, 14.9%), 1,8-cineole (17.9%, 7.43%) and linalool (10.4%, 14.9%), respectively, as the major compounds. C. cyminum oil exhibited stronger antimicrobial activity than did R. officinalis oil against E. coli, S. aureus and L. monocytogenes. Complete death time on exposure to Cuminum cyminum L. and Rosmarinus officinalis L. oils were 20 and 25 min 180 and 240 min and 90 and 120 min for E. coli, S. aureus and L. monocytogenes, respectively. Radical-scavenging and antioxidant properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the β-carotene bleaching test. These properties were compared to those of Thymus x-porlock essential oil, used as a reference ingredient. The radical scavenging performance of the rosemary oil was better than that of C. cyminum. Results from the antioxidant test were better than those provided by the radical-scavenging activity. C. cyminum and R. officinalis essential oils may be considered as potent agents in food preservation.     

Antibacterial activity of the essential oils of Salvia officinalis L. and Salvia triloba L. cultivated in South Brazil

The essential oils of Salvia officinalis and Salvia triloba cultivated in South Brazil were analyzed by GC–MS. The major constituents of the oil of S. officinalis were α-thujone, 1,8-cineole, camphor, borneol and β-pinene, whereas those of S. triloba were α-thujone, 1,8-cineole, camphor, and β-caryophyllene. The essential oils of both species exhibited remarkable bacteriostatic and bactericidal activities against Bacillus cereus, Bacillus megatherium, Bacillus subtilis, Aeromonas hydrophila, Aeromonas sobria, and Klebsiella oxytoca. Moreover, the essential oil of S. triloba efficiently inhibited the growth of Staphylococcus aureus. S. aureus and A. hydrophila growth were drastically reduced even in the presence of 0.05 mg/ml of the essential oil of S. triloba.     

Inhibitory effect of Turkish Rosmarinus officinalis L. on acetylcholinesterase and butyrylcholinesterase enzymes

In the current study, we have tested acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity of the petroleum ether, ethyl acetate, chloroform, and methanol extracts, rosmarinic acid as well as the essential oil obtained from Rosmarinus officinalis L. growing in Turkey by a spectrophotometric method of Ellman using ELISA microplate-reader at 0.2, 0.5, and 1.0 mg/mL concentrations. In addition, quantification of rosmarinic acid, a common phenolic acid found in rosemary, was carried out by reversed-phase HPLC in the methanolic extract of the plant, which was found to have 12.21 ± 0.95% (122.1 ± 9.5 mg/g extract) of rosmarinic acid. Rosmarinic acid was also tested for its AChE and BChE inhibitory effect and found to cause 85.8% of inhibition against AChE at only 1.0 mg/mL. Besides, the essential oil was analyzed by GC–MS technique, which was shown to be dominated by 1,8-cineol (44.42%) and followed by α-pinene (12.57%).     

Comparison of essential oil compositions of Salvia mirzayanii obtained by supercritical carbon dioxide extraction and hydrodistillation methods

Essential oil of Salvia mirzayanii cultivated in Iran was obtained by hydrodistillation and supercritical (carbon dioxide) extraction methods. The oil was analysed by capillary gas chromatography using flame ionization and mass spectrometric detections. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters such as pressure, temperature, modifier volume and extraction times (dynamic and static) on the supercritical fluid extraction (SFE) of S. mirzayanii oil were investigated. The results showed that, under a pressure of 35.5 MPa, temperature of 35 °C, 6% methanol, dynamic extraction time of 50 min and static extraction time of 30 min, extraction was more selective for the linalyl acetate. Thirty four compounds were identified in the hydrodistilled oil. The major components of S. mirzayanii were linalyl acetate (7.6%), 1,8-cineole (8.0%), linalool (9.0%) and 8-acetoxy linalool (11.0%). However, by using supercritical carbon dioxide in optimum conditions, only three components contain more than 63% of the oil. The yield of the obtained oil based on hydrodistillation was 2.20% (v/w). Extraction yield based on the SFE varied in the range of 1.50–9.67% (w/w) under different conditions. The results revealed that, in Iranian S. mirzayanii oil, linalyl acetate is a major component.     

Composition of rosemary essential oil (Rosmarinus officinalis) as affected by drying method

The influence of the drying method on volatile compounds of Rosmarinus officinalis was evaluated. The drying methods tested were convective (CD) and vacuum-microwave (VMD), as well as a combination of convective pre-drying and VM finish-drying (CPD–VMFD). Rosemary drying kinetics was described by a simple exponential model for CD and VMD, while VMFD kinetics consisted of two periods: linear until a critical point and exponential beyond that point. Volatile compounds of rosemary samples were extracted by steam-hydrodistillation and analyzed by GC–MS. Thirty-four compounds were tentatively identified, with α-pinene, bornyl acetate, camphene and 1,8-cineole being the major components. The total volatiles concentration of fresh rosemary (135 g kg⁻¹) decreased considerably during both CD (87.2 g kg⁻¹) and VMD (61.9 g kg⁻¹). CPD–VMFD was the best option for drying rosemary because the time required was relatively short (30 min), and the aroma quality was good according to both instrumental (100 g kg⁻¹) and sensory analyses.     

Analysis of the anti-inflammatory properties of Rosmarinus officinalis L. in mice

The aim of this study was to investigate the anti-inflammatory effects of the crude extract (CE) of Rosmarinus officinalis L. its derived fractions: hexane (HEX), ethyl acetate (AcOEt), and ethanolic (ET), and isolated compounds: carnosol, betulinic acid and ursolic acid, in the mouse pleurisy model induced by carrageenan. Swiss mice were used in the in vivo experiments. The CE and its derived fractions and isolated compounds inhibited leukocytes, exudation, interleukin-1 beta (IL-1β) and tumour necrosis factor-alpha (TNF-α) levels, myeloperoxidase activity (MPO), and nitrite/nitrate production (NO_x) (p < 0.05). R. officinalis L. showed an important anti-inflammatory activity by inhibition not only of leukocytes and exudation, but also of a pro-inflammatory enzyme and mediators (MPO, NO_x, IL-1β, and TNF-α). The present study showed that carnosol, betulinic acid and ursolic acid compounds could be responsible for this anti-inflammatory effect.     

In vitro antioxidant activities of Rosmarinus officinalis extracts treated with supercritical carbon dioxide

The leaves of Rosmarinus officinalis (rosemary) were subjected to supercritical CO₂ extraction (SFE). Different sources of variability, including location (Izmir, Canakkale and Mersin) and harvesting time (December, March, June and September), were considered. Among active constituents of rosemary, carnosic acid, carnosol and rosmarinic acid were analyzed by HPLC. Variability of the amounts of active constituents appears to be due to different geographical locations of growth and seasonal variations. The levels of the constituents were higher in the months of December 2003 and September 2004. In addition to this, 12 SFE extracts were screened for their radical-scavenging capacities and antioxidant activities by various in vitro assays, namely total phenol assay, DPPH radical-scavenging activity and trolox equivalent antioxidant capacity (TEAC).     

Suppression of LPS-induced inflammatory activities by Rosmarinus officinalis L.

Rosemary (Rosmarinus officinalis L.) has been used in folk medicine to treat headaches, epilepsy, poor circulation, and many other ailments. It was found that rosemary could act as a stimulant and mild analgesic and could reduce inflammation. However, the mechanisms underlying the anti-inflammatory effects of rosemary need more study to be established. Therefore, in this study, the effects of rosemary on the activation of nuclear factor kappa beta (NF-kB) and mitogen-activated protein kinases (MAPKs), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), and cytokine in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were investigated. A methanol extract of rosemary and its hexane fraction reduced NO generation with an IC₅₀ of 2.75 and 2.83 μg/ml, respectively. Also, the methanol extract and the hexane fraction inhibited LPS-induced MAPKs and NF-kB activation associated with the inhibition of iNOS or COX-2 expression. LPS-induced production of PGE₂ and tumour necrosis factor-alpha (TNF-α) were blocked by rosemary. Rosemary extract and its hexane fraction are important for the prevention of phosphorylation of MAPKs, thereby blocking NF-kB activation, which in turn leads to decreased expression of iNOS and COX-2, thus preventing inflammation.     

Composition and biological activities of the essential oil from Schisandra chinensis obtained by solvent-free microwave extraction

Applicability of solvent-free microwave extraction (SFME) for extraction of the fruits of Schisandra chinensis essential oil was examined; the composition and antioxidant activities and antibacterial activities of the essential oil were assessed in vitro. An orthogonal experiment (L₉ (3)⁴) was applied to optimize the extraction process. The optimum conditions were: extraction time, 45 min; microwave power, 800 W; diameter of powder particles, 0.25 mm; and proportion of water pretreatment, 30%. Under these conditions, the extraction yield was 1.75%. Thirty-five compounds, representing 91.12% of the oil, were identified, of which the major ones, ylangene (50.11%), β-himachalene (10.76%)，α-bergamotene (9.52%) and β-Chamigrene (5.41%), accounted for of 75.80% the oil.Antioxidant activity, IC₅₀ value of the essential oil was determined as 3.87 mg/mL by DPPH assay, and the inhibition values of the essential oil at 1.8 mg/mL was 41.88% by β-Carotene–linoleic acid bleaching assay. The essential oil was screened for antibacterial activity against both Gram positive (Staphylococcus epidermidis, Staphylococcus aureus, Bacillus subtilis) and Gram negative (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris) bacteria. The essential oil showed antibacterial effect against all the gram (+) bacteria and gram (−) bacteria tested. These results show that S. chinensis essential oil could be considered as a natural alternative to food antioxidants and preservatives.     

Essential oil composition and antibacterial activity of the grapefruit (Citrus Paradisi. L) peel essential oils obtained by solvent‐free microwave extraction: comparison with hydrodistillation

The chemical composition of the essential oil (EO) obtained by solvent‐free microwave extraction (SFME) and hydrodistillation (HD) from the peel of grapefruit (Citrus Paradisi. L) was analysed by gas chromatography/mass spectrometry (GC/MS). Totally, twenty‐five components were identified in the EO. Limonene was observed as dominant (91.5–88.6%) for two extraction methods, SFME and HD, respectively. β‐Pinene (0.8–1.2%), linalool (1.1–0.7%), α‐terpinene (0.7–1.0%) and the other minor components were also detected. Disc diffusion method was applied to determine the antibacterial properties of the EO. The results showed that the EO of grapefruit peel had a wide spectrum of antimicrobial activities against Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Salmonella typhimurium, Serratia marcescens and Proteus vulgaris, with their inhibition zones ranging from 11 to 53 mm.     

Solvent-free microwave extraction of essential oil from Dryopteris fragrans and evaluation of antioxidant activity

Solvent-free microwave extraction (SFME) of the essential oil from Dryopteris fragrans and its antioxidant activity were investigated. A central composite design combined with response surface methodology was applied to study the influences of extraction time, irradiation power and humidity (proportion of water pretreatment). A maximal extraction yield of 0.33% was achieved under optimal conditions of extraction time 34 min, irradiation power 520 W and humidity 51%. Sixteen compounds, representing 89.65% of the oil, were identified, of which the major ones, (1R,4S,11R)-4,6,6,11-tetramethyltricyclo[5.4.0.0(4,8)]undecan-1-ol (30.49%), 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo[5.3.1.0(4,11)]undec-8-ene (22.91%) and, 1,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethyl-1-naphthalenemethanol (15.11%), accounted for 68.51% of the oil. The antioxidant activity of the essential oil was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene/linoleic acid, and reducing power assay, the IC₅₀ values were 0.19, 0.09 and 0.18 mg/mL, respectively. All these results suggest that SFME represents an excellent alternative protocol for production of essential oils from plant materials.     

Abietane diterpenoids of Rosmarinus officinalis and their diacylglycerol acyltransferase-inhibitory activity

Inhibition of acyl CoA:diacylglycerol acyltransferase (DGAT) has been proposed as one of the drug targets for treating obesity and type 2 diabetes. Bioassay-guided fractionation of the MeOH-soluble extract of Rosmarinus officinalis yielded two new diacylglycerol acyltransferase (DGAT) inhibitory-abietane diterpenoids, 7β-hydroxy-20-deoxo-rosmaquinone (1) and 7β-methoxy-20-deoxo-rosmanol (2), along with six known components, carnosol (3), 7α-methoxyrosmanol (4), 7β-methoxyrosmanol (5), 12-methoxy-canosic acid (6), rosmanol (7), and rosmadial (8). Compounds 1–8 inhibited DGAT1 activity, with the IC₅₀ values ranging from 39.5 ± 0.6 to 144.2 ± 3.1 μM. In particular, carnosol (3), which is one of the major compounds of MeOH-soluble extract of R. officinalis exhibits inhibition of de novo intracellular triacylglycerol synthesis in human hepatocyte HepG2 cells.     

Phytochemical composition and antimicrobial activities of the essential oils from Satureja subspicata Vis. growing in Croatia

The present study describes the phytochemical profile and antimicrobial activity of Satureja subspicata Vis. essential oils, collected in Dalmatia (Croatia). Three samples of essential oils were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC–MS. From the 24 compounds representing 97.47% of the oils, carvacrol (16.76%), α-pinene (13.58), p-cymene (10.76%), γ-terpinene (9.54%) and thymol methyl ether (8.83%) appear as the main components. The oils also contained smaller percentages of myrcene, linalool, β-caryophyllene, limonene, geranyl acetate, 1-Octen-3-ol, nerol, thymol and borneol. Furthermore, antimicrobial activity of the oil was evaluated using agar diffusion and broth microdilution methods. The antimicrobial test results showed that the oils had a great potential antimicrobial activity against all 13 bacteria and 9 fungal strains. Gram-positive bacteria are more sensitive to the investigated oil, with a range of 0.09 to 6.25 μl/ml than Gram-negative bacteria in the range which is significantly higher from 1.56 to 25.00 μl/ml. Results presented here may suggest that the essential oil of S. subspicata possesses antimicrobial properties, and is therefore a potential source of antimicrobial ingredients for the food and pharmaceutical industry.     

Antioxidative activity of Rosmarinus officinalis L. essential oil compared to its main components

This study was designed to examine the in vitro antioxidant activities of Rosmarinus officinalis L. essential oil compared to three of its main components (1,8-cineole, α-pinene, β-pinene). GC–MS analysis of the essential oil resulted in the identification of 19 compounds, representing 97.97% of the oil, the major constituents of the oil were described as 1,8-cineole (27.23%), α-pinene (19.43%), camphor (14.26%), camphene (11.52%) and β-pinene (6.71%). The oil and the components were subjected to screening for their possible antioxidant activity by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test. In the DPPH test system, free radical-scavenging activity of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were determined to be 62.45% ± 3.42%, 42.7% ± 2.5%, 45.61% ± 4.23% and 46.21% ± 2.24% (v/v), respectively. In the β-carotene bleaching test system, we tested series concentration of samples to show the antioxidant activities of the oil and its main components, whereas the concentrations providing 50% inhibition (IC₅₀) values of R. officinalis L. essential oil, 1,8-cineole, α-pinene and β-pinene were 2.04% ± 0.42%, 4.05% ± 0.65%, 2.28% ± 0.23% and 2.56% ± 0.16% (v/v), respectively. In general, R. officinalis L. essential oil showed greater activity than its components in both systems, and the antioxidant activities of all the tested samples were mostly related to their concentrations. Antioxidant activities of the synthetic antioxidant, ascorbic acid and BHT, were also determined in parallel experiments as positive control.     

Extraction of phenolics and essential oil from dried sage (Salvia officinalis) using ethanol–water mixtures

Effects of particle size, temperature, contact time, solvent-to-sage ratio and the ethanol–water ratio on the extraction of the active compounds rosmarinic acid, carnosic compounds and essential oil from dried sage (Salvia officinalis) were studied. Optimal extraction conditions giving highest yield of all three active compounds were particle diameter 1 mm, extraction temperature 40 °C, solvent-to-sage ratio of 6:1 and 55–75 wt% ethanol for up to 3 h. This gave an extract equivalent to 14.9% of dry sage, containing 6.9% rosmarinic acid (55% recovery), 10.6% carnosic compounds (75% recovery) and 7.3% essential oil (42% recovery). Scale up of the process by a factor of 100 demonstrated that the optimised laboratory scale process can be carried out without any loss of efficiency at an industrial scale.     

Antimicrobial activity and chemical composition of Origanum glandulosum Desf. essential oil and extract obtained by microwave extraction: Comparison with hydrodistillation

Origanum glandulosum Desf. essential oils obtained by hydrodistillation (HD), solvent-free microwave extraction (SFME) and the extract obtained by microwave-assisted extraction (MAE) were investigated by capillary gas chromatography and gas chromatography/mass spectrometry. The main components of both oils obtained by HD and SFME were thymol (41.6–81.1%) followed by γ-terpinene (27.0–3.1%), p-cymene (17.1–4.0%) and carvacrol (2.2–4.4%), respectively. In the same way, thymol (65.4%), γ-terpinene (13.1%), p-cymene (7.2%) and carvacrol (3.5%) were the main components of the extract obtained by hexane microwave extraction. The SFME method was most selective for the extraction of thymol. The examination of the antimicrobial activity of both essential oils against 10 bacteria, two yeasts and four moulds revealed that O. glandulosum oil is more antifungal than antibacterial. To our knowledge, the antifungal activity of the O. glandulosum oil obtained by HD and both antimicrobial and antifungal activities of O. glandulosum SFME oil were not yet reported. Our study suggests that O. glandulosum essential oil has the potential to be used as a food preservative and to prevent the growth of nosocomial bacteria.     

Composition and biological activities of essential oils from four Heracleum species

The composition of essential oils from aerial parts of Heracleum persicum, a widely used medicinal plant, and three other Heracleum species growing wild in Iran were analysed by GC and GC–MS. Myristicin (53.6%), (E)-anethole (25.0%), hexyl butanoate (29.7%) and elemicin (41.1%) were the major compounds of Heracleum pastinacifolium, H. persicum, Heracleum rechingeri and Heracleum transcaucasicum, respectively. Cytotoxic activity assessed on three human cancer cell lines (HeLa, LS180 and Raji), showed that essential oils from H. transcaucasicum (IC₅₀ values; 0.362–0.594 mg/ml) followed by H. pastinacifolium (0.497–1.398 mg/ml) had moderate antitumoral activities. In the DPPH radical scavenging assay, H. pastinacifolium and H. persicum oils showed the highest activities with IC₅₀ values of 7.3 and 7.4 mg/ml, respectively. Antioxidant activity correlated well with the total phenolic content of the oils. None of the essential oils showed significant antimicrobial activities.     

Supercriticial fluid extraction of flavors and fragrances from Hyssopus officinalis L. cultivated in Iran

Hyssopus officinalis L. (hyssop) as a food ingredient has its own importance in flavor industry and also in sauce formulations. Supercritical fluid extraction (SFE) of hyssop, cultivated in Iran, was performed at various pressures, temperatures, extraction (dynamic and static) times and modifier (methanol) concentrations using an orthogonal array design with an OA₂₅(5⁵) matrix conditions. Pressure, temperature and modifier in the SFE system influenced the extraction yield. Also, the composition of the extracted oils was greatly impacted by the operating conditions. Main components of the extracts under different SFE conditions were sabinene (4.2–17.1%, w/w), iso-pinocamphene (0.9–16.5%) and pinocamphene (0.7–13.6%). The extraction of sabinene, for example, was favored at 100 atm, 55 °C, 1.5% (v/v) methanol, 30 min dynamic time and 35 min static time. Use of SFE under different conditions can allow targeting the extraction of different constituents.