Enrica Tuveri

Chemical characterization and biological activity of essential oils from Daucus carota L. subsp. carota growing wild on the Mediterranean coast and on the Atlantic coast

The essential oils and supercritical CO(2) extracts of wild Daucus carota L. subsp. carota growing spontaneously in Sardinia and in Portugal were investigated. The main components in the Sardinian essential oil of flowering and mature umbels with seeds are beta-bisabolene (17.6-51.0%) and 11-alpha-(H)-himachal-4-en-1-beta-ol (9.0-21.6%); instead, the oils from Portuguese samples are predominantly composed of geranyl acetate (5.2-65.0%) and alpha-pinene (3.5-37.9%). Supercritical extracts contain lower amounts of monoterpenes and higher amounts of sesquiterpene hydrocarbons. Antifungal activities of the Sardinian oils were the highest, particularly for dermatophytes and Cryptococcus neoformans, with MIC values of 0.16-0.64 microL mL(-1).

Chemical and biological comparisons on supercritical extracts of Tanacetum cinerariifolium (Trevir) Sch. Bip. with three related species of chrysanthemums of Sardinia (Italy)

In this manuscript, the authors compare the chemical composition and the biological effects of extracts of some Sardinian plant species: Glebionis coronaria (L.) Spach [=Chrysanthemum coronarium L.], locally known as ‘caragantzu’, Glebionis segetum (L.) Fourr. [=Chrysanthemum segetum L.], known as ‘caragantzu masedu’, and Sardinian endemic species Plagius flosculosus (L.) Alavi and Heywood [=Chrysanthemum flosculosus L.], known as ‘caragantzu burdu’. In addition, the authors compare the pyrethrins contained in these species with an extract of Tanacetum cinerariifolium (Trevir.) Sch. Bip. [=Chrysanthemum cinerariifolium (Trevir.) Vis.], a commercial species rich in pyrethrins. The volatile fractions from chrysanthemum flowers were obtained by supercritical fluid extraction (SFE) with CO2 at 90 bar and 50°C and by hydrodistillation. Pyrethrins were extracted, together with other high molecular mass compounds, by SFE at high pressure, 300 bar and 40°C. The composition of the volatile oils is determined by GC–MS analysis and the amount of pyrethrins by HPLC analysis. Moreover, the antibacterial and antimycotic activities of volatile fractions were investigated in order to compare to their traditional uses.

Antimicrobial activity of Inula helenium L. essential oil against Gram-positive and Gram-negative bacteria and Candida spp.

In this work we report results regarding the in vitro antimicrobial activity of Inula helenium L. dried root extracts obtained by stepwise supercritical fluid extraction (SFE) and by hydrodistillation (HD). Inula helenium L. (Compositae family) is a perennial plant widely occurring in Europe and East Asia. Its oil is one of the richest sources of sesquiterpenoid lactones, which have strong anthelminthic activity and have the potential to induce detoxifying enzymes. Inula helenium L. roots (C-040705130905) were purchased from Minardi (Bagnacavallo-Ravenna, Italy). Supercritical CO 2 extraction was performed in a laboratory apparatus equipped with a 400 cm3 extraction vessel operated in the single-pass mode of passing CO 2 through the fixed bed of charged vegetable particles. Extraction was carried out in a semibatch mode: batch charging of vegetable matter and continuous flow solvent. HD was performed for 4 h in a circulatory Clevenger-type apparatus up to exhaustion of the oil contained in the matrix, which was the same material as used in the SFE.

Isolation of Crithmum maritimum L. volatile oil by supercritical carbon dioxide extraction and biological assays

The chemical composition of the volatile concentrate obtained by supercritical CO2 extraction of aerial parts of Crithmum maritimum L. growing spontaneously in one area of Mediterranean coast (Buggerru, Sardinia Island, Italy) and in two areas of the Atlantic coast (Figueira da Foz and S. Pedro de Moel, Portugal) was investigated by GC and GC-MS. The major oil components identified were p-cymene, β-phellandrene, γ-terpinene, thymol methyl ether and dillapiole. The results showed the presence of two chemotypes of C. maritimum with different dillapiole contents, ranging from 0.2 to 64.2% in Portuguese and Italian plants, respectively. The minimal inhibitory concentration (MIC) and the minimal lethal concentration (MLC) were used to evaluate the antifungal activity of the oils against yeasts and dermatophyte strains. All the oils exhibited significant antifungal activity against dermatophyte strains. The oil with the higher amount of dillapiole (64.2%) was the most active with MIC values ranging from 0.08–0.32 µL mL−1.

Evaluation of Antimicrobial-Antibiofilm Activity of a Hydrogen Peroxide Decontaminating System Used in Dental Unit Water Lines

A dental unit water line (DUWL) equipped with a device designed to automatically and continually flush a bacteriostatic solution of hydrogen peroxide (WHE) and a discontinuous disinfecting system (BIOSTER) was evaluated. In the first instance a preliminary sensitivity test on a large number of microorganisms (bacteria and fungi) was tried with a H2O2 range from 100 to 800 ppm. The bacteria frequently reported in DUWL (including Pseudomonas spp, Streptococcus spp., Staphylococcus spp., E. coli) and some periodontal pathogens showed a minimum inhibitory concentration from 100 to 300 H2O2 ppm (also including M. marinum and C. albicans). However, H2O2 did not show any inhibitory effects against: A. actinomycetemcomitans, C. glabrata C. parapsilos, F. nucleatum, M. micros. In a second step, the DUWL was experimentally infected with S. faecalis, E. coli, P. aeruginosa, S. aureus. After disinfection steps with 3% H2O2, the inhibitory effect on planktonic forms and on sessile biofilm was measured. In a third step, the count of 16S rRNA gene copies by real time PCR at different points of the DUWL described an accrue of bacterial slime in “hot spot” regions characterized by irregular/slow water flux (valves, elbows). However these results suggest that hydrogen peroxide is not only able to inhibit bursts of planktonic bacteria inside the DUWL, but that it could also be effective against sessile biofilm containing heterotrophic microorganisms derived from domestic water line contamination. In addition some oral pathogens could be contaminating and surviving in DUWL.

Comparison of the antimicrobial activity and the essential oil composition of Juniperus oxycedrus subsp. macrocarpa and J. oxycedrus subsp. rufescens obtained by hydrodistillation and supercritical carbon dioxide extraction methods

Different Juniperus species have been used in traditional medicine for centuries as incense, diuretic, remedy for indigestion, and as a tar resource. Juniperus oxycedrus L. belongs to the genus Juniperus. The main use of J. oxycedrus is to prepare the so-called cade oil (also known in pharmacy as juniper tar) by destructive distillation of the branches and wood of the plant. This empyreumatic oil has been widely employed in human and veterinary dermatology to treat chronic eczema and other skin diseases [1], and rectified cade oil is used as a fragrance component in soaps, detergents, creams, lotions, and perfumes [2]. In Tunisia, Juniperus oxycedrus L. comprise two subspecies: Juniperus oxycedrus L. subsp. rufescens (L.K) Deb. which is characterized by a subglobular reddish cone (diameter 3–10 mm) having in their vertex a deep triangular depression. It is widespread in the scrubs and hilly forests especially in the continental localities. J. oxycedrus L. subsp. macrocarpa (S. & SM.) Ball. has voluminous berries (diameter 2.0–2.5 cm) with a reddish brown colour and a slight depression in their summit. It occurs the maritime sand hill and hilly forests [3]. The essential oil of J. oxycedrus is obtained by hydrodistillation of leaves, berries, or wood. Although these oils are usually characterized by a high content of α-pinene, whatever the subspecies, the origin and the extractions process are responsible for the variation in the chemical composition of the essential oils [4]. Previous studies on the chemical composition of the hydrodistilled or supercritical extracted oil leaves (subspecies not specified, ssp. oxycedrus, ssp. badia, and ssp. macrocarpa) have been reported by others [5–9] but up to now no study has been reported on the chemical composition of Juniperus oxycedrus ssp. rufescens. The main methods to obtain essential oils from the plant materials are hydrodistillation (HD), steam distillation (SD), and solvent extraction (SE). Among these methods, HD has been the most common approach to extract the essential oils from the medicinal herbs/plants. However, in order to reduce the extraction time and possibly improve the extraction yield, to enhance the quality of the extraction, new approaches such as microwave-assisted extraction (MAE), pressurized solvent extraction, supercritical fluid extraction, and ultrasound-assisted extraction have also been sought [10, 11]. Supercritical fluid extraction (SFE) has gained increasing attention over the traditional techniques in the recovery of edible and essential oils, as the use of a nontoxic and volatile fluids in SFE such as CO2 protects the extracts from thermal degradation and solvent contamination [12]. In view of the increasing environmental and health concern over the use of organic solvents in the extraction of natural products, there has been growing interest in using supercritical fluids. SFE has been applied to a wide range of nonpolar biologically active constituents from natural products, including essential oils, other flavor and fragrance compounds, medicinal compounds, carotenes, and alkaloids [13, 14].

Comparative analysis of the oil and supercritical CO2 extract of Cymbopogon citratus Stapf.

Dried and ground leaves of lemon grass (Cymbopogon citratus Stapf.) were used as a matrix for supercritical extraction of essential oil with CO2. The objective of this study was to analyze the influence of pressure on the supercritical extraction. A series of experiments were carried out, for 360 min, at 50°C and at different pressures: 90, 100, 110 and 120 bar. Extraction conditions were chosen to maximize citral content in the extract oil. The collected extracts were analysed by GC–MS and their composition was compared with that of the essential oil isolated by hydrodistillation and by steam distillation. At higher solvent density the extract aspect changes passing from a characteristic yellow essential oil to yellowish semi-solid mass because of the extraction of high molecular mass compounds. The optimum conditions for citral extraction were 90 bar and 50°C, at these conditions citral represent more than 68% of the essential oil and the extraction yield was 0.65% while the yield obtained from hydrodistillation was 0.43% with a content of citral of 73%.

Oil Essential Mouthwashes Antibacterial Activity against Aggregatibacter actinomycetemcomitans: A Comparison between Antibiofilm and Antiplanktonic Effects

The aim of this work is to determine the antibacterial activity of three marketed mouthwashes on suspended and sessile states of Aggregatibacter actinomycetemcomitans. The efficacy of two commonly used products in clinical practice, containing essential oils as active ingredients (menthol, thymol, methyl salicylate, and eucalyptol) in association with or without alcohol, has been evaluated in comparison with a chlorhexidine-based mouthwash. The microtiter plate assay, in order to obtain a spectrophotometric measurement of bacterial responses at growing dilutions of each antiseptic, was used for the study. The analysis revealed that a good antibacterial activity is reached when the abovementioned mouthwashes were used at concentration over a 1/24 dilution and after an exposure time of 30 seconds at least. In conclusion, the alcoholic mouthwash appears to have a better biofilm inhibition than its antiplanktonic activity while the nonalcoholic product demonstrates an opposite effect with a better antiplanktonic behavior.

Comparative analysis of the oil and supercritical CO2 extract of Ridolfia segetum (L.) Moris

Supercritical carbon dioxide extraction allowed to obtain the volatile oil of different aerial parts of Ridolfia segetum (L.) Moris. Extraction conditions were as follows: pressure, 90 bar; temperature, 50°C and carbon dioxide flow, Φ = 1.0 kg h−1. Waxes were entrapped in the first separator set at 90 bar and −10°C. The oil was recovered in the second separator working at 15 bar and 10°C. The main components of the flower oil were α-phellandrene (19.4%), terpinolene (20.5%), piperitenone oxide (11.6%), β-phellandrene (8.2%), (Z)-β-ocimene (7.8%), myristicin (7.5%) and p-cymene (4.4%). The comparison with the hydrodistilled (HD) oil reveal that the significative difference was the content of sesquiterpenes which are higher in the supercritical fluid extraction (SFE) products. Collection of samples at different extraction times during supercritical extraction, allowed to monitor the change of the oil composition. Lighter compounds, as hydrocarbon monoterpenes, were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes. The oil from the steams was characterized by a high content of α-phellandrene (12.9%), terpinolene (11.6%), myristicin (11.0%), p-cymene (9.9%), β-phellandrene (8.2%) and (Z)-β-ocimene (6.0%) while the main components of the fruits were found to be myristicin (70.8%), piperitenone oxide (19.9%) and dill apiole (4.2%).

Extraction of Lantana camara essential oil by supercritical carbon dioxide: influence of the grinding and biological activity.

The aim of this study was to produce Lantana camara essential oil by SFE and to study the effect of matrix grinding on the yield and/or composition of the extract. Experiments were carried out on grinding matrices (G) and on not grinding matrices (NG). The extracts were analyzed by GC–MS. A comparison with the oil obtained by hydrodistillation is also given. Finally, the antibacterial and antifungal activity of the various extracts has been assayed.