Supercritical carbon dioxide extraction allowed essential oil of Laurus nobilis to be obtained. Extraction conditions were as follows: pressure, 90 bar; temperature, 50 degrees C; and carbon dioxide flow, Phi = 1.0 kg/h. Waxes were entrapped in the first separator set at 90 bar and -10 degrees C. The oil was recovered in the second separator working at 15 bar and 10 degrees C. The main components were 1,8-cineole (22.8%), linalool (12.5%), alpha-terpinyl acetate (11.4%), and methyleugenol (8.1%). Comparison with the hydrodistilled oil did not reveal any significant difference. Collection of samples at different extraction times during supercritical extraction allowed the change of the oil composition to be monitored. Lighter compounds such as hydrocarbon and oxygenated monoterpenes were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes.

Supercritical carbon dioxide extraction of the leaves and berries of Juniperus oxycedrus L. ssp. oxycedrus, coupled with a two-stage separation, allowed the entrapment of cuticular waxes in the first separator (90 bar, −10°C), thereby allowing pure essential oils to be collected in the second separator (15 bar, 10°C). An extraction carried out on a charge of leaves, at 90 bar and 50°C, gave a yield of 0.8% (w/w) with respect to the charged material, of an oil whose major constituents were germacrene D (15.9%), manoyl oxide (10.2%) and 1-epicubenol (5.4%). The berry oil obtained, at the same pressure and temperature as those for the leaves, gave a yield of 0.45% (w/w) and was composed chiefly of germacrene D (13.8%), α-pinene (10.5%) and β-myrcene (8.1%). At a constant temperature of 50°C, different extraction pressures (80, 90 and 100 bar) were tested in order to obtain the juniper wood essential oil. The extraction yield depended strongly on the extraction pressure, reaching a maximum of 14.7% (w/w) at 100 bar. The main constituents in the extract were δ-cadinene, calamenene, cubenol and 1-epi-cubenol. Hydrodistillation of the wood of J. oxycedrus gave a yield of 11.0% (w/w) of essential oil, with a reduced level of sesquiterpene hydrocarbons and an enhanced amount of oxygenated sesquiterpenes, with respect to the oil obtained by supercritical carbon dioxide extraction. The extracts obtained at different pressures were tested for cytotoxicity, antiviral and antimicrobial activities. The results showed that the extracts of leaves and berries obtained at 200 bar were cytotoxic against different cell lines used to support virus growth. As far as antiviral activiy is concerned, some of the extracts were active against a single-stranded RNA + virus (Poliovirus-1). When tested for antimicrobial activity, none of the samples were shown to be active.

The use of a fibre optic device for spectrophotometric measurements in solution equilibria studies is presented. In particular the precision obtainable with such equipment is evaluated as a function of different experimental conditions, such as path length, averaging time and stirring of the solution. Analysis of 3-hydroxybenzoic acid ionization is presented to assess the results obtained in the study of an equilibrium system.

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