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Biologically active lignans from caulomas (stems) and leaves of Schisandra chinensis were extracted with supercritical carbon dioxide at the pressures 20–27 MPa, temperatures 40, 50 and 60 °C, and solvent-to-feed ratio 36–43. Six major lignans were determined by means of HPLC: schizandrin, gomisin A, deoxyschizandrin, γ-schizandrin, gomisin N and wuweizisu C. At the optimum conditions 27 MPa and 50 °C, the extraction yield of lignans from caulomas was 1.3% dry weight and their content in the extract was higher than 32 wt.%. At the optimum conditions for CO 2 extraction from S. chinensis leaves, 27 MPa and 60 °C, the yield of lignans was 0.22% d.w. and the yield of ( E )-cinnamic acid was 0.18% d.w. Addition of 2–4% ethanol to CO 2 increased the extraction rate but not the final yield of lignans. The solubility of extracted substances in supercritical CO 2 was estimated from their extraction rates.

β-Sitosterol (22,23-dihydrostigmasterol) and scopoletin (7-hydroxy-6-methoxycoumarin) were extracted from roots of stinging nettle ( Urtica dioica L.) with supercritical and liquid CO 2 . Extraction rates were measured for both oleoresin and the individual substances in dependence on extraction conditions. The solvent modified with ethanol (0–9.4 wt.%) was applied at the pressures of 100, 200, 250 and 280 bar and the temperatures of 25, 40 and 60 °C. Extracts were analysed by means of HPLC method. The maximum yields of β-sitosterol and scopoletin were 0.63 and 0.058 mg/g dry mass, respectively. In comparison with the extract obtained with diethyl ether, the maximum yields obtained with CO 2 were at least two times higher for both investigated substances. A model describing the extraction of a solute that is present in two forms, free and interacting with matrix, was applied to interpret the experimental extraction curves.

Chlorophylls and carotenoids were extracted from leaves of stinging nettle ( Urtica dioica L.) with supercritical and liquid CO 2 . The solvent modified with ethanol (0–7 wt.%) was applied at the pressures of 200, 250 and 280 bar and the temperatures of 25, 40 and 60 °C. Extracts were analysed by means of HPLC and RP-HPLC methods. The maximum yields of chlorophyll a, chlorophyll b, β-carotene and lutein obtained with CO 2 were 73, 100, 24 and 39 mg/100 g dry matter, respectively. In comparison with the extract obtained using conventional solvents, the maximum yields obtained with CO 2 were similar for carotenoids, higher for chlorophyll b and lower for chlorophyll a. Chlorophyll a partially degraded in the extractor to the more soluble pheophytin a; the extent of carotenoid degradation was much lower than that of chlorophylls. The degradation was substantially reduced by addition of a small amount of antioxidant to the solvent. Extraction rates in dependence on extraction conditions were measured both for individual pigments and for oleoresin. A model describing the extraction of a solute that is present in two forms, free and interacting with matrix, was applied to interpret the experimental extraction curves. A loss of volatile substances from the ground nettle leaves and a decrease in β-carotene content from 24 to 18 mg/100 g dry matter was observed during the period of 155 days between the first and last experimental run.