Supercritical fluid fractionation for thymoquinone enrichment in black cumin and savory isolates

Supercritical fluid extraction (SFE) using carbon dioxide has been widely studied as a modern, environmentally friendly method to separate high-added value compounds from plants that allows dissolving preferably the required compounds by changing extraction pressure and temperature. Thymoquinone (TQ) is a pharmacologically significant compound which has potential use for the treatment of colon cancer and inflammatory and asthma diseases. In recent studies [1,2] we have shown that with help of this "green" technology, it is possible to obtain extracts with TQ concentration and biological activity significantly higher than those isolated by conventional separation methods.

This work is focused on the enhancement of TQ concentration in volatile oil using SFE of black cumin (Nigella sativa L.) seeds and savory (Satureja hortensis L.) aerial parts. Black cumin volatile oil is one of the richest sources of TQ contrary to savory, where TQ is the minor component. For both materials the volatile oil composition in extracts was determined using GC-MS and GC-FID. It was found to be strongly influenced by extraction pressure (12–28 MPa) and solvent composition (0–4.7 wt. % of acetone in CO₂). The highest concentration of TQ in savory extracts, 1.5 wt. %, was obtained at 28 MPa, 50°C and 4.7 wt. % of acetone. On the contrary, in case of black cumin, the use of mild conditions (12 MPa, 50°C and 0 wt. % acetone) allowed us to separate the volatile oil from fatty oil (almost 40% of seeds). A high concentration of TQ in the extract, 20 wt. %, was reached using 3.7g CO₂/g seeds.

Acknowledgement: The authors thank the Ministry of Education, Youth and Sports (Project No. 2B06049) and the Czech Science Foundation (Project No. 525/08/1179) for financial support.

References: [1] Kokoska, L. et al. (2008)J. Food Prot. 71:2475–2480.

[2] Pavela, R. et al. (2008) Appl. Entomol. Zool. 43:377–382.