Solubility of Carnosic acid and Carnosol from Rosemary Extract in Supercritical CO₂

Klavdija Rižnar,^a Štefan Čelan,^a Mojca Škerget^b and Željko Knez^b*

^a Scientific research centre Bistra Ptuj, Slovenski trg 6, Ptuj 2250, Slovenia
^b University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova 17, Maribor 2000, Slovenia
* Corresponding author: E-mail: zeljko.knez@uni-mb.si, Fax: +386 25 27 774

Abstract
Rosemary leaves extract are known to have significant antioxidant properties and are widely used in foods and nutritional supplements. Compounds responsible for these antioxidant properties are mainly the phenolic diterpenes. The major phenolic diterpenes are carnosic acid and carnosol. Much interest has been focused on the isolation of carnosic acid, due to its wide spectrum of actions and beneficial effects on human health. In this work a natural rosemary extract, containing 73.9% carnosic acid and 14.7% carnosol, was investigated regarding the solubility of carnosic acid and carnosol in supercritical CO₂. The solubility measurements, using a static-analytic method, were performed at temperatures 40, 60 and 80 °C and at pressures ranging from 98 to 402 bar. The Chrastil model was used to correlate the obtained experimental solubility data.

Keywords: Solubility, carbon dioxide, carnosic acid, carnosol, rosemary extract