Supercritical CO2 extraction of Marrubium vulgare: intensification of marrubiin†
Supercritical carbon dioxide and Soxhlet extraction were employed for delivering Marrubium vulgare extracts. By varying process temperature and pressure, the impact of different densities of carbon dioxide on the extraction yield and chemical profile of the extracts was investigated. The highest extraction yields of M. vulgare were obtained by supercritical carbon dioxide extraction (3.51%) at 300 bar and 60 °C, while the yield obtained with the Soxhlet extraction was 3.23%. The chemical profiles of these two extracts were significantly different and marrubiin, the most dominant component of supercritical extracts was not present in extracts obtained by this conventional method. This labdane diterpene was the most abundant in extracts obtained at 200 bar and temperatures of 40, 50, and 60 °C (62.60, 68.41, and 71.96%, respectively). For the intensification of marrubiin, supercritical fractions were collected in successive time intervals over the course of the extraction (300 bar/60 °C). It was determined that after 1 h of extraction the highest content of marrubiin (75.14%) can be achieved. The similarities between the obtained extracts were estimated and the correlations to the content of identified lipophilic compounds were established using multivariate data analysis tools.