Bioactivity of solanesol extracted from tobacco leaves with carbon dioxide–ethanol fluids

The central composite design combined with response surface methodology was used to optimal operating parameters of ethanol-modified supercritical CO2 extraction and evaluate the effects of operating parameters on crude-solanesol yield and extract anti-free-radical activity (DPPH radical scavenging activity). The results show that pressure, temperature and time appeared independent and interactive effects on the crude solanesol yield as well as the extract anti-free-radical activity. The optimal conditions for crude-solanesol yield were 45 °C, 38 MPa and 2.6 h, while that for the extract anti-free-radical activity 47 °C, 36 MPa and 2.5 h. Under the optimal conditions, the highest solanesol extracted could arrived at 3.74 wt% with 52.3 wt% purity (96.8% extraction ratio), and the maximal extract anti-free-radical activity 57.49%. Meanwhile, it was found that the extract anti-free-radical activity was correlated very well with the crude solanesol yield, resulting in model with high coefficient of determination (R2 = 0.946). The research demonstrates that ethanol-modified supercritical CO2 extraction conducted by the central composite design combined with response surface methodology, which could produce high crude solanesol yield with high quality as well high level of bioactivity, is a prospective alternative to the traditional heat-reflux extraction.