Comparisons between Hydro and Steam Distillation Processes to Extract Prunella Vulgaris Volatile Compounds, and their Anti-oxidative Activities

Abstract

Objective The aim is to verify our earlier suggestion which accounted for the dynamics of volatile compounds extraction from the herb Prunella vulgaris (PV) using steam distillation. Then, the anti-oxidative property of PV is explored.
 Methods Because we suggested earlier that the inefficient extraction using steam distillation was due to the obstruction of a mass of herb in the steam flow path, we used hydro distillation which tried to eliminate this obstacle. We used GC-MS to characterize the volatile compounds extracted, and thus compare the extraction efficiency. Then, treating the cancer cells from the SCC154 cell-line with the distillate, the cancer cell cytotoxicity was assessed using the colorimetric test reagent, the Cell Counting Kit-8. To assess the anti-oxidative activity of the PV distillate, Folin-Ciocalteu reagent was used.
 Results We successfully showed that the removal of the obstacle, formed by the mass of herb in the steam flow path, enhanced the efficiency of volatile compound extraction. Also, we showed that the PV distillate did not exhibit anti-oxidative activity.
 Conclusions Hydro distillation is a more efficient method than steam distillation to extract volatile compounds from the PV herb. However, mild heating did not provide sufficient energy to the convection of the boiling water to move the floating herb; the obstacle still existed and limited the efficiency of extraction also. For another issue of the antioxidant effect of the volatile compounds from PV, it was studied using the Folin-Ciocalteu reagent. It showed that the PV volatile compounds did not possess antioxidant property.
 Keywords: Prunella vulgaris, Xia Ku Cao, Chinese Medicine, steam distillation, hydro distillation, anti-oxidative effect