Comparison the Soxhlet and Supercritical Fluid Extraction of Nettle Root (Urtica dioica L.)

The leaves of stinging nettle (Urtica dioica L.) are used for medical purposes since centuries while the nettle roots are applied only in the last decades. According to the latest researches the root of nettle contains many important ingredients, for example scopoletin, sterols, fatty acids, polysaccharides, polyphenols, minerals, etc. The polyphenols have antioxidant effect, reduce the hematological disorders, but also have anti-cancer and anti-bacteriological effects. The H-donating ability expresses the antioxidant activity. In this study two kinds of extraction techniques and three kinds of solvents have been applied. The extraction techniques were: Soxhlet extraction with 96% ethanol, Soxhlet extraction with n-hexane and supercritical fluid extraction (SFE) with CO2. All the measurements and the analysises were repeated three times. Comparing the yields of the three extraction methods it was established that the highest yield value was reached by Soxhlet extraction with ethanol. The Soxhlet extraction and the supercritical extraction has lower yield, the total polyphenol content and the H-donating ability of these extracts were low.