TOTAL PHENOL CONTENT AND ANTIOXIDANT CAPACITY (FRAP) OF URTICA DIOICA L. LEAF EXTRACTS

The aim of our investigations was to compare the total phenol content and antioxidant capacity of stinging nettle (Urtica dioica L.) leaf extracts of different origin. Plant materials were collected in two small regions in Hungary, from each region three collection places were marked. Plant material was compared to commercial teas (drug from the pharmacy, teas from conventional and organic collection). Aqueous and ethanolic (water/ethanol 80/20, v/v) extracts were prepared from the dried leaves and the teas. Total phenol content was measured using the method of Singleton and Rossi. The amount of phenolics ranged from 0,9298 to 2,3846 mg GAE/L in aqueous extracts, and from 0,9649 to 1,9924 mg GAE/L in ethanolic extracts. For determining the antioxidant capacity the FRAP method was used. In the case of aqueous extracts FRAP values ranged from 3,980 to 9,104 mM AA/L in aqueous extracts, while from 1,987 to 5,265 mM AA/L in ethanolic extracts. Total phenol content and antioxidant capacity were significantly higher in the aqueous extracts than in the ethanolic extracts. Markable differences were found also between the collection places and between the commercial teas.