Phenolic compounds analysis of roots, stalks and leaves of nettle (Urtica dioica L.)

The aim of the research:to determine the qualitative and quantitative composition of phenolic compounds of roots, stalks and leaves of Stinging nettle, which grow in Lithuanian climatic conditions and to evaluate the antioxidant activityof their extracts. The objectives of the research: to select the extraction conditions of phenolic compounds from the samples of roots, stalks and leaves of Stinging nettle. To determine total phenolic compounds, total hidroxycinnamic acid derivativesand total flavonoids content variation in the samples of roots, stalks and leaves of Stinging nettle collected during vegetation period and from various regions of Lithuania. To determinethe antioxidant activityand correlation between the phenolic compounds content in the samples of Stinging nettle and the antioxidant activityof their extracts. To evaluate the qualitative and quantitative composition of phenolic compounds in samples of roots, stalks and leaves of Stinging nettleby UHPLC methodology. The results and conclusions of the research: Total phenolic compounds amount in leaves of Stinging nettle varies from 64,90±0,54 mg/g to114,80±0,80 mg/g during vegetation periodand from 122,95±4,98 mg/g to 154,97±1,68 mg/g in different regions of Lithuania. During vegetation period total flavonoids amount in leaves of Stinging nettle varies from 11,47 ± 0,11 mg/g to 16,27±0,16 mg/g, and in different regions of Lithuania varies from 11,04±0,41 mg/g to 20,16±0,16 mg/g. Total phenolic compounds amount in stalks and roots of Stinging nettle was significantly lower than in leaves. The average amount of hydroxycinnamic acid derivates in leaves –23,87 mg/g, stalks – 3,37 mg/g, roots – 2,74 mg/g. The strongest antioxidant activity was determinedin extracts of leaves, cultivated in Jurbarkas reg., Girdžiai and in Rokiškis town. The strongest correlation was determined between the total amount of phenolic compounds and antioxidant activity, which was measured by FRAP method (0,975, p