Sesquiterpene lactones and phenolic compounds content in Arnica montana flowers and leaves samples harvested from wild sites in North-East Romania

Our study aimed to assess the phenolic compounds and sesquiterpene lactones (SL) content in the flowers and leaves of Arnica montana collected from wild populations at different altitudes: 5 sites at 800 – 1000 m and 5 sites at 1000 – 1700 m. The dried plant materials were extracted with a mixture of methanol/acetone/water for the extraction of the phenolic compounds. The method from the European Pharmacopoeia [1] was used for the determination of the SLs. The separation and quantification of the phenolic compounds and SLs was performed by HPLC-DAD analysis.

In flowers, the following phenolic compounds were identified: chlorogenic acid, caffeic acid, cynarin and the flavonoids isoquercitrin, apigenin and apigenin-7-O-glucoside. In the leaf samples, we found chlorogenic acid and cynarin, while from the group of flavonoids only apigenin was identified. In both flower and leaf samples, cynarin was the major phenolic acid (4.27 – 9.51 mg/g d.w. in flowers and 6.44 – 8.65 mg/g in leaves), while isoquercitrin was the major flavonoid in flowers (1.66 – 3.90 mg/g). The leaves had fewer flavonoids and in significantly lower amounts. The SLs content in flowers varied from 1.02 to 1.59%, and from 0.31 – 0.51% in the leaves.

Flowers collected at altitudes of 1000 – 1700 m had a higher content of phenolic acids (17.51 – 21.25 mg/g), flavonoids (7.58 – 12.17 mg/g) and SLs (1.36 – 1.59%), compared to the samples from lower altitudes with 11.05 – 21.51 mg/g phenolic acids, 7.58 – 12.17 mg/g flavonoids and 1.02 – 1.40% SLs, respectively. In contrast, the amounts for the bioactive compounds groups were lower in the leaf samples harvested at higher altitudes. The content of phenolic compounds and SLs is similar with literature data [2 – 4]. The variability of the bioactive compounds content may be due to the reaction of the plants to the environmental peculiarities of the sites generated by the altitude gradient (vegetation, phytophagous species, meteorological and climatic factors, soil, and slope).

Acknowledgements: The work was conducted within the Program Partnership in Priority Area – PNII supported byMEN-UEFISCDI, Project No. 74/2014.

Keywords: Altitude gradient, Arnica montana, phenolic acids, flavonoids, sesquiterpene lactones.

References:

[1] European Pharmacopoeia 7.0

[2] Stefanache CP, Peter S, Meier B, Danila D, Tanase C, Wolfram E. Phytochemical composition of Arnicae flos from wild populations in the northern area of the Romanian Eastern Carpathians. Rev Chim 2015; 66: 784 – 787

[3] Aiello N, Bontempo R, Vender C, Ferretti V, Innocenti G, Dall'Acqua S. Morpho-quantitative and qualitative traits of Arnica montana L. wild accessions of Trentino, Italy. Industrial Crops and Products 2012; 40: 127 – 140

[4] [5] Ganzera M, Egger C, Zidorn C, Stuppner H. Quantitative analysis of flavonoids and phenolic acids in Arnica montana L. by micellar electrokinetic capillary chromatography. Anal Chim Acta 2008; 614: 196 – 200