Chemical composition and antioxidant activity of ultrasound-assisted extract of the endemic plant Haberlea rhodopensis Friv.

The antioxidant capacity of extracts from leaves of Haberlea rhodopensis Friv. obtained by a highly efficient and simple method of the ultrasound-assisted extraction was investigated. The total polyphenolic content was determined spectrophotometrically using the Folin - Ciocalteu's phenol reagent and the polyphenols composition was analyzed by HPLC method. Antioxidant activity of the extract was evaluated as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) cation decolorization activity assays and the ferric reducing/antioxidant power method (FRAP). The total phenolics of the extract were determined to be 148.71 ± 5.33 mg GAE on a dry weight basis. The HPLC analysis showed a large number of flavonoids and phenolic acids present in the ultrasound ethanol extract of H. rhodopensis. Results also revealed that the major flavonoids were luteolin (2730.18 μg/g DW), hesperidin (928.56 μg/g DW) and kaempferol (578.52 μg/g DW), whereas the most abundant phenolic acids identified in the extract were ferulic acid (630.48 μg/g DW) and sinapic acid (580.80 μg/g DW). DPPH(•) and ABTS(•+) values were 0.803 ± 0.007 and 0.769 ± 0.040 mmol TE/g DW, respectively and FRAP values were 1.362 ± 0.05 mmol TE/g DW.