Heracleum ternatum from Mt. Durmitor: furanocoumarins, polyphenols and antioxidant activity of leaf and flower extracts

Abstract

In this work, composition and antioxidant activity of dry dichloromethane and methanol extracts of Heracleum ternatum Velen. (Apiaceae) leaves and flowers from Mt Durmitor (Montenegro) were investigated. Using LC-MS, five furanocoumarins were identified in leaf dichloromethane extract (accounting for 23.00 mg/g of dry extract) and eight in flower dichloromethane extract (60.47 mg/g). Dominant in leaf extract was heraclenin (11.64 mg/g), followed by imperatorin (5.90 mg/g), and in flower extract heraclenol (17.55 mg/g), followed by heraclenin (15.04 mg/g). LC-MS analysis revealed eight flavonol glycosides in leaf methanol extract (accounting for 16.18 mg/g of dry extract) and 11 in flower methanol extract (65.82 mg/g), as well as chlorogenic acid in both extracts (4.72 mg/g and trace, respectively). Among detected flavonoids, dominant was quercetin 7-O-rhamnosyl 3-O-glucoside (vincetoxicoside A; 7.95 and 16.77 mg/g), followed by biosides and triosides of kaempferol and methylquercetin. Content of total polyphenols, determined spectrophotometrically using Folin-Ciocalteu reagent, was 87.29 and 98.12 mg of gallic acid equivalents/g of dry methanol extracts. Among methanol extracts, polyphenol richer flower extract showed higher, spectrophotometrically determined, total antioxidant and anti-DPPH activities compared to leaf extract (FRAP=0.80 and 0.65 mmol Fe2+/g; DPPH SC50=83.12 and 90.95 μg/mL). Dichloromethane extracts showed lower anti-DPPH activity (SC50=860.58 and 515.76 μg/mL).