Antioxidant potential, cytotoxic activity and phenolic content of Clematis flammula leaf extracts

Abstract

Five fractions of Clematis flammula, a plant widely used in the Mediterranean traditional medicine, were isolated from the leaves using a selective extraction procedure and their total antioxidant capacity was measured by both the ABTS and ORAC tests. Furthermore, their capacities to inhibit microsomal lipid peroxidation and to scavenge the hydroxyl radical were assessed. The cytotoxic potential of the crude ethanolic extract and the aqueous fraction obtained from chloroform was also evaluated on three human hepatoma cell lines CHL, PLC and HuH7. The results showed a stronger antioxidant capacity for the two aqueous phases obtained from ethyl acetate and chloroform concerning ABTS (7.9 and 10.5 mmoles Trolox eq/g of plant extract, respectively), ORAC (487 and 387 mmoles Trolox eq/g of plant extract, respectively) and hydroxyl radical scavenging activity (IC50 = 56.5 and 48.4 µg/mL, respectively), compared to their organic counterparts which, however, inhibited microsomal lipid peroxidation more efficiently (IC50 = 390.7 and 523.5 µg/mL, respectively). The ethanol crude extract exhibited a fairly good cytotoxic potential on the two cell lines CHL and PLC (IC50 = 58.5 and 47.3 µg/mL, respectively), in contrast to the aqueous phase obtained from chloroform (IC50 = 457.7 and 304.9 µg/mL, respectively). A positive correlation was also found between the phenol content and the different activities. These results provide experimental support for the therapeutic virtues ofClematis flammula leaf extracts. Key words: Clematis flammula, chloroform extract, antioxidant, caffeic acid, lipid peroxidation.