Evaluation of the dietetic and therapeutic potential of a high molecular weight hydroxycinnamate-derived polymer from Symphytum asperum lepech.: Regarding its antioxidant, antilipoperoxidant, antiinflammatory, and cytotoxic properties

A water-soluble hydroxycinnamate-derived polymer (> 1000 kDa) from Symphytum asperum Lepech. (Boraginaceae) strongly reduced the diphenylpicrylhydrazyl radical (IC50 approximate to 0.7 mug/mL) and inhibited the nonenzymatic lipid peroxidation of bovine brain extracts (IC50 approximate to 10 ng). This polymer exhibited only a low hydroxyl radical scavenging effect in the Fe3+-EDTA-H2O2 deoxyribose system (IC50 > 10 mug/mL) but strongly decreased superoxide anion generation in either the reaction of phenazine methosulfate with NADH and molecular oxygen (IC50 approximate to 13.4 mug/mL) or in rat PMA-activated leukocytes (IC50 approximate to 5 mug/mL). The ability to inhibit both degranulation of azurophil granules and superoxide generation in primed leukocytes indicates that the NADPH oxidase responsible for this later effect is inhibited, pointing to the Symphytum asperum polymer as a potent antiinflammatory and vasoprotective agent. At all concentrations tested (0-200 mug/mL), we observed no cytotoxicity on normal human fibroblasts and neither antiproliferative effects nor proliferation activation on neoplastic cells.