Evolution of the anticholinesterase, antioxidant, and anti-inflammatory activity of Epilobium angustifolium L. infusion during in vitro digestion

Abstract

• The aqueous infusion from fireweed exhibits potent anticholinesterase activity. • In vitro digestion influenced the evolution of anti-AChE activity. • Anti-AChE activity was correlated with total polyphenolic content in digestive fluids. • Antioxidant/reducing methods confirmed the activity of the fireweed infusion. Fireweed ( Epilobium angustifolium L.) has attracted attention due to its numerous biological activities. In the present work, we produced a polyphenol-rich freeze-dried infusion (407.02 ± 7.10 mg GAE/g) in order to measure, for the first time, the evolution of anticholinesterase activity during in vitro digestion. During the ‘gastric’ phase, there was an increase in the inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity followed by a decrease during the ‘small intestinal’ phase. A strong correlation between total polyphenolic content (TPC) and the anticholinesterase activity of the digested fluids was observed (r = 0.90 for TPC/AChE; r = 0.88 for TPC/BChE, p < 0.05). Anti-cyclooxygenase-2 (COX-2) activity was significantly influenced by the digestion phase. Antioxidant/reducing assays (with ABTS and DPPH radicals, linoleic acid, or β-carotene; Cupric Reducing Antioxidant Capacity, Ferric Antioxidant Power, Hydroxyl Radical Antioxidant Capacity; and inhibition of superoxide dismutase, glutathione peroxidase, and glutathione reductase activity) yielded mixed results, but all of these methods confirmed activity during the digestion processes.