Alkaloids from Corydalis decumbens suppress neuronal excitability in primary cultures of mouse neocortical neurons

Eight previously undescribed alkaloids, named corydemine, dihydrocorydemine, corydedine, 8,13-dioxo-14-hydroxytetrahydropalmatine, egenine-alpha-N-oxide, egenine-beta-N-oxide, 7'-O-ethylegenine-alpha-N-oxide, and 7'-O-ethylegenine-beta-N-oxide, together with three known ones, muramine, L-tetrahydropalmatine, and (+)-egenine, were isolated from the bulbs of Corydalis decumbens. Their structures were elucidated by comprehensive spectroscopic analysis and chemical correlation. The isolated compounds were tested for their ability to modulate neuronal excitability in primary cultured neocortical neurons. Four of the compounds, corydemine, dihydrocorydemine, muramine, and L-tetrahydropalmatine, inhibited neuronal excitability with IC50 values of 3.6, 16.7, 13.5 and 14.0 mu M, respectively. (C) 2018 Elsevier Ltd. All rights reserved.