Iridoid and aromatic glycosides from Scrophularia ningpoensis HEMSL. and their inhibition of [Ca2+]i increase induced by KCl

Bioassay-guided fractionation of EtOH extract of the roots of Scrophularia ningpoensis HEMSL. resulted in the isolation of three new iridoid glycosides, i.e. 6 ''-O-caffeoylharpagide (1), 6 ''-O-feruloylharpagide (2), and 6 ''-O-beta-glucopyranosylharpagoside (3), and five new aromatic glycosides, i.e., 2-(3-hydroxy-4-methoxyphenyl)ethyl O-alpha-arabinopyranosyl-(1 -> 6)-O-alpha-rhamnopyranosyl-(1 -> 3)-O-beta-glucopyranoside (4), phenyl O-beta-xylopyranosyl-(1 -> 6)-O-beta-glucopyranoside (5), 3-methylphenyl O-beta-xylopyranosyl-(1 -> 6)-O-beta-glucopyranoside (6), 6-O-cinnamoyl beta-fructofuranosyl-(2 -> 1)-O-alpha-glucopyranosyl-(6 -> 1)-O-alpha-glucopyranoside (7), and 6-O-feryloyl beta-fructofuranosyl-(2 -> 1)-O-alpha-glucopyranosyl-(6 -> 1)-O-alpha-glucopyranoside (8), together with four known compounds, i.e., 6 ''-O-alpha-D-galactopyranosyl harpagoside (9), 6 ''-O-(p-coumaroyl) harpagide (10), harpagoside (11), and angoroside C (12). Activity of the isolated compounds on [Ca2+](i) increase induced by KCl was evaluated on rat cardiac myocytes using confocal laser scanning microscopy. Iridoid glycosides 1, 10, and 11, and aromatic glycosides 5 and 6 significantly inhibited the increase of [Ca2-](i) induced by KCl at 100 mu M.