Neuroprotective phenylpropanoid esters of rhamnose isolated from roots of Scrophularia buergeriana.

Four phenylpropanoid esters of rhamnose, buergerisides A1, B1, B2 and C1 were isolated from roots of Scrophularia huergeriana MIQ. (Scrophulariaceae), and were characterized as 2-O-acetyl-3,4-di-O-(E)-p-methoxycinnamoyl-alpha-L-rhamnopyranosid e, 2-O-acetyl-3-O-(E)-p-methoxycinnamoyl-alpha-L-rhamnopyranoside, 2-O-acetvl-3-O-(Z)-p-methoxycinnamoyl-alpha-L-rhamnopyranosi de and 4-O-(E)-p-methoxycinnamoyl-alpha-L-rhamnopyranoside, respectively. In addition, six known phenylpropanoids were authenticated as: (E)-cinnamic acid, (E)-p-methoxycinnamic acid, (E)-p-methoxycinnamic acid methyl ester, (E)-p-coumaric acid, (E)-caffeic acid, (E)-ferulic acid and a phenylalcohol, 2-(3-hydroxy-4-methoxyphenyl)ethanol. These ten phenylpropanoids all attenuated glutamate-induced neurotoxicity when added to primary cultures of rat cortical cells in a dose-dependent manner. These results demonstrate that phenylpropanoids isolated from S. buergeriana may exert significant protective effects against glutamate-induced neurodegeneration in primary cultures of cortical neurons.