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 buergeriana MIQ. (Scrophulariaceae), and were characterized as 2- O-acetyl-3,4-di-O-(E). p-methoxycinnamoyl-α-L-rhamnopyranoside 2-O-acetyl-3-O-(E)-p-methoxycinnamoyl-α-L-rhamnopyranoside. 2-O- acetyl-3-O-(Z)-p-methoxycinnamoyl-α-L-rhamnopyranoside and 4-O- (E)-p-methoxycinnamoyl-α-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. (C) 2000 Elsevier Science Ltd.