Abstract

Background/Objectives: Tall Gastrodia Tuber (tuber of Gastrodia elata, Tianma) is an important herb with therapeutic effects on multiple central nervous system diseases. Although some chemical compounds with their bioactivities have been reported, there are still unrevealed bioactive compounds. This study focuses on discovering new compounds with pharmacological effects in Tianma. Methods: Compounds were isolated from ethyl acetate extract of Tianma by column chromatography and semi-preparative HPLC. Their chemical structures were elucidated by spectroscopic analysis including two-dimensional NMR (DEPT90/135, COSY, HSQC, HMBC), HR-ESI-MS, and IR, compared with reported data. Meanwhile, the protective effects against glutamate-induced excitotoxicity of two phenolic glucosides and two rare phenolic nucleosides were screened by a HT-22 cell model. Results: Fourteen compounds were identified, comprising six new natural products and eight known compounds. The six new compounds were named gastrotribenzyloside A (1), gastrotribenzyloside B (2), gastrotribenzyloside C (3), gastrotetrabenzyloside D (4), gastronucleoside B (5) and gastronucleoside C (6). Compounds 1–4 were phenolic glucosides. Compounds 5 and 6 were the first discovery of phenolic nucleosides substituted by multiple benzyl groups in Tianma. A bioactive experiment indicated that the two phenolic glucosides 1 and 2 did not exhibit protective effects against glutamate-induced excitotoxicity of HT-22 cells, while both of the phenolic nucleosides 5 and 11 significantly relieved the cell viability reduction caused by glutamate. Conclusions: Six new phenolic glucosides and phenolic nucleosides are discovered in Tianma. These phenolic nucleosides are potential bioactive components exhibiting cytoprotective effects against excitotoxicity. They deserve further in vivo studies to verify their bioactivity and investigate the mechanism.

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