Abstract
From an aqueous extract of “tian ma” (the steamed and dried rhizomes of Gastrodia elata), ten new compounds gastrodibenzins A−D (1−4) and gastrotribenzins A−F (5−10), along with known analogues (11−20), having structure features coupling between two and three p-hydroxybenzyl-derived units via carbon- and/or ether-bonds, were isolated and characterized by spectroscopic data analysis. Meanwhile, the new compounds 5a, 6a, 8a, 22, and 23, as well as the known derivatives 13a, 14a, 15, 17−21, 24, 25, and p-hydroxybenzyl aldehyde were isolated and identified from a refluxed aqueous solution of p-hydroxybenzyl alcohol. Methylation of 5a and 6a in methanol and ethylation of 6a, 8a, 13a, and 14a in ethanol produced 5 and 6 and 7, 8, 13, and 14, respectively. using ultra-performance liquid chromatography high-resolution electrospray ionization mass spectrometry (UPLC-HRESIMS) analysis of the refluxed solutions of p-hydroxybenzyl alcohol and the refluxed extracts of the fresh G. elata rhizome and “tian ma” extracts indicated consistent production and variation of the dimeric and trimeric derivatives of p-hydroxybenzyl alcohol upon extracting solvents and refluxing time. In various assays, the dimeric and trimeric derivatives showed more potent activities than p-hydroxybenzyl alcohol itself and gastrodin, which are the main known active constituents of “tian ma”. These results revealed for the first time that the more effective dimers and trimers can be produced through condensation of the co-occurring p-hydroxybenzyl alcohol during processing and decocting of the G. elata rhizomes, demonstrating insights into medicinal chemistry behind application protocols of traditional Chinese medicines.Graphic
Highlights
The steamed and dried rhizomes of Gastrodia elata Blume (Orchidaceae) is a precious and important tonic herbal medicine, named “tian ma” in Chinese, having health benefits enhancing strength and virility as well as improving memory and blood circulation [1]
The structure of compound 1 was determined as ethyl 4-hydroxy-5-methoxy-2-(4′-hydroxybenzyl)benzyl ether and named gastrodibenzin A
G. elata rhizomes with H 2O, MeOH, and EtOH for 0.5 h refluxing for 2.0 h, respectively that the main components gastrodin and p-hydroxybenzyl alcohol were less active or inactive as compared with the “tian ma” extracts as well as the dimers and trimers [90, 93, 94]
Summary
The steamed and dried rhizomes of Gastrodia elata Blume (Orchidaceae) is a precious and important tonic herbal medicine, named “tian ma” in Chinese, having health benefits enhancing strength and virility as well as improving memory and blood circulation [1]. We found that several p-hydroxybenzyl-modified gastrodins from the extract could be produced from a coupling reaction of the co-occurring p-hydroxybenzyl alcohol and gastrodin in H2O under refluxing [80] This unraveled production of the new components during processing and decocting of “tian ma” in the classical application protocol. Subsequent UPLC-HRESIMS analysis of the refluxed H2O, MeOH, and EtOH solutions of p-hydroxybenzyl alcohol and the extracts of the fresh G. elata rhizomes and “tian ma” provides insights into medicinal chemistry behind the processing and decocting protocols of TCM.
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