Gastrolatathioneine, an unusual ergothioneine derivative from an aqueous extract of "tian ma": A natural product co-produced by plant and symbiotic fungus

Gastrolatathioneine (1), an unusual natural product derived from ergothioneine, a fungal amino acid containing an imidazole-2-thione moiety, was isolated from an aqueous extract of "tian ma" (the Gastrodia elata rhizomes). The structure of 1 including the absolute configuration was determined by extensive spectroscopic data analysis, combined with comparison of an experimental circular dichroism spectrum and calculated electronic circular dichroism spectra of stereoisomers, and confirmed by X-ray crystallography. The natural origin of 1 was proved by HPLC-ESIMS analysis of the crude extract. A biogenetic pathway of 1 is proposed on the basis of metabolic post-modification of ergothioneine that is biosynthesized by a symbiotic fungus. The plant and symbiotic fungus are co-producers of I. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.