4-Hydroxybenzyl-substituted amino acid derivatives from Gastrodia elata

Seven new 4-hydroxyben l-substituted amino acid derivatives (1-7), together with 11 known compounds, were isolated from an aqueous extract of the rhizomes of Go,arodia data Blume. Their structures were determined by spectroscopic and chemical methods. Compounds 1-3 are pyroglutamate derivatives containing 4-hydroxybenzyl units at the N atom and 4-7 are the first examples of natural products with the 4-hydroxybenzyl unit linked vici a thioether bond to 2-hydroxy-3mercaptopropanoic acid (4-6) and 2-hydroxy-4-mercaptobutanoic acid (7), which would be biogenetically derived from cysteine and homocysteine, respectively. The structures of 1 and 2 were verified hi synthesis, while the absolute configurations of 4, 5 and 7 were assigned using Mosher 's method based on the MPA determination rule of A5Rs values. The known compound 4-(hydroxymethy0-5-nifrobenzene1,2-diol (8) exhibited activity against Fe2 r--cysteine induced rat liver microsomal lipid peroxidation with 1050 values of 9.99 x 10 6 mon. (C) 2015 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.'s/. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).