Purification of an isoflavonoid 7-O-β-apiosyl-glucoside β-glycosidase and its substrates from Dalbergia nigrescens Kurz

Abstract

A β-glycosidase was purified from the seeds of Dalbergia nigescens Kurz based on its ability to hydrolyse p-nitrophenyl β-glucoside and β-fucoside. This enzyme did not hydrolyze various glycosidic substrates efficiently, so it was used to identify its own natural substrates. Two substrates were identified, isolated and their structures determined as: compound 1, dalpatein 7-O-β-d-apiofuranosyl-(1 → 6)-β-d- glucopyranoside and compound 2, 6,2′,4′,5′-tetramethoxy-7- hydroxy-7-O-β-d-apiofuranosyl-(1 → 6)-β-d-glucopyranoside (dalnigrein7-O-β-d-apiofuranosyl-(1 → 6)-β-d-glucopyranoside). The β-glycosidase removes the sugar from these glycosides as a disaccharide, despite its initial identification as a β-glucosidase and β-fucosidase. © 2005 Elsevier Ltd. All rights reserved.