Extractives of Cercidiphyllum japonicum twigs: isolation and structural elucidation of a new galloylflavonol glycoside, anomeric tannins and flavonoids

Cercidiphyllum japonicum is a deciduous tree that grows in East Asia, where its raw extracts have long been used in folk medicnes to treat various disorders or diseases. In the current work, extracts from C. japonicum twigs were studied for the first time. Seven individual compounds were isolated from the extracts, including a new galloylflavonol glycoside, namely 8-methoxykaempferol-4′-O-galloyl-3-O-α-L-rhamnopyranoside (VII), and six known phenolics [two anomeric galloyltannins (3,4,6-tri-O-galloyl-β-D-glucopyranoside (I) and 2,2′,5-tri-O-galloyl-α/β-D-hamamelose (III)), one anomeric ellagictannin, pedunculagin (II), one flavonol, kaempferol (V) and two flavonol derivatives (kaempferol-3-O-α-L-rhamnopyranoside (IV) and 8-methoxykaempferol (VI))]. Structural elucidation of I–VII was conducted mainly on the basis of their spectroscopic [ultraviolet (UV), infrared (IR), nuclear magnetic resonance (NMR), mass spectrometry (MS)] and physicochemical analysis, as well as by comparison of the analytical data with those in the literature. Compounds I, II, IV and VI have not yet been reported in the genus Cercidiphyllum. Compound VII, a previously undescribed flavonoid, was isolated and elucidated in this work for the first time.