A new phenolic glycoside and saponins from roots of Adenophora triphylla var. japonica

The traditional Chinese medicine, Adenophorae Radix, roots of Adenophora triphylla var. japonica (Campanulaceae) is known to be an antitussive and anti-inflammatory drug used in the treatment of lung disease, and tonics. Previous studies on Adenophora spp., have afforded several phenolic glycosides, triterpenes, steroids, polyhydroxylated pyrrolidine and piperidine alkaloids, and have investigated various biological activities including anti-diabetes, antifungal and antitussive effects. In our continuing studies to find bioactive compound from natural products, we have found that the MeOH extract of A. triphylla var. japonica has anti-obesity effect. The MeOH extract of Adenophorae Radix was consecutively partitioned with hexane, CH₂Cl₂, EtOAc and n-BuOH to give five solvent fractions. Among these fractions, the n-BuOH fraction which showed comparatively higher inhibitory effect on 3T3-L1 adipocyte differentiation than the other fractions was subjected to column chromatographic separation. A new phenolic glycoside, three saponins and two phenolic compounds were isolated from the n-BuOH fraction, and the structures of isolated compounds were identified by comparing their spectral data with literature values. The structure of a new compound, named adenophoroside A, was established as 4-O-α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosyl-3,5-dimethoxy chavicol by spectroscopic analysis. The anti-obesity activity of the isolates was evaluated using 3T3-L1 adipocyte differentiation assay.