Two Novel Tetrairidoid Glucosides from Dipsacus asper

[reaction: see text] Two new iridoid glucoside tetramers, dipsanosides A (1) and B (2), the first-reported iridoid tetramers with four glucosides, were isolated from Dipsacus asper. Their structures were determined by analysis of 1D and 2D NMR data as well as by comparison with model compounds. Their cytotoxicities were tested, but neither of them showed obvious activity.