Iridoid constituents of Tarenna attenuata.

Members of a rare type of iridoid with two alpha,beta-unsaturated acid units were isolated from the whole plant of Tarenna attenuata, including a new compound, tarennin (1), an extraction artifact, and seven new glucosides, tarenninosides A-G (2-8), together with two known iridoid glucosides, ixoside and 10-methylixoside. The structures of 1-8 were elucidated by analysis of spectroscopic data including HMQC, HMBC, 1H-1H COSY, and ROESY NMR spectra and by comparison with known analogues. Antioxidant and cytotoxic activities were evaluated for these 10 compounds, but none showed positive activity.