Rigenolide A, a new secoiridoid glucoside with a cyclobutane skeleton, and three new acylated secoiridoid glucosides from Gentiana rigescens Franch.

Rigenolide A (1), a new secoiridoid glucoside with a cyclobutane skeleton and three new acylated secoiridoid glucosides, 2'-(2,3-dihydroxybenzoyl)-gentiopicroside (2), 2'-(2,3-dihydroxybenzoyl)-swertiamarin (3), 3'-(2,3-dihydroxybenzoyl)-sweroside (4), along with two noriridoids (7 and 8) and two known secoiridoid glucosides (5 and 6), were isolated from Gentiana rigescens Franch. The structures of new compounds were elucidated by extensive spectroscopic analyses. The isolated compounds were evaluated for DPPH free-radical scavenging activity.