Sweritranslactone D, a hepatoprotective novel secoiridoid dimer with tetracyclic lactone skeleton from heat-transformed swertiamarin.

Swertia mileensis, known as Qing-Ye-Dan (QYD), has been documented in Chinese Pharmacopoeia to cure hepatitis. Interestingly, its announced main active component, swertiamarin, could not be detected in the decoction, which indicated that the efficacy of QYD might be attributed to heat-transformed products of swertiamarin (HTPS). Further investigation on HTPS led to the isolation of sweritranslactone D (1), a novel secoiridoid dimer possessing a tetracyclic lactone skeleton, with better hepatoprotective activity than N-acetyl-L-cysteine in vitro.