Further Study on Chemical Constituents of Parnassia wightiana Wall: Four New Dihydro-β-agarofuran Sesquiterpene Polyesters

Four new (1-4), along with six known (5-10) dihydro-β-agarofuran sesquiterpene polyesters were isolated from the whole plants of Parnassia wightiana. The new compounds were structurally elucidated through spectroscopic analysis including UV (Ultraviolet Spectrum), IR (Infrared Spectrum), ¹H-NMR (¹Hydrogen-Nuclear Magnetic Resonance), ¹³C-NMR (¹³Carbon-Nuclear Magnetic Resonance), DEPT (Distortionless Enhancement by Polarization Transfer), ¹H-¹H COSY (¹H-¹H Correlation Spectroscopy), HSQC (Heteronuclear Single Quantum Coherence), HMBC (Heteronuclear Multiple Bond Correlation), NOESY (Nuclear Overhauser Enhancement Spectroscopy) and HR-MS (High Resolution Mass Specttrum) and their absolute configurations were proposed by comparison of NOESY spectra and specific optical rotations with those of known compounds and biosynthesis grounds. Compound 2 is the first sesquiterpene alkaloid isolated from this plant. New compounds 1-4 exhibited some cytotoxic activities against NB4, MKN-45 and MCF-7 cells at 20 μM and of which 4 showed the highest activity against NB4 and MKN-45 cells with inhibition rates of 85.6% and 30.5%, respectively.