Alkaloids from a Tibetan medicine Meconopsis quintuplinervia Regel

Aim To reinvestigate the chemical constituents of the ethanolic extract of Meconopsis quintuplinervia Regel which is a traditional Tibetan medicine used for treatments of hepatitis, tuberculosis etc.. Methods The compounds were enriched by column chromatography techniques over silica gel, macro porous resin and Sephadex LH-20 absorbents, and finally purified by reverse phase preparative HPLC methods with isocratic mobile phase systems of methanol-H₂O-acetic acid (500∶500∶1) and acetonitrile-H₂O-acetic acid (200∶800∶1). Structural determination of the pure compounds were based on extensive analyses of modern spectroscopic methods including IR, MS, HRMS, 1D- and 2D-NMR spectra. Results Three alkaloids were obtained and their structures were elucidated as norsanguinarine (I), O-methylflavinantine (II) and 6-methoxy-17-methyl-2,3-［methylenebis(oxy)］-morphin-5-en-7-one (III). Conclusion Norsanguinarine (I) was isolated from genus Meconopsis for the first time, and 6-methoxy-17-methyl-2,3-［methylenebis(oxy)］-morphin-5-en-7-one (III) is a new alkaloid named as meconoquintupline.