Rehmannins A–D, Anti-inflammatory Carotenoid Pigments from the Fresh Root of Rehmannia glutinosa

High Resolution Image Download MS PowerPoint Slide Four novel carotenoid derivatives, rehmannins A–D ( 1 – 4 ), were isolated from the fresh roots of the traditional Chinese medicinal plant Rehmannia glutinosa . The structures of these new compounds were determined by extensive spectroscopic methods (high-resolution mass spectrometry, NMR, and electronic circular dichroism) and X-ray diffraction analysis. Rehmannins B–D ( 2 – 4 ) possess a novel tricyclic ring system bearing five contiguous stereocenters on the heterocyclic core together with a unique amide group on the long chain, rendering them attractive targets for total synthesis. Furthermore, plausible biosynthetic routes for these metabolites are suggested. Compound 3 exhibited the inhibition of NO secretion in LPS-induced RAW264.7 cells.