Bioactive natural products from traditionally used Mexican plants .5. Isolation and structural characterization of new glycolipid ester type dimers from the resin of Ipomoea tricolor (Convolvulaceae)

An extensive structural investigation using high field NMR spectroscopy and FAB mass spectrometry led to the characterization of tricolorins F-J, minor phytogrowth inhibitor glycolipids purified by recycling HPLC from the resins of Ipomoea bicolor Cav. (Convolvulaceae). The potential of various two-dimensional NMR techniques in deducing information about the saccharide substitution and the positions of acylation in these complex oligosaccharides is presented. Tricolorins F and G were found to be trisaccharides forming a macrolactone with the aglycone, (11S)-hydroxyhexadecanoic acid (jalapinolic acid). Tricolorins H, I and J consisted of three ester type dimers of either tricolorins F or G and tricoloric acid C, a new hetero-trisaccharide of jalapinolic acid. (C) 1997 Elsevier Science Ltd.