ABSTRACT
Root cultures of Swertia chirata (Gentianaceae) were grown with supplements of [1-13C]glucose, [U-13C6]glucose or [carboxy-13C]shikimic acid. 1,3,5,8-Tetrahydroxyxanthone was isolated and analysed by quantitative NMR analysis. The observed isotopomer distribution shows that 1,3,5,8-tetrahydroxyxanthone is biosynthesized via a polyketide-type pathway. The starter unit, 3-hydroxybenzoyl-CoA, is obtained from an early shikimate pathway intermediate. Phenylalanine, cinnamic acid and benzoic acid were ruled out as intermediates.
Subject(s)
Gentianaceae/metabolism , Phenylalanine/metabolism , Xanthenes/metabolism , Xanthones , Acyl Coenzyme A/metabolism , Benzoic Acid/chemistry , Benzoic Acid/metabolism , Carbon Isotopes , Cinnamates/chemistry , Cinnamates/metabolism , Glucose/analogs & derivatives , Glucose/metabolism , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Phosphoenolpyruvate/metabolism , Plant Roots/growth & development , Plant Roots/metabolism , Shikimic Acid/analogs & derivatives , Shikimic Acid/metabolism , Sugar Phosphates/metabolism , Xanthenes/chemistry , Xanthenes/isolation & purificationABSTRACT
The seeds of Lepidium sativum afforded five new dimeric imidazole alkaloids lepidine B, C, D, E and F in addition to the known imidazole alkaloid lepidine and two new monomeric imidazole alkaloids semilepidinoside A and B. Their structure were elucidated on the basis of spectroscopic evidence.
