title: Isolation and identification of a red pigment from Allium subgenus Melanocrommyum.
abstract: Three new sulfur-containing compounds were identified in Allium L. species belonging to the subgenus Melanocrommyum as the first examples of sulfur-containing pyrrole derivatives in nature. Some of these species are traditionally used in Southwest and Central Asia as vegetables and herbal drugs. A hypothetical biogenetic scheme is proposed in which L-(+)- S-(3-pyrrolyl)cysteine sulfoxide is enzymically degraded. The resulting 2-lactyl-3'-pyrrolyl sulfoxide is condensed readily to the red pigment 3,3'-dithio-2,2'-dipyrrole. All compounds are chemically unstable, rendering the analysis extremely difficult. Correlation NMR in combination with diffusion NMR allowed the identification of these low molecular weight compounds. For the first time, the compounds involved in the coloring process of Allium plant material have been identified from native plant material.
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Marburg, Germany.
authors.forename: Jarmila
authors.initials: J
authors.lastname: Jedelská
authors.forename: Anja
authors.initials: A
authors.lastname: Vogt
authors.forename: Uwe Michael
authors.initials: UM
authors.lastname: Reinscheid
authors.forename: Michael
authors.initials: M
authors.lastname: Keusgen
mesh_terms: D000490:Allium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010858:Pigmentation; D010860:Pigments, Biological / Q000302:isolation & purification*; D013045:Species Specificity
chemical_list: D010860:Pigments, Biological