title: Stereoisomeric Composition of Natural Myrtucommulone A.
abstract: Myrtucommulone A (MC A) (1), isolated from Myrtus communis (myrtle), shows the same pharmacological activity for inhibition of inflammation and induction of apoptosis as synthetic MC A, which consists of three stereoisomers, i.e., two enantiomers and one meso form. This led to the question of whether the natural MC A is a pure stereoisomer or a mixture of stereoisomers. The specific rotation and electronic circular dichroism (ECD) data of natural MC A (1) as well as of a pentacyclic derivative 4 revealed that naturally occurring MC A (1) consists of the racemate and the meso form in a 1:1 ratio. A probable precursor of MC A (1), nor-semimyrtucommulone (5), was also isolated from myrtle as a racemate. The absolute configurations of the enantiomers of 1 and 5 were determined using a combination of experimental and quantum-chemical calculated ECD spectra.
authors.affiliation: Institute of Organic Chemistry, Saarland University , Campus C 4.2, 66123 Saarbrücken, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Hans
authors.affiliation: Institute of Organic Chemistry, Saarland University , Campus C 4.2, 66123 Saarbrücken, Germany.
authors.forename: Maël
authors.initials: M
authors.lastname: Charpentier
authors.affiliation: Institute of Inorganic Chemistry, Saarland University , Campus C 4.1, 66123 Saarbrücken, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Huch
authors.affiliation: Institute of Organic Chemistry, Saarland University , Campus C 4.2, 66123 Saarbrücken, Germany.
authors.forename: Johann
authors.initials: J
authors.lastname: Jauch
authors.affiliation: Institute of Organic Chemistry, University of Würzburg , Am Hubland, 97074 Würzburg, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Bruhn
authors.affiliation: Institute of Organic Chemistry, University of Würzburg , Am Hubland, 97074 Würzburg, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bringmann
authors.affiliation: Nees-Institute for Biodiversity of Plants, University of Bonn , Meckenheimer Allee 170, 53115 Bonn, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Quandt
mesh_terms: D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D005858:Germany; D015394:Molecular Structure; D031651:Myrtus / Q000737:chemistry*; D010696:Phloroglucinol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C455139:myrtucommulone A; C455138:semimyrtucommulone; D010696:Phloroglucinol