title: Structural and conformational analysis of proanthocyanidins from Parapiptadenia rigida and their wound-healing properties.
abstract: Structure elucidation and conformation analysis of four proanthocyanidins isolated from the bark of Parapiptadenia rigida were performed by two-dimensional NMR spectroscopy, HRESIMS, CD, and molecular mechanics (MM+) force field calculations. The known prodelphinidin, epigallocatechin-(4β→8)-epigallocatechin-3-O-gallate (1) was accompanied by the new epigallocatechin-(4β→8)-4'-O-methylgallocatechin (2), epicatechin-(4β→8)-4'-O-methylgallocatechin (3), and (4α→8)-bis-4'-O-methylgallocatechin (4). Compound 4 was previously published but the earlier structure must presumably be revised to 4'-O-methylgallocatechin-(4α→8)-4'-O-methylepigallocatechin. Conformational studies showed the compact rotamer with B and E rings in quasi-equatorial orientations as the preferred conformation for compounds 1-3, whereas 4 consists of two stable rotamers, each with a quasi-equatorial orientation of ring B and E, respectively. The isolated compounds were studied for their wound-healing effects in a scratch assay and showed promising results.
authors.affiliation: Department of Pharmaceutical Biology and Biotechnology, Albert-Ludwigs-Universität, 79104 Freiburg, Germany.
authors.forename: Cleber A
authors.initials: CA
authors.lastname: Schmidt
authors.forename: Renato
authors.initials: R
authors.lastname: Murillo
authors.forename: Berta
authors.initials: B
authors.lastname: Heinzmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Laufer
authors.forename: Victor
authors.initials: V
authors.lastname: Wray
authors.forename: Irmgard
authors.initials: I
authors.lastname: Merfort
mesh_terms: D001938:Brazil; D018360:Crystallography, X-Ray; D007887:Fabaceae / Q000737:chemistry*; D006801:Humans; D008968:Molecular Conformation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D024301:Plant Bark / Q000737:chemistry; D044945:Proanthocyanidins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D044945:Proanthocyanidins