Structural Elucidation of an Atropisomeric Entcassiflavan-(4β→8)-Epicatechin Isolated from <i>Dalbergia monetaria</i> L.f. Based on NMR and ECD Calculations in Comparison to Experimental Data
Patrícia Homobono Brito de Moura,
Wolfgang Brandt,
Andrea Porzel,
Roberto Carlos Campos Martins,
Ivana Correa Ramos Leal,
Ludger A. Wessjohann
Affiliations
Patrícia Homobono Brito de Moura
Natural Products Research Institute (IPPN), Center of Health Sciences, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, RJ, Brazil
Wolfgang Brandt
Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry (IPB), Weinberg 3, 06114 Halle, Germany
Andrea Porzel
Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry (IPB), Weinberg 3, 06114 Halle, Germany
Roberto Carlos Campos Martins
Natural Products Research Institute (IPPN), Center of Health Sciences, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, RJ, Brazil
Ivana Correa Ramos Leal
Natural Products and Food Department, Pharmacy Faculty, Center of Health Sciences, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, RJ, Brazil
Ludger A. Wessjohann
Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry (IPB), Weinberg 3, 06114 Halle, Germany
A rare dihydoxyflavan-epicatechin proanthocyanidin, entcassiflavan-(4β→8)-epicatechin, was isolated from Dalbergia monetaria, a plant widely used by traditional people from the Amazon to treat urinary tract infections. The constitution and relative configuration of the compound were elucidated by HR-MS and detailed 1D- and 2D-NMR measurements. By comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra of all 16 possible isomers, the absolute configuration, the interflavan linkage, and the atropisomers could be determined.
