title: An unprecedented neolignan skeleton from Chimarrhis turbinata.
abstract: A lignan with a new skeleton named chimarrhinin (1) was isolated from an extract of the leaves of Chimarrhis turbinata, a Rubiaceae plant species. (13)C NMR spectrometric techniques including 1D and 2D experiments and HRESIMS provided unequivocal structural confirmation of this new C(6).C(3) skeleton type. The relative configuration of 1 was established by 2D (1)H-H analysis and J couplings, while its conformation was evaluated through molecular modeling using the RM1 semiempirical method, with the aid of coupling constants obtained by NMR analysis. The antioxidant activity of the new derivative 1 and two known and previously isolated phenolic derivatives (2 and 3) was investigated. An IC(50) value of 7.50 ± 0.5 μmol L(-1) was obtained for the new derivative 1, while 2 and 3 showed IC(50) values of 18.60 ± 0.4 and 18.50 ± 0.6 μmol, respectively.
authors.affiliation: Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, São Paulo, Brazil.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Cardoso
authors.forename: Ian
authors.initials: I
authors.lastname: Castro-Gamboa
authors.forename: Giovana M
authors.initials: GM
authors.lastname: Bergamini
authors.forename: Alberto J
authors.initials: AJ
authors.lastname: Cavalheiro
authors.forename: Dulce H S
authors.initials: DH
authors.lastname: Silva
authors.forename: Marcia N
authors.initials: MN
authors.lastname: Lopes
authors.forename: Angela R
authors.initials: AR
authors.lastname: Araújo
authors.forename: Maysa
authors.initials: M
authors.lastname: Furlan
authors.forename: Hugo
authors.initials: H
authors.lastname: Verli
authors.forename: Vanderlan da S
authors.initials: Vda S
authors.lastname: Bolzani
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001938:Brazil; D017705:Lignans / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018515:Plant Leaves / Q000737:chemistry; D019666:Rubiaceae / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D017705:Lignans; C558476:chimarrhinin