| Autor: |
Oliveira DR; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil., Silva MRD; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil., Chaves OA; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil.; Instituto Oswaldo Cruz (IOC), Fundação Oswaldo Cruz (Fiocruz), Laboratório de Imunofarmacologia, Av. Brasil 4365, Manguinhos, 21040-360, Rio de Janeiro, RJ, Brazil., Castro RN; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil., Oliveira MCC; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil., Braz-Filho R; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil., Carvalho MG; Instituto de Química, Universidade Federal Rural do Rio de Janeiro, Departamento de Química Orgânica, BR 465, Km 07, 23890-000 Seropédica, RJ, Brazil. |
| Abstrakt: |
Phytochemical studies of Cespedesia spathulata (Ochnaceae) leaves using 1H, 13C NMR, and GC-MS have led to the isolation of some metabolites identified for the first time in these species such as cathechin, epicatechin, vitexin, orientin, 6''-O-acetyl-vitexin, sitosterol, stigmasterol, phytol, 4,5-dihydrovomifoliol and a mixture of aliphatic methyl esters, together with ochnaflavone, which was previously isolated from this plant. The modulating activity of some fractions and compounds from Cespedesia spathulata towards tyrosinase enzyme was assayed by spectroscopic and theoretical means/experiments. The dichloromethane fraction (133 μg mL-1) and ochnaflavone (333 μM) inhibited tyrosinase activity by 20 % and 2.0 %, respectively, whereas the ethyl acetate fraction (666 μg mL-1) and ±catechins (catechin and epicatechin - 800 μM) activated it by 104 % and 384 %, respectively. Quantum chemical calculations suggested that catechin and epicatechin are better activators than L-DOPA by interacting with Cu (II) ions. Molecular docking results suggested that hydrogen bonding and hydrophobic interactions are the main binding forces between each tyrosinase activator and the amino acid residues inside the active protein binding pocket. |
