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.
An Acad Bras Cienc. 2021 Sep 3;93(4):e20200443. doi: 10.1590/0001-3765202120200443. eCollection 2021.
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.
利用 1H、13C NMR 和 GC-MS 对山铜木（Ochnaceae）叶的植物化学研究导致分离出一些首次在这些物种中鉴定出的代谢物，如儿茶素、表儿茶素、牡荆素、荭草苷、6'-O-乙酰牡荆素、豆甾醇、β-谷甾醇、植醇、4,5-二氢沃布丰醇和混合脂肪族甲酯，以及之前从该植物中分离出的ochnaflavone。通过光谱和理论/实验手段测定了山铜木叶的一些馏分和化合物对酪氨酸酶的调节活性。二氯甲烷馏分（133 μg mL-1）和 ochnaflavone（333 μM）分别抑制酪氨酸酶活性 20%和 2.0%，而乙酸乙酯馏分（666 μg mL-1）和 ±儿茶素（儿茶素和表儿茶素 - 800 μM）分别激活 104%和 384%。量子化学计算表明，儿茶素和表儿茶素通过与 Cu（II）离子相互作用，比 L-DOPA 更能激活酪氨酸酶。分子对接结果表明，氢键和疏水相互作用是每种酪氨酸酶激活剂与活性蛋白结合口袋内氨基酸残基之间的主要结合力。
