title: Condensed tannins from Ficus virens as tyrosinase inhibitors: structure, inhibitory activity and molecular mechanism.
abstract: Condensed tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark condensed tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the condensed tannins were studied. The results indicated that the condensed tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark condensed tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the condensed tannins on the diphenolase activity were further investigated. The results indicated that the condensed tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the condensed tannins could chelate the dicopper irons of the enzyme. Moreover, the condensed tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.
authors.affiliation: Key Lab of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Xiao-Xin
authors.initials: XX
authors.lastname: Chen
authors.affiliation: Key Lab of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Key Lab of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Chai
authors.affiliation: Key Lab of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Feng
authors.affiliation: Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, College of Medicine, Xiamen University, Xiamen, China.
authors.forename: Jiang-Xing
authors.initials: JX
authors.lastname: Zhuang
authors.affiliation: Key Lab of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, China.
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
mesh_terms: D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology; D003300:Copper / Q000737:chemistry; D030681:Ficus / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000737:chemistry* / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
chemical_list: D002614:Chelating Agents; D010936:Plant Extracts; D044945:Proanthocyanidins; D003300:Copper; D010088:Oxidoreductases; C412191:monophenolase; D014442:Monophenol Monooxygenase