title: NMR, HPLC-ESI-MS, and MALDI-TOF MS analysis of condensed tannins from Delonix regia (Bojer ex Hook.) Raf. and their bioactivities.
abstract: The structures of the condensed tannins isolated from leaf, fruit, and stem bark of Delonix regia (Bojer ex Hook.) Raf. have been investigated with (13)C nuclear magnetic resonance ((13)C NMR) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. The results showed that these condensed tannins from D. regia possessed structural heterogeneity in monomer units and degree of polymerization. Propelargonidin (PP) and procyanidin (PC) were found in the leaf, fruit, and stem bark of D. regia, while prodelphinidin (PD) was found only in the leaves. The polymer chain lengths of condensed tannins from leaf and fruit organs were detected to be trimers to hexadecamers but from trimers to tridecamers for stem bark. B-type linkages were present in all these compounds. Condensed tannins from different parts of D. regia can be explored as tyrosinase inhibitors and food antioxidants because of their potent antityrosinase and antioxidant activities. The inhibitor concentration leading to 50% enzyme activity (IC(50)) was estimated to be 38 ± 1, 73 ± 2, and 54 ± 1.5 μg/mL for the condensed tannins of leaf, fruit, and stem bark. Condensed tannins extracted from stem bark exhibited the highest antioxidant activity; the DPPH scavenging activity (IC(50)) and the FRAP values were 90 ± 2 μg/mL and 5.42 ± 0.09 mmol AAE/g, respectively.
authors.affiliation: School of Life Sciences, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361005, China.
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Chai
authors.forename: Yan
authors.initials: Y
authors.lastname: Shi
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Feng
authors.forename: Ling
authors.initials: L
authors.lastname: Qiu
authors.forename: Hai-Chao
authors.initials: HC
authors.lastname: Zhou
authors.forename: Zi-Wei
authors.initials: ZW
authors.lastname: Deng
authors.forename: Chong-Ling
authors.initials: CL
authors.lastname: Yan
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007887:Fabaceae / Q000737:chemistry*; D007700:Kinetics; D008279:Magnetic Resonance Imaging; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology; D058105:Polymerization; D044945:Proanthocyanidins / Q000737:chemistry* / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D010936:Plant Extracts; D044945:Proanthocyanidins; D014442:Monophenol Monooxygenase