title: Relationships between degree of polymerization and antioxidant activities: a study on proanthocyanidins from the leaves of a medicinal mangrove plant Ceriops tagal.
abstract: Tannins from the leaves of a medicinal mangrove plant, Ceriops tagal, were purified and fractionated on Sephadex LH-20 columns. 13C nuclear magnetic resonance (13C-NMR), reversed/normal high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDT-TOF MS) analysis showed that the tannins were predominantly B-type procyanidins with minor A-type linkages, galloyl and glucosyl substitutions, and a degree of polymerization (DP) up to 33. Thirteen subfractions of the procyanidins were successfully obtained by a modified fractionation method, and their antioxidant activities were investigated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity and ferric reducing antioxidant power (FRAP) method. All these subfractions exhibited potent antioxidant activities, and eleven of them showed significantly different mean DP (mDP) ranging from 1.43±0.04 to 31.77±1.15. Regression analysis demonstrated that antioxidant activities were positively correlative with mDP when around mDP <10, while dropped and then remained at a level similar to mDP = 5 with around 95 µg ml(-1) for DPPH scavenging activity and 4 mmol AAE g(-1) for FRAP value.
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, China; Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR, China; Futian-CityU Mangrove R&D Centre, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China.
authors.forename: Hai-Chao
authors.initials: HC
authors.lastname: Zhou
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR, China; Futian-CityU Mangrove R&D Centre, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China.
authors.forename: Nora Fung-yee
authors.initials: NF
authors.lastname: Tam
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Lin
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, China.
authors.forename: Zhen-Hua
authors.initials: ZH
authors.lastname: Ding
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, China.
authors.forename: Wei-Ming
authors.initials: WM
authors.lastname: Chai
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, China.
authors.forename: Shu-Dong
authors.initials: SD
authors.lastname: Wei
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D010946:Plants, Medicinal / Q000737:chemistry / Q000378:metabolism; D058105:Polymerization; D044945:Proanthocyanidins / Q000737:chemistry* / Q000302:isolation & purification; D012044:Regression Analysis; D043982:Rhizophoraceae / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000975:Antioxidants; D010636:Phenols; D010936:Plant Extracts; D044945:Proanthocyanidins