title: Fractionation of Gallotannins from mango (Mangifera indica L.) kernels by high-speed counter-current chromatography and determination of their antibacterial activity.
abstract: High-speed counter-current chromatography was applied to the separation of gallotannins from mango (Mangifera indica L.) kernels. The kernels were defatted and subsequently extracted with aqueous acetone [80% (v/v)]. The crude extract was purified by being partitioned against ethyl acetate. A hexane/ethyl acetate/methanol/water solvent system [0.5:5:1:5 (v/v/v/v)] was used in the head-to-tail mode to elute tannins according to their degree of galloylation (tetra-O-galloylglucose to deca-O-galloylglucose). The compounds were characterized using liquid chromatography and mass spectrometry in the negative ionization mode. Purities ranged from 72% (tetra-O-galloylglucose) to 100% (octa-O-galloylglucose). The iron binding capacity of gallotannins was dependent on the number of galloyl groups in the molecule, with a larger capacity at lower degrees of galloylation. The minimum inhibitory concentration against Bacillus subtilis did not change among the different gallotannins tested and was in the range of 0.05-0.1 g/L in Luria-Bertani broth but up to 20 times higher in media containing more iron and divalent cations.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, 410 Ag/For Centre, Edmonton, Alberta T6G2P5, Canada.
authors.forename: Christina
authors.initials: C
authors.lastname: Engels
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gänzle
authors.forename: Andreas
authors.initials: A
authors.lastname: Schieber
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects; D003377:Countercurrent Distribution / Q000379:methods*; D047348:Hydrolyzable Tannins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D031022:Mangifera / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047348:Hydrolyzable Tannins; D010936:Plant Extracts