title: Proanthocyanidins: target compounds as antibacterial agents.
abstract: Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.
authors.affiliation: Institute of Analytical Chemistry and Radiochemistry, University of Innsbruck, Innrain 52a, 6020 Innsbruck, Austria.
authors.forename: Robert
authors.initials: R
authors.lastname: Mayer
authors.forename: Guenther
authors.initials: G
authors.lastname: Stecher
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wuerzner
authors.forename: Rolando Colonia
authors.initials: RC
authors.lastname: Silva
authors.forename: Tahira
authors.initials: T
authors.lastname: Sultana
authors.forename: Lukas
authors.initials: L
authors.lastname: Trojer
authors.forename: Isabell
authors.initials: I
authors.lastname: Feuerstein
authors.forename: Christof
authors.initials: C
authors.lastname: Krieg
authors.forename: Gudrun
authors.initials: G
authors.lastname: Abel
authors.forename: Michael
authors.initials: M
authors.lastname: Popp
authors.forename: Ortwin
authors.initials: O
authors.lastname: Bobleter
authors.forename: Guenther Karl
authors.initials: GK
authors.lastname: Bonn
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000187:drug effects; D056604:Grape Seed Extract; D006193:Haemophilus influenzae / Q000187:drug effects; D007709:Klebsiella / Q000187:drug effects; D013058:Mass Spectrometry; D010936:Plant Extracts / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D013291:Streptococcus / Q000187:drug effects; D027843:Vitis / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D010936:Plant Extracts; D044945:Proanthocyanidins