title: Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii.
abstract: The number of fully active antibiotic options that treat nosocomial infections due to multidrug-resistant Acinetobacter baumannii (A. baumannii) is extremely limited. Magnolia officinalis, Mahonia bealei, Rabdosia rubescens, Rosa rugosa, Rubus chingii, Scutellaria baicalensis, and Terminalia chebula plant extracts were previously shown to have growth inhibitory activity against a multidrug-resistant clinical strain of A. baumannii. In this study, the compounds responsible for their antimicrobial activity were identified by fractionating each plant extract using high performance liquid chromatography, and determining the antimicrobial activity of each fraction against A. baumannii. The chemical structures of the fractions inhibiting >40% of the bacterial growth were elucidated by liquid chromatography/mass spectrometry analysis and nuclear magnetic resonance spectroscopy. The six most active compounds were identified as: ellagic acid in Rosa rugosa; norwogonin in Scutellaria baicalensis; and chebulagic acid, chebulinic acid, corilagin, and terchebulin in Terminalia chebula. The most potent compound was identified as norwogonin with a minimum inhibitory concentration of 128 µg/mL, and minimum bactericidal concentration of 256 µg/mL against clinically relevant strains of A. baumannii. Combination studies of norwogonin with ten anti-Gram negative bacterial agents demonstrated that norwogonin did not enhance the antimicrobial activity of the synthetic antibiotics chosen for this study. In conclusion, of all identified antimicrobial compounds, norwogonin was the most potent against multidrug-resistant A. baumannii strains. Further studies are warranted to ascertain the prophylactic and therapeutic potential of norwogonin for infections due to multidrug-resistant A. baumannii.
authors: Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America. yoko.miyasaki@cshs.org
authors: Yoko
authors: Y
authors: Miyasaki
authors: John D
authors: JD
authors: Rabenstein
authors: Joshua
authors: J
authors: Rhea
authors: Marie-Laure
authors: ML
authors: Crouch
authors: Ulla M
authors: UM
authors: Mocek
authors: Patricia Emmett
authors: PE
authors: Kittell
authors: Margie A
authors: MA
authors: Morgan
authors: Wesley Stephen
authors: WS
authors: Nichols
authors: M M
authors: MM
authors: Van Benschoten
authors: William David
authors: WD
authors: Hardy
authors: George Y
authors: GY
authors: Liu
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001578:Benzopyrans / Q000302:isolation & purification / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D004610:Ellagic Acid / Q000302:isolation & purification / Q000494:pharmacology; D047309:Flavones / Q000302:isolation & purification / Q000494:pharmacology; D005960:Glucosides / Q000302:isolation & purification / Q000494:pharmacology; D047348:Hydrolyzable Tannins / Q000302:isolation & purification / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D027826:Rosa / Q000737:chemistry; D031364:Scutellaria baicalensis / Q000737:chemistry; D029766:Terminalia / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D001578:Benzopyrans; D047309:Flavones; D005960:Glucosides; D047348:Hydrolyzable Tannins; D010936:Plant Extracts; C575149:terchebulin; D004610:Ellagic Acid; C076178:chebulagic acid; C055505:norwogonin; C049096:corilagin
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