title: Antibacterial xanthones from Kielmeyera variabilis mart. (Clusiaceae).
abstract: The bioassay-guided fractionation of stems from Kielmeyera variabilis, traditionally used in Brazilian folk medicine, yielded assiguxanthone-B (1), kielcorin (4), 2,5-dihydroxybenzoic acid (3), and a mixture of xanthones containing assiguxanthone-B (1) and 1,3,5,6-tetrahydroxy-2-prenylxanthone (2) (1:1 w/w). The xanthone mixture inhibited Staphylococcus aureus and Bacillus subtilis at a concentration of 6.25  g/ml. When tested alone, the minimal inhibitory concentration of assiguxanthone-B was 25  g/ml against B. subtilis. Kielcorin and 2,5-dihydroxybenzoic acid were inactive against both strains. None of the fractions was active against Escherichia coli or Pseudomonas aeruginosa. Viable cells of S. aureus were reduced by a 1-3 log CFU/ml within 12 h after exposure of one to eight times the MIC of the xanthone mixture. It is not known whether the tetrahydroxy-2-prenylxanthone or other components of the xanthone mixture are responsible for the main antibacterial activity or whether additive or synergistic action is involved
authors.affiliation: Departamento de Farmácia e Farmacologia, Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Lucimar
authors.initials: L
authors.lastname: Pinheiro
authors.forename: Celso Vataru
authors.initials: CV
authors.lastname: Nakamura
authors.forename: Benedito Prado
authors.initials: BP
authors.lastname: Dias Filho
authors.forename: Antonio Gilberto
authors.initials: AG
authors.lastname: Ferreira
authors.forename: Maria Claudia Marx
authors.initials: MC
authors.lastname: Young
authors.forename: Diógenes Aparicio Garcia
authors.initials: DA
authors.lastname: Cortez
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects; D028084:Clusiaceae; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects; D013997:Time Factors; D014966:Xanthenes / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D014966:Xanthenes