title: Direct and indirect antimicrobial effects and antioxidant activity of Cordia gilletii De Wild (Boraginaceae).
abstract: Cordia gilletii De Wild (Boraginaceae) root bark is traditionally used in Democratic Republic of Congo (DRC) for the treatment of various disorders, including malaria, diarrhea, wounds and skin diseases; part of these activities may rely on antimicrobial and antioxidant properties. Successive extracts of root barks powder with n-hexane, dichloromethane, ethyl acetate, methanol and water were tested for antimicrobial activity, both direct and indirect (antibiotic resistance reversal), against 10 strains of bacteria and 1 strain of fungi by broth microdilution and agar diffusion methods. The eventual synergy between plant extracts and antibiotics was investigated by the determination of the fractional inhibitory concentration index (FIC index). The methanol extract showed direct antimicrobial activity against all tested microorganisms with minimum inhibitory concentrations (MIC) ranging between 125 and 1000 microg/ml, whereas the ethyl acetate and the dichloromethane extracts showed activity on four and three strains, respectively. 200 microg/ml of n-hexane and dichloromethane extracts decreased the MICs of penicillin and streptomycin 4-64-fold for methicillin-resistant Staphylococcus aureus. A synergistic effect was found between the methanol extract and tetracycline, whereas additive effects were observed for the other combinations tested. The methanol and dichloromethane extracts showed the greater antioxidant activity by scavenging the free radical DPPH with IC(50) values of 3.2 and 8.1 microg/ml, respectively. These results support the use of the plant in the treatment of infectious diseases and wounds; they warrant further studies as to the nature of active compounds.
authors.affiliation: Laboratoire de Pharmacognosie, de Bromatologie et de Nutrition Humaine, Institut de Pharmacie, Université Libre de Bruxelles, CP 205/09, Boulevard du Triomphe, 1050 Brussels, Belgium.
authors.forename: P N
authors.initials: PN
authors.lastname: Okusa
authors.forename: O
authors.initials: O
authors.lastname: Penge
authors.forename: M
authors.initials: M
authors.lastname: Devleeschouwer
authors.forename: P
authors.initials: P
authors.lastname: Duez
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D031213:Cordia / Q000737:chemistry*; D015023:Democratic Republic of the Congo; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D016166:Free Radical Scavengers / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D005658:Fungi / Q000187:drug effects / Q000254:growth & development; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D000432:Methanol / Q000737:chemistry; D008752:Methylene Chloride / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
chemical_list: D000890:Anti-Infective Agents; D000975:Antioxidants; D016166:Free Radical Scavengers; D010936:Plant Extracts; D012997:Solvents; D008752:Methylene Chloride; D000432:Methanol