Antibacterial activities of the methanol extracts, fractions and compounds from Harungana madagascariensis Lam. ex Poir. (Hypericaceae).
BACKGROUND
Harungana madagascariensis Lam. ex Poir. (Hypericaceae) is used in folk medicine to treat a variety of human ailments, mainly antibacterial, antifungal, antiviral and viral infections. In the present study, the methanol extract from the leaves (HML) and bark (HMB) of this plant as well as fractions (HMBa-c), sub-fractions (HMBa1-5) and compounds isolated from HMBa and HMBb namely betulinic acid (1), madagascin (2), ferruginin A (3) and Kaempferol-3-O-β-d-glucopyranoside (4) were tested for their antimicrobial activities against a panel of 28 g-negative bacteria including multidrug resistant (MDR) phenotypes.


METHODS
The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the bark extract whilst the chemical structures of compounds were determined using spectroscopic techniques.


RESULTS
Crude extract HMB together with fraction HMBa and sub-fraction HMBa3 were active on the 28 tested bacterial strains. HML as well as fractions HMBb, HMBc and sub-fractions HMBa1, HMBa2, HMBa4 and HMBa5 were selectively active. MIC values below or equal to 1024µg/mL were recorded with these samples on 92.9% (for HML and HMBa 4), 82.1% (for HMBb), 78.6% (for HMBa2), 50.0% (for HMBa5) and 42.9% (for HMBc) tested bacteria. For crude material, the lowest MIC value below 8µg/mL was obtained with HMB against Escherichia coli ATCC10536 and W3110 strains, and with sub-fraction HMBa3 against Klebsiella pneumoniae K2 strains. MIC values below 10µg/mL were recorded with compound 3 against E. coli ATCC10536, Enterobacter aerogenes ATCC13048 and EA294, Pseudomonas aeruginosa PA01, K. pneumoniae K2 and Kp55 and Enterobacter cloacae BM67.


CONCLUSIONS
Harungana madagascariensis is a potential source of antimicrobial drugs to fight against MDR bacteria. The anthranol 3 is the main antibacterial constituents of the bark of the plant. HMB and compound 3 deserve further investigations to develop natural drug to combat Gram-negative bacteria and otherwise MDR phenotypes.
Department of Biochemistry, Faculty of Science, University of Dschang, Cameroon.
Simplice B
SB
Tankeo
Department of Chemistry, Faculty of Science, University of Dschang, Cameroon.
Francois
F
Damen
Department of Pharmaceutical Sciences, CCS, Universidade Federal de Santa Catarina, Florianópolis 88040-900, Santa Catarina, Brazil.
Louis P
LP
Sandjo
Department of Chemistry, Faculty of Science, Anadolu University, Eskişehir, Turkey.
Ilhami
I
Celik
Department of Chemistry, Faculty of Science, University of Dschang, Cameroon.
Pierre
P
Tane
Department of Biochemistry, Faculty of Science, University of Dschang, Cameroon. Electronic address: kuetevictor@yahoo.fr.
Victor
V
Kuete
D000875:Anthralin / Q000302:isolation & purification / Q000494:pharmacology; D000880:Anthraquinones / Q000302:isolation & purification / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000254:growth & development; D028084:Clusiaceae / Q000737:chemistry*; D024901:Drug Resistance, Multiple, Bacterial; D045782:Hemiterpenes / Q000302:isolation & purification / Q000494:pharmacology; D044949:Kaempferols / Q000302:isolation & purification / Q000494:pharmacology; D000432:Methanol / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D053978:Pentacyclic Triterpenes; D008517:Phytotherapy; D024301:Plant Bark; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves; D010946:Plants, Medicinal; D012997:Solvents / Q000737:chemistry*; D014315:Triterpenes / Q000302:isolation & purification / Q000494:pharmacology; D000094062:Betulinic Acid
C586084:3-isopentenyloxyemodin; D000880:Anthraquinones; D000900:Anti-Bacterial Agents; D045782:Hemiterpenes; D044949:Kaempferols; D053978:Pentacyclic Triterpenes; D010936:Plant Extracts; D012997:Solvents; D014315:Triterpenes; D000875:Anthralin; D000432:Methanol; D000094062:Betulinic Acid
Antibacterial; Betulinic acid; Crude extract; Ferruginin A; Kaempferol-3-O-β-D-glucopyranoside; Madagascin; Multi-drug resistance; ciprofloxacin; dimethyl sulfoxide; ferruginin A; madagascin; p-Iodonitrotetrazolium chloride