Antimicrobial activity of the methanolic extract and compounds from the stem bark of Drypetes tessmanniana.
OBJECTIVE
To evaluate the antimicrobial activity of the methanol extract from the stem bark of Drypetes tessmanniana, fractions (DTB1-5) as well as compounds [friedelin (2), 3,7-dioxofriedelane (3), 3,15-dioxofriedelane (4), 3beta- O-(E)-3,5-dihydroxycinnamoyl-11-oxo-olean-12-ene (6), and 3beta,6alpha-dihydroxylup-20(29)-ene (7).


METHODS
Agar disc diffusion was used to determine the sensitivity of the above samples, whilst the microdilution method was used for the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentrations (MMC).


RESULTS
The diffusion test showed that the crude extract was able to prevent the growth of all tested organisms. All other samples showed selective activity. The inhibitory effect of the fraction DTB2 was noted on 63.7%, that of DTB1 and DBT3 on 54.6%, whilst DTB4 and DTB5 were active on 9.1% of the 11 tested organisms. The tested compounds prevented the growth of 81.8% of the tested microbial species for compounds 3 and 4, 36.7% for compound 6, and 18.2% for compound 7. The results of the MIC determinations indicated perceptible values for DTB and compound 4 on 81.8% of the tested organisms. For other samples, MICs were detected on 0-63.7%. The lowest MIC value (78.12 microg/mL) for the crude extract and fractions (DTB2) was observed on M. audouinii. The corresponding value for isolated compounds (156.25 microg/mL) was noted with compounds 3 on S. faecalis and 4 on M. audouinii audouinii. The results of the MMC determination suggested that the microbicidal effect of most of the tested samples on the studied microorganisms could be expected.


CONCLUSIONS
The methanol extract from the stem bark of Drypetes. tessmanniana (Euphorbiaceae) as well as some of the isolated compounds might be potential sources of new antimicrobial drugs.
Kuete
Victor
V
Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon. kuetevictor@yahoo.fr
Dongfack
Marlise D J
MD
Mbaveng
Armelle T
AT
Lallemand
Marie-Christine
MC
Van-Dufat
Hanh T
HT
Wansi
Jean-Duplex
JD
Seguin
Elisabeth
E
Tillequin
François
F
Wandji
Jean
J
D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D052978:Disk Diffusion Antimicrobial Tests; D019665:Euphorbiaceae / Q000737:chemistry*; D005658:Fungi / Q000187:drug effects*; D000432:Methanol / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D024301:Plant Bark / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology*; D018547:Plant Stems / Q000737:chemistry*; D012015:Reference Standards
D000890:Anti-Infective Agents; D010936:Plant Extracts; D000432:Methanol