title: Isolation and characterization of six labdane diterpenes and one pregnane steroid of Turraeanthus africanus.
abstract: Six labdane diterpene derivatives, named turraeanins F-J (3-6, 8) and epi-turraeanin J (7), and a pregnane steroid derivative named turraeasterodionene (2), were isolated by preparative high performance liquid chromatography together with thirteen known compounds from the Cameroonian medicinal plant Turraeanthus africanus. Their structures were elucidated by means of nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry in conjunction with the published data for the analogs, as well as the fragmentation patterns of each compound. Most of the known compounds were obtained for the first time from this plant. The compounds (2-7) were tested for their antibacterial efficacies against both Gram-positive and Gram-negative bacteria, including some clinically-important Risk group 2 human pathogens. Compound 4 exhibited the most pronounced antibacterial effectiveness comparable to standard reference streptomycin, with more potency against Gram-positive than Gram-negative bacteria. By comparing compounds 3, 4 and 5, a tentative structure-activity relationship could be drawn; selected oxidations at C-16 and C-18 drastically reduced the antibacterial efficacy of the parent compound (4). These results revealed the potential of compound 4 as a suitable antibacterial lead compound that might be used for further development of other derivatives to increase the antimicrobial efficacy.
authors.affiliation: Department of Chemistry, Higher Teachers' Training College, University of Yaoundé I, P.O. Box 47, Yaoundé, Cameroon; Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany.
authors.forename: Laurice Bracine Njanang
authors.initials: LBN
authors.lastname: Chenda
authors.affiliation: Department of Chemistry, Higher Teachers' Training College, University of Yaoundé I, P.O. Box 47, Yaoundé, Cameroon. Electronic address: kfogue@yahoo.com.
authors.forename: Simeon Fogue
authors.initials: SF
authors.lastname: Kouam
authors.affiliation: Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Lamshöft
authors.affiliation: Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany.
authors.forename: Souvik
authors.initials: S
authors.lastname: Kusari
authors.affiliation: Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany.
authors.forename: Ferdinand Mouafo
authors.initials: FM
authors.lastname: Talontsi
authors.affiliation: Department of Organic Chemistry, University of Yaoundé, B.P. 812, Yaoundé, Cameroon.
authors.forename: Bonaventure Tchaleu
authors.initials: BT
authors.lastname: Ngadjui
authors.affiliation: Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund, Otto-Hahn-Str. 6, D-44221 Dortmund, Germany. Electronic address: m.spiteller@infu.tu-dortmund.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Spiteller
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D004224:Diterpenes / Q000737:chemistry* / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D029582:Meliaceae / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D011278:Pregnanes / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004224:Diterpenes; D011278:Pregnanes
keywords: Antibacterial; High-resolution mass spectrometry; Labdane diterpenoids; Meliaceae; Pregnane steroid; Turraeanthus africanus