Browsing Research articles (Dept of Chemistry) by Author "Ngameni, B."
Now showing items 1-8 of 8
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Mbaveng, A.; Ngameni, B.; Kuete, V.; Simo, I.K.; Ambassa, P.; Roy, R.; Bezabili, M.; Etoa, F.X.; Ngadjui, B.; Abegaz, B.; Meyer, J.J.M.; Lall, N.; Beng, V.P. (Elsevier Ireland Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/506035/description#description, NaN, 2008)[more][less]
Abstract: The aim of this study was to evaluate the antimicrobial activity of the crude extract of the twigs of Dorstenia barteri (DBT) as well as that of four of the five flavonoids isolated from this extract. Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and fungi (four species) were used. The agar disc diffusion test was used to determine the sensitivity of the tested samples while the well micro-dilution was used to determine the minimal inhibition concentrations (MIC) and the minimal microbicidal concentration (MMC) of the active samples. The results of the disc diffusion assay showed that DBT, isobavachalcone (1), and kanzonol C (4) prevented the growth of all the 22 tested microbial species. Other compounds showed selective activity. The inhibitory activity of the most active compounds namely compounds 1 and 4 was noted on 86.4% of the tested microorganisms and that of 4-hydroxylonchocarpin (3) was observed on 72.7%. This lowest MIC value of 19.06 g/ml was observed with the crude extract on seven microorganisms namely Citrobacter freundii, Enterobacter aerogens, Proteus mirabilis, Proteus vulgaris, Bacillus megaterium, Bacillus stearothermophilus and Candida albicans. For the tested compounds, the lowest MIC value of 0.3 g/ml (on six of the 22 organisms tested) was obtained only with compound 1, which appeared as the most active compound. This lowest MIC value (0.3 g/ml) is about 4-fold lower than that of the RA, indicating the powerful and very interesting antimicrobial potential of isobavachalcone (1). The antimicrobial activities of DBT, as well as that of compounds 1, 3, 4, amentoflavone (5) are being reported for the first time. The overall results provide promising baseline information for the potential use of the crude extracts from DBT as well as some of the isolated compounds in the treatment of bacterial and fungal infections. URI: http://hdl.handle.net/10311/234 Files in this item: 2
Antimicrobial activity of the crude.pdf (2.258Mb)license.txt (1.998Kb) -
Kuete, V.; Ngameni, B.; Tsafack, A.M.; Ambassa, P.; Simo, I.K.; Bezabih, M.; Etoa, F.; Ngadjui, BT; Abegaz, B.M.; Beng, V.P. (Pharmacologyonline. http://www.pharmacologyonline.org/, NaN, 2007)[more][less]
Abstract: The crude extract from the twigs of Dorstenia elliptica (DET) as well one of the five compounds isolated from this extract namely O-[3-(2, 2-dimethyl-3-oxo-2H-furan-5-yl)-3- hydroxybutyl]bergaptol (5) were tested for their antimicrobial activity against bacteria and fungi. The Agar disc diffusion test was used to determine the sensitivity of the tested samples while the well micro-dilution was used to determine the minimal inhibition concentrations (MIC) and the minimal microbicidal concentration (MMC) of the active samples. The results of the disc diffusion assay showed that DET prevented the growth of all the 22 tested microbial species while the two tested compounds showed selective activity. At the tested MIC interval ranged from 1.22 to 156.25 μg/ml for the crude extracts and 0.08 to 39.06 μg/ml for the compounds, the activity of DET was noted on 20 of the 22 microbial species. The antimicrobial activities of DET as well as that compound 5 are being reported for the first time. The overall results provide promising baseline information for the potential use of the crude extract in the treatment of bacterial and fungal infections. URI: http://hdl.handle.net/10311/287 Files in this item: 1
ANTIMICROBIAL ACTIVITY OF THE.pdf (4.398Mb) -
Kuete, V.; Metuno, R.; Ngameni, B.; Ngandeu, F.; Bezabih, M.; Etoa, F-X.; Ngadjui, B.; Abegaz, B.; Beng, V. (Elsevier Ltd. www.elsevier.com/locate/sajb, NaN, 2007)[more][less]
Abstract: The crude methanolic extracts from Treculia africana and Treculia acuminata, three compounds isolated from T. africana and identified as, Phyllocoumarin (1), Catechin (2) and 6, 9-dihydroxy-megastigmane-3-one (3), four compounds namely 2, 3, 2,3-dihydroxypropyl-heptadecanoate (4), and Ferulic acid (5) isolated from T. acuminata were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gramnegative bacteria (12 species) and three Candida species. The micro-dilution method for the determination of the minimal inhibition concentration (MIC) and the Minimal microbicidal concentration (MMC) was used. The MIC values obtained with the crude extracts varied from 78 to 156 à ¼g/ ml against 12 (57.14%) and 20 (95.24%) of the 21 tested microorganisms respectively for T. acuminata and T. africana. Apart from compound 2 that prevented the growth of all the tested microorganisms, other bioactive compounds showed selective activity. The obtained results provide promising baseline information for the potential use of these crude extracts as well as some of the isolated compounds in the treatment of bacterial and fungal infections. URI: http://hdl.handle.net/10311/245 Files in this item: 2
license.txt (1.998Kb) -
Kuete, V.; Metuno, R.; Ngameni, B.; Tsafack, A.M.; Ngandeu, F.; Fotso, G.W.; Bezabih, M.; Etoa, F.; Ngadjui, B.T.; Abegaz, B.M.; Penlap, B.V. (Elsevier Ireland Ltd. www.elsevier.com/locate/jethpharm, NaN, 2007)[more][less]
Abstract: The crude extract from Treculia obovoidea was subjected to purification by repeated chromatography. Eight compounds were isolated from Treculia obovoidea and identified as Psoralen (1), Bergapten (2), 7-methoxycoumarin (3), 7-hydroxycoumarin (4), 4,2 ,4 -trihydroxychalcone (5), 4,2 ,4 -trihydroxy-3-prenylchalcone (6), 3-hydroxy-4-methoxybenzoic acid (7) and O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl) butyl] bergaptol (8). These compounds together with the extract were tested for their antimicrobial activity against Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and three Candida species using micro-dilution methods for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC). The MIC values obtained with the crude extracts varied from 78.12 to 156.25 g/ml against 17 (80.95%) of the 21 tested microorganisms. All the isolated compounds showed selective activity. The antimicrobial activity of this plant as well as that of compounds 6 and 8 is being reported for the first time. The obtained results provide promising baseline information for the potential use of these crude extract as well as some of the isolated compounds in the treatment of bacterial and fungal infections. URI: http://hdl.handle.net/10311/288 Files in this item: 1
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Abegaz, B.M.; Ngadjui, B.T.; Dongo, E.; Ngameni, B.; Nindi, M.N.; Bezabih, M. (Elsevier Science Ltd. www.elsevier.com/locate/phytochem, NaN, 2002)[more][less]
Abstract: The twigs of Dorstenia prorepens furnished the digeranylated chalcone, 5,30-(3,7-dimethyl-2,6-octadienyl)-3,4, 20,40-tetrahydroxychalcone while Dorstenia zenkeri yielded the 30,40-(3-hydroxy-2,2-dimethyldihydropyrano)-4,20-dihydroxychalcone and a bichalcone. 4-Hydroxylonchocarpin was found in both plants. D. prorepens also yielded the known compounds: psoralen, bergapten, b-sitosterol and its D-glucopyranosyl derivative. D. zenkeri yielded p-hydroxybenzaldehyde, dorsmanin A, 4,20,40-trihydroxychalcone and 4,20,40-trihydroxy-30-prenylchalcone. Structures of the new compounds were established by UV, IR, MS and 2-D NMR analysis. URI: http://hdl.handle.net/10311/254 Files in this item: 2
Chalcones and other constituents.pdf (3.760Mb)license.txt (1.998Kb) -
Metuno, R.; Ngandeu, F.; Tchinda, A.T.; Ngameni, B.; Kapche, G.D.W.F.; Djemgou, P.C.; Ngadjui, B.T.; Bezabih, M.; Abegaz, B.M. (Elsevier Ltd. www.elsevier.com/locate/biochemsyseco, NaN, 2007)[more][less]
Abstract: Three species of the genus Treculia namely, Treculia acuminata Baill., Treculia africana Decne ex. Treà ´cul and Treculia obovoidea N.E.Br. grow in the humid rain forest of southwest Cameroon. They are also widely distributed in tropical Africa. T. africana is commonly known as African bread fruit. These three species are commonly used in folk medicine against skin diseases and dental allergies (Berg et al., 1985). The twigs, stem and wood of T. acuminata and the leaves of T. africana, whose chemical constituents are reported herein, were collected from Kumba, Cameroon, in August 2004, and identified by Mr Victor Nana of the National Herbarium in Yaounde, Cameroon where voucher specimens (N 2921/Srf/CAM and 29053/SRF/Cam, respectively) are deposited. URI: http://hdl.handle.net/10311/291 Files in this item: 1
Chemical constituents of Treculia.pdf (2.209Mb) -
Ngameni, B.; Ngadjui, B.; Folefoc, G.; Watchueng, J.; Abegaz, B. (Elsevier Ltd; www.elsevier.com/locate/phytochem, NaN, 2003)[more][less]
Abstract: The twigs of Dorstenia barteri var. subtriangularis yielded three diprenylated chalcones: ( )-3-(3,3-dimethylallyl)-50-(2-hydroxy-3- methylbut-3-enyl)-4,20,40-trihydroxychalcone, (+)-3-(3,3-dimethylallyl)-40,50-[2000-(1-hydroxy-1-methylethyl)-dihydrofurano]-4,20- dihydroxychalcone and 3,4-(600,600-dimethyldihydropyrano)-40,50-[2000,-(1-hydroxy-1-methylethyl)-dihydrofurano]-20-hydroxychalcone for which the names bartericins A, B and C, respectively, are proposed. Stipulin, b-sitosterol and its 3-b-D-glucopyranosyl derivative were also isolated. The structures of these secondary metabolites were determined on the basis of spectroscopic analysis, especially, NMR spectra in conjunction with 2D experiments, COSY, HMQC and HMBC. The structural relationship of bartericins B and C was further established by the chemical cyclization of one to the other. URI: http://hdl.handle.net/10311/258 Files in this item: 2
Diprenylated chalcones and other.pdf (3.479Mb)license.txt (1.998Kb) -
Ngadjui, B.; Watchueng, J.; Keumedjio, F.; Ngameni, B.; Simo, I.; Abegaz, B. (Elsevier Ltd. www.elsevier.com/locate/phytochem, NaN, 2004)[more][less]
Abstract: The twigs of Dorstenia angusticornis and Dorstenia barteri var. subtriangularis yielded 16 compounds. Two novel diprenylated chalcones: 3,50-di-(2-hydroxy-3-methylbut-3-enyl)-4,20,40-trihydroxychalcone, 3, 4-(2,2-dimethylpyrano)-30-(2-hydroxy-3-methylbut- 3-enyl)-20,40-dihydroxychalcone and the known stipulin were isolated from both species. 3-(2-Hydroxy-3-methylbut-3-enyl)- 50-(3,3-dimethylallyl)-4,20,40-trihydroxychalcone and the known compounds: 4-hydroxylonchocarpin, kanzonol B, bartericins A, B, C and 30-(2-hydroxy -3-methylbut-3-enyl)-4,20,40-trihydroxychalcone were isolated from D. barteri while the known compounds: gancaonin Q, paratocarpins C, F, and lupeol were obtained from Dorstenia angusticornis. b-Sitosterol and its b-D-glucopyranoside were isolated from both species. Structures of these secondary metabolites were established using spectroscopic analysis, especially, NMR spectra in conjunction with 2D experiments, COSY, HMQC and HMBC. URI: http://hdl.handle.net/10311/253 Files in this item: 2
license.txt (1.998Kb)Prenylated chalcones, flavone.pdf (3.563Mb)
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