Browsing Chemistry by Author "Bezabih, M."
Now showing items 1-14 of 14
-
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
-
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) -
Mutanyatta, J.; Bezabih, M.; Abegaz, B.; Dreyer, M.; Brun, R.; Kocher, N.; Bringmann, G (Elsevier Ltd.http://www.elsevier.com/wps/find/journaldescription.cws_home/942/description#description, NaN, 2005)[more][less]
Abstract: From the roots of Bulbine frutescens, the first sulfated phenylanthraquinones were isolated, together with their known sulfate-free analogs. Their structures were elucidated by spectroscopic and chiroptical methods, by acid hydrolysis or by partial synthesis. The new compounds have the usual stereo-orientation at the biaryl axis (i.e., with the acetyl portion above the anthraquinone plane) except for sodium ent-knipholone 60-O-sulfate (and thus, also its hydrolysis product, ent-knipholone), which exhibit an opposite axial configuration. We also describe the first stereoanalysis of natural phenylanthraquinones, some of which were found to be not enantiomerically pure, some even nearracemic. We furthermore, report on the first X-ray structure analysis of a phenylanthraquinone, viz. 40-O-demethylknipholone. URI: http://hdl.handle.net/10311/246 Files in this item: 2
license.txt (1.998Kb) -
Abegaz, B.M.; Bezabih, M.; Msuta, T.; Brun, R.; Menche, D.; Muhlbacher, J.; Bringmann, G. (American Chemical Society. http://pubs.acs.org/jnp/, NaN, 2002)[more][less]
Abstract: The novel phenylanthraquinones 4'-O-demethylknipholone-4'-O-β-D-glucopyranoside (2) and gaboroquinones A (3) and B (4) were isolated from the African medicinal plant Bulbine frutescens. Biaryl 2 represents the first phenylanthraquinone glucoside, while 3 and 4 are the first side-chain-hydroxylated phenylanthraquinones. Their constitutions were determined by spectroscopic analysis, in particular by HMBC, HMQC, and ROESY NMR investigations, and by chemical transformations. The axial configurations were elucidated chemically, by deglucosylation of 2 and by side-chain deoxygenation of 3 and 4 to give the known phenylanthraquinones 4'-O-demethylknipholone (5), isoknipholone (6), and knipholone (1), respectively, and chiroptically, by CD investigations. Compounds 2, 3, and 4 showed moderate to good antiplasmodial and antitrypanosomal activities in vitro. URI: http://hdl.handle.net/10311/346 Files in this item: 1
Gaboroquinones.pdf (407.3Kb) -
Ngamga, D.; Yankep, E.; Tane, P.; Bezabih, M.; Ngadjui, B.T.; Fomum, Z.T.; Abegaz, B.M. (Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com, NaN, 2005)[more][less]
Abstract: Three new isoflavonoids, griffonianone F, G and H were isolated from the seeds of Millettia griffoniana, along with the known prebarbigerone, pseudobaptigenin, pseudobaptigenin methyl ether, tephrosin, dipterixine, odorantine, 7,4’,5’-tetramethoxyisoflavone and isojamaicin. Their structures were assigned on the basis of spectroscopic data and chemical transformations. URI: http://hdl.handle.net/10311/274 Files in this item: 1
Isoflavonoids from Seeds.pdf (1.353Mb) -
Abegaz, B.M.; Ngadjui, B.T.; Bezabih, M.; Mdee, L.K. (International Union of Pure and Applied Chemistry. http://www.iupac.org/publications/pac/, NaN, 1999)[more][less]
Abstract: Marketed plants are an important but a vulnerable group of plants whose investigations as well as conservation should be considered with priority. The chemistry, and in some cases biological activities of novel iso¯avonoids, nor-lignans, anthracene and naphthalene derivatives and poly prenylated ¯avonoids isolated and characterized from Hagenia abyssinica, Salsola somalensis, Hypoxis spp., Taverniera abyssinica, Aloe spp., Bulbine capitata, Rhamnus prinoides and Dorstenia spp. are discussed. URI: http://hdl.handle.net/10311/289 Files in this item: 1
Novel natural products.pdf (4.533Mb) -
Kapche, G.D.W.F.; Fozing, C.D.; Donfack, J.H.; Fotso, G.W.; Amadou, D.; Tchana, A.N.; Bezabih, M.; Moundipa, P F; Ngadjui, B.N.; Abegaz, B.M. (Elsevier Ltd. www.elsevier.com/locate/phytochem, NaN, 2008)[more][less]
Abstract: Five prenylated arylbenzofurans, moracins Q–U, were isolated from Morus mesozygia (Moraceae). Their structures were elucidated on the basis of spectroscopic evidence. Along with these compounds, 3b-acetoxyurs- 12-en-11-one, marsformoxide, moracin C, moracin M, moracin K, artocarpesin, cycloartocarpesin, morachalcone A were also isolated. Four of the five compounds, (moracins R–U) displayed potent antioxidant activity. URI: http://hdl.handle.net/10311/315 Files in this item: 1
Prenylated arylbenzofuran.pdf (3.853Mb) -
Abegaz, B.M.; Ngadjui, B.T.; Folefoc, G.N.; Fotso, S.; Ambassa, P.; Bezabih, M.; Dongo, E.; Rise, F.; Petersen, D. (Elsevier Ltd. www.elsevier.com/locate/phytochem, NaN, 2003)[more][less]
Abstract: A monoprenylated flavan and two monoterpenoid substituted furanocoumarins were isolated from the twigs of Dorstenia elliptica along with 3-(3,3-dimethylallyl)-4,20,40-trihydroxylchalcone, psoralen, bergapten, O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)butyl] bergaptol, b-sitosterol and its b-d-glucopyranoside. The structure of the flavan was determined as 6(1,1-dimethylallyl)-7,40- dihydroxylflavan and the monoterpenoid substituted furanocoumarins were assigned as O-[3-(2,2-dimethyl-3-oxo-2H-furan-5-yl)-3- hydroxybutyl]-bergaptol and O-[2-(5-hydroxy-2,6,6-trimethyl-3-oxo-2H-pyran-2-yl)ethyl]bergaptol, respectively, using spectroscopic analysis, especially, 2D NMR spectra. URI: http://hdl.handle.net/10311/286 Files in this item: 1
Prenylated flavonoids,.pdf (3.692Mb) -
Majinda, R.R.T; Abegaz, B.M.; Bezabih, M.; Ngadjui, B.T; Wanjala, C.C.W.; Mdee, L.K.; Bojase, G.; Silayo, A.; Masesane, I.; Yeboah, S.O. (IUPAC. http://www.iupac.org/publications/pac/, NaN, 2001)[more][less]
Abstract: Marketed plants are very important items of trade in many parts of the world. The community uses these for a variety of purposes such as foods, cosmetics, flavors, spices, and medicines. It seems that plants that are used for medicinal purposes form the most common category. Four plants used for treatment of microbial infections, viz., Bolusanthus speciosus, Erythrina latissima, Crotalaria podocarpa, and Elephantorrhiza goetzei, were investigated, and these yielded several known and novel structures, some with appreciable antibiotic activity against the test organisms. The activity of some of the isolated plants and the parts of the plant from which these were obtained lend support to their traditional use. Bulbine abyssinica and B. capitata yielded phenylanthraquinones, some of which were shown to possess strong antiplasmodial activity. In addition, these yielded isofuranonaphthoquinones, which were also found to be weakly antiplasmodial and antioxidant. Scilla nervosa yielded several known and novel homoisoflavoinds of the 3-benzylchroman-4-ones and 3-benzylidinechroman- 4-one type, as well as some stilbenoids. The homoisoflavonoids showed strong antitumor activity against various cancer cell lines. Rhus pyroides gave a novel bichalcone, which showed weak antifeedant activity, consistent with the observation by farmers that the plant was avoided by corn cricket. Results from investigated Dorstenia species originating from Cameroon, Ethiopia, and Tanzania yielded styrenes, coumarins, chalcones, and flavonoids. The chalcones and flavonoids showed various levels of prenylation or geranylation, and an observation made so far is that prenylated flavonoids are only found in Dorstenia species of African origin. The only example of a bis-geranylated chalcone is found in Dorstenia. URI: http://hdl.handle.net/10311/308 Files in this item: 1
Recent results from.pdf (4.630Mb) -
Ngandeu, F.; Bezabih, M.; Ngamga, D.; Tchinda, A.; Ngadjui, B.; Abegaz, B.; Dufat, H.; Tillequin, F. (Elsevier Ltd. www.elsevier.com/locate/phytochem, NaN, 2007)[more][less]
Abstract: Three prenylated rotenoids, elliptol, 12-deoxo-12a-methoxyelliptone and 6-methoxy-6a,12a-dehydrodeguelin were isolated from the twigs of Millettia duchesnei, together with the known compounds, 6a,12a-dehydrodeguelin, 6-hydroxy-6a,12a-dehydrodeguelin, 6-oxo- 6a,12a-dehydrodeguelin, elliptone, 12a-hydroxyelliptone and eriodictyol. Their structures were elucidated on the basis of spectral data and comparison with information reported in the literature and with authentic specimens for some known compounds. The full NMR data of 6-oxo-6a,12a-dehydrodeguelin and 6-hydroxy-6a,12a-dehydrodeguelin are reported here for the first time. URI: http://hdl.handle.net/10311/243 Files in this item: 2
license.txt (1.998Kb) -
Ngamba, D.; Awouafack, M.; Tane, P.; Bezabih, M.; Abegaz, B. (Elsevier Ltd. www.elsevier.com/locate/biochemsyseco, NaN, 2007)[more][less]
Abstract: Gladiolus psittascinus HOOK, an herbaceous plant, is propagated by its bulb. This onion-looking plant occurs in rocky places in western province of Cameroon. The bulbs are used to treat asthma, gonorrhoea, diabetes and intestinal parasites (Adjanohoun et al., 1990). The bulbs of G. psittascinus were collected in Dschang (West Province of Cameroon) in July 2005 and identified by Mr Francois Nana, a botanist at the National Herbarium, Yaounde where a voucher specimen (55925 HCN) is deposited. We report here the isolation and structural elucidation from the chloroform extract of two new anthraquinones namely: 1,6,7-trihydroxy-3-methoxy-8-methyl-anthraquinone (1) and 1-hydroxy-3,6,7-trimethoxy-8-methyl-anthraquinone (2) along with four known compounds. The structures of the compounds were elucidated by spectroscopic analysis, mainly, 1D and 2D NMR and by comparing their physical (mp) and spectroscopic (Table 1) data with those reported in the literature. URI: http://hdl.handle.net/10311/248 Files in this item: 4
license.txt (1.998Kb)license.txt (1.998Kb)license.txt (1.998Kb)
Now showing items 1-14 of 14