James Mbah - Academia.edu (original) (raw)
Papers by James Mbah
Chemical Papers, 2021
A new anthraquinone, 1,6-dihydroxy-2-hydroxymethyl-5-methoxy-9,10-anthracenedione ( 1 ), along wi... more A new anthraquinone, 1,6-dihydroxy-2-hydroxymethyl-5-methoxy-9,10-anthracenedione ( 1 ), along with four known compounds, including 1,2-dimethoxyanthraquinone ( 2 ), morindone-5-methylether ( 3 ), scopoletin ( 4 ), and fraxidin ( 5 ) were isolated from the methylene chloride extract of the stem bark of Morinda lucida Benth. Structure elucidation was accomplished by analysis of the 1D and 2D NMR, IR and mass spectra. Compounds 1 , 2 , 4 and 5 were tested against five Salmonella strains. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined. The results indicated that the four compounds have different antibacterial activities, with MIC values ranging from 8 to 256 µg/mL. Among these four compounds, the best activity was observed for compound 4 against Salmonella enterica subsp. enterica serovar Typhimurim (STM), with a MIC value of 8 µg/mL. Compound 1 showed selective antibacterial activity toward the five Salmonella strains, with MICs of 16 µg/mL against STM, 32 µg/mL against S. enteritidis (STE), 64 µg/mL against S. enterica subsp. enterica serovar Typhi (ST) and S. enterica subsp. enterica serovar Typhi (ST566), and 128 µg/mL against S. enteritidis , S. enterica subsp. enterica serovar Typhi ATCC 6539 (STS). Compounds 1 , 2 , 4 , and 5 have bactericidal effects (MBC/MIC ≤ 4) against the tested Salmonella strains, except for compound 4 , which is bacteriostatic to STM with a MBC/MIC value of 16.
Physical Sciences Reviews, 2021
In the quest to know why natural products (NPs) have often been considered as privileged scaffold... more In the quest to know why natural products (NPs) have often been considered as privileged scaffolds for drug discovery purposes, many investigations into the differences between NPs and synthetic compounds have been carried out. Several attempts to answer this question have led to the investigation of the atomic composition, scaffolds and functional groups (FGs) of NPs, in comparison with synthetic drugs analysis. This chapter briefly describes an atomic enumeration method for chemical libraries that has been applied for the analysis of NP libraries, followed by a description of the main differences between NPs of marine and terrestrial origin in terms of their general physicochemical properties, most common scaffolds and “drug-likeness” properties. The last parts of the work describe an analysis of scaffolds and FGs common in NP libraries, focusing on huge NP databases, e.g. those in the Dictionary of Natural Products (DNP), NPs from cyanobacteria and the largest chemical class of N...
Journal of Medicinal Plants Research, Apr 10, 2015
This study was carried out to isolate active ingredients from Voacanga africana Stapf (Apocynacea... more This study was carried out to isolate active ingredients from Voacanga africana Stapf (Apocynaceae) used as herbal medicine in Cameroon, and also to assess the efficacy of the compounds on Onchocerca ochengi and Loa loa worms. The compounds were isolated using solvent partitioning, column chromatography and fractional crystallization. The O. ochengi worms were isolated from cow skin while Loa loa was isolated from humans. Filaricidal activity was determined based on motility for adult male worms and microfilariae (Mfs), while adult female worm viability was assessed biochemically by the dimethylthiazol (MTT)/formazan assay. Cytotoxicity was assessed using monkey kidney epithelial cells. Auranofin was used as the positive control drug. Two compounds, voacangine (compound 1) and voacamine (compound 2) were isolated from the stem bark of Voacanga africana. Both compounds were found to inhibit the motility of both the microfilariae (Mfs) and adult male worms of O. ochengi in a concentration-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 µM drug concentration. The IC 50 s for voacangine were 5.49 µM for Mfs and 9.07 µM for adult male worms; while for voacamine the values were 2.49 µM for Mfs and 3.45 µM for adult males. At 10 µM, voacamine showed 100% inhibition of Loa loa Mfs motility after 24 h. This is the first report of the anti-Onchocerca activity of voacangine (compound 1) and voacamine (compound 2) as well as activity of voacamine (compound 2) on L. loa. The results of this study support the traditional use of V. africana in the treatment of human onchocerciasis.
African Journal of Traditional, Complementary and Alternative Medicines, 2006
We screened forty crude extracts of twenty Cameroonian medicinal plants commonly used to treat ba... more We screened forty crude extracts of twenty Cameroonian medicinal plants commonly used to treat bacterial infections for broad spectrum antibacterial activity, as a more affordable alternative against resistant organisms. The extracts were screened on common pathogenic gram negative and gram positive bacteria initially by the disc diffusion method followed by the tube dilution method. Using discs containing 30µg of extract, Escherichia coli showed sensitivity to 23 extracts with diameter of zone of inhibition ranging from 7-19mm, fifteen of which were up to or > 10mm. Pseudomonas aeruginosa was sensitive to 11 extracts, whereas Salmonella typhimurium and Staphylococcus aureus were not sensitive to any of the extracts. Based on the zones of inhibition the activity of the extracts were equivalent to 30 to 138 % efficacy of the standard antibiotic discs. The lowest Minimum Inhibitory Concentration (MIC) recorded was 2 mg/ml for Euphorbia hirta against S. aureus and P. aeruginosa and the lowest Minimum Bactericidal Concentration (MBC) was 6 mg/ml for six extracts from Ageratum conyzoides, Aframomum citratum, Euphorbia hirta, Momordica charantia, Mangifera indica and Khaya senegalensis against three bacterial species. Three extracts had broad spectrum bacteriostatic activity (MICs ≤ 4 mg/ml) while in terms of MBCs none of the extracts showed broad spectrum bactericidal activity. We conclude that most of the tested plants used as traditional antibacterials have a bacteriostatic effect on gram-negative pathogenic bacteria.
Current Chinese Science, 2021
Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typho... more Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typhoid drugs are becoming more and more unavailable to most patients in Africa due to the increased costs and emerging drug resistance. Therefore, there is a need for the discovery of new antimicrobial agents to combat typhoid fever. Objective: This work aimed to investigate the bioactive components in Cyperus sphacelatus Rottb. (Cyperaceae) and test the antisalmonellal activity of the isolated compounds. Methods: Compound purification was done through column chromatography. Structure elucidation was accomplished based on the 1D and 2D NMR, IR and mass spectra. The biological assay was done using five bacterial strains, including Salmonella enterica subsp. enterica sérovars Typhi ATCC 6539 (STS), S. enterica subsp. enterica sérovars Typhi (ST), S. enteritidis (STE), S. enterica subsp. enterica sérovars Typhimurim (STM), and a resistant isolate of S. enterica subsp. enterica sérovars Typhi (S...
A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight kno... more A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight known compounds, voacangine (2), voacristine (3), coronaridine (4), tabernanthine (5), iboxygaine (6), voacamine (7), voacorine (8), and conoduramine (9), were isolated from the stem bark of Voacanga africana. The structures of the compounds were determined by comprehensive spectroscopic analyses (1D- and 2D-NMR). Compounds 1, 2, 3, 4, 6, 7 and 8 were found to inhibit the motility of both the microfilariae (Mf) and adult male worms of Onchocerca ochengi, in a dose-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 μM drug concentrations. The IC50 values of the isolates are 2.49-5.49 µM for microfilariae and 3.45-17.87 µM for adult males. Homology modeling was used to generate a 3D model of the the O. ochengi thioredoxin reductase target and docking simulation attempted to offer an explanation of the anti-onchocercal structure-activi...
Molecules
A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight kno... more A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight known compounds—voacangine (2), voacristine (3), coronaridine (4), tabernanthine (5), iboxygaine (6), voacamine (7), voacorine (8) and conoduramine (9)—were isolated from the stem bark of Voacangaafricana. The structures of the compounds were determined by comprehensive spectroscopic analyses. Compounds 1, 2, 3, 4, 6, 7 and 8 were found to inhibit the motility of both the microfilariae (Mf) and adult male worms of Onchocerca ochengi, in a dose-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 μM drug concentrations. The IC50 values of the isolates are 2.49–5.49 µM for microfilariae and 3.45–17.87 µM for adult males. Homology modeling was used to generate a 3D model of the O. ochengi thioredoxin reductase target and docking simulation, followed by molecular dynamics and binding free energy calculations attempted to offer an explanat...
![Research paper thumbnail of Synthesis, Molecular Structure and Antibacterial Activity of Spiro[2,2']indane-1',3'-dione-3-(o-chloro)phenyl-4-nitro Pyrrolizidine](https://attachments.academia-assets.com/68335720/thumbnails/1.jpg)
](Asian Journal of Chemistry
Spiro[2,2']indane-1',3'-dione-3-(o-chloro)phenyl-4-nitro pyrrolizidine was synthesized by 1,3-dip... more Spiro[2,2']indane-1',3'-dione-3-(o-chloro)phenyl-4-nitro pyrrolizidine was synthesized by 1,3-dipolar cycloaddition reaction. It was characterized by NMR, MS and single-crystal X-ray diffraction. It crystallizes in the triclinic space group, P-1, with unit cell dimensions a = 7.6074(4) Å, b = 9.7454(5) Å and c = 12.6538(7) Å, α = 85.313(2)º, β = 84.217(2)º, γ = 86.571(2)º and Z = 2. It was screened for antibacterial activity against oilfield water-borne bacteria and it showed good to moderate activity against sulfate reducing bacteria.
BMC Complementary and Alternative Medicine, 2016
Background: Onchocerciasis is the world's second leading infectious cause of blindness. Its contr... more Background: Onchocerciasis is the world's second leading infectious cause of blindness. Its control is currently hampered by the lack of a macrofilaricidal drug and by severe adverse events observed when the lone recommended microfilaricide, ivermectin is administered to individuals co-infected with Loa loa. Therefore, there is the need for a safe and effective macrofilaricidal drug that will be able to cure the infection and break transmission cycles, or at least, an alternative microfilaricide that does not kill L. loa microfilariae (mf). Methods: Fourteen extracts from two medicinal plants, Tragia benthami and Piper umbellatum were screened in vitro against Onchocerca ochengi parasite and L. loa mf. Activities of extracts on male worms and microfilariae were assessed by motility reduction, while MTT/Formazan assay was used to assess biochemically the death of female worms. Cytotoxicity and acute toxicity of active extracts were tested on monkey kidney cells and Balb/c mice, respectively. Results: At 500 μg/mL, all extracts showed 100 % activity on Onchocerca ochengi males and microfilariae, while 9 showed 100 % activity on female worms. The methylene chloride extract of Piper umbellatum leaves was the most active on adult male and female worms (IC 50 s: 16.63 μg/mL and 35.65 μg/mL, respectively). The three most active extracts on Onchocerca ochengi females were also highly active on Loa loa microfilariae, with IC 50 s of 35.12-13. 9 μg/mL. Active extracts were generally more toxic to the worms than to cells and showed no acute toxicity to Balb/c mice. Phytochemical screening revealed the presence of saponins, steroids, tannins and flavanoids in the promising extracts. Conclusions: These results unfold potential sources of novel anti-Onchocerca lead compounds and validate the traditional use of the plants in onchocerciasis treatment.
Objective: In a search for natural substances with potential for the treatment of typhoid fevers ... more Objective: In a search for natural substances with potential for the treatment of typhoid fevers and urogenital infections, the methylene chloride extract of the seeds of Peucedanum zenkeri was investigated. Methodology: The extract was subjected to column chromatography leading to the isolation of seven compounds. Their structures were determined using modern 2D NMR techniques and by comparison with published NMR data. These compounds were tested against Salmonella typhi, Salmonella paratyphi B, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus, using both agar diffusion and broth dilution techniques. Results: The compounds isolated were umbelliprenin (1), prangenin (2), imperatorin (3), isopimpinellin (4), bergapten (5), cnidilin (6) and stigmasterol (7). Among the above seven compounds, only two (1 and 2) exhibited antibacterial activity. For compound 1, the MIC value was 300 µg/ml against P. aeruginosa, S. aureus, S. typhi and S. paratyphi B. For compound 2, the MIC values varied between 200 and 300 µg/ml against all the bacteria strains tested. Conclusion: These data suggest that Peucedanum zenkeri seed extract contains antibacterial agents which are active against Salmonella species causing typhoid and paratyphoid fevers, and some bacteria strains causing urogenital infections. The antibacterial activity of compound 2 appears to be due to the epoxide group present in its structure.
Cheminform, 2010
Anti-Plasmodial Sesquiterpenoids from the African Reneilmia cincinnata-[isolation and structure e... more Anti-Plasmodial Sesquiterpenoids from the African Reneilmia cincinnata-[isolation and structure elucidation of a new isodaucane sesquiterpenoid (I) along with some known sesquiterpenoids with noteworthy anti-plasmodial activity].-(TCHUENDEM, MAGUERITE H. K.; MBAH,
Journal of Medicinal Plants Research, 2015
The determination of absorption, distribution, metabolism, elimination and toxicity (ADMET) of dr... more The determination of absorption, distribution, metabolism, elimination and toxicity (ADMET) of drug molecules is an essential step in drug discovery programs, owing to the fact that a good proportion of drugs do not reach clinical trials as a result of poor pharmacokinetic profiles. The use of computer programs to predict drug metabolism and pharmacokinetics (DMPK) is gaining ground in this area, as a result of the fact that it is faster and less costly. Thus, it becomes imperative to design new chemical entities (NCEs) with improved pharmacokinetic profiles. In this paper, we present a number of computational models which have been applied in ADMET prediction with relative success and show some applications in the development of natural product libraries from medicinal plants growing in Africa. Keywords: ADMET, in silico, metabolism, natural products, pharmacokinetics
Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 ... more Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%),
Chemical Papers, 2021
A new anthraquinone, 1,6-dihydroxy-2-hydroxymethyl-5-methoxy-9,10-anthracenedione ( 1 ), along wi... more A new anthraquinone, 1,6-dihydroxy-2-hydroxymethyl-5-methoxy-9,10-anthracenedione ( 1 ), along with four known compounds, including 1,2-dimethoxyanthraquinone ( 2 ), morindone-5-methylether ( 3 ), scopoletin ( 4 ), and fraxidin ( 5 ) were isolated from the methylene chloride extract of the stem bark of Morinda lucida Benth. Structure elucidation was accomplished by analysis of the 1D and 2D NMR, IR and mass spectra. Compounds 1 , 2 , 4 and 5 were tested against five Salmonella strains. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined. The results indicated that the four compounds have different antibacterial activities, with MIC values ranging from 8 to 256 µg/mL. Among these four compounds, the best activity was observed for compound 4 against Salmonella enterica subsp. enterica serovar Typhimurim (STM), with a MIC value of 8 µg/mL. Compound 1 showed selective antibacterial activity toward the five Salmonella strains, with MICs of 16 µg/mL against STM, 32 µg/mL against S. enteritidis (STE), 64 µg/mL against S. enterica subsp. enterica serovar Typhi (ST) and S. enterica subsp. enterica serovar Typhi (ST566), and 128 µg/mL against S. enteritidis , S. enterica subsp. enterica serovar Typhi ATCC 6539 (STS). Compounds 1 , 2 , 4 , and 5 have bactericidal effects (MBC/MIC ≤ 4) against the tested Salmonella strains, except for compound 4 , which is bacteriostatic to STM with a MBC/MIC value of 16.
Physical Sciences Reviews, 2021
In the quest to know why natural products (NPs) have often been considered as privileged scaffold... more In the quest to know why natural products (NPs) have often been considered as privileged scaffolds for drug discovery purposes, many investigations into the differences between NPs and synthetic compounds have been carried out. Several attempts to answer this question have led to the investigation of the atomic composition, scaffolds and functional groups (FGs) of NPs, in comparison with synthetic drugs analysis. This chapter briefly describes an atomic enumeration method for chemical libraries that has been applied for the analysis of NP libraries, followed by a description of the main differences between NPs of marine and terrestrial origin in terms of their general physicochemical properties, most common scaffolds and “drug-likeness” properties. The last parts of the work describe an analysis of scaffolds and FGs common in NP libraries, focusing on huge NP databases, e.g. those in the Dictionary of Natural Products (DNP), NPs from cyanobacteria and the largest chemical class of N...
Journal of Medicinal Plants Research, Apr 10, 2015
This study was carried out to isolate active ingredients from Voacanga africana Stapf (Apocynacea... more This study was carried out to isolate active ingredients from Voacanga africana Stapf (Apocynaceae) used as herbal medicine in Cameroon, and also to assess the efficacy of the compounds on Onchocerca ochengi and Loa loa worms. The compounds were isolated using solvent partitioning, column chromatography and fractional crystallization. The O. ochengi worms were isolated from cow skin while Loa loa was isolated from humans. Filaricidal activity was determined based on motility for adult male worms and microfilariae (Mfs), while adult female worm viability was assessed biochemically by the dimethylthiazol (MTT)/formazan assay. Cytotoxicity was assessed using monkey kidney epithelial cells. Auranofin was used as the positive control drug. Two compounds, voacangine (compound 1) and voacamine (compound 2) were isolated from the stem bark of Voacanga africana. Both compounds were found to inhibit the motility of both the microfilariae (Mfs) and adult male worms of O. ochengi in a concentration-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 µM drug concentration. The IC 50 s for voacangine were 5.49 µM for Mfs and 9.07 µM for adult male worms; while for voacamine the values were 2.49 µM for Mfs and 3.45 µM for adult males. At 10 µM, voacamine showed 100% inhibition of Loa loa Mfs motility after 24 h. This is the first report of the anti-Onchocerca activity of voacangine (compound 1) and voacamine (compound 2) as well as activity of voacamine (compound 2) on L. loa. The results of this study support the traditional use of V. africana in the treatment of human onchocerciasis.
African Journal of Traditional, Complementary and Alternative Medicines, 2006
We screened forty crude extracts of twenty Cameroonian medicinal plants commonly used to treat ba... more We screened forty crude extracts of twenty Cameroonian medicinal plants commonly used to treat bacterial infections for broad spectrum antibacterial activity, as a more affordable alternative against resistant organisms. The extracts were screened on common pathogenic gram negative and gram positive bacteria initially by the disc diffusion method followed by the tube dilution method. Using discs containing 30µg of extract, Escherichia coli showed sensitivity to 23 extracts with diameter of zone of inhibition ranging from 7-19mm, fifteen of which were up to or > 10mm. Pseudomonas aeruginosa was sensitive to 11 extracts, whereas Salmonella typhimurium and Staphylococcus aureus were not sensitive to any of the extracts. Based on the zones of inhibition the activity of the extracts were equivalent to 30 to 138 % efficacy of the standard antibiotic discs. The lowest Minimum Inhibitory Concentration (MIC) recorded was 2 mg/ml for Euphorbia hirta against S. aureus and P. aeruginosa and the lowest Minimum Bactericidal Concentration (MBC) was 6 mg/ml for six extracts from Ageratum conyzoides, Aframomum citratum, Euphorbia hirta, Momordica charantia, Mangifera indica and Khaya senegalensis against three bacterial species. Three extracts had broad spectrum bacteriostatic activity (MICs ≤ 4 mg/ml) while in terms of MBCs none of the extracts showed broad spectrum bactericidal activity. We conclude that most of the tested plants used as traditional antibacterials have a bacteriostatic effect on gram-negative pathogenic bacteria.
Current Chinese Science, 2021
Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typho... more Background: Typhoid fever is a major health burden in Sub-Saharan Africa. Conventional anti-typhoid drugs are becoming more and more unavailable to most patients in Africa due to the increased costs and emerging drug resistance. Therefore, there is a need for the discovery of new antimicrobial agents to combat typhoid fever. Objective: This work aimed to investigate the bioactive components in Cyperus sphacelatus Rottb. (Cyperaceae) and test the antisalmonellal activity of the isolated compounds. Methods: Compound purification was done through column chromatography. Structure elucidation was accomplished based on the 1D and 2D NMR, IR and mass spectra. The biological assay was done using five bacterial strains, including Salmonella enterica subsp. enterica sérovars Typhi ATCC 6539 (STS), S. enterica subsp. enterica sérovars Typhi (ST), S. enteritidis (STE), S. enterica subsp. enterica sérovars Typhimurim (STM), and a resistant isolate of S. enterica subsp. enterica sérovars Typhi (S...
A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight kno... more A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight known compounds, voacangine (2), voacristine (3), coronaridine (4), tabernanthine (5), iboxygaine (6), voacamine (7), voacorine (8), and conoduramine (9), were isolated from the stem bark of Voacanga africana. The structures of the compounds were determined by comprehensive spectroscopic analyses (1D- and 2D-NMR). Compounds 1, 2, 3, 4, 6, 7 and 8 were found to inhibit the motility of both the microfilariae (Mf) and adult male worms of Onchocerca ochengi, in a dose-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 μM drug concentrations. The IC50 values of the isolates are 2.49-5.49 µM for microfilariae and 3.45-17.87 µM for adult males. Homology modeling was used to generate a 3D model of the the O. ochengi thioredoxin reductase target and docking simulation attempted to offer an explanation of the anti-onchocercal structure-activi...
Molecules
A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight kno... more A new iboga-vobasine-type isomeric bisindole alkaloid named voacamine A (1), along with eight known compounds—voacangine (2), voacristine (3), coronaridine (4), tabernanthine (5), iboxygaine (6), voacamine (7), voacorine (8) and conoduramine (9)—were isolated from the stem bark of Voacangaafricana. The structures of the compounds were determined by comprehensive spectroscopic analyses. Compounds 1, 2, 3, 4, 6, 7 and 8 were found to inhibit the motility of both the microfilariae (Mf) and adult male worms of Onchocerca ochengi, in a dose-dependent manner, but were only moderately active on the adult female worms upon biochemical assessment at 30 μM drug concentrations. The IC50 values of the isolates are 2.49–5.49 µM for microfilariae and 3.45–17.87 µM for adult males. Homology modeling was used to generate a 3D model of the O. ochengi thioredoxin reductase target and docking simulation, followed by molecular dynamics and binding free energy calculations attempted to offer an explanat...
Asian Journal of Chemistry
Spiro[2,2']indane-1',3'-dione-3-(o-chloro)phenyl-4-nitro pyrrolizidine was synthesized by 1,3-dip... more Spiro[2,2']indane-1',3'-dione-3-(o-chloro)phenyl-4-nitro pyrrolizidine was synthesized by 1,3-dipolar cycloaddition reaction. It was characterized by NMR, MS and single-crystal X-ray diffraction. It crystallizes in the triclinic space group, P-1, with unit cell dimensions a = 7.6074(4) Å, b = 9.7454(5) Å and c = 12.6538(7) Å, α = 85.313(2)º, β = 84.217(2)º, γ = 86.571(2)º and Z = 2. It was screened for antibacterial activity against oilfield water-borne bacteria and it showed good to moderate activity against sulfate reducing bacteria.
BMC Complementary and Alternative Medicine, 2016
Background: Onchocerciasis is the world's second leading infectious cause of blindness. Its contr... more Background: Onchocerciasis is the world's second leading infectious cause of blindness. Its control is currently hampered by the lack of a macrofilaricidal drug and by severe adverse events observed when the lone recommended microfilaricide, ivermectin is administered to individuals co-infected with Loa loa. Therefore, there is the need for a safe and effective macrofilaricidal drug that will be able to cure the infection and break transmission cycles, or at least, an alternative microfilaricide that does not kill L. loa microfilariae (mf). Methods: Fourteen extracts from two medicinal plants, Tragia benthami and Piper umbellatum were screened in vitro against Onchocerca ochengi parasite and L. loa mf. Activities of extracts on male worms and microfilariae were assessed by motility reduction, while MTT/Formazan assay was used to assess biochemically the death of female worms. Cytotoxicity and acute toxicity of active extracts were tested on monkey kidney cells and Balb/c mice, respectively. Results: At 500 μg/mL, all extracts showed 100 % activity on Onchocerca ochengi males and microfilariae, while 9 showed 100 % activity on female worms. The methylene chloride extract of Piper umbellatum leaves was the most active on adult male and female worms (IC 50 s: 16.63 μg/mL and 35.65 μg/mL, respectively). The three most active extracts on Onchocerca ochengi females were also highly active on Loa loa microfilariae, with IC 50 s of 35.12-13. 9 μg/mL. Active extracts were generally more toxic to the worms than to cells and showed no acute toxicity to Balb/c mice. Phytochemical screening revealed the presence of saponins, steroids, tannins and flavanoids in the promising extracts. Conclusions: These results unfold potential sources of novel anti-Onchocerca lead compounds and validate the traditional use of the plants in onchocerciasis treatment.
Objective: In a search for natural substances with potential for the treatment of typhoid fevers ... more Objective: In a search for natural substances with potential for the treatment of typhoid fevers and urogenital infections, the methylene chloride extract of the seeds of Peucedanum zenkeri was investigated. Methodology: The extract was subjected to column chromatography leading to the isolation of seven compounds. Their structures were determined using modern 2D NMR techniques and by comparison with published NMR data. These compounds were tested against Salmonella typhi, Salmonella paratyphi B, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus, using both agar diffusion and broth dilution techniques. Results: The compounds isolated were umbelliprenin (1), prangenin (2), imperatorin (3), isopimpinellin (4), bergapten (5), cnidilin (6) and stigmasterol (7). Among the above seven compounds, only two (1 and 2) exhibited antibacterial activity. For compound 1, the MIC value was 300 µg/ml against P. aeruginosa, S. aureus, S. typhi and S. paratyphi B. For compound 2, the MIC values varied between 200 and 300 µg/ml against all the bacteria strains tested. Conclusion: These data suggest that Peucedanum zenkeri seed extract contains antibacterial agents which are active against Salmonella species causing typhoid and paratyphoid fevers, and some bacteria strains causing urogenital infections. The antibacterial activity of compound 2 appears to be due to the epoxide group present in its structure.
Cheminform, 2010
Anti-Plasmodial Sesquiterpenoids from the African Reneilmia cincinnata-[isolation and structure e... more Anti-Plasmodial Sesquiterpenoids from the African Reneilmia cincinnata-[isolation and structure elucidation of a new isodaucane sesquiterpenoid (I) along with some known sesquiterpenoids with noteworthy anti-plasmodial activity].-(TCHUENDEM, MAGUERITE H. K.; MBAH,
Journal of Medicinal Plants Research, 2015
The determination of absorption, distribution, metabolism, elimination and toxicity (ADMET) of dr... more The determination of absorption, distribution, metabolism, elimination and toxicity (ADMET) of drug molecules is an essential step in drug discovery programs, owing to the fact that a good proportion of drugs do not reach clinical trials as a result of poor pharmacokinetic profiles. The use of computer programs to predict drug metabolism and pharmacokinetics (DMPK) is gaining ground in this area, as a result of the fact that it is faster and less costly. Thus, it becomes imperative to design new chemical entities (NCEs) with improved pharmacokinetic profiles. In this paper, we present a number of computational models which have been applied in ADMET prediction with relative success and show some applications in the development of natural product libraries from medicinal plants growing in Africa. Keywords: ADMET, in silico, metabolism, natural products, pharmacokinetics
Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 ... more Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%), 7 etc..... Ntie Kang, F Database, NPs, Virtual Screening 3 alkaloids (12.8%), 4 xanthones (5.7%), 5 glycosides (5.4%), 6 quinones (5.0%),