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1.  Cytotoxicity of four Aframomum species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) towards multi-factorial drug resistant cancer cell lines 
Background
The search for natural products as potential cytotoxic agents has yielded promising candidates. However multidrug resistance (MDR) is still a major hurdle for patients receiving chemotherapy. In the present study, we evaluated the cytotoxicity of the methanol extracts of four dietary Aframomum plant species (A. arundinaceum, A. alboviolaceum, A. kayserianum and A. polyanthum) against nine sensitive and MDR cancer cell lines. We have also identified the bioactive constituents of A. arundinaceum.
Methods
The cytotoxicity of the methanol extracts of the above plants was determined using a resazurin reduction assay. Chromatographic techniques were used to isolate the constituents of A. arundinaceum.
Results
A preliminary experiment on leukemia CCRF-CEM cells at 40 μg/mL showed that the extracts from A. kayserianum and A. alboviolaceum as well as the isolated compounds namely compounds aframodial (1), 8(17),12-labdadien-15,16-dial (2), galanolactone (3), 1-p-menthene-3,6-diol (6) and 1,4-dimethoxybenzene (7) were less active, inducing more than 50% growth of this cell line contrary to A. polyanthum and A. arundinaceum extracts, galanals A (4) and B (5), naringenin (8) and kaempferol-3,7,4’-trimethylether (9). The IC50 values below or around 30 μg/mL were recorded with A. arundinaceum extract against eight of the nine tested cancer cell lines. This extract as well as compound 8 displayed IC50 values below 40 μg/mL towards the nine tested cancer cell lines whilst A. polyanthum extract, compounds 4, 5 and 9 showed selective activities. Collateral sensitivity (hypersensitivity) was observed with A. arundinaceum extract towards leukemia CEM/ADR5000 cells and glioblastoma U87MG.ΔEGFR compared to their respective sensitive counterparts CEM/CEM and U87MG.
Conclusion
The results of this study provide evidence of the cytotoxicity selected Aframomum species as well as a baseline information for the potential use of Aframomum arundinaceum in the fight against drug sensitive and otherwise drug-resistant cancers.
doi:10.1186/1472-6882-14-340
PMCID: PMC4177760  PMID: 25239700
Aframomum; Cameroon; Cancer; Cytotoxicity; Multidrug resistant; Zingiberaceae
2.  Antibiotic-potentiation activities of four Cameroonian dietary plants against multidrug-resistant Gram-negative bacteria expressing efflux pumps 
Background
The continuous spread of multidrug-resistant (MDR) bacteria, partially due to efflux pumps drastically reduced the efficacy of the antibiotic armory, increasing the frequency of therapeutic failure. The search for new compounds to potentiate the efficacy of commonly used antibiotics is therefore important. The present study was designed to evaluate the ability of the methanol extracts of four Cameroonian dietary plants (Capsicum frutescens L. var. facilulatum, Brassica oleacera L. var. italica, Brassica oleacera L. var. butyris and Basilicum polystachyon (L.) Moench.) to improve the activity of commonly used antibiotics against MDR Gram-negative bacteria expressing active efflux pumps.
Methods
The qualitative phytochemical screening of the plant extracts was performed using standard methods whilst the antibacterial activity was performed by broth micro-dilution method.
Results
All the studied plant extracts revealed the presence of alkaloids, phenols, flavonoids, triterpenes and sterols. The minimal inhibitory concentrations (MIC) of the studied extracts ranged from 256-1024 μg/mL. Capsicum frutescens var. facilulatum extract displayed the largest spectrum of activity (73%) against the tested bacterial strains whilst the lower MIC value (256 μg/mL) was recorded with Basilicum polystachyon against E. aerogenes ATCC 13048 and P. stuartii ATCC 29916. In the presence of PAβN, the spectrum of activity of Brassica oleacera var. italica extract against bacteria strains increased (75%). The extracts from Brassica oleacera var. butyris, Brassica oleacera var. italica, Capsicum frutescens var. facilulatum and Basilicum polystachyon showed synergistic effects (FIC ≤ 0.5) against the studied bacteria, with an average of 75.3% of the tested antibiotics.
Conclusion
These results provide promising information for the potential use of the tested plants alone or in combination with some commonly used antibiotics in the fight against MDR Gram-negative bacteria.
doi:10.1186/1472-6882-14-258
PMCID: PMC4223522  PMID: 25047005
Cameroonian dietary plants; Potentiation; Gram–negative bacteria; Multidrug resistant; Efflux pumps
3.  Antibacterial activities of Beilschmiedia obscura and six other Cameroonian medicinal plants against multi-drug resistant Gram-negative phenotypes 
Background
The rapid spread of bacteria expressing multi-drug resistance propels the search for new antibacterial agents. The present study was designed to evaluate the antibacterial activities of the methanol extracts from Beilschmiedia obscura and six other Cameroonian plants against a panel of twenty nine Gram-negative bacteria including Multi-drug resistant (MDR) phenotypes.
Methods
The phytochemical investigations of the extracts were carried out according to the standard methods and the liquid micro-dilution assay was used for all antibacterial assays.
Results
Phytochemical analysis showed the presence of alkaloids in all studied extracts. Other chemical classes of secondary metabolites such as anthocyanines, anthraquinones flavonoids, saponins, tannins, sterols and triterpenes were selectively detected in the extracts. The extract from the fruits of Beilschmiedia obscura, Pachypodanthium staudtii leaves and Peperomia fernandopoiana (whole plant) displayed the best spectrum of activity with MIC values ranging from 16 to 1024 μg/mL against at least 65% and above of the tested bacteria. The extract from Beilschmiedia obscura was the most active with MIC values below 100 μg/mL against ten of the tested bacteria. This extract also showed MBC values below 1024 μg/mL against 55.17% of the studied microorganisms. Phenylalanine arginine β-naphthylamide (PAβN) significantly modulated the activities of extracts from the leaves and fruits of Pachypodanthium staudtii and Beilschmiedia obscura respectively, by increasing their inhibitory activity against Klebsiella pneumoniae KP55 strain at least four fold.
Conclusion
The overall results of the present investigation provide information for the possible use of the methanol extracts of the studied plant species, especially B. obscura to fight infectious diseases caused by Gram-negative bacteria including MDR phenotypes.
doi:10.1186/1472-6882-14-241
PMCID: PMC4223721  PMID: 25023038
Antibacterial activity; Beilschmiedia obscura; Gram-negative bacteria; Multi-drug resistance; Efflux pumps; Medicinal plants
4.  In Vitro and In Vivo antifungal activities of selected Cameroonian dietary spices 
Background
Spices and herbs have been used in food since ancient times to give taste and flavor and also as food preservatives and disease remedies. In Cameroon, the use of spices and other aromatic plants as food flavoring is an integral part of dietary behavior, but relatively little is known about their antifungal potential.
The present work was designed to assess the antifungal properties of extracts from spices used in Cameroonian dietary.
Methods
The in vitro antifungal activities of twenty three extracts from twenty one spices were assessed by the broth micro-dilution method against eight fungi. Also, the in vivo activity of Olax subscorpioidea extract (the most active extract) was evaluated in rat model of disseminated candidiasis due to Candida albicans by estimating the fungal burden in blood and kidney.
Results
Seven extracts (30%) exhibited moderate to significant antifungal activities, inhibiting the growth of the microorganisms at concentrations ranging from 0.048 to 0.39 mg/mL. Olax subscorpioidea extract exhibited the highest antifungal activity particularly against Candida albicans and Candida tropicalis (MIC of 0.097 mg/mL and 0.048 mg/mL respectively). Sixteen extracts (70%) were weakly active (MICs > 6.25 mg/mL). Oral administration of O. subscorpioidea extract at the dose 2 g/kg of body weight (bw) to artificially infected rats revealed a drop in the number of colony forming units per milliliter (cfu/mL) of Candida albicans cells in the blood below the detection limit (100 cfu/mL) while a modest decrease was observed in the kidney.
Conclusion
The present work shows that some of the spices studied possess interesting antifungal properties and could be used to treat candidiasis. Among the plant species tested, Olax subscorpioidea displayed the most promising result.
doi:10.1186/1472-6882-14-58
PMCID: PMC3933192  PMID: 24533718
Antifungal; Spices; Yeasts; Disseminated candidosis
5.  Cytotoxicity, mode of action and antibacterial activities of selected Saudi Arabian medicinal plants 
Background
The flora of Saudi Arabia is one of the richest biodiversity areas in the Arabian Peninsula and comprises very important genetic resources of crop and medicinal plants. The present study was designed to investigate the cytotoxicity and the antibacterial activities of the organic extracts from twenty six Saudi Arabian medicinal plants. The study was also extended to the investigation of the effects of the extracts from the four best plants, Ononis serrata (SY160), Haplophyllum tuberculatum (SY177), Pulicaria crispa (SY179), and Achillea beiberstenii (SY-200) on cell cycle distribution, apoptosis, caspases activities and mitochondrial function in leukemia CCRF-CEM cell line.
Methods
A resazurin assay was used to assess the cytotoxicity of the extracts on a panel of human cancer cell lines whilst the microbroth dilution was used to determine the minimal inhibitory concentration (MIC) of the samples against twelve bacterial strains belonging to four species, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae and Pseudomonas aeruginosa.
Results
The best activity on leukemia cell lines were recorded with SY177 (IC50 of 9.94 μg/mL) and SY179 (IC50 of 1.81 μg/mL) against CCRF-CEM as well as Ach-b (IC50 of 9.30 μg/mL) and SY160 (IC50 of 5.06 μg/mL) against HL60 cells. The extracts from SY177 and SY179 were also toxic against the seven solid cancer cell lines studied with the highest IC50 values of 31.64 μg/mL (SY177 against Hep-G2 cells). SY177 and Ach-b induced cell cycle arrest in G0/G1 and S phases whilst SY160 and SY179 induced arrest in G0/G1 phase. All the four plant extracts induced apoptosis in CCRF-CEM cells with the alteration of the mitochondrial membrane potential. In the antibacterial assays, only Ach-b displayed moderate antibacterial activities against E. coli and E. aerogenes ATCC strains (MIC of 256 μg/mL), AG100ATeT and K. pneumoniae ATCC strains (MIC of 128 μg/mL).
Conclusions
Finally, the results of the present investigation provided supportive data for the possible use of some Saudi Arabian plants investigated herein, and mostly Haplophyllum tuberculatum, Pulicaria crispa, Ononis serrata and Achillea beiberstenii in the control of cancer diseases.
doi:10.1186/1472-6882-13-354
PMCID: PMC4029389  PMID: 24330397
Antibacterial; Cytotoxicity; Mode of action; Medicinal plants; Saudi Arabia
6.  Cytotoxicity of Elaoephorbia drupifera and other Cameroonian medicinal plants against drug sensitive and multidrug resistant cancer cells 
Background
Multidrug resistance (MDR) is a major hurdle for cancer treatment worldwide and accounts for chemotherapy failure in over 90% of patients with metastatic cancer. Evidence of the cytotoxicity of Cameroonian plants against cancer cell lines including MDR phenotypes is been intensively and progressively provided. The present work was therefore designed to evaluate the cytotoxicity of the methanol extracts of twenty-two Cameroonian medicinal plants against sensitive and MDR cancer cell lines.
Methods
The methanol maceration was used to obtain the crude plant extracts whilst the cytotoxicity of the studied extracts was determined using a resazurin reduction assay.
Results
A preliminary assay on leukemia CCRF-CEM cells at 40 μg/mL shows that six of the twenty plant extract were able to enhance less than 50% of the growth proliferation of CCRF-CEM cells. These include Crinum zeylanicum (32.22%), Entada abyssinica (34.67%), Elaoephorbia drupifera (35.05%), Dioscorea bulbifera (45.88%), Eremomastax speciosa (46.07%) and Polistigma thonningii (45.11%). Among these six plants, E. drupifera showed the best activity with IC50 values below or around 30 μg/mL against the nine tested cancer cell lines. The lowest IC50 value of 8.40 μg/mL was recorded with the extract of E. drupifera against MDA-MB231 breast cancer cell line. The IC50 values below 10 μg/mL were recorded with the extracts of E. drupifera against MDA-MB231 breast cancer cells, C. zeylanicum against HCT116 p53+/+ and HCT116p53-/- colon cancer cells and E. abyssinica against HCT116 p53+/+ cells.
Conclusion
The results of the present study provide evidence of the cytotoxic potential of some Cameroonian medicinal plants and a baseline information for the potential use of Elaoephorbia drupifera in the treatment of sensitive and drug-resistant cancer cell lines.
doi:10.1186/1472-6882-13-250
PMCID: PMC3852045  PMID: 24088184
Cameroon; Cytotoxicity; Elaoephorbia drupifera; Medicinal plants
7.  In Vitro antibacterial and antibiotic-potentiation activities of four edible plants against multidrug-resistant gram-negative species 
Background
The present study was designed to investigate the antibacterial activities of the methanol extracts of four Cameroonian edible plants, locally used to treat microbial infections, and their synergistic effects with antibiotics against a panel of twenty nine Gram-negative bacteria including Multi-drug resistant (MDR) phenotypes expressing active efflux pumps.
Methods
The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of the extracts [alone and in the presence of the efflux pumps inhibitor (EPI) Phenylalanine-Arginine β-Naphtylamide (PAβN)], and those of antibiotics in association with the two of the most active ones, Piper nigrum and Telfairia occidentalis. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods.
Results
Phytochemical analysis showed the presence of alkaloids and flavonoids in all studied extracts. Other chemical classes of secondary metabolites were selectively present in the extracts. The results of the MIC determination indicated that the crude extracts from P. nigrum and V. amygdalina were able to inhibit the growth of all the twenty nine studied bacteria within a concentration range of 32 to 1024 μg/mL. At a similar concentration range (32 to 1024 μg/mL) the extract from T. occidentalis inhibited the growth of 93.1% of the tested microorganisms. At MIC/2 and MIC/5, synergistic effects were noted between the extracts from P. nigrum and T. occidentalis and seven of the tested antibiotics on more than 70% of the tested bacteria.
Conclusion
The overall results of the present study provide information for the possible use of the studied edible plants extracts in the control of bacterial infections including MDR phenotypes.
doi:10.1186/1472-6882-13-190
PMCID: PMC3734210  PMID: 23885762
Antibacterial activities; Edible plants; Gram-negative bacteria; Multidrug resistance; Efflux pumps
8.  Antibacterial activities of selected edible plants extracts against multidrug-resistant Gram-negative bacteria 
Background
In response to the propagation of bacteria resistant to many antibiotics also called multi-drug resistant (MDR) bacteria, the discovery of new and more efficient antibacterial agents is primordial. The present study was aimed at evaluating the antibacterial activities of seven Cameroonian dietary plants (Adansonia digitata, Aframomum alboviolaceum, Aframomum polyanthum, Anonidium. mannii, Hibiscus sabdarifa, Ocimum gratissimum and Tamarindus indica).
Methods
The phytochemical screening of the studied extracts was performed using described methods whilst the liquid broth micro dilution was used for all antimicrobial assays against 27 Gram-negative bacteria.
Results
The results of the phytochemical tests indicate that all tested extracts contained phenols and triterpenes, other classes of chemicals being selectively present. The studied extracts displayed various degrees of antibacterial activities. The extracts of A. digitata, H. sabdarifa, A. polyanthum, A. alboviolaceum and O. gratissimum showed the best spectra of activity, their inhibitory effects being recorded against 81.48%, 66.66%, 62.96%, 55.55%, and 55.55% of the 27 tested bacteria respectively. The extract of A. polyanthum was very active against E. aerogenes EA294 with the lowest recorded minimal inhibitory concentration (MIC) of 32 μg/ml.
Conclusion
The results of the present work provide useful baseline information for the potential use of the studied edible plants in the fight against both sensitive and MDR phenotypes.
doi:10.1186/1472-6882-13-164
PMCID: PMC3710276  PMID: 23837916
Antibacterial; Multi-drug resistant bacteria; Dietary plants
9.  Antibacterial constituents of three Cameroonian medicinal plants: Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis 
Background
Multidrug resistance is a worrying cause of treatment failure in bacterial infections. The search of bioactive constituents from medicinal plants against multidrug resistant (MDR) bacteria has significantly evolved in the two last decades. In the present study, twenty-two compounds (three terpenoids, eleven phenolics and eight alkaloids) isolated from three Cameroonian medicinal plants, namely Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis, as well as the crude extracts were tested for their antibacterial activities against Mycobacterium tuberculosis and Gram-negative bacteria amongst which were MDR active efflux pumps expressing phenotypes.
Methods
The microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of the studied samples.
Results
The results of the MIC determinations indicate that, the best crude extract was that from G. nobilis (GNB), its inhibitory effects being noted against 12 of the 14 tested bacteria. The extract of GNB also exhibited better anti-tuberculosis (MIC of 128 μg/ml M. tuberculosis against ATCC 27294 strain) and antibacterial (MIC of 64 μg/ml against Escherichia coli ATCC10536) activities compared to the extracts of O. suaveolens and B. camerunensis. Interestingly, 4-prenyl-2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone (2), isolated from the most active extract GNB, also showed the best activity amongst compounds, inhibiting the growth of all the fourteen tested microorganisms. The lowest MIC value obtained with compound 2 was 8 μg/ml against M. tuberculosis ATCC 27294 and M. tuberculosis clinical MTCS2 strains. Other compounds showed selective activities with 11 of the 14 tested bacteria being sensitive to the xanthone, morusignin I (5) and the alkaloid, kokusaginine (13).
Conclusions
The results of the present investigation provide evidence that the crude extract from G. nobilis, O. suaveolens and B. camerunensis as well as some of their compounds, and mostly compound 2 (isolated from G. nobilis,) could be considered as interesting natural antibacterial products.
doi:10.1186/1472-6882-13-81
PMCID: PMC3637112  PMID: 23574627
Antimycobacterial; Antibacterial; Cameroon; Compounds; Garcinia nobilis; Oricia suaveolens; Balsamocitrus camerunensis
10.  Cytotoxic and antimicrobial activity of selected Cameroonian edible plants 
Background
In Cameroon, the use of edible plants is an integral part of dietary behavior. However, evidence of the antimicrobial as well as the cytotoxic effects of many of them has not been investigated. In the present study, aqueous and methanol extracts from barks, seeds, leaves and roots of three Cameroonian edible plants namely Garcina lucida, Fagara heitzii and Hymenocardia lyrata were evaluated for their cytotoxic and antimicrobial activities.
Methods
Antibacterial and antifungal activities were assessed by the broth micro-dilution method meanwhile the cytotoxicity was performed using sulphorhodamine B assay (SRB) against the human leukemia THP-1, the alveolar epithelial A549, prostate cancer PC-3, breast adenocarcinoma MCF-7 and cervical cancer HeLa cell lines.
Results
The minimum inhibitory concentration (MIC) values of the seven tested extracts ranged from 62.5 μg/ml to 1000 μg/ml. The methanol (MeOH) extract from the roots of H. lyrata showed the highest antibacterial activity against Gram-positive bacteria S. aureus and S. epidermitis. The best antifungal activity was obtained with the MeOH extract from the leaves of G. lucida against C. tropicalis (MIC value of 62.5 μg/ml). The in vitro antiproliferative activity revealed that, extract from the bark of F. heitzii and extract from H. lyrata roots had significant cytotoxic activity on THP-1 (IC50 8.4 μg/ml) and PC-3 (IC50 9.5 μg/ml) respectively.
Conclusion
Our findings suggest that Cameroonian spices herein studied could be potentially useful for the development of therapeutic agents against bacterial infections as well as for prostate and leukemia cancer.
doi:10.1186/1472-6882-13-78
PMCID: PMC3635900  PMID: 23565827
Cytotoxic; Antimicrobial; Edible plants; Cameroon
11.  Antibacterial activities of the methanol extracts of ten Cameroonian vegetables against Gram-negative multidrug-resistant bacteria 
Background
Many edible plants are used in Cameroon since ancient time to control microbial infections. This study was designed at evaluating the antibacterial activities of the methanol extracts of ten Cameroonian vegetables against a panel of twenty nine Gram negative bacteria including multi-drug resistant (MDR) strains.
Methods
The broth microdilution method was used to determine the Minimal Inhibitory Concentrations (MIC) and the Minimal Bactericidal Concentrations (MBC) of the studied extracts. When chloramphenicol was used as a reference antibiotic, the MICs were also determined in the presence of Phenylalanine-Arginine β-Naphtylamide (PAβN), an efflux pumps inhibitor (EPI). The phytochemical screening of the extracts was performed using standard methods.
Results
All tested extracts exhibited antibacterial activities, with the MIC values varying from 128 to 1024 mg/L. The studied extracts showed large spectra of action, those from L. sativa, S. edule, C. pepo and S. nigrum being active on all the 29 bacterial strains tested meanwhile those from Amaranthus hybridus, Vernonia hymenolepsis, Lactuca.carpensis and Manihot esculenta were active on 96.55% of the strains used. The plant extracts were assessed for the presence of large classes of secondary metabolites: alkaloids, anthocyanins, anthraquinones, flavonoids, phenols, saponins, steroids, tannins and triterpenes. Each studied plant extract was found to contain compounds belonging to at least two of the above mentioned classes.
Conclusion
These results confirm the traditional claims and provide promising baseline information for the potential use of the tested vegetables in the fight against bacterial infections involving MDR phenotypes.
doi:10.1186/1472-6882-13-26
PMCID: PMC3598735  PMID: 23368430
Antibacterial; Gram-negative bacteria; Multi-drug resistant; Extract; Vegetable
12.  Antibacterial activities of the extracts, fractions and compounds from Dioscorea bulbifera 
Background
Dioscorea bulbifera is an African medicinal plant used to treat microbial infections. In the present study, the methanol extract, fractions (DBB1 and DBB2) and six compounds isolated from the bulbils of D. bulbifera, namely bafoudiosbulbins A (1), B (2), C (3), F (4), G (5) and 2,7-dihydroxy-4-methoxyphenanthrene (6), were tested for their antimicrobial activities against Mycobacteria and Gram-negative bacteria involving multidrug resistant (MDR) phenotypes expressing active efflux pumps.
Methods
The microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples.
Results
The results of the MIC determinations indicated that when tested alone, the crude extract, fractions DBB1 and DBB2 as well as compounds 2 to 5 were able to prevent the growth of all the fifteen studied microorganisms, within the concentration range of 8 to 256 μg/mL. The lowest MIC value for the methanol extract and fractions (16 μg/mL) was obtained with DBB1 and DBB2 on E, coli AG100A and DBB2 on Mycobacterium tuberculosis MTCS2. The lowest value for individual compounds (8 μg/mL) was recorded with compound 3 on M. smegmatis and M. tuberculosis ATCC and MTCS2 strains respectively. The activity of the samples on many MDR bacteria such as Enterobacter aerogenes EA289, CM64, Klebsiella pneumoniae KP63 and Pseudomonas aeruginosa PA124 was better than that of chloramphenicol. When tested in the presence of the efflux pump inhibitor against MDR Gram-negative bacteria, the activity of most of the samples increased. MBC values not greater than 512 μg/mL were recorded on all studied microorganisms with fraction DBB2 and compounds 2 to 5.
Conclusions
The overall results of the present investigation provided evidence that the crude extract D. bulbifera as well as some of the compounds and mostly compounds 3 could be considered as potential antimicrobial drugs to fight against MDR bacteria.
doi:10.1186/1472-6882-12-228
PMCID: PMC3528471  PMID: 23176193
Diterpenoids; Antimycobacterial; Antibacterial; Dioscorea bulbifera; Dioscoreaceae
13.  Antimicrobial activities of the methanol extract and compounds from the twigs of Dorstenia mannii (Moraceae) 
Background
Dorstenia mannii (Moraceae) is a medicinal herb used traditionally for the treatment of many diseases. In the present study, the methanol extract of D. mannii and nine of its isolated compounds, namely dorsmanin A (1), B (2), C (3), D (4), E (6), F (7), G (8) dorsmanin I (9) and 6,8-diprenyleriodictyol (5), were tested for their antimicrobial activities against yeast, Mycobacteria and Gram-negative bacteria.
Methods
The microplate alamar blue assay (MABA) and the broth microdilution method were used to determine the minimal inhibitory concentration (MIC) and minimal microbicidal concentration (MMC) of the above extract and compounds on a panel of bacterial species.
Results
The results of the MIC determinations demonstrated that the methanol extract as well as compounds 3 and 8 were able to prevent the growth of all the fourteen studied microorganisms within the concentration range of 4 to 1024 μg/ml. The lowest MIC value for the methanol extract (64 μg/ml) was obtained on Candida albicans. The lowest value for individual compounds (4 μg/ml) was recorded with compounds 3 on Pseudomonas aeruginosa PA01 and 7 on Eschericia coli ATCC strain. The MIC values recorded with compounds 3 on P. aeruginosa PA01, 6 on C. albicans,7 on P. aeruginosa PA01 and K. pneumoniae ATCC strain and C. albicans,and 8 on P. aeruginosa PA01, PA124, P. stuartii, M. tuberculosis MTCS1 were lower than or equal to those of the reference drugs. MMC values not greater than 1024 μg/ml were recorded on all studied microorganisms with compounds 3 and 8.
Conclusion
The overall results of the present investigation provided evidence that the crude extract of D. mannii as well as some of its compounds such compounds 3 and 8 could be a potential source of natural antimicrobial products.
doi:10.1186/1472-6882-12-83
PMCID: PMC3403998  PMID: 22747736
14.  Antimicrobial activity of selected South African medicinal plants 
Background
Nearly 3,000 plant species are used as medicines in South Africa, with approximately 350 species forming the most commonly traded and used medicinal plants. In the present study, twelve South African medicinal plants were selected and tested for their antimicrobial activities against eight microbial species belonging to fungi, Mycobacteria, Gram-positive and Gram-negative bacteria.
Methods
The radiometric respiratory technique using the BACTEC 460 system was used for susceptibility testing against Mycobacterium tuberculosis, and the liquid micro-broth dilution was used for other antimicrobial assays.
Results
The results of the minimal inhibitory concentration (MIC) determinations indicated that the methanol extracts from Acacia karoo, Erythrophleum lasianthum and Salvia africana were able to prevent the growth of all the tested microorganisms. All other samples showed selective activities. MIC values below 100 μg/ml were recorded with A. karoo, C. dentate, E. lasianthum, P. obligun and S. africana on at least one of the nine tested microorganisms. The best activity (MIC value of 39.06 μg/ml) was noted with S. africana against E. coli, S. aureus and M. audouinii, and Knowltonia vesitoria against M. tuberculosis.
Conclusion
The overall results of the present work provide baseline information for the possible use of the studied South African plant extracts in the treatment of microbial infections.
doi:10.1186/1472-6882-12-74
PMCID: PMC3479042  PMID: 22704594
15.  Antibacterial activities of selected Cameroonian spices and their synergistic effects with antibiotics against multidrug-resistant phenotypes 
Background
The emergence of multi-drug resistant (MDR) phenotypes is a major public health problem today in the treatment of bacterial infections. The present study was designed to evaluate the antibacterial activities of the methanol extracts of eleven Cameroonian spices on a panel of twenty nine Gram negative bacteria including MDR strains.
Methods
The phytochemical analysis of the extracts was carried out by standard tests meanwhile the liquid micro-broth dilution was used for all antimicrobial assays.
Results
Phytochemical analysis showed the presence of alkaloids, phenols and tannins in all plants extracts. The results of the antibacterial assays indicated that all tested extracts exert antibacterial activities, with the minimum inhibitory concentration (MIC) values varying from 32 to 1024 μg/ml. The extracts from Dichrostachys glomerata, Beilschmiedia cinnamomea, Aframomum citratum, Piper capense, Echinops giganteus, Fagara xanthoxyloïdes and Olax subscorpioïdea were the most active. In the presence of efflux pump inhibitor, PAßN, the activity of the extract from D. glomerata significantly increased on 69.2% of the tested MDR bacteria. At MIC/5, synergistic effects were noted with the extract of D. glomerata on 75% of the tested bacteria for chloramphenicol (CHL), tetracycline (TET) and norfloxacin (NOR). With B. cinnamomea synergy were observed on 62.5% of the studied MDR bacteria with CHL, cefepime (FEP), NOR and ciprofloxacin (CIP) and 75% with erythromycin (ERY).
Conclusion
The overall results provide information for the possible use of the studied extracts of the spices in the control of bacterial infections involving MDR phenotypes.
doi:10.1186/1472-6882-11-104
PMCID: PMC3228721  PMID: 22044718
16.  Antimicrobial activities of the methanol extract and compounds from Artocarpus communis (Moraceae) 
Background
Artocarpus communis is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antimicrobial activities of the methanol extract (ACB) and compounds isolated from the bark of this plant, namely peruvianursenyl acetate C (1), α-amyrenol or viminalol (2), artonin E (4) and 2-[(3,5-dihydroxy)-(Z)-4-(3-methylbut-1-enyl)phenyl]benzofuran-6-ol (5).
Methods
The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species.
Results
The MIC results indicated that ACB as well as compounds 4 and 5 were able to prevent the growth of all tested microbial species. All other compounds showed selective activities. The lowest MIC value of 64 μg/ml for the crude extract was recorded on Staphylococcus aureus ATCC 25922 and Escherichia coli ATCC 8739. The corresponding value of 32 μg/ml was recorded with compounds 4 and 5 on Pseudomonas aeruginosa PA01 and compound 5 on E. coli ATCC 8739, their inhibition effect on P. aeruginosa PA01 being more than that of chloramphenicol used as reference antibiotic.
Conclusion
The overall results of this study provided supportive data for the use of A. communis as well as some of its constituents for the treatment of infections associated with the studied microorganisms.
doi:10.1186/1472-6882-11-42
PMCID: PMC3118951  PMID: 21612612
17.  Antimicrobial activities of the methanol extract, fractions and compounds from Ficus polita Vahl. (Moraceae) 
Background
Many plants of the family Moraceae are used in the treatment of infectious diseases. Ficus polita Vahl., an edible plant belonging to this family is used traditionally in case of dyspepsia, infectious diseases, abdominal pains and diarrhea. The present work was designed to assess the antimicrobial activity of the methanol extract from the roots of F. polita (FPR), as well as that of its fractions (FPR1-5) and two of the eight isolated compounds, namely euphol-3-O-cinnamate (1) and (E)-3,5,4'-trihydroxy-stilbene-3,5-O-β-D-diglucopyranoside (8).
Methods
The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species.
Results
The results of the MIC determination showed that the crude extract, fractions FPR1, FPR2 and compound 8 were able to prevent the growth of the eight tested microorganisms. Other samples showed selective activity. The lowest MIC value of 64 μg/ml for the crude extract was recorded on 50% of the studied microbial species. The corresponding value for fractions of 32 μg/ml was obtained on Salmonella typhi, Escherichia coli and Candida albicans ATCC strains. The MIC values recorded with compound 8 on the resistant Pseudomonas aeruginosa PA01 strain was equal to that of chloramphenicol used as reference antibiotic.
Conclusion
The obtained results highlighted the interesting antimicrobial potency of F. polita as well as that of compound 8, and provided scientific basis for the traditional use of this taxon in the treatment of microbial infections.
doi:10.1186/1472-6882-11-6
PMCID: PMC3037948  PMID: 21269424

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