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Stephen T. Lacmata

Bio: Stephen T. Lacmata is an academic researcher from University of Dschang. The author has contributed to research in topics: Broth microdilution & Multiple drug resistance. The author has an hindex of 6, co-authored 9 publications receiving 284 citations.

Papers
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Journal ArticleDOI
TL;DR: The overall results of the present study provide supportive data on the use of some Cameroonian plants for cancer treatment and indicate that the anti-angiogenic properties of the most active extracts were able to inhibit angiogenesis by more than 50% in quail embryo.

143 citations

Journal ArticleDOI
TL;DR: 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 multi-drug resistant (MDR) strains.
Abstract: 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. 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. 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. 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.

95 citations

Journal ArticleDOI
TL;DR: The results of this study suggest that the tested plant extracts and mostly those from P. nitida, G. lucida and G. kola could be used alone or in association with common antibiotics in the fight of bacterial infections involving MDR strains.
Abstract: The present work was designed to assess the antibacterial properties of the methanol extracts of some Cameroonian medicinal plants and the effect of their associations with currently used antibiotics on multidrug resistant (MDR) Gram-negative bacteria overexpressing active efflux pumps. The antibacterial activities of twelve methanol extracts of medicinal plants were evaluated using broth microdilution. The results of this test showed that three extracts Garcinia lucida with the minimal inhibitory concentrations (MIC) varying from 128 to 512 g/mL, Garcinia kola (MIC of 256 to 1024 g/mL), and Picralima nitida (MIC of 128 to 1024 g/mL) were active on all the twenty-nine studied bacteria including MDR phenotypes. The association of phenylalanine arginine -naphthylamide (PAN or efflux pumps inhibitor) to different extracts did not modify their activities. At the concentration of MIC/2 and MIC/5, the extracts of P. nitida and G. kola improved the antibacterial activities of some commonly used antibiotics suggesting their synergistic effects with the tested antibiotics. The results of this study suggest that the tested plant extracts and mostly those from P. nitida, G. lucida and G. kola could be used alone or in association with common antibiotics in the fight of bacterial infections involving MDR strains.

66 citations

Journal ArticleDOI
TL;DR: The overall results obtained provide the baseline information for the use of the tested plants in the treatment of bacterial infections, and E. robusta extract showed good synergistic effects, improving the activity of commonly used antibiotics in about 85% of cases.
Abstract: (7) In the present work, we investigated the antibacterial activity of some of the commonly used food plants in Cameroon against some multidrug resistant (MDR) Gram- negative bacteria These plants include Zingiber offi cinale Roscoe, Thymus vulgaris L, Cymbopogon citratus Stapf, Petroselinum crispum Ngn, Apium graveolens L, Ocimum basilicum Linn, Allium porrum Welus, Gnetum africanum L, Eucalyptus robusta L, Ocimum gratissimum L and Capsicum annuum L The study was also extended to the evaluation of the potencies of some of the above plant extracts to increase the activity of some antibiotics against MDR strains The role of bacterial effl ux pumps in resistance to the extracts was also studied ABSTRACT Objective: To evaluate the : To evaluate the in vitro antibacterial properties and the ability to potentiate some common antibacterial properties and the ability to potentiate some common antibiotics effects of the methanol extracts of 11 Cameroonian food plants on 29 Gram-negative bacteria expressing antibiotics effects of the methanol extracts of 11 Cameroonian food plants on 29 Gram-negative bacteria expressing multidrug resistant (MDR) phenotypes multidrug resistant (MDR) phenotypes Methods: The antimicrobial activity of the extracts was performed using the broth : The antimicrobial activity of the extracts was performed using the broth microdilution method The phytochemical screening of these extracts was also performed using standard methods microdilution method The phytochemical screening of these extracts was also performed using standard methods Results: Ocimum basilicum Ocimum basilicum, Gnetum africanum Gnetum africanum and Eucalyptus robusta Eucalyptus robusta extracts possessed an antibacterial activity extracts possessed an antibacterial activity against all the 29 studied bacteria The extracts from against all the 29 studied bacteria The extracts from G africanum and E robusta were the most active with the were the most active with the lowest minimal inhibitory concentration of 64 μg/mL on lowest minimal inhibitory concentration of 64 μg/mL on Escherichia coli Escherichia coli AG100A for both extracts and also against AG100A for both extracts and also against Klebsiella pneumoniae Klebsiella pneumoniae K24 for K24 for G africanum When tested in the presence of phenylalanine-arginine β-Naphtylamide When tested in the presence of phenylalanine-arginine β-Naphtylamide (PAβN), an effl ux pump inhibitor, the extract of (PAβN), an effl ux pump inhibitor, the extract of Thymus vulgaris Thymus vulgaris and E Robusta showed the best activities on most showed the best activities on most tested strains tested strains E Robusta extract showed good synergistic effects, improving the activity of commonly used antibiotics extract showed good synergistic effects, improving the activity of commonly used antibiotics in about 85% of cases in about 85% of cases Conclusion: The overall results obtained provide the baseline information for the use of the : The overall results obtained provide the baseline information for the use of the tested plants in the treatment of bacterial infections tested plants in the treatment of bacterial infections KEYWORDS food plants, Cameroon, multidrug resistant Gram-negative bacteria, effl ux pumps food plants, Cameroon, multidrug resistant Gram-negative bacteria, effl ux pumps

20 citations

Journal ArticleDOI
TL;DR: A bis-isoflavone derivative, named amphiis-of-lavone (1), was isolated from the roots of Amphimas pterocarpoides, together with three known isoflavones, namely 8-methoxyiso-formononetin (2), 6-methylisoformonetin (3), and isoformoneto-labelin (4). Chemical transformations carried out on compound 3 led to two new derivatives, 4´-acetoxy-6,7-dimethylisoflone (3a
Abstract: A new bis-isoflavone derivative, named amphiisoflavone (1), was isolated from the roots of Amphimas pterocarpoides, together with three known isoflavones, namely 8-methoxyisoformononetin (2), 6-methoxyisoformononetin (3) and isoformononetin (4). Chemical transformations carried out on compound 3 led to two new derivatives, 4´-acetoxy-6,7-dimethylisoflavone (3a) and 4´-O-prenyl- 6,7-dimethylisoflavone (3p), along with a known compound, 4´,6,7-trimethoxyisoflavone (3m). The structures of all compounds were elucidated from spectroscopic evidence, in particular by 1D and 2D NMR spectroscopic methods. These compounds were evaluated for their antioxidant properties and for their antimicrobial activities against a wide range of bacteria and fungi. Graphical Abstract Antimicrobial and Antioxidant Isoflavonoid Derivatives from the Roots of Amphimas pterocarpoides

10 citations


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Journal ArticleDOI
TL;DR: This review is an attempt to establish which characteristics associated with biofilm formation—virulence determinants of S. mutans—are responsible for the development of dental caries.
Abstract: In some diseases, a very important role is played by the ability of bacteria to form multi-dimensional complex structure known as biofilm. The most common disease of the oral cavity, known as dental caries, is a top leader. Streptococcus mutans, one of the many etiological factors of dental caries, is a microorganism which is able to acquire new properties allowing for the expression of pathogenicity determinants determining its virulence in specific environmental conditions. Through the mechanism of adhesion to a solid surface, S. mutans is capable of colonizing the oral cavity and also of forming bacterial biofilm. Additional properties enabling S. mutans to colonize the oral cavity include the ability to survive in an acidic environment and specific interaction with other microorganisms colonizing this ecosystem. This review is an attempt to establish which characteristics associated with biofilm formation—virulence determinants of S. mutans—are responsible for the development of dental caries. In order to extend the knowledge of the nature of Streptococcus infections, an attempt to face the following problems will be made: Biofilm formation as a complex process of protein–bacterium interaction. To what extent do microorganisms of the cariogenic flora exemplified by S. mutans differ in virulence determinants “expression” from microorganisms of physiological flora? How does the environment of the oral cavity and its microorganisms affect the biofilm formation of dominant species? How do selected inhibitors affect the biofilm formation of cariogenic microorganisms?

397 citations

Journal ArticleDOI
TL;DR: A range of therapeutic strategies that could be employed in conjunction with antibiotics and may help to prolong the life span of these life‐saving drugs are explored.
Abstract: The growing number of bacterial pathogens that are resistant to numerous antibiotics is a cause for concern around the globe. There have been no new broad-spectrum antibiotics developed in the last 40 years, and the drugs we have currently are quickly becoming ineffective. In this article, we explore a range of therapeutic strategies that could be employed in conjunction with antibiotics and may help to prolong the life span of these life-saving drugs. Discussed topics include antiresistance drugs, which are administered to potentiate the effects of current antimicrobials in bacteria where they are no longer (or never were) effective; antivirulence drugs, which are directed against bacterial virulence factors; host-directed therapies, which modulate the host's immune system to facilitate infection clearance; and alternative treatments, which include such therapies as oral rehydration for diarrhea, phage therapy, and probiotics. All of these avenues show promise for the treatment of bacterial infections and should be further investigated to explore their full potential in the face of a postantibiotic era.

244 citations

Journal ArticleDOI
TL;DR: The functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions.
Abstract: Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

241 citations

Journal ArticleDOI
TL;DR: 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.
Abstract: 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). 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. 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. 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.

229 citations

Journal ArticleDOI
TL;DR: The results of the antibacterial assays indicated that all tested extracts exert antibacterial activities, with the minimum inhibitory concentration values varying from 32 to 1024 μg/ml.
Abstract: 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. The phytochemical analysis of the extracts was carried out by standard tests meanwhile the liquid micro-broth dilution was used for all antimicrobial assays. 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 xanthoxyloides and Olax subscorpioidea were the most active. In the presence of efflux pump inhibitor, PAsN, 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). 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.

144 citations