Cameroonian Plants Research Articles

Antibacterial and Antibiotic-Potentiating Activities of Thirteen Cameroonian Edible Plants against Gram-Negative Resistant Phenotypes.

This work was designed to investigate the antibacterial activities of methanol extracts from thirteen Cameroonian edible plants and their antibiotic-potentiating effects against Gram-negative multidrug-resistant (MDR) phenotypes. The broth microdilution method was used to evaluate the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts, as well as their antibiotic-potentiating activities. The phytochemical screening of the extracts was carried out according to the standard methods. The results of phytochemical tests revealed the presence of sterols, polyphenols, and tannins in most of the tested extracts, with the other classes of secondary metabolites being selectively distributed. Tested extracts showed variable antibacterial activities with MIC values ranging from 64 to 1024 μg/mL. However, some extracts were significantly active against certain bacterial strains: seeds extract of Theobroma cacao (64 μg/mL) against Escherichia coli AG100Atet and Klebsiella pneumoniae K24, and the bark extract of Uapaca guineensis against E. coli ATCC 8739. The leaves extract of T. cacao displayed the best MBC values (256 μg/mL) against E. aerogenes EA27. Some tested extracts included extracts from the leaves of T. cacao and P. vulgaris, and the seeds of D. edulis and barks A. indica has selectively improved (2- to 64-fold) the antibacterial activities of some of the tested antibiotics, chloramphenicol (CHL), tetracycline (TET), kanamycin (KAN), streptomycin (STR), and erythromycin (ERY), against more than 70% of tested MDR bacteria. The findings of this work showed that tested plant extracts and particularly those from T. cacao and Phaseolus vulgaris can be used alone or in combination with conventional antibiotics in the treatment of infections involving multiresistant bacteria.

Antistaphylococcal and Antibiotic Resistance Modulatory Activities of Thirteen Cameroonian Edible Plants against Resistant Phenotypes.

Background In this study, 18 methanol extracts from Cameroonian edible plants were tested for their antibacterial activities against 26 strains of S. aureus; the role of efflux pumps in the resistance of tested bacteria and the antibiotic resistance-modulating activities against selected multidrug-resistant (MDR) phenotypes were also investigated. Methods Broth microdilution assay was used to evaluate the antibacterial activity, the role of efflux pumps, and the antibiotic resistance-modulating effects of plant extracts. Results Extracts from Dacryodes edulis seeds (DES) and Dacryodes edulis bark (DEB) were active against all 26 tested bacterial strains, within the minimal inhibitory concentration (MIC) range of 256–1024 µg/mL. MIC values varied from 64 to 1024 µg/mL against 96.2% of the 26 tested bacteria for Phaseolus vulgaris leaves (PVL), 92.3% for Azadirachta indica bark (AIB), Dacryodes edulis leaves (DEL), and Ricinodendron heudelotii leaves (RHL). The lowest MIC value of 64 µg/mL was obtained with the extract from Cucurbita maxima beans (CMB) against MRSA4 strain and from Uapaca guineensis bark (UGB) against MRSA9 strain. Bacterial efflux pump inhibitor (EPI), carbonyl cyanide m-chlorophenyl hydrazone (CCCP), improved the activity of DES and UGB as well as that of extracts from Hibiscus esculentus leaves (HEL) and Uapaca guineensis leaves (UGL) against resistant S. aureus strains. Antibiotic-modulating effects against more than 70% of the S. aureus strains tested were obtained when RHL (at MIC/2) was combined with CIP, ERY, and KAN (88.89%), CHL (88.89%), TET (77.78%), and STR (88.89%). Conclusion The present study demonstrated that the 13 tested plants had antistaphylococcal effects and that DES, HEL, UGL, and UGB could be used in combination with EPI to combat resistance to Staphylococcus aureus. Also, it demonstrated that some studied extracts and mostly RHL could be used as antibiotic resistance modulators to fight against resistant strains of S. aureus.

Conditioned media and organic elicitors underpin the production of potent antiplasmodial metabolites by endophytic fungi from Cameroonian medicinal plants.

Plasmodial resistance to artemisinin-based combination therapies emphasizes the need for new drug development to control malaria. This paper describes the antiplasmodial activity of metabolites produced by endophytic fungi of three Cameroonian plants. Ethyl acetate extracts of fungi cultivated on three different media were tested against Plasmodium falciparum chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfINDO) strains using the SYBR green florescence assay. Selected endophytes were further grown in potato dextrose broth supplemented with small organic elicitors and their extracts tested for activity. The effect of elicitors on de novo metabolite synthesis was assessed by reverse-phase HPLC. Activity screening of 81 extracts indicated that Aspergillus niger 58 (IC50 2.25-6.69μg/mL, Pf3D7), Fusarium sp. N240 (IC50 1.62-4.38μg/mL, Pf3D7), Phomopsis sp. N114 (IC50 0.34-7.26μg/mL, Pf3D7), and Xylaria sp. N120 (IC50 2.69-6.77μg/mL, Pf3D7) produced potent extracts when grown in all three media. Further culture of these endophytes in potato dextrose broth supplemented with each of the eight small organic elicitors and subsequent extracts screening indicated the extract of Phomopsis sp. N114 grown with 1% 1-butanol to be highly selective and extremely potent (IC50 0.20-0.33μg/mL; SI > 666). RPHPLC profiles of extracts of Phomopsis sp. N114 grown with or without 1-butanol showed some peaks of enhanced intensities in the former without any qualitative change in the chromatograms. This study showed the ability of selected endophytes to produce potent and selective antiplasmodial metabolites in varied culture conditions. It also showed how the production of desired metabolites can be enhanced by use of small molecular weight elicitors.

Tristemma hirtum and Five Other Cameroonian Edible Plants with Weak or No Antibacterial Effects Modulate the Activities of Antibiotics against Gram-Negative Multidrug-Resistant Phenotypes.

In order to contribute to the fight against infectious diseases, the in vitro antibacterial activity and the antibiotic-potentiating effects of Tristemma hirtum and five other Cameroonian edible plants have been evaluated against Gram-negative multidrug-resistant (MDR) phenotypes. The microdilution method was used to evaluate the bacterial susceptibility of the extracts and their combination to common antibiotics. The phytochemical screening of the extracts was carried out according to standard methods. Phytochemical analysis of the extracts revealed the presence of alkaloids, triterpenes, steroids, and polyphenols, including flavonoids in most of the tested extracts. The entire tested extracts showed moderate (512 μg/mL ≤ MIC ≤ 2048 μg/mL) to weak (MIC > 2048 μg/mL) antibacterial activities against the tested bacteria. Furthermore, extracts of leaf of Tristemma hirtum and pericarps of Raphia hookeri (at their MIC/2 and MIC/4) strongly potentiated the activities of all antibiotics used in the study, especially those of chloramphenicol (CHL), ciprofloxacin (CIP), kanamycin (KAN), and tetracycline (TET) against 70% (7/10) to 100% (10/10) of the tested MDR bacteria, with the modulating factors ranging from 2 to 128. The results of this study suggest that extracts from leaves of Tristemma hirtum and pericarps of Raphia hookeri can be sources of plant-derived products with antibiotic modifying activity.

BIOACTIVITY OF ESSENTIAL OILS FROM MEDICINAL PLANTS OF CAMEROON AND THEIR COMBINATION AGAINST INFANT DIARRHEA INDUCED BY BACTERIA

Background: In Cameroon, one of the most common childhood illnesses after malaria is diarrhea, which generally has
 a bacterial origin. In rural areas, plant utilization is often one of the first ways of treatment though, with no scientific
 bases. Therefore, the aim of this work was to evaluate the antibacterial activities of nine essential oils (EOs) of
 Cameroonian plants and their combinations against some strains responsible for diarrhea.
 Material and Methods: To determine the bacterial species generally involved in childhood diarrheal infections, a
 retrospective study was done. The EOs of Eucalyptus globulus, Cymbopogon citratus, Xylopia aethiopica, Thymus
 vulgaris, Ocimum canum, Cananga odorata, Citrus medica, Citrus paradisi and Citrus reticulata were screened against
 the most incriminated bacterial species using the spot-on-agar test and microdilution methods. Some of the EOs with
 good antibacterial activity were analyzed by Gas Chromatography and Gas Chromatography/Mass Spectrometry.
 According to their composition, Thymus vulgaris and Eucalyptus globulus EOs were combined with that of
 Cymbopogon citratus using the ratios 2/1; 1/1; 1/2 (w/w) and tested against on bacterial growth.
 Results: The retrospective study showed that 10.8% of infant diarrhea was caused by Escherichia coli, Salmonella
 typhimurium and Salmonella paratyphimurium. The Minimum inhibition Concentrations (MIC) of single EOs was
 between 0.78 and 25 mg/mL which were observed to be greater than those of their combinations which ranged between
 0.195 and 6.52 mg/mL. The active essential oils contained mainly hydrocarbonated and oxygenated monoterpens.
 Conclusion: The good antibacterial effects of two Thymus combinations Th1 and Th2 observed on Salmonella
 typhimurium and Salmonella paratyphimurium suggest their used in aromatherapy to cure bacterial diarrhea.

Clausena anisata and Dysphania ambrosioides essential oils: from ethno-medicine to modern uses as effective insecticides.

Dysphania ambrosioides (L.) Mosyakin & Clemants (Amaranthaceae) and Clausena anisata (Willd.) Hook. f. ex Benth. (Rutaceae) are two aromatic species traditionally used in Cameroon to repel and kill insects. The present work was carried out to substantiate this traditional use and to evaluate the possible incorporation in commercial botanical insecticides of their essential oils (EOs). The EOs were distilled from leaves of C. anisata and aerial parts of D. ambrosioides and analyzed by gas chromatography-mass spectrometry (GC-MS). The insecticidal activity of both EOs was investigated against the filariasis vector, Culex quinquefasciatus, and the housefly, Musca domestica. As possible mode of action, the inhibition of acetylcholinesterase (AChE) by the two EOs was investigated as well. The D. ambrosioides EO was characterized by the monoterpene peroxide ascaridole (61.4%) and the aromatic p-cymene (29.0%), whereas the C. anisata EO was dominated by the phenylpropanoids (E)-anethole (64.6%) and (E)-methyl isoeugenol (16.1%). The C. anisata EO proved to be very toxic to third instar larvae of C. quinquefasciatus showing LC50 of 29.3μl/l, whereas D. ambrosioides EO was more toxic to adults of M. domestica showing a LD50 of 51.7 μg/adult. The mixture of both EOs showed a significant synergistic effect against mosquito larvae with LC50 estimated as 19.3μl/l, whereas this phenomenon was not observed upon application to M. domestica adults (LD50 = 75.9 μg/adult). Of the two EOs, the D. ambrosioides one provided a good inhibition of AChE (IC50 = 77 μg/ml), whereas C. anisata oil was not effective. These findings provide new evidences supporting the ethno-botanical use of these two Cameroonian plants, and their possible application even in synergistic binary blends, to develop new eco-friendly, safe and effective herbal insecticides.

Antibacterial and Antibiotic-Modifying Activity of Methanol Extracts from Six Cameroonian Food Plants against Multidrug-Resistant Enteric Bacteria.

The present work was designed to investigate the antibacterial activities of methanol extracts from six Cameroonian edible plants and their synergistic effects with some commonly used antibiotics against multidrug-resistant (MDR) Gram-negative bacteria expressing active efflux pumps. The extracts were subjected to qualitative phytochemical screening and the microdilution broth method was used for antibacterial assays. The results of phytochemical tests indicate that all tested crude extracts contained polyphenols, flavonoids, triterpenes, and steroids. Extracts displayed selective antibacterial activities with the minimal inhibitory concentration (MIC) values ranging from 32 to 1024 μg/mL. The lowest MIC value (32 μg/mL) was recorded with Coula edulis extract against E. coli AG102 and K. pneumoniae K2 and with Mangifera indica bark extract against P. aeruginosa PA01 and Citrus sinensis extract against E. coli W3110 which also displayed the best MBC (256 μg/mL) value against E. coli ATCC8739. In combination with antibiotics, extracts from M. indica leaves showed synergistic effects with 75% (6/8) of the tested antibiotics against more than 80% of the tested bacteria. The findings of the present work indicate that the tested plants may be used alone or in combination in the treatment of bacterial infections including the multidrug-resistant bacteria.

Antibacterial activity of six medicinal Cameroonian plants against Gram-positive and Gram-negative multidrug resistant phenotypes.

BackgroundInfectious diseases due to multidrug-resistant bacteria are one of the causes of treatment failures contributing to an increase in mortality and/or morbidity. In this study, we evaluated the antibacterial potential of different parts of six medicinal plants namely Alstonia boonei, Ageratum conyzoides, Croton macrostachys, Cassia obtusifolia, Catharanthus roseus and Paullinia pinnata against a panel of 36 multi-drug resistant (MDR) Gram-negative and Gram-positive bacteria.MethodsMinimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of the methanol extracts from different parts of the plants were determined using broth microdilution method; standard phytochemical methods were used for phytochemical screening.ResultsSeveral phytochemical classes such as polyphenols, sterols, triterpenes, alkaloids, flavonoids and saponins were identified in the plant extracts. MIC values obtained ranged from 64 to 1024 μg/mL. Leaves extract of Catharanthus roseus (86.11 %), Croton macrostachys (83.33 %) and Paullinia pinnata (80.55 %) displayed the best antibacterial spectra. The lowest MIC value of 64 μg/mL was obtained with the Paullinia pinnata stems extract and Cassia obtusifolia extract against the strain of Staphylococcus aureus MRSA8. Results also showed that the tested samples generally displayed bacteriostatic effects with MBC values obtained in only 3.35 % of the cases where plant extracts were active.ConclusionThe results obtained at the end of this study demonstrate for the first time the antibacterial activity of the studied medicinal plants against MDR bacteria. The tested plants could be a reservoir of molecules to fight against MDR bacterial infections.

Antimicrobial Activity of Single And Combined Extracts of Medicinal Plants From Cameroon

Selected Cameroonian plants have been investigated for their antifungal and antibacterial activity against five species: four bacteria, namely S. aureus, S. pyogenes, S. mutans, Pseudomonas aeruginosa and the yeast C. albicans. The solvents used for plant extraction were either ethanol or water. The in vitro antimicrobial activity was performed by disk diffusion and microdilution method. The aqueous extracts showed no activity whereas the ethanolic extracts showed a significant antibacterial activity, which may be associated to the high content in tannins shown by some of the extracts. In conclusion, this work adds to the accumulating evidences supporting the development of new alternatives to antibiotics based on the use of natural products.

Antibacterial activities of the methanol extracts of Albizia adianthifolia, Alchornea laxiflora, Laportea ovalifolia and three other Cameroonian plants against multi-drug resistant Gram-negative bacteria.

In the last 10 years, resistance in Gram-negative bacteria has been increasing. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of six Cameroonian medicinal plants Albizia adianthifolia, Alchornea laxiflora, Boerhavia diffusa, Combretum hispidum, Laportea ovalifolia and Scoparia dulcis against a panel of 15 multidrug resistant Gram-negative bacterial strains. The broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the reference qualitative phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols and triterpenes, other classes of chemicals being selectively distributed. The best antibacterial activities were recorded with bark and root extracts of A. adianthifolia as well as with L. ovalifolia extract, with MIC values ranging from 64 to 1024 μg/mL on 93.3% of the fifteen tested bacteria. The lowest MIC value of 64 μg/mL was recorded with A. laxiflora bark extract against Enterobacter aerogenes EA289.Finally, the results of this study provide evidence of the antibacterial activity of the tested plants and suggest their possible use in the control of multidrug resistant phenotypes.

Antibacterial activities of methanol extracts from Alchornea cordifolia and four other Cameroonian plants against MDR phenotypes

Multidrug-resistant (MDR) bacterial infections, especially those caused by Gram-negative phenotypes, have emerged as one of the major health concerns worldwide. In the present study, we investigated the antibacterial activity of methanol extracts from five Cameroonian medicinal plants (Alchornea cordifolia, Eremomastax speciosa, Laportea aestuans, Pennisetum purpureum and Spathodea campanulata) against 15 Gram-negative bacteria that included MDR phenotypes. The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and the minimal bactericidal concentrations (MBC) of all of the samples. Standard phytochemical methods were used for a preliminary phytochemical screening of the plant extracts. Phytochemical analysis showed the presence of polyphenols, tannins, triterpenes and sterols in all of the studied extracts. Other chemical classes of secondary metabolites were selectively identified. The best antibacterial activities (MICs ranges of 64–1024 μg/mL) obtained against the 15 tested bacteria were found in extracts of leaves (93.3%), bark (86.7%) and roots (80%) of A. cordifolia as well as extracts of L. aestuans (86.7%) and P. purpureum (66.7%). The lowest MIC value of 64 μg/mL was recorded for the A. cordifolia bark extract against Pseudomonas aeruginosa PA01. The findings of this study provide deep insights into the possible use of the studied plants, especially A. cordifolia and L. aestuans, for the control of Gram-negative bacterial infections, especially against MDR species.

Researchers use zeolites to improve polylactic acid (PLA)

Bacterial infections are among the major cause of morbidity and mortality worldwide. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of five Cameroonian edible plants namely Colocasia esculenta, Triumfetta pentandra, Hibiscus esculentus, Canarium schweinfurthii and Annona muricata against a panel of 19 multidrug resistant Gram-negative bacterial strains. The liquid broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols, triterpenes and steroids, other classes of chemicals being selectively distributed. Canarium schweinfurthii extract showed the best activity with MIC values ranging from 64 to 1024 μg/mL against 89.5% of the 19 tested bacteria strains. MIC values below or equal to 1024 μg/mL were also recorded with Triumfetta pentandra, Annona muricata, Colocasia esculenta and Hibiscus esculentus extracts respectively against 15/19 (78.9%), 11/19 (57.9%), 10/19 (52.6%) and 10/19 (52.6%) tested bacteria. Extract from C. schweinfurthii displayed the lowest MIC value (64 μg/mL) against Escherichia coli AG100ATet. Finally, the results of this work provide baseline information for the use of C. esculenta, T. pentandra, H. esculentus, C. schweinfurthii and A. muricata in the treatment of bacterial infections including multidrug resistant phenotypes.

Antibacterial activities of the methanol extracts of Canarium schweinfurthii and four other Cameroonian dietary plants against multi-drug resistant Gram-negative bacteria.

Bacterial infections are among the major cause of morbidity and mortality worldwide. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of five Cameroonian edible plants namely Colocasia esculenta, Triumfetta pentandra, Hibiscus esculentus, Canarium schweinfurthii and Annona muricata against a panel of 19 multidrug resistant Gram-negative bacterial strains. The liquid broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols, triterpenes and steroids, other classes of chemicals being selectively distributed. Canarium schweinfurthii extract showed the best activity with MIC values ranging from 64 to 1024 μg/mL against 89.5% of the 19 tested bacteria strains. MIC values below or equal to 1024 μg/mL were also recorded with Triumfetta pentandra, Annona muricata, Colocasia esculenta and Hibiscus esculentus extracts respectively against 15/19 (78.9%), 11/19 (57.9%), 10/19 (52.6%) and 10/19 (52.6%) tested bacteria. Extract from C. schweinfurthii displayed the lowest MIC value (64 μg/mL) against Escherichia coli AG100ATet. Finally, the results of this work provide baseline information for the use of C. esculenta, T. pentandra, H. esculentus, C. schweinfurthii and A. muricata in the treatment of bacterial infections including multidrug resistant phenotypes.

Anticonvulsant activity of extracts from six Cameroonian plants traditionally used to treat epilepsy

Epilepsy remains one of the leading public health problems that affects about 50 million people worldwide, thus stressing the need for new anticonvulsant drug. This study was designed to evaluate the anticonvulsant activity against Penty lenetetrazole induced–convulsion in mice. Plants were extracted by maceration with water or organic solvents. The extracts were tested against PTZ-induced convulsion by measuring onset seizure, clonic seizure onset, convulsion duration, death time and percentage of protection. A. cordifolia leaf extract protected all animals from death at 1000 mg/kg. A. muricata stem extract delayed seizures at 200 and 400 mg/kg, while the onset of tonicoclonic (TC) seizures was significantly delayed at the highest doses tested for the seed extract (800 mg/kg). Stem and leaf extracts of A. senegalensis significantly delayed seizure onset at all doses. D. adescendes extract significantly protected mice from death. F. thonningii leaf extract at the smallest dose tested (200 mg/kg), significantly delayed the seizure onset and the occurrence of TC convulsions. Bark extract of V. doniana significantly delayed the seizure onset at all doses tested. The results obtained corroborate with the traditional claims that these plants can be a valuable source of new anticonvulsant compounds.Keywords: Plant extracts, PTZ-induced seizures, anticonvulsant effect, mice.

Antibiotic-potentiation activities of four Cameroonian dietary plants against multidrug-resistant Gram-negative bacteria expressing efflux pumps.

BackgroundThe 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.MethodsThe qualitative phytochemical screening of the plant extracts was performed using standard methods whilst the antibacterial activity was performed by broth micro-dilution method.ResultsAll 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.ConclusionThese 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.

Antibacterial activities of Beilschmiedia obscura and six other Cameroonian medicinal plants against multi-drug resistant Gram-negative phenotypes.

BackgroundThe 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.MethodsThe 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.ResultsPhytochemical 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.ConclusionThe 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.

Antibacterial and antibiotic-potentiation activities of some Cameroonian food plants against multi-drug resistant gram-negative bacteria.

To evaluate the in vitro 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 multidrug resistant (MDR) phenotypes. 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. Ocimum basilicum, Gnetum africanum and Eucalyptus robusta extracts possessed an antibacterial activity against all the 29 studied bacteria. The extracts from G. africanum and E. robusta were the most active with the lowest minimal inhibitory concentration of 64 μg/mL on Escherichia coli AG100A for both extracts and also against Klebsiella pneumoniae K24 for G. africanum. When tested in the presence of phenylalanine-arginine β-Naphtylamide (PAβN), an efflux pump inhibitor, the extract of Thymus vulgaris and E. Robusta showed the best activities on most tested strains. E. Robusta extract showed good synergistic effects, improving the activity of commonly used antibiotics in about 85% of cases. The overall results obtained provide the baseline information for the use of the tested plants in the treatment of bacterial infections.

Cytotoxicity of Elaoephorbia drupifera and other Cameroonian medicinal plants against drug sensitive and multidrug resistant cancer cells

BackgroundMultidrug 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.MethodsThe methanol maceration was used to obtain the crude plant extracts whilst the cytotoxicity of the studied extracts was determined using a resazurin reduction assay.ResultsA 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.ConclusionThe 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.

Antibacterial activities of the methanol extracts of seven Cameroonian dietary plants against bacteria expressing MDR phenotypes.

The morbidity and mortality caused by bacterial infections significantly increased with resistance to commonly used antibiotics. This is partially due to the activation of efflux pumps in Gram-negative bacteria. The present work designed to assess the in vitro antibacterial activities of seven Cameroonian dietary plants (Sesamum indicum, Sesamum radiatum, Cinnamomum zeylanicum, Corchous olitorius, Cyperus esculentus, Adansonia digitata, Aframomum kayserianum), against multidrug resistant (MDR) Gram-negative bacteria over expressing active efflux pumps. The standard phytochemical methods were used to detect the main classes of secondary metabolites in the extracts. The antibacterial activities of the studied extracts in the absence or presence of an efflux pump inhibitor (PAβN) were evaluated using liquid microbroth dilution method. The results obtained indicated that apart from the extract of C. esculentus, all other samples contained alkaloids, phenols and polyphenols meanwhile other classes of chemicals were selectively present. The studied extracts displayed antibacterial activities with minimal inhibitory concentrations (MICs) values ranged from 64 to 1024 μg/mL on the majority of the 27 tested microbial strains. The extract of S. indicum was active against 77.77% of the tested microorganisms whilst the lowest MIC value (64 μg/mL) was recorded with that of A. kayserianum against E. aerogenes EA294. The results of the present work provide baseline information on the possible used of the tested Cameroonian dietary plants in the treatment of bacterial infections including multi-drug resistant phenotypes.

In Vitro antibacterial and antibiotic-potentiation activities of four edible plants against multidrug-resistant gram-negative species

BackgroundThe 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.MethodsThe 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.ResultsPhytochemical 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.ConclusionThe 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.