Cameroonian Plants Research Articles

Anti-Inflammatory, Antioxidant Activities, and Phytochemical Characterization of Edible Plants Exerting Synergistic Effects in Human Gastric Epithelial Cells

Dietary bioactive compounds from natural sources (e.g., herbal medicines, foods) are known to potentially suppress acute or chronic inflammation and promote the effectiveness of treatment to reduce the harmful effects of gastritis alone or in combination. In this regard, we have characterized four Cameroonian spice extracts, namely Aframomum citratum, Dichrostachys glomerata, Tetrapleura tetraptera, and Xylopia parviflora through reverse phase-high-performance liquid chromatography (RP-HPLC), ultra-performance liquid chromatography-electrospray ionization high-resolution mass spectrometry (UPLC-ESI-HRMS/MS), and Fourier transform infrared spectroscopic (FTIR) analyses and investigated their antioxidant and synergistic anti-inflammatory activities in human gastric adenocarcinoma (AGS) and gastric epithelial (GES-1) cells. The extracts showed a high amount of total phenolic (TPC: 150-290 mg gallic acid equivalents (GAE)/g of extract) and flavonoid content (TFC: 35-115 mg catechin equivalents (CE)/g of extract) with antioxidant properties in a cell-free system (1,1-Diphenyl-2-picryl-hydrazyl (DPPH) half maximal inhibitory concentration (IC50s) ≤ 45 µg/mL; 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) half maximal inhibitory concentration (IC50s) ≤ 29 µg/mL. The extracts in combination (MIX) exert a synergistic beneficial effect (combination index (CIs) < 1 and dose reduction index (DRIs) > 1) on inflammatory markers (interleukin (IL)-8 and -6 release, and nuclear factor kappa B (NF-κB) driven transcription) in human gastric epithelial cells, which may result from the presence of phenolic compounds (phenolic acids, flavonoids) or other compounds (protein, lipid, aromatic, and polysaccharide compounds) tentatively identified in the extracts. The general findings of the present study provide supporting evidence on the chemical composition of four Cameroonian dietary plants and their significant synergistic inhibitory activities on inflammatory markers of gastric epithelial cells.

Anti-Klebsiella and antibiotic-potentiation activities of the methanol extracts of seven Cameroonian dietary plants against multidrug-resistant phenotypes over-expressing AcrAB-TolC efflux pumps

Background: Bacterial infections continue to wreak havoc around the world with high death rates. African medicinal plants and the phytoconstituents showed high efficiency in impeding the growth of the resistance phenotypes of bacteria The present work was designed to determine the antibacterial activity of seven Cameroonian dietary plants against clinical MDR isolated of Klebsiella sp. These plants included Persea americana Miller (Lauraceae), Psidium guajava Linn. (Myrtaceae), Mangifera indica Linn. (Anacardiaceae), Citrus sinensis Linn. (Rutaceae), Passiflora edulis Sims (Passifloraceae), Garcinia kola Heckel (Guttiferae), and Artocarpus heterophylus Lam. (Moraceae). Methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determinations on the used bacterial strains alone, in the presence of an efflux pump inhibitor, phenylalanine arginine beta naphthylamide (PAβN), and in combination with antibiotics, were performed by the microbroth dilution method using a rapid colorimetric para-Iodonitrotetrazolium chloride (INT) assay. Results: The tested botanicals had different extend of antibacterial activities, with MIC ranges of between 256 μg/mL and 2048 μg/mL. Botanicals from Persea americana, Psidium guajava, Mangifera indica, Artocarpus heterophyllus, and Garcinia kola bark had detected MIC values on all 15 tested Klebsiella strains. PAβN potentiated the activity of the botanicals on all tested bacteria, with the increase of activity ranging from 4 to more than 128-fold. The most significant increase of 4 to more than 128-fold was observed with botanicals from leaves and bark of Psidium guajava and Mangifera indica. The botanicals from the leaves of Mangifera indica potentiated the activity of eight out of ten tested antibiotics (Ceftriaxone, Chloramphenicol, Levofloxacin, Ampicillin, Tetracycline, Imipenem, Doxycycline, and Levofloxacin) against 100% of the tested bacteria. Conclusion: In the present study, it was demonstrated that botanicals from Persea Americana, Psidium guajava, Mangifera indica, Artocarpus heterophyllus, and Garcinia kola had the highest spectrum of activity, and can be used to combat the resistance of Klebsiella species

Anti-staphylococcal and antibiotic-potentiating activities of botanicals from nine Cameroonian food plants towards multidrug-resistant phenotypes

Background: Staphylococcus aureus is a commensal and pathogenic bacterium responsible for both community and nosocomial infections, superficial or deep, and benign or lethal. Staphylococcus aureus is a commensal and pathogenic bacterium responsible for both community and nosocomial infections, superficial or deep, and benign or lethal. Because of its infectious potential and its ability to develop resistance to many antibiotics, staphylococcal infections remain the target of reinforced clinical surveillance. To contribute to the fight against resistant staphylococcal infections, the in vitro assessment of the anti-staphylococcal activity of methanol extracts (or botanicals) of nine food plants from Cameroon, Persea americana, Psidium guajava, Syzygium jambos, Vernonia amygdalina, Citrus sinensis, passiflora edulis, Carica papaya, Aframomum letestuanum, and Garcinia kola), as well as the effects of the association of some of these botanicals with antibiotics against resistant and multidrug-resistant staphylococci. Methods: The plant secondary metabolites were extracted by maceration in methanol; the microdilution method using the rapid para-Iodonitrotetrazolium chloride (INT) colorimetric method was applied to evaluate the antibacterial activities of the botanicals as well as the effects of combining these extracts with antibiotics. Results: The botanicals had a minimum inhibitory concentration (MIC) range of 64-2048 µg/mL on the 17 staphylococcal strains and isolates tested. Extracts from Aframomum letestuanum seeds and Psidium guajava leaves and bark had the broadest activity spectra, inhibiting the growth of 95% and 85% of the studied bacteria, respectively. In the presence of an efflux pump inhibitor, reserpine, methanol extracts from Syzygium jambos leaves, Psidium guajava bark and epicarp, and Afromomum letestuanum epicarp showed a considerable increase in their activity. Botanicals from the leaves of Syzygium jambos improved the activities of tetracycline, ceftriaxone, chloramphenicol, and ampicillin against more than 80% of the tested bacteria. Conclusion: The investigated pants, mostly Psidium guajava, Syzygium jambos, and Aframomum letestuanum could be used in the treatment of staphylococcal infections with multidrug-resistant phenotypes.

Botanicals from nine selected Cameroonian edible plants displayed Anti-pseudomonas effects and potentiated the activities of antibiotics against multidrug-resistant phenotypes over-expressing MexAB-OprM efflux pumps

Background: Despite the recognized efficiency of antibiotic therapy, the annual cases of deaths related to bacterial diseases is still growing in developing countries. In the present study, the in vitro antipseudomonal activity of the methanol extracts of nine food plants from Cameroon against the multidrug-resistant strains and isolates of Pseudomonas aeruginosa overexpressing active efflux pumps was determined. These plants included Persea americana, Syzygium jambos, Mangifera indica, Garcinia kola, Citrus sinensis, Passiflora edulis, Vernonia amygdalina, Aframomum letestuanum, and Artocarpus heterophylus. Methods: The liquid microplate dilution method using the rapid para-Iodonitrotetrazolium chloride (INT) colorimetric method was applied to evaluate the antipseudomonal activities of botanicals, as well as their association with the efflux pump inhibitor and antibiotics. Results: All botanicals displayed an antibacterial activity that varies from one bacterium to another, in the minimal inhibitory concentration (MIC) range of 64 µg/mL to 2048 µg/mL. The extracts from a mixture of leaves and bark of Syzygium jambos and Mangifera indica, the bark of Garcinia kola, and the leaves of Persea americana had the highest spectrum of antipseudomonal activity, with their inhibitory effects being noted in 100% of the 15 tested bacteria. Botanical from the leaves of Garcinia cola, were active against 90% of the strains tested, that from the bark of Persea americana and the leaves of Citrus sinensis were active against 70% and 60% of tested strains and isolates. Botanicals from the leaves and bark of Mangifera indica were very active against the isolates P124 and P57 with a MIC value of 64 µg/mL. At the concentration of MIC/2 and MIC/4, the extract from the leaves of Mangifera indica and Syzygium jambos potentiated the activity of four antibiotics (Penicillin, Ampicillin, Imipenem, Augmentin) on 100% (7/7) of the strains and isolates tested. Persea americana leaf extract also enhanced the activity of penicillin, tetracycline, chloramphenicol, levofloxacin, ampicillin, and augmentin in 85% (6/7) of strains and isolates tested. The activity of all tested antibiotics increased in the presence of botanicals against at least one bacterial strain. The extract of leaves and bark of Persea americana, Psidium guajava, and leaves of Syzygium jambos potentiated the activity of 80% of the antibiotics on the strains and isolates tested. Conclusion: Finally, the methanol extracts from the leaves and bark of Mangifera indica could be used effectively alone or in combination with antibiotics in the treatment of bacterial infection caused by Pseudomonas aeruginosa including antibiotic-resistant phenotypes expressing efflux pumps.

The Antiplasmodial Potential of Medicinal Plants Used in the Cameroonian Pharmacopoeia: An Updated Systematic Review and Meta-Analysis.

Malaria is a real public health problem. It is the leading cause of morbidity and mortality in the world. Research in herbal medicine has so far shown that the use of plants against malaria is not to be neglected. This review aims to highlight the antiplasmodial potential of Cameroonian plants. In order to achieve this objective, we conducted a bibliographic search in April 2022 using the PubMed search engine. This research included both the published and unpublished studies. A narrative approach was used to describe the antiplasmodial potential of the various species of plants investigated. Quantitative data were analyzed using R studio 4.1.1 software and random effects model was used to estimate the effect size. The research of the antiplasmodial activity of Cameroonian plants dates back to 2000. This area of research has since provided extensive data to indicate the antiplasmodial potential of several plants, most of which originate from the central region. Despite the heterogeneity observed between the different plant families studied in Cameroon for their in vitro antiplasmodial effect, there is strong evidence that 17 active compounds from these plants would be ideal candidates for the synthesis of new antimalarial drugs. The Dacryodes edulis species could be considered as the best natural alternative in the treatment of uncomplicated malaria according to its properties. It is clear that the traditional Cameroonian pharmacopoeia has many species that contain compounds with antiplasmodial activity. More studies need to be conducted to explore the multitude of unexplored plants that are used in traditional medicine. These studies should take into account the nature of the cell model used for cytotoxicity assessment.

Essential Oils from Cameroonian Aromatic Plants as Effective Insecticides against Mosquitoes, Houseflies, and Moths.

Recently, spices have attracted the attention of scientists and agrochemical companies for their potential as insecticidal and acaricidal agents, and even as repellents to replace synthetic compounds that are labeled with detrimental impacts on environment and human and animal health. In this framework, the aim of this study was to evaluate the insecticidal potential of the essential oils (EOs) obtained from three Cameroonian aromatic plants, namely Monodora myristica (Gaertn.) Dunal, Xylopia aethiopica (Dunal) A. Rich., and Aframomum citratum (J. Pereira) K. Schum. They were produced by hydrodistillation, with yields of 3.84, 4.89, and 0.85%, respectively. The chemical composition was evaluated by GC-MS analysis. The EOs and their major constituents (i.e., geraniol, sabinene, α-pinene, p-cymene, α-phellandrene, and β-pinene) were tested against the polyphagous moth pest, i.e., Spodoptera littoralis (Boisd.), the common housefly, Musca domestica L., and the filariasis and arbovirus mosquito vector, Culex quinquefasciatus Say. Our results showed that M. myristica and X. aethiopica EOs were the most effective against M. domestica adults, being effective on both males (22.1 µg adult−1) and females (LD50: 29.1 µg adult−1). The M. myristica EO and geraniol showed the highest toxicity on S. littoralis, with LD50(90) values of 29.3 (123.5) and 25.3 (83.2) µg larva−1, respectively. Last, the EOs from M. myristica and X. aethiopica, as well as the major constituents p-cymene and α-phellandrene, were the most toxic against C. quinquefasciatus larvae. The selected EOs may potentially lead to the production of cheap and effective botanical insecticides for African smallholders, although the development of effective formulations, a safety evaluation, and an in-depth study of their efficacy on different insect species are needed.

Antibacterial and antibiotic-potentiation activity of Coffea arabica and six other Cameroonian edible plants against multidrug-resistant phenotypes

Background: Medicinal plants have always played an important role in human health. Many plants are traditionally used as drugs against microbial infections. In this study, a panel of seven methanol extracts from Cameroonian edible was assessed for their antibacterial potentiality against multidrug-resistant Gram-positive and Gram-negative bacteria. Methods: The microdilution technique using a 96-well plate was used to assess the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the crude extracts, as well as their potential to improve the antimicrobial activity of certain families of antibiotics. Phytochemical screening of the extracts was carried out according to the standard methods. Results: The most detected classes of pharmaceuticals were tannins, triterpenes, polyphenols, and steroids. Coffea arabica bark extract inhibited all 20 tested MDR bacteria strains; Coffea arabica leaf and seeds extracts, Adansonia digitata bark extract, Sechium edule leaf extract, all inhibited 95% (19/20) of the strains tested, Beilschmeidia louisii stem extract inhibited the growth of 85% (17/20) of the tested bacteria, while Hyphaene therbaica displayed 70% (14/20) bacterial inhibition. The MIC values of the plant extracts ranged from 256 to 2048 μg/mL. However, the best MIC value (256 μg/mL) was obtained with B. louisii stem extract against E. coli AG102 and S. aureus MRSA12. The leaf extract of S. edule improved the anti-bacterial activities of kanamycin, tetracycline, and Cloxacillin against the MDR strain P. stuartii 29916 by up to 16 times; furthermore, this extract improved the antibacterial effect of tetracycline, Cloxacillin, kanamycin, and doxycycline by 16 folds against the MDR strain E. coli AG100ATET; the bark extract of C. arabica improved the activities of ofloxacin, chloramphenicol the activities of ofloxacin, chloramphenicol, and doxycycline toward all the tested MDR Gram positive and Gram-negative bacteria with improvement activity factor (IAF) ranging from 2 to 16, while the leaf extract of B. louisii increased up to 8-fold the activity of Cloxacillin against P. aeruginosa PA 124. Conclusion: Coffea arabica, Adansonia digitata, Sechium edule, and Beilschmeidia louisii are the explorable sources of antibacterial agents usable alone or in combination with conventional antibiotics to tackle diseases caused by resistant bacterial phenotypes. Keywords: Bacterial infections; Cameroon; edible plants; Multidrug resistance; Antibiotic-potentiation.

Antibacterial potential of some Cameroonian ornamental plants and their isolated endophytic fungi

Bacterial resistance to antibiotics is a real challenge for health practitioners and society in general today, bringing a constant need for the search for new molecules. The present study is focused on the antibacterial effect of extracts of three ornamental plants and their endophytes. The endophytic fungi isolated from the ornamental plants included Sansevieria trifasciata leaves, Monstera deliciosa fruits, Monstera deliciosa and Cordyline fruticosa roots. The morphocultural features were studied, the antibacterial activities of the endophytes as well as those of their host plant extracts were determined through the agar diffusion and broth microdilution methods. The plant extracts were obtained by ethanol maceration, while those from the endophytes were obtained by ethyl acetate depletion. Phytochemical screening of the different extracts was done using standard methods. Four endophytes were isolated from the three plants: Geotrichum sp. from the leaves of Sansevieria trifasciata; Colletotrichum sp. and Rhizopus sp. from the roots of Cordyline fruticosa and Monstera deliciosa respectively and Phoma sp. from the fruits of Monstera deliciosa. Endophyte isolates inhibited the growth of almost all the tested bacterial with inhibition diameters ranging from 5 to 40 mm. The host endophytic plant extracts were less active than endophytic extracts, with inhibition diameters ranging from 0 to 20 mm. Some endophytic fungal secretions and plant extracts exhibited antibacterial activities in liquid media, with MICs ranging from 512 to 2048 µg/ml. Finally, endophytic extracts were more active than plant extracts. There was no concordance between the activities of endophytes and those of plant extracts, reflecting their independence.

Phytochemical analysis and antibiotic-modulating activity of Cocos nucifera, Glycine max and Musa sapientum methanol extracts against multidrug resistant Gram-negative bacteria

Background: The rapid emergence of multidrug resistant (MDR) bacteria is occurring worldwide, endangering the efficacy of antibiotics, which have transformed medicine and saved millions of lives. Antibiotic-resistant infections are already widespread in the Sub-Saharan Africa and across the globe. To extend the search for new and more efficient antimicrobial drugs from natural sources, this work has been carried out to study the phytochemical composition and the antibacterial activities of some Cameroonian dietary plants (Cocos nucifera, Glycine max and Musa sapientum) against several MDR Gram-negative strains including Escherichia coli, Enterobacter aerogenes, Providencia stuartii, Klebsiella pneumoniae, Pseudomonas aeruginosa species expressing efflux pumps. Methods: Phytochemical screening of plant extracts was performed using qualitative standard methods and the antimicrobial assays of these extracts alone and in combination with antibiotics were done using serial 96-wells microplate dilution essays. Results: Each plant extract contained at least three mean classes of secondary metabolites. Glycine max, epicarps, leaves and bark of C. nucifera as well as mesocarps of M. sapientum contained each alkaloids, polyphenols, flavonoids, and triterpenes. Moreover, steroids were also found in G. max, steroids and saponins in epicarps and saponins in bark of C. nucifera. Meanwhile epicarps from M. sapientum contained only polyphenols, flavonoids and saponins. Antibacterial assays showed that different parts of C. nucifera were more active than other extracts. Their minimal inhibitory concentrations (MICs) varied from 128 to 2048 µg/mL. The bark part presented the highest antibacterial potential inhibiting the growth of 90% of strains with significant activity (100≤MIC≤512 µg/mL) against 50% of them (three E. coli, four E. aerogenes and three K. pneumoniae). It showed bactericidal effects (MBC/MIC≤4) on 45% of the same bacterial species. It was followed by epicarps and leaves parts which exhibited an inhibitory power against 75% and 60% of bacteria with significant activity on 40% and 20% of them respectively. They also showed bactericidal effects on E. coli ATCC8739 for epicarps extract and E. coli ATCC8739 and P. stuartii NEA16 for leaves extract. Extracts from G. max were less active and those from mesocarps and epicarps of M. sapientum did not showed any activity on all studied bacteria. Bark and epicarps extracts of C. nucifera potentiated the activities of all used antibiotics against at least 70% of bacteria while leaves extract exhibited this effect improving the activities of 67% of antibiotics with improvement activity factors (IAF) ranging from 2 to 256 suggesting that they contain bioactive compounds which could be considered as efflux pumps inhibitors. Extracts from G. max, epicarps and mesocarps of M. sapientum enhanced the inhibitory potential of 56%, 34% and 23% of antibiotics respectively against at least 70% of studied bacteria. These increases of activities also characterize synergistic effects between antibiotics and bioactive compounds of plants. Conclusion: The findings of this work suggest that infections by resistant bacteria can be treated using different parts of C. nucifera as an alternative to commonly used antibiotics.

In vitro antioxidant potential and antimicrobial activity of some Cameroonian plant extracts

A study on Cameroonian edible and medicinal plants was undertaken to assess their potential as food preservatives and natural food colorants. The ultrasound-assisted technique was used for the extraction of bioactive compounds. A total of 16 extracts prepared from 7 plants (Aframomum melegueta S., Ageratum conyzoides L., Cympobogon citratus Stapf, Garcinia kola Heckel, Lantana camara L., Nauclea diderrichii, Vernonia amygdalina) were assayed to detect phytochemicals and assess antioxidant potential using the scavenging DPPH radical method and antimicrobial activity (10 mg/mL) against ten microorganisms by the agar well diffusion method. The ethanolic extract from L. camara leaves revealed the highest polyphenols and flavonoids contents. In contrast, the hexane/acetone extract from A. conyzoides and L. camara leaves had the highest chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, whereas the highest carotenoid content was found in L. camara leaves. The ethanol extracts exhibited more significant antioxidant activity than hexane/acetone extracts. All seven plants (100%) inhibited the growth of at least one tested foodborne and spoilage bacteria and fungi. The germination of both Bacillus spp. spores were also affected. The hexane/acetone extracts were by far the best antimicrobial agent, and extract from L. camara leaves was one of the most effective, with a large antimicrobial spectrum. The antimicrobial activity of extracts was correlated to the amount of carotenoids and chlorophylls. HPLC-DAD revealed bioactive compounds as chlorogenic and caffeic acids found as major phenols in ethanolic extract of L. camara leaves, whereas lutein, carotene, and zeaxanthin were the specific carotenoids present in hexane/acetone extract of the same plant.

In vitro antimicrobial activity of Millettia laurentii De Wild and Lophira alata Banks ex C. F. Gaertn on selected foodborne pathogens associated to gastroenteritis

This study aimed at evaluating the antimicrobial potential of aqueous, ethanolic and methanolic extracts of two Cameroonian plants against selected foodborne pathogens. Bioactive compounds were extracted from Millettia laurentii De Wild seeds and Lophira alata Banks ex. C. F. Gaertn leaves using distilled water, ethanol and methanol as solvents. The extracts were tested against Escherichia coli O157, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis, Moraxella morganii, Salmonella enteritidis, Klebsiella pneumoniae and Listeria monocytogenes using the microdilution method. The results showed that distilled water extracted a more important mass of phytochemical compounds (18.0–24.60%) compared to ethanol (4.80–5.0%) and methanol (4.20–4.60%). All the extracts exhibited significant antimicrobial activity with MIC values ranging from 5 to 20 μg/mL for M. laurentii seeds extracts and from 1.0 to 20 μg/mL for L. alata leaves extracts. The different plant extracts were ten times less active than gentamicin. The most active extracts were obtained using ethanol as solvent and K. pneumoniae was the most resistant pathogen to all extracts (MBC>20 μg/mL). M. laurentii extracts were bactericidal against L. monocytogenes and P. mirabilis while the reference antibiotic (gentamicin) was bacteriostatic against these pathogens. The results obtained from this study suggest the studied local plant materials as a source of antimicrobial compounds which can be valorized in the medical field as substitute of antibiotics for which many microorganisms have nowadays developed resistance mechanisms. Further studies need to be performed in order to characterize and identify these antimicrobial active molecules.

Afrostyrax lepidophyllus Mildbr. and Monodora myristica (Gaertn.) Dunal Extracts Decrease Doxorubicin Cytotoxicity on H9c2 Cardiomyoblasts.

Materials and Methods Bark extracts of these plants (1 and 25 µg/mL) were added 3 hours before coincubating H9c2 cardiomyoblasts with Dox (0.5 and 1 µM) for 24 hours more. We measured cell mass and metabolic viability, mitochondrial transmembrane potential, superoxide anion content, and activity-like of caspase-3 and caspase-9 following treatment with the extracts and/or Dox. Also, selenium and vitamin C contents were measured in the plant extracts. Results The results confirmed that Dox treatment decreased cell mass, mitochondrial membrane potential and metabolic viability, increased mitochondrial superoxide anion, and stimulated caspase-3 and caspase-9-like activities. Pretreatment of the cells with the plant extracts significantly inhibited Dox cytotoxicity, with more significant results at the higher concentration. Measurements of selenium and vitamin C in the extracts revealed higher concentration of both when compared with other Cameroonian spices. Conclusion Both extracts of A. lepidophyllus and M. myristica were effective against Dox-induced cytotoxicity, most likely due to their content in antioxidants.

Analytical Determination of Mechanical Characteristics of Bio-Composites with Reinforcement of Fibers and Particles of Cameroonian's Plants

This work involves calculating the mechanical characteristics of bio-composites reinforced with plant fibers and plant particles from semi-empirical formulas and comparing them with the results obtained experimentally, the aim of this approach being to determine the analytical model which gives results close to experimental results with the aim of reducing the delays linked to the experimental characterization of composites with reinforcement of Cameroonian fibers and particles. To carry out this work, we used the mechanical characteristics of the fibers of the trunks of Carica papaya, of the petioles of Elaeis guineensis and of the particles of the nuclei canarium schweinfurthii (black fruit); these elements were collected in the regions of Center and West Cameroon. These features have been implemented in the semi-empirical models of Voigt, Reuss, Hirsch, and Alpine-Tsai. From these implementations, it emerged on the one hand a framework of the constitutive law with the longitudinal modulus resulting from each semi-empirical model. On the other hand, the models of Voigt, Hopkins-Chamis and Halpin-Tsai best approach the experimental results for fiber-reinforced composite materials (papaya trunk and oil palm petioles), while the models of Voigt and Hopkins-Chamis are ideal for composites with reinforcement of black fruit kernel particles. Regarding the transverse moduli, the Hopkins-Chamis model gives higher values ​​than those obtained from the halpin-Tsai model. The Hopkins-Chamis and Halpin-Tsai models are best suited because they take into account the Voigt estimate.

In vitro antibacterial and antibiotic-potentiation activities of five edible plant extracts and mode of action against several MDR Gram-negative phenotypes

Abstract Background: Bacterial infections involving the multidrug resistant (MDR) strains are among the top leading causes of death throughout the world. Healthcare system across the globe has been suffering from an extra-ordinary burden in terms of looking for the new and more potent antimicrobial compounds. The aim of the present study was to determine the antibacterial activity of some Cameroonian edible plants (Garcinia lucida bark, Phoenix dactylifera pericarps, Theobroma cacao pod, Solanum macrocarpon leaves and Termitomyces titanicus whole plant) and their antibiotics-potentiation effects against some MDR Gram-negative bacteria phenotypes expressing efflux pumps (Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Providencia stuartii strains). Methods: The antibacterial activities of plant extract alone and in combination with usual antibiotics were carried out using the micro-dilution method. The effects of the most active plant extract (Garcinia lucida bark) on H+-ATPase-mediated proton pumps and on bacterial growth kinetic were performed using experimental protocols, while qualitative reference methods were used to highligh the major groups of secondary metabolites present in the extracts. Results: Qualitative phytochemical screening of plant extracts indicated that all analysed secondary metabolites were present in Theobroma cacao and Termitomyces titanicus while one (saponins) of them was absent in Garcinia lucida and Solanum macrocarpon. Only three of them (polyphenols, flavonoids and saponins) were detected in Phoenix dactylifera. Antibacterial essays showed that G. lucida was the most active plant as it inhibited the growth of all studied bacteria with strong activity (MIC&lt;100 µg/mL) against E. coli ATCC8739, significant activity (100≤MIC≤512 µg/mL) against 80% of bacteria and moderate activity (512&lt;MIC≤2048 µg/mL) against E. coli AG100A and E. aerogenes (EA289 and CM64). It was followed by T. cacao and S. macrocarpon extracts which exhibited an antibacterial potential against 95% and 80% of bacterial strains, respectively. These three extracts exhibited a bactericidal effect on a few bacteria. Extracts from T. titanicus and P. dactylifera were less active as they moderately (512&lt;MIC≤2048 µg/mL) inhibited the growth of 35% and 10% of bacteria. All extracts selectively potentiated the activities of all antibiotics with improvement activity factors (IAF) ranging from 2 to 256. G. lucida, T. cacao and S. macrocarpon potentiated the activities of 100%, 89% and 67% of antibiotics respectively against more than 70%, suggesting that they contain bioactive compounds which could be considered as efflux pumps inhibitors. Whereas T. titanicus and P. dactylifera improved the activities of almost 40% and 20% of antibiotics, respectively. This increase of activities also characterizes synergistic effects between antibiotics and these bioactive compounds. G. lucida extract at all tested concentrations, strongly inhibited the growth of bacterial strain E. coli ATCC8739 and exhibited an inhibitory effect on this bacterial H+-ATPase-mediated proton pumps increasing the pH of the medium. Conclusion: The overall results indicated that food plants among which G. lucida, T. cacao and S. macrocarpon could have a benefit interest in combatting resistant types of bacteria. Keywords: Food plants; infectious diseases; MDR bacteria; efflux pumps; antibiotics; secondary metabolites.

Dietary Cameroonian Plants Exhibit Anti-Inflammatory Activity in Human Gastric Epithelial Cells.

In Cameroon, local plants are traditionally used as remedies for a variety of ailments. In this regard, several papers report health benefits of Cameroonian spices, which include antioxidant and anti-microbial properties, whereas gastric anti-inflammatory activities have never been previously considered. The present study investigates the antioxidant and anti-inflammatory activities of hydro-alcoholic extracts of eleven Cameroonian spices in gastric epithelial cells (AGS and GES-1 cells). The extracts showed antioxidant properties in a cell-free system and reduced H2O2-induced ROS generation in gastric epithelial cells. After preliminary screening on TNFα-induced NF-κB driven transcription, six extracts from Xylopia parviflora, Xylopia aethiopica, Tetrapleura tetraptera, Dichrostachys glomerata, Aframomum melegueta, and Aframomum citratum were selected for further studies focusing on the anti-inflammatory activity. The extracts reduced the expression of some NF-κB-dependent pro-inflammatory mediators strictly involved in the gastric inflammatory process, such as IL-8, IL-6, and enzymes such as PTGS2 (COX-2), without affecting PTGS1 (COX-1). In conclusion, the selected extracts decreased pro-inflammatory markers by inhibiting the NF-κB signaling in gastric cells, justifying, in part, the traditional use of these spices. Other molecular mechanisms cannot be excluded, and further studies are needed to better clarify their biological activities at the gastric level.

Antioxidant Activities of Methanol Extracts of Thirteen Cameroonian Antibacterial Dietary Plants

This study falls within the search for alternative solutions to problems related to diseases associated with oxidative stress. It involved the evaluation of antioxidant activities extracts from thirteen antibacterial Cameroonian food plants, namely, P. nigrum, A. cruentus, L. sativa, S. edule, S. nigrum, V. amygdalina, A. hybridus, V. hymenolepis, L. capensis, M. esculenta, C. melo, T. occidentalis, and T. triangulare. The thirteen plant extracts with a broad spectrum of antibacterial activity all showed total reducing powers ranging between 2.41 and 27.81 AAE (mg ascorbic acid equivalents per gram of dried extract) and total phenol contents between 2.65 and 35.03 GAE (mg of gallic acid equivalents per gram of dried extract) of dry extract. Except for extracts of L. capensis, the other 12 extracts showed flavonoid contents ranging between 0.29 and 5.99 RE (rutin equivalents per gram of dried extract). All 13 plant extracts also showed free radical scavenging activity against DPPH· with IC50 ranging between 1.65 and 310.52 μg/ml, while 12 of these extracts exhibited inhibitory activity against NO· radical (IC50 ranging from 19.77 to 157.72 μg/ml). Statistically insignificant positive correlations (p&gt;0.5) were found between antibacterial activities of these plants and their antioxidant activities. The different results of this study provide scientific evidence for the use of these antibacterial food plants in the control of different conditions associated with oxidative stress.

Phytochemical Screening and Antioxidant Potential of Aqueous Extracts of Millettia laurenti, Lophira alata and Milicia excelsa, Commonly Used in the Cameroonian Pharmacopoeia

Aims: As the world nowadays is turning towards the research of biologically active natural compounds, this work aimed at assessing the antioxidant potential of compounds contained in the aqueous extracts of three common Cameroonian pharmacopoeia plants, namely Millettia laurenti (Wengé) seeds, Lophira alata (Azobé) leaves and Milicia excelsa (Iroko) barks and the associated bioactive compounds.&#x0D; Methodology: After being dried and ground, they were macerated in water and the polyphenols, tannins, flavonoids, and alkaloids quantified. The antioxidant potential of the extracts was evaluated through DPPH free radical scavenging, NO scavenging, phosphomolybdate method (TAC), and iron-reducing power (FRAP).&#x0D; Results: The mean concentrations obtained ranged between 527 and 1213 µg GAE/g DM for polyphenols, 0.39 and 0.65 µg GAE/g DM for tannins, 19.79 and 27.06 µg QE/g DM for flavonoids, 15.72 and 16.02 µg QuE/g DM for alkaloids. Aqueous extracts of Wengé (AE-WG) and Azobé (AE-AZ) exhibited the highest and significantly similar contents. AE-AZ presented the highest iron reducing power (0.015 µg AAE/g DM at 10 mg/mL) and NO scavenging (IC50=3.63 mg/mL) while AE-WG showed the highest DPPH scavenging activity (IC50 = 4.20 mg/mL) and total antioxidant capacity (0.39 µg AAE/g DM at 10 mg/mL). No significant correlation was observed between studied bioactive compounds and the different antioxidant responses except flavonoids and tannins with TAC (p&lt;0.05).&#x0D; Conclusion: AE-AZ and AE-WG exhibited different antioxidant mechanisms and are therefore of high interest for potential use in the food industry and medicine with reserves to toxicological studies.

Oxidative Stress Modulation by Cameroonian Spice Extracts in HepG2 Cells: Involvement of Nrf2 and Improvement of Glucose Uptake.

Oxidative stress plays a relevant role in the progression of chronic conditions, including cardiometabolic diseases. Several Cameroonian plants, including spices, are traditionally used as herbal medicines for the treatment of diseases where oxidative stress contributes to insulin resistance, like type 2 diabetes mellitus. This study evaluated the antioxidant capacity and the effects on oxidative-stress-induced impairment of glucose uptake of 11 Cameroonian spice extracts. H2O2-induced reactive oxygen species (ROS) production by human HepG2 cells was significantly reduced by 8/11 extracts. The most effective extracts, Xylopia parviflora, Echinops giganteus, and Dichrostachys glomerata, showed a concentration-dependent ROS-scavenging activity, which involved Nrf2 translocation into the nucleus. Xylopia parviflora, Tetrapleura tetraptera, Dichrostachys glomerata, Aframomum melegueta, and Aframomum citratum extracts showed the highest antioxidant capacity, according to oxygen radical absorbance capacity (ORAC) (2.52–88 μM Trolox Eq/g of extract), ferric-reducing antioxidant power (FRAP) (40.23–233.84 mg gallic acid Eq/g of extract), and total phenol (8.96–32.96% mg gallic acid Eq/g of extract) assays. In HepG2 cells, glucose uptake was stimulated by 4/11 extracts, similarly to insulin and metformin. H2O2-induced oxidative stress reduced glucose uptake, which was rescued by pretreatment with Xylopia aethiopica, Xylopia parviflora, Scorodophloeus zenkeri, Monodora myristica, and Dichrostachys glomerata extracts. The ROS-scavenging ability of the spice extracts may reside in some secondary metabolites observed by phytochemical profiling (reverse-phase high-performance liquid chromatography coupled to a diode array detector (HPLC-UV-DAD)). Further studies are needed to better clarify their biological activities and potential use to control oxidative stress and promote insulin sensitivity.

Conditions for Better uses of Some Cameroonian Plants Potentially Anti-Diabetic and Reversing Insulin Resistance

Background: Hyperglycemia-induced oxidative and inflammatory harm are the major causes of chronic and fatal complications of diabetes. In many developing countries the products of socio-cultural medicine are more used by low income populations to fight against diseases particularly diabetes. The economic crises, the slump of agricultural product’s prizes and the significant increase of the population, are at the origin of the strong dependence on African traditional medicine. Objective: The objectives were to identify factors that influenced the better uses of potential bioactive plants published by Cameroonians, particularly used for diabetes management in order to select those that can improve insulin sensitivity and can be principally used to avoid diabetic complications. Methods: To achieve this objective, the review was carried out in online databases including Google, Google Scholar and Pubmed, between 2018 and 2019. For the ethnopharmacological standardization of recipes, we proposed in this work the doses calculated by deduction from the doses used to treat in vivo alloxan or streptozotocin induced diabetic rats. The presence of one or several antihyperglycemic compounds in recorded plants and the hypoglycemic effects of their extract reinforced the herbal use of these species. Results: All the admitted plants exhibited antidiabetic properties. Twenty-eight point fifty-seven percent (28, 57%) of them were confirmed antihyperglycemic and improved insulin sensitivity. Permanent stress is the important factor influencing the better management of diabetes by these plants. 1.5. Conclusion: The results of this study can be the scientific basis for antidiabetic drugs discovery that can prevent insulin resistant and consequently complications of diabetes type 2.

Potential of essential oils from four Cameroonian aromatic plants used in integrated protection of stored products programs: Presentation

The efficacy of essential oils extracted from fruits of Piper capense and Xylopia parviflora, and roots of Echinops giganteus and Mondia whitei were evaluated against Acanthoscelides obtectus and fungi isolated from bean seeds in laboratory conditions in Cameroon. The essential oils were extracted by water-distillation and their chemical composition identified by Gas Chromatography-Flame Ionization Detection (GC-FID) and Gas Chromatography- Mass Spectrometry (GC-MS). Toxicity assays of essential oils against A. obtectus were carried out by fumigation in which insect pests were exposed fumes of the essential oils, and mortality recorded after 6, 12, and 24 hours. Additionally, the toxicity by contact of the essential oils was evaluated through coating grains with essential oils or impregnating the essential oils onto the filter paper, allowing the insects to physically get in contact with the essential oil, and assessing weevil mortality recorded after 1, 2, 3, and 4 days. The essential oils from P. capense and X. parviflora consisted mainly of hydrocarbon monoterpenes (56.5% and 50.0% respectively), whereas the essential oils from E. giganteus was mostly constituted of sesquiterpenes (94.3%) in which the tricyclic compounds are more abundant. A major compound identified in the essential oil from M. whitei was 2-hydroxy- 4-methoxy-benzaldehyde (81%). The essential oil from X. parviflora was the most effective as contact and fumigant against A. obtectus, causing 100% mortality within 1 day at low lethal concentrations. On the other hand, the essential oil from M. whitei exhibited the best anti-fungal activity. These essential oils could play an important role in pest protection of stored beans and reduce the risks associated with use of synthetic insecticides especially in low income small holder farming systems.