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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.

Background: The antibiotic resistance of pathogenic bacteria is one of the major health problems worldwide. The development of novel antimicrobial therapies based on natural products that greatly reduce this resistance is urgent. The present study aimed at evaluating the antimicrobial potential of four animal methanol extracts, Gryllus campestris, Testudo hermanni, Cardisoma guanhumi, and Rhinella jimi as well as their synergistic effects with antibiotics against twenty Gram-negative bacteria. Methods: Zoochemical analysis of extracts was performed using qualitative reference methods for the detection of secondary metabolites and the ninhydrin reaction for the detection of protein constituents. The antibacterial activity of animal extracts alone and in combination with antibiotics was carried out using broth microdilution methods. Results: Amino acids, peptides, or proteins were present in all extracts. Alkaloids were detected in extracts of C. guanhumi and R. jimi and were absent in other extracts. Flavonoids, tannins, and steroids were evidenced only in dried and fresh extracts of R. jimi. Polyphenols, anthocyanins, anthraquinones, and saponins were not detected in all extracts. Dried extract from R. jimi was most active. It had antibacterial potential against 85% of the tested bacterial strains with significant activity (100≤MIC≤512 µg/mL) against 35% of bacteria; this included three E. coli (ATCC8739, AG100ATet and MC4100), one E. aerogenes (ATCC13048), one K. pneumoniae (ATCC11296) and two P. aeruginosa (PA01 and PA124). Dried and fresh extracts from C. guanhumi displayed an antibacterial activity against 40% and 20% of the bacteria tested, respectively, whereas dried extracts from G. campestris and fresh extracts from T. hermanni inhibited the growth of 15% and 10% of bacteria, respectively (MIC range of 512 to 2048 µg/mL). The dried and fresh extracts of R. jimi, at MIC/2 and MIC/4, potentialized the activities of more than 70% of the antibiotics respectively against more than 70% of studied bacteria. Both extracts highly improved the activity of oxacillin, gentamicin, erythromycin, and ciprofloxacin with improved activity factors (IAFs) ranging from 16 to 256. Conclusion: This work demonstrated that R. jimi extracts had a broad spectrum of antibacterial activities. The overall data provided evidence that animals investigated in this study might be potential sources of natural antimicrobial agents; They can be combined with clinically used antibiotics to overcome bacterial resistance. Keywords: Animal extract, antibiotics; Gram-negative bacteria; efflux pumps; multidrug resistance; Rhinella jimi.

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

Background: In recent years, drug resistance to human pathogenic bacteria has been commonly reported from all over the world. As antimicrobial activities of most medicinal plants and antibiotics have been already explored, it is more important to make investigations on animal species mainly invertebrates which could constitute an efficient source of antimicrobial molecules. This work was aimed at contributing to the fight against microbial resistance through the study of antibacterial potential of three animal species (Helix aspersa, Bitis arietans, Aristaeomorpha foliacea) on several multidrug-resistant (MDR) Gram-negative strains overexpressing efflux pumps including Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa. Methods: The microdilution technique was used to evaluate the antibacterial activities of the tested samples by determining their minimal inhibitory concentrations (MICs), as well as the effect of their combination with antibiotics. Studies on the mechanisms of action of the most active sample, dried Bitis arietans extract, was carried out using standard methods for evaluating the effects of this extract on bacterial H+-ATPases-mediated proton pumps and on bacterial growth kinetics. In this latter case, the optical density was read spectrophotometrically. Results: Zoochemical screening indicated the presence of protein constituents and alkaloids and the absence of other metabolites in all tested extracts. Dried B. arietans showed the best antibacterial activity by inhibiting the growth of 90% of studied bacterial strains with MICs ranging from 128 to 2048 μg/ml. Moreover, this extract presented a significant activity (100≤MIC≤512 µg/ml) against 35% of bacteria that are E. coli (ATCC8739, AG100ATet, MC4100), E. aerogenes EA27, K. pneumoniae ATCC11296, P. aeruginosa (PA01, PA124) and a moderate activity (512

Background Tetrapleura tetraptera is a medicinal spice traditionally used to treat cancer, diabetes, and several other ailments. This study analyzed the cytotoxicity of the dichloromethane methanol extract of T. tetraptera fruits (TTF) and its constituents. The toxicity profile of the TTF extract was also evaluated in rats. Methods The Cytotoxicity of this extract was evaluated using the resazurin reduction assay (RRA). Acute and sub-chronic toxicity studies were performed according to the protocol described by the Organisation for Economic Cooperation, and Development (OECD). Hematological, serum, and urine biochemical parameters, as well as histological sections of the liver and kidney, were also evaluated based on standard methods. Results The TTF extract, compound 5, and the reference drug doxorubicin were active in all 9 tested cancer cell lines. The recorded IC50 ranged from 18.32 µM (against B16-F1 murine melanoma cells) to 36.18 µM (against SKMel-505 BRAF wildtype melanoma cells) for TTF, from 10.02 µM (towards MaMel-80a BRAF-V600E homozygous mutant melanoma cells) to 31.73 µM (against SKMel-28 BRAF-V600E homozygous mutant melanoma cells) for compound 5, and from 0.22 µM (against B16-F1 cells) to 9.39 µM (against SKMel-505 cells) for doxorubicin. The study of acute toxicity test showed that the lethal dose (LD50) of this extract was greater than 5000 mg/kg body weight. In the sub-chronic toxicity studies, variations were observed in some biochemical parameters, especially at higher doses. Conclusion TTF and its most active compound (5) are found to be potential cytotoxic agents, meanwhile, TTF was safe when given a single oral dose of 5000 mg/kg. However, caution is necessary in case of prolonged oral administration due to potential alterations of renal function at high doses (> 1000 mg/kg).

Raphia vinifera is widely used to treat several diseases including digestive disorders, dysentery, and genitourinary infections. In this study, the mineral contents, the cytotoxicity, and the toxicological effect of the crude CHCl3/MeOH extract (RVM) from the mesocarp of Raphia vinifera were evaluated. The mineral contents were evaluated using the method described by the Association of Official Analytical Chemists (AOAC). The cytotoxicity of both extract and chemical compounds from the plants was determined by a resazurin reduction assay (RRA). The toxicological studies were carried out using the experimental procedure of the Organization for Economic Cooperation and Development (OECD). After killing the rats, biochemical, histopathological, and hematological studies were performed. The result indicated that RVM is rich in zinc (6.52 mg/100 g of DM) and sodium (194.5 mg/100 g of DM). RVM had a cytotoxicity effect with IC50 values lower than 30 μg/mL in 18/18 cancer cell lines tested. These recorded IC50 values were between 12.35 µg/mL (toward CCRF-CEM leukemia cells) and 26.66 µg/mL (toward SKMel-505 BRAF wild-type melanoma cells). Raphvinin 4 displayed good cytotoxicity against MaMel-80aBRAF-V600E homozygous mutant with the IC50 of 10.42 μM. RVM was relatively nontoxic to rats, the median lethal dose (DL50) being above 5000 mg/kg body weight. However, during the oral administration period extending for 28 days, precautions should be taken due to the increase in urinary creatinine level and decrease in spleen weight in the male rats given the highest dose (1000 mg/kg) of extract. Conclusively, the extract of Raphia vinifera is weakly toxic in rats and could be further used in the development of anticancer phytomedicines.

Ethnopharmacological relevance Tetrapleura tetraptera is an African medicinal spice used in traditional medicine to treat several ailments including cancer. Aim of the study The present study was designed to evaluate the cytotoxicity of the dichloromethane-methanol (1:1) extract of the fruits of Tetrapleura tetraptera (TTF) and its constituents: (3R, 4S)-3,4-dimethyloxetan-2-one (1), luteolin (2), stigmasterol (4), 3-O-[6′-O-undecanoyl-β-D-glucopyranosyl]stigmasterol (6), olean-12-en-3-β-O-D-glucopyranoside (7), 3-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosylurs-12-en-28-oic acid (8), 3-O-β-D-glucopyranosyl-(1 → 3)-β-D-glucopyranosyl-27-hydroxyolean-12-ene-28-oic acid (9), methyl-O-β-D-glucopyranoside (10), β-D-fructofuranosyl-(2 → 1)-β-D-glucopyranoside (11) towards a panel of cancer cell lines including MDR phenotypes. The cellular mode of induction of apoptosis by TTF and compound 7 was further investigated. Materials and methods The resazurin reduction assay (RRA) was applied to determine the cytotoxicity of the studied samples. The cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H2DCFH-DA) were measured by flow cytometry. Column chromatography was used for the purification of TTF, whilst nuclear magnetic resonance (NMR) spectroscopic analysis was applied for structural elucidation. Results The botanical, TTF and the phytochemicals, 2, 7, 8 and 9 as well as doxorubicin exerted cytotoxicity against 9 cancer cell lines including drug-sensitive and drug resistant phenotypes. TTF, compound 7 and doxorubicin were the most active samples, and displayed IC50 values ranging from 10.27 μg/mL (in CCRF-CEM leukemia cells) to 23.61 μg/mL (against HCT116 p53−/− colon adenocarcinoma cells) for TTF, from 4.76 μM (against CCRF-CEM cells) to 12.92 μM (against HepG2 hepatocarcinoma cells) for compound 7, and from 0.02 μM (against CCRF-CEM cells) to 122.96 μM (against CEM/ADR5000 cells) for doxorubicin. TTF induced apoptosis in CCRF-CEM cells through MMP alteration and increased ROS production while compound 7 induced apoptosis mediated by caspases activation, MMP alteration and increased ROS production. Conclusion Tetrapleura tetraptera and some of its constituents, mostly compound 7 are good cytotoxic natural products that should be explored in depth to develop new drugs to fight cancers.

Background The discovery of novel phytochemicals represents a reasonable approach to fight malignancies, especially those which are resistant to standard chemotherapy. Purpose We evaluated the cytotoxic potential of a naturally occurring N-acetylglycoside of oleanolic acid, aridanin, on 18 cancer cell lines, including sensitive and drug-resistant phenotypes mediated by P-glycoprotein, BCRP, p53 knockout, deletion-mutated EGFR, or BRAF mutations. Furthermore, metastasizing B16/F10 cells, HepG2 hepatocarcinoma and normal AML12 hepatocytes were investigated. The mechanisms of aridanin-induced cell death was further investigated. Methods The resazurin reduction assay (RRA) was applied to evaluate the cytotoxicity, autophagy, ferroptotic and necroptotic cell death. CCRF-CEM leukemia cells were used for all mechanistic studies. A caspase-Glo assay was applied to evaluate the caspase activities. Flow cytometry was applied for the analyses of cell cycle (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1) and reactive oxygen species (ROS; H2DCFH-DA). Results Aridanin and doxorubicin (positive control) inhibited the proliferation of all cancer cell lines tested. The IC50 values for aridanin varied from 3.18 µM (CCRF-CEM cells) to 9.56 µM (HepG2 cells). Aridanin had considerably lower IC50 values than that of doxorubicin against multidrug-resistant CEM/ADR5000 cells and melanoma cell lines (MaMel-80a, Mel-2a, MV3, and SKMel-505). Aridanin induced apoptosis in CCRF-CEM cells through increase of ROS levels and MMP breakdown, and to a lesser extent via caspases activation. Aridanin also induced ferroptotic and necroptotic cell death. Conclusion The present study opens good perpectives for the use of this phytochemical as an anticancer drug to combat multi-facorial resistance to established chemotherapeutics.