Synthesis and Bioactivity of Isoflavones from Ficus carica and Some Non-Natural Analogues.

Ficucaricone D (1) and its 4'-demethyl congener 2 are isoflavones isolated from fruits of Ficus carica that share a 5,7-dimethoxy-6-prenyl-substituted A-ring. Both natural products were, for the first time, obtained by chemical synthesis in six steps, starting from 2,4,6-trihydroxyacetophenone. Key steps are a microwave-promoted tandem sequence of Claisen- and Cope-rearrangements to install the 6-prenyl substituent and a Suzuki-Miyaura cross coupling for installing the B-ring. By using various boronic acids, non-natural analogues become conveniently available. All compounds were tested for cytotoxicity against drug-sensitive and drug-resistant human leukemia cell lines, but were found to be inactive. The compounds were also tested for antimicrobial activities against a panel of eight Gram-negative and two Gram-positive bacterial strains. Addition of the efflux pump inhibitor phenylalanine-arginine-ß-naphthylamide (PAßN) significantly improved the antibiotic activity in most cases, with MIC values as low as 2.5 µM and activity improvement factors as high as 128-fold.

In Silico and In Vitro Identification of P-Glycoprotein Inhibitors from a Library of 375 Phytochemicals.

Cancer therapy with clinically established anticancer drugs is frequently hampered by the development of drug resistance of tumors and severe side effects in normal organs and tissues. The demand for powerful, but less toxic, drugs is high. Phytochemicals represent an important reservoir for drug development and frequently exert less toxicity than synthetic drugs. Bioinformatics can accelerate and simplify the highly complex, time-consuming, and expensive drug development process. Here, we analyzed 375 phytochemicals using virtual screenings, molecular docking, and in silico toxicity predictions. Based on these in silico studies, six candidate compounds were further investigated in vitro. Resazurin assays were performed to determine the growth-inhibitory effects towards wild-type CCRF-CEM leukemia cells and their multidrug-resistant, P-glycoprotein (P-gp)-overexpressing subline, CEM/ADR5000. Flow cytometry was used to measure the potential to measure P-gp-mediated doxorubicin transport. Bidwillon A, neobavaisoflavone, coptisine, and z-guggulsterone all showed growth-inhibitory effects and moderate P-gp inhibition, whereas miltirone and chamazulene strongly inhibited tumor cell growth and strongly increased intracellular doxorubicin uptake. Bidwillon A and miltirone were selected for molecular docking to wildtype and mutated P-gp forms in closed and open conformations. The P-gp homology models harbored clinically relevant mutations, i.e., six single missense mutations (F336Y, A718C, Q725A, F728A, M949C, Y953C), three double mutations (Y310A-F728A; F343C-V982C; Y953A-F978A), or one quadruple mutation (Y307C-F728A-Y953A-F978A). The mutants did not show major differences in binding energies compared to wildtypes. Closed P-gp forms generally showed higher binding affinities than open ones. Closed conformations might stabilize the binding, thereby leading to higher binding affinities, while open conformations may favor the release of compounds into the extracellular space. In conclusion, this study described the capability of selected phytochemicals to overcome multidrug resistance.

Antimicrobial and Cytotoxic Potential of Helminthosporin from Rumex abyssiniscus Jacq. Discovered as a Novel Source of Syringic Acid and Bis(2-ethyloctyl) Phthalate.

Rumex abyssinicus Jacq. is a perennial medicinal herb widely used in traditional medicine to treat many diseases. Phytochemicals of the plant were isolated using column chromatography and thin layer chromatography techniques. Extract, fractions and pure compounds were screened for antimicrobial activity against sensitive and multi-drug resistant microbes and their cytotoxicity was performed on different cancer cell lines. The mechanism of action of purified helminthosporin as well as the potent fraction containing a mixture of two compounds was assessed. Fraction R7C3 was the most potent antibacterial with the lowest MIC value of 0.12 µg/mL. Helminthosporin was the most potent compound with the lowest MIC value of 1.95 µg/mL. The compound was more potent than the antibiotic chloramphenicol against multi-drug resistant (MDR) bacteria with MIC equal to 16 µg/mL. The fraction and helminthosporin were shown to destroy the cell wall of the yeast and bacteria, and DNA fragmentation effect on the genome of Candida albicans and Bacillus cereus. Helminthosporin was the most cytotoxic compound with IC50 ˂ 10 µM. Fraction R7C3 showed the most potent cytotoxic effects on all cancer cell lines, with IC50 ranging from ˂1 to 4.35 ng/mL. Our study is the first report on the mechanism of action of helminthosporin, a potent candidate in the development of new drugs against multi-resistant bacteria and cancer cells. In addition, this study uncovered Rumex abyssinicus as a new source of syringic acid and bis(2-ethyloctyl) phthalate.

Design, synthesis, characterization, and anticancer activity of a novel series of O-substituted chalcone derivatives.

A new series of O-substituted chalcone derivatives bearing an/a allyl-, prenyl- or propargyl-substituent at different positions of rings A and B and their derivatives as drug leads, was designed, synthesized, and characterized. The chalcone derivatives were synthesized via base catalyzed Claisen-Schmidt condensation in MeOH or EtOH solutions of appropriately substituted aromatic ketones with O-allyl, and O-propargylvanillin, respectively. The intermediates O-substituted phenylketone derivatives were firstly synthesized by nucleophilic substitution reaction. All the newly synthesized compounds were characterized by IR, NMR spectral data and elemental analyses. A preliminary cytotoxicity was performed with the compounds (1a, 1b, 2a, 2b, 3a, 3b, 4a, 5a-f, 6a-d, 7a-d) and the positive control, doxorubicin towards CCRF-CEM leukemia cells. Amongst them, compounds 1a, 2a, 5b-d, 6b, 7a, 7c and doxorubicin displayed IC50 values below 20 µM while other compounds were less or not active at up to 50 µM. Remarkably interesting cytotoxic effects, with IC50 values below 1 µM were recorded with 5c against HCT116 p53-/- colon adenocarcinoma cells, 5e against CCRF-CEM cells and MDA-MB-231-BCRP breast adenocarcinoma cells, and 6b against HCT116 p53+/+ cells and HCT116 p53-/- cells.

An Efflux Pumps Inhibitor Significantly Improved the Antibacterial Activity of Botanicals from Plectranthus glandulosus towards MDR Phenotypes.

Bacterial multidrug resistance causes many therapeutic failures, making it more difficult to fight against bacterial diseases. This study aimed to investigate the antibacterial activity of extract, fractions, and phytochemicals from Plectranthus glandulosus (Lamiaceae) against multidrug-resistant (MDR) Gram-negative phenotypes expressing efflux pumps. The crude extract after extraction was subjected to column chromatography, and the structures of the isolated compounds were determined using spectrometric and spectroscopic techniques. Antibacterial assays of samples alone and in the presence of an efflux pump inhibitor (phenylalanine-arginine ß-naphthylamide, PAßN) were carried out using the broth microdilution method. The phytochemical study of P. glandulosus plant extract afforded seven major fractions (A-G) which lead to the isolation of seventeen known compounds. The ethanol extract of P. glandulosus was not active at up to 1024 µg/mL, whereas its fractions showed MICs varying from 32 to 512 µg/mL on the studied bacteria. Fraction C of P. glandulosus showed the lowest MIC (32 µg/mL) on E. coli ATCC8739 strain. Fraction D presented the highest activity spectrum by inhibiting the growth of 90% (9/10) of the studied bacteria. The presence of PAßN has improved the activity of extract and all fractions. Overall, the tested phytochemicals showed low activity against the studied bacteria. The overall results obtained in this study show that some fractions from P. glandulosus, mainly fractions C and D, should be investigated more for their possible use to fight against MDR bacteria.

Prenylated Flavonoids and C-15 Isoprenoid Analogues with Antibacterial Properties from the Whole Plant of Imperata cylindrica (L.) Raeusch (Gramineae).

The local botanical Imperata cylindrica in Cameroon was investigated for its antibacterial potency. The methanol extract afforded a total of seven compounds, including five hitherto unreported compounds comprising three flavonoids (1-3) and two C-15 isoprenoid analogues (4 and 5) together with known derivatives (6 and 7). The novelty of the flavonoids was related to the presence of both methyl and prenyl groups. The potential origin of the methyl in the flavonoids is discussed, as well as the chemophenetic significance of our findings. Isolation was performed over repeated silica gel and Sephadex LH-20 column chromatography and the structures were elucidated by (NMR and MS). The crude methanol extract and isolated compounds showed considerable antibacterial potency against a panel of multi-drug resistant (MDR) bacterial strains. The best MIC values were obtained with compound (2) against S. aureus ATCC 25923 (32 µg/mL) and MRSA1 (16 µg/mL).

Synthesis and Biological Evaluation of Four New Ricinoleic Acid-Derived 1-O-alkylglycerols.

A series of novel substituted 1-O-alkylglycerols (AKGs) containing methoxy (8), gem-difluoro (9), azide (10) and hydroxy (11) group at 12 position in the alkyl chain were synthesized from commercially available ricinoleic acid (12). The structures of these new synthesized AKGs were established by NMR experiments as well as from the HRMS and elementary analysis data. The antimicrobial activities of the studied AKGs 8-11 were evaluated, respectively, and all compounds exhibited antimicrobial activity to different extents alone and also when combined with some commonly used antibiotics (gentamicin, tetracycline, ciprofloxacin and ampicillin). AKG 11 was viewed as a lead compound for this series as it exhibited significantly higher antimicrobial activity than compounds 8-10.

Antibacterial and antibiotic-modifying activities of fractions and compounds from Albizia adianthifolia against MDR Gram-negative enteric bacteria.

BACKGROUND: Albizia adianthifolia (Schum.) is medicinally used in Cameroon to manage bronchitis and skin diseases. Our previous study documented the antibacterial potential of its roots' methanol extract. In this study, methanol roots extract was subjected to chromatography techniques and fractions (AARa and AARb), sub-fractions (AARa1-4, AARb1-2 and AARb11-14) together with isolated phytochemicals were assessed for their antimicrobial as well as their antibiotic-potentiating effects towards Gram-negative multidrug resistant (MDR) bacteria. METHODS: The antibacterial activities of the samples (determination of Minimal Inhibitory « MIC ¼ and Minimal Bactericidal Concentration « MBC ¼) were determined by the modified rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay, as well as those of antibiotics in association with the compounds. Column chromatography was applied to isolate phytochemicals from roots extract and their chemical structures were determined using spectroscopic techniques. RESULTS: The phytochemicals isolated were stearic acid (1), a mixture (1:1) of stigmasterol and ß-sitosterol (2 +  3), ß-sitosterol 3-O-ß-D-glucopyranoside (4), palmatin (5), homomangiferin (6) and mangiferin (7). Fraction AARa exhibited selective inhibitory effects whilst all tested bacteria were inhibited by AARb in MIC ranges of 8 to 1024 µg/mL. Sub-fractions AARb1-2 had MIC values between 8 µg/mL and 1024 µg/mL on all tested bacteria. Phytochemicals 4, 2 +  3 and 7 inhibited the growth of 54.54% (6/11), 45.45% (5/11) and 27.27% (3/11) tested bacterial strains, respectively. When tested with an efflux pumps inhibitor (Phenylalanine-Arginine-ß-Naphthylamide or PAßN), the inhibitory effects of compounds 2 + 3 and 4 increased towards all the tested bacteria. In association with erythromycin (ERY), streptomycin (STR) and tetracycline (TET), compounds 2 + 3 and 4 had the most significant synergistic activity on the seven selected bacteria. CONCLUSION: The present study provides information on the possible use of Albizia adianthifolia and its constituents in the control of Gram-negative infections including MDR phenotypes.

Antibiotic Resistance of Enteric Bacteria in HIV-Infected Patients at the Banka Ad-Lucem Hospital, West Region of Cameroon.

Human immunodeficiency virus (HIV) infection is a serious problem throughout the world and especially in developing countries. This study was conducted to define the bacterial aetiologies of enteric disorders and their association with CD4+ T-lymphocyte cell count and serum hs-CRP in HIV-seropositive patients coming for consultation at the AD-Lucem Banka Hospital. Stool samples from one-hundred HIV-positive patients with enteric disorders and forty HIV negative patients with enteric disorders were examined for the presence of bacteria by different diagnostic techniques. CD4+ T-lymphocyte count and serum hs-CRP of HIV-positive and HIV-negative patients were examined, respectively, by flux cytometry and the ELISA solid-phase direct sandwich method. Among all the participants, 39 (26.35%) were males and 109 (73.65%) were females. HIV-seropositive mean age (43.79 years) was significantly higher compared to HIV-seronegative (27.13 years) patients (p < 0.000). The average values of CD4+ T-cell count (p < 0.0001), lymphocytes (p=0.0258), monocytes (p=0.0317), and total WBC count (p=0.0277) were significantly higher in HIV- patients compared to HIV+ patients. Salmonella sp., Escherichia coli, and Klebsiella pneumoniae were more isolated in HIV+ patients 5 (83.33), 18 (75.00), and 37 (71.15) compared to HIV- patients 1 (16.67), 6 (25.00), and 15 (28.85), respectively. Majority of isolates were susceptible to IPM, NOR, and CIP. Klebsiella pneumoniae, the most prevalent isolate, showed resistance to AMC (45.95) in HIV+ patients, whereas in HIV- patients, Enterobacter aerogenes and Shigella sp. showed resistance to AMC (80.00% and 85.71%, respectively) and to CFM (80.00% and 57.14%, respectively). Enterobacter aerogenes (40.00%) and Shigella sp. (14.29) isolates showed multidrug resistance in HIV- patients, whereas Escherichia coli (5.56%) and Klebsiella pneumoniae (2.70%) showed multidrug resistance in HIV+ patients. Understanding the burden of bacteria disease in HIV patients as shown in the present study is important for planning effective control programs for the overall reduction of bacteria diseases in HIV-infected patients.

In vitro antibacterial and antibiotic modifying activity of crude extract, fractions and 3',4',7-trihydroxyflavone from Myristica fragrans Houtt against MDR Gram-negative enteric bacteria.

BACKGROUND: Nutmeg is the seed kernel inside the fruit of Myristica fragrans Houtt. (Myristicaceae). It possesses various pharmacological activities but is used in Cameroon only for its flavor in making cakes. The present study thus aimed to investigate the in vitro antibacterial activity and antibiotic modifying activities of crude seed kernel methanol extract (MFS), fractions (MFSa-e) as well as 3',4',7-trihydroxyflavone from Myristica fragrans against a panel of multi-drug resistant (MDR) Gram-negative bacteria. METHODS: The modified rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay was used to determine the Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) on the tested bacteria, as well as those of antibiotics in association with the extract and/or isolated compound. Column chromatography was used for the fractionation and purification of the seed kernel extract whilst the chemical structures of compounds were determined using spectroscopic techniques. RESULTS: Phytochemical investigations lead to the isolation of 3',4',7-trihydroxyflavone from the fraction MFSb. The crude extract showed antibacterial activity with MICs ranging from 32 to 1024 µg/mL on the majority of the 29 tested Gram-negative bacterial strains. Fraction MFSb inhibited the growth of 100% (29/29) of the tested bacterial strains, as well as the compound 3',4',7-trihydroxyflavone (12/12) with a MIC values ranging from 32 to 1024 µg/mL, and 4 to 128 µg/mL respectively. The lowest MIC value (4 µg/mL) was recorded with 3',4',7-trihydroxyflavone against Providencia stuartii ATCC299645 as well as the best MBC value (16 µg/mL) against the same strain. In the presence of Phenylalanine-Arginine-ß-Naphthylamide (PAßN), an efflux pumps inhibitor, the activity of the extract increased on 73.33% (11/15) meanwhile that of 3',4',7-trihydroxyflavone increased on 100% tested bacteria. The compound 3',4',7-trihydroxyflavone potentiated the activity of antibiotics in the majority of the tested bacterial strains. CONCLUSION: The results of the present work provide additional information on the use of nutmeg and it major antibacterial component, 3',4',7-trihydroxyflavone, as a potential drug in the treatment of bacterial infections including multidrug resistant phenotypes.

Cytotoxicity of seputhecarpan D, thonningiol and 12 other phytochemicals from African flora towards human carcinoma cells.

BACKGROUND: Despite the remarkable progress in cancer therapy in recent years, this disease still remains a serious public health concern. The use of natural products has been and continues to be one of the most effective ways to fight malignancies. The cytotoxicity of 14 compounds from African medicinal plants was evaluated in four human carcinoma cell lines and normal fibroblasts. The tested samples included: ß-spinasterol (1), friedelanone (2), 16ß-hydroxylupeol (3), ß-amyrin acetate (4), lupeol acetate (5), sequoyitol (6), rhamnitrin (7), europetin 3-O-rhamnoside (8), thonningiol (9), glyasperin F (10), seputhecarpan B (11), seputhecarpan C (12), seputhecarpan D (13) and rheediaxanthone A (14). METHODS: The neutral red uptake (NR) assay was used to evaluate the cytotoxicity of samples; caspase-Glo assay, flow cytometry for cell cycle analysis and mitochondrial membrane potential (MMP) as well as spectrophotometry to measure levels of reactive oxygen species (ROS) were performed to detect the mode of action of compounds 9 and 13 in MCF-7 breast adenocarcinoma cells. RESULTS: Compounds 3, 9-13 displayed cytotoxic effects against the four tested cancer cell lines with IC50 values below 85 µM. Compounds 9 and 13 had IC50 values below 10 µM in 4/4 and 3/4 tested cell lines respectively. The IC50 values varied from 0.36 µM (against MCF7 cells) to 5.65 µM (towards colon carcinoma DLD-1 cells) for 9, from 9.78 µM (against MCF7 cells) to 67.68 µM (against HepG2 cells) for 13 and 0.18 µM (towards HepG2 cells) to 72 µM (towards Caco-2 cells) for the reference drug, doxorubicin. Compounds 9 and 13 induced cell cycle arrest in Go/G1 whilst doxorubicin induced arrest in G2/M. The two molecules (9 and 13) also induced apoptosis in MCF-7 cells through activation of caspases 3/7 and 9 as well as enhanced ROS production. CONCLUSION: Compounds 9 and 13 are good cytotoxic phytochemicals that should be explored more in future to develop a cytotoxic drug to fight human carcinoma.

Prospecting for cytotoxic and antiprotozoal 4-aryl-4H-chromenes and 10-aryldihydropyrano[2,3-f]chromenes.

Different studies reported that genetic predisposition or metabolic dysfunction are the risk factors for cancer. Infectious parasitic diseases were listed among factors that predispose to cancer. Because of the resemblance between the life cycle of cancer cells and some parasites, this study aimed to prepare pyran derivatives with cytotoxic and antiprotozoal potencies. Therefore, 7 chromenes, 10 pyranocoumarins, and an unexpected intermediate were obtained from a multi-reagent one-pot reaction. These compounds were evaluated for their cytotoxicity on sensitive and resistant leukemia cancer cells lines and against two protozoan parasites, namely Trypanosoma cruzi and Leishmania amazonensis amastigote. Promising cytotoxicity (IC50 values of less than 1 µM) was obtained for two of the synthetic products (12 and 15). Compound 12 induced apoptosis and cell cycle arrest in CCRF-CEM leukemia cells in G0/G1 while compound 15 and doxorubicin induced apoptosis and arrest in the S and G2/M phases. Ten of these products showed trypanocidal activity, while only five of them were weakly active on L. amazonensis. Three of the obtained pyrans showed significant cytotoxicity and antitrypanocidal activity, simultaneously. Nevertheless, all antiparasitic compounds revealed potency with low selectivity toward THP-1 cells used as host.

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.

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.

Antibacterial and antibiotic resistance modulatory activities of leaves and bark extracts of Recinodindron heudelotii (Euphorbiaceae) against multidrug-resistant Gram-negative bacteria.

BACKGROUND: Recinodindron heudelotii (Euphorbiaceae) is a plant used in Africa, particularly in Cameroon to treat various ailments including bacterial infections. In this study, we evaluated the extracts of the leaves (RHL) and bark (RHB) of R. heudelotii for their antibacterial and antibiotic resistance modulating activities against 29 Gram-negative bacteria, including multidrug-resistant (MDR) phenotypes. METHODS: The broth micro-dilution assay was used to evaluate the antibacterial activity, and the antibiotic resistance modulating effects of the plant extracts. RESULTS: RHL displayed the most important spectrum of activity with minimal inhibitory concentrations (MICs) values ranging from 256 to 1024 µg/mL against 75.86% of the 29 tested bacteria strains while RHB was not active. RHL also showed killing effects with minimal bactericidal concentrations (MBCs) ranging from 256 to 1024 µg/mL. The activities of tetracycline and kanamycin associated with RHL were improved on 88.89% and 77.78% of the tested MDR bacteria, at MIC/2 at MIC/4 respectively, with 2 to 16-folds decreasing of MIC. This suggests the antibiotic resistance modulating effects of these antibiotics. CONCLUSION: The present study provides data indicating a possible use of the leaves extract of Recinodindron heudelotii alone or in association with common antibiotics in the fight against bacterial infections including those involving MDR bacteria.

Cytotoxicity of the methanol extracts of Elephantopus mollis, Kalanchoe crenata and 4 other Cameroonian medicinal plants towards human carcinoma cells.

BACKGROUND: Cancer still constitutes one of the major health concerns globally, causing serious threats on patients, their families, and the healthcare system. METHODS: In this study, the cytotoxicity of the methanol extract of Elephantopus mollis whole plant (EMW), Enantia chlorantha bark (ECB), Kalanchoe crenata leaves (KCL), Lophira alata bark (LAB), Millettia macrophylla leaves (MML) and Phragmanthera capitata leaves (PCL) towards five human solid cancer cell lines and normal CRL2120 fibroblasts, was evaluated. Extracts were subjected to qualitative chemical screening of their secondary metabolite contents using standard methods. The cytotoxicity of samples was evaluated using neutral red uptake (NR) assay meanwhile caspase activation was detected by caspase-Glo assay. Flow cytometry was used to analyze the cell cycle distribution and the mitochondrial membrane potential (MMP) whilst spectrophotometry was used to measure the levels of reactive oxygen species (ROS). RESULTS: Phytochemical analysis revealed the presence of polyphenols, triterpenes and sterols in all extracts. The IC50 values of the best samples ranged from 3.29 µg/mL (towards DLD-1 colorectal adenocarcinoma cells) to 24.38 µg/mL (against small lung cancer A549 cells) for EMW, from 2.33 µg/mL (mesothelioma SPC212 cells) to 28.96 µg/mL (HepG2 hepatocarcinoma) for KCL, and from 0.04 µg/mL (towards SPC212 cells) to 0.55 µg/mL (towards A549 cells) for doxorubicin. EMW induced apoptosis in MCF-7 cells mediated by MMP loss and increased ROS production whilst KCL induced apoptosis via ROS production. CONCLUSION: This study provides evidences of the cytotoxicity of the tested plant extract and highlights the good activity of Elephantopus mollis and Kalanchoe crenata. They deserve more exploration to develop novel cytotoxic drugs.

Antibacterial activities of the methanol extract, fractions and compounds from Elaeophorbia drupifera (Thonn.) Stapf. (Euphorbiaceae).

BACKGROUND: Elaeophorbia drupifera (Thonn.) Stapf. (Euphorbiaceae) is used in Cameroonian folk medicine to treat several ailments including bacterial-related diseases such as skin infections. In this study, the methanol extract from the leaves (EDL), fractions (EDLa-d), sub-fractions EDLc1-7 and EDLc31-35 as well as isolated compounds were tested for their antimicrobial activities against a panel of Gram-negative and Gram-positive bacteria including multidrug resistant (MDR) phenotypes. METHODS: The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the leaves extract whilst the chemical structures of compounds were determined using spectroscopic techniques. RESULTS: Phytochemical investigation lead to the isolation of a mixture (1:3) of stigmasterol and ß-sitosterol (1 + 2), euphol (3), sitosterol-O-ß- D -xylopyranoside (4), 3,3',4'-tri-O-methylellagic acid (5), a mixture (1:1) of afzelin and quercetin-3-O-ß-D-xylopyranoside (6 + 7), 3,3',4'-tri-O-methylellagic acid 4-O-ß-D-glucopyranoside (8), ellagic acid-4-O-ß-xylopyranoside-3,3',4'-trimethyl ether (9) from EDLc. Crude extract and fractions displayed selective activities with MIC values ranged from 32 to 1024 µg/mL for EDL against 84.9% of the 33 tested bacteria, 93.9% for EDLc, 69.7% for EDLb, 33.4% for EDLa and 0.03% for EDLd. MIC values ranged from 16 to 1024 µg/mL were obtained with EDLc3 and EDLc4 on all tested bacteria meanwhile other sub-fractions displayed selective activities. MIC value of 32 µg/mL was obtained with fractions EDLa against Escherichia coli AG100, EDLc against Enterobacer aerogenes ATCC13048 and EA298. For sub-fractions obtained from EDLc, the lowest MIC value of 16 µg/mL was recorded with EDLc3 against Staphylococcus aureus MRSA11. A corresponding value of 8 µg/mL against Providencia stuartii NAE16 was recorded with EDLc33 obtained from further fractionation of EDLc3. EDLc3 had MIC values below 100 µg/mL against all tested bacteria. Compound 5 as well as the mixture (1:1) of 6 and 7 inhibited the growth of all the tested bacteria with MICs ranged from 64 to 256 µg/mL. CONCLUSION: Elaeophorbia drupifera is a potential source of phytomedicine to tackle MDR bacteria. Sub-fraction EDLc3 was more active than all isolated compounds and deserves further investigations to develop natural drug to combat Gram-negative, Gram-positive bacteria and otherwise MDR phenotypes.

Individual and combined antiparasitic effect of six plant metabolites against Leishmania amazonensis and Trypanosoma cruzi.

Six plant metabolites including isobavachalcone (1), 4-hydroxylonchocarpine (2), and (E)-1-(2,2-dimethyl-2H-chromen-6-yl)-3-(4-hydroxyphenyl)prop-2-en-1-one (3), 6,8-(di-3-methyl-but-2-enyl)eriodictyol (4), damnacanthal (5), and buesgenine (6) were evaluated for their leishmanicidal and trypanocidal activities against intracellular amastigotes of Leishmania amazonensis and Trypanosoma cruzi. Compounds 2-4 and 6 displayed antileishmanial activity while 3 and 5 showed trypanocidal effect. The leishmanicidal activity of 6 was expressed with the lowest IC50 (5.70µg/mL) whereas the most trypanocidal metabolite (5) showed its activity with IC50 at 11.14µg/mL. In addition, antiprotozoal effect of mixtures of 1-6 prepared at different ratios (3:1, 1:1, and 1:3) was also investigated. Interestingly, 1 and 2 initially inactive against T. cruzi, displayed trypanocidal activities when mixed together. This activity increased when 3 (13.63µg/mL) was combined with 1 in ratios 1:1 (10.01µg/mL) and 3:1 (7.78µg/mL). Moreover, the leishmanicidal effect of 4 against L. amazonensis increased in the mixture 6/4 (1:3).

Antibacterial and antibiotic-modifying activities of three food plants (Xanthosoma mafaffa Lam., Moringa oleifera (L.) Schott and Passiflora edulis Sims) against multidrug-resistant (MDR) Gram-negative bacteria.

BACKGROUND: The present study was designed to investigate the antibacterial activities of the methanol extract of three edible plants, namely Xanthosoma mafaffa, Moringa oleifera and Passiflora edulis and their synergistic effects with some commonly used antibiotics against MDR Gram-negative bacteria expressing active efflux pumps. METHODS: Broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of the extracts, as well as those of antibiotics in association with the extracts. RESULTS: The phytochemical test indicate that all tested crude extracts contained polyphenols, triterpenes and steroids whilst other phytochemical classes were selectively distributed. Extracts showed antibacterial activities with minimum inhibitory concentrations ranging from 128-1024 µg/mL on the majority of the 19 tested Gram-negative bacterial strains. Extract from the pericarp of P. edulis inhibited the growth of 89.5% of the 19 tested bacterial strains, the lowest minimal inhibitory concentration (MIC) value of 128 µg/mL being recorded against Escherichia coli AG100 strain. In the presence of Phenylalanine-Arginine ß-Naphtylamide (PAßN)], an efflux pump inhibitor (EPI), the activity of the extract from X. mafaffa increased on 40% of tested strains. In combination with antibiotics, extracts of X. mafaffa, M. oleifera and pericarp of P. edulis showed synergistic effects with some antibiotics against more than 75% of the tested bacteria. CONCLUSION: The results of the present study indicate that the tested plants may be used in the treatment of bacterial infections including the multi-resistant bacteria.

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

BACKGROUND: Infectious 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. METHODS: Minimum 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. RESULTS: Several 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. CONCLUSION: The 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.