The genus Canthium: A comprehensive summary on its traditional use, phytochemistry, and pharmacological activities.

Canthium Lam. is a genus of flowering plants of the Rubiaceae family with about 80-102 species mainly distributed in Asia, tropical and subtropical Africa. The genus is closely related to Keetia E. Phillips and Psydrax Gaertn. and plants of this genus are used in folk medicine for the treatment of diarrhea, worms, leucorrhoea, constipation, snake bites, diabetes, hypertension, venereal diseases, and malaria. The present review covers a period of 52 years of biological and chemical investigations into the genus Canthium and has resulted in the isolation of about 96 secondary metabolites and several reported biological properties. For the Rubiaceae family, iridoids were reported as being the chemotaxonomic markers of this genus (∼25%). Other reported classes of compounds include alkaloids, flavonoids, phenolic compounds, cyanogenic glycosides, coumarins, sugar alcohols, lignans, triterpenoids, and benzoquinones. The main reported pharmacological properties of most species of this genus include antioxidant, antiplasmodial, antipyretic, anti-inflammatory, antidiabetic, neuroprotective and antimicrobial activities with the latter being the most prominent. Considering the diversity of compounds reported from plants of this genus and their wide range of biological activities, it is considered to be worthy to further investigate them for the discovery of potentially new and cost effective drugs.

Cytotoxicity of the methanol extracts and compounds of Brucea antidysenterica (Simaroubaceae) towards multifactorial drug-resistant human cancer cell lines.

BACKGROUND: Cancer remains a global health concern and constitutes an important barrier to increasing life expectancy. Malignant cells rapidly develop drug resistance leading to many clinical therapeutic failures. The importance of medicinal plants as an alternative to classical drug discovery to fight cancer is well known. Brucea antidysenterica is an African medicinal plant traditionally used to treat cancer, dysentery, malaria, diarrhea, stomach aches, helminthic infections, fever, and asthma. The present work was designed to identify the cytotoxic constituents of Brucea antidysenterica on a broad range of cancer cell lines and to demonstrate the mode of induction of apoptosis of the most active samples. METHODS: Seven phytochemicals were isolated from the leaves (BAL) and stem (BAS) extract of Brucea antidysenterica by column chromatography and structurally elucidated using spectroscopic techniques. The antiproliferative effects of the crude extracts and compounds against 9 human cancer cell lines were evaluated by the resazurin reduction assay (RRA). The activity in cell lines was assessed by the Caspase-Glo assay. The cell cycle distribution, apoptosis via propidium iodide (PI) staining, mitochondrial membrane potential (MMP) through 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) staining, and the reactive oxygen species (ROS) via 2´,7´-dichlorodihydrofluoresceine diacetate (H2DCFH-DA) staining, were investigated by flow cytometry. RESULTS: Phytochemical studies of the botanicals (BAL and BAS) led to the isolation of seven compounds. BAL and its constituents 3, (3-(3-Methyl-1-oxo-2-butenyl))1H indole (1) and hydnocarpin (2), as well as the reference compound, doxorubicin, had antiproliferative activity against 9 cancer cell lines. The IC50 values varied from 17.42 µg/mL (against CCRF-CEM leukemia cells) to 38.70 µg/mL (against HCT116 p53-/- colon adenocarcinoma cells) for BAL, from 19.11 µM (against CCRF-CEM cells) to 47.50 µM (against MDA-MB-231-BCRP adenocarcinoma cells) for compound 1, and from 4.07 µM (against MDA-MB-231-pcDNA cells) to 11.44 µM (against HCT116 p53+/+ cells) for compound 2. Interestingly, hypersensitivity of resistant cancer cells to compound 2 was also observed. BAL and hydnocarpin induced apoptosis in CCRF-CEM cells mediated by caspase activation, the alteration of MMP, and increased ROS levels. CONCLUSION: BAL and its constituents, mostly compound 2, are potential antiproliferative products from Brucea antidysenterica. Other studies will be necessary in the perspective of the discovery of new antiproliferative agents to fight against resistance to anticancer drugs.

Antibacterial and antibiotic-potentiation activities of the hydro-ethanolic extract and protoberberine alkaloids from the stem bark of Enantia chlorantha against multidrug-resistant bacteria expressing active efflux pumps.

ETHNOPHARMACOLOGICAL RELEVANCE: Enantia chlorantha is traditionally used to treat various ailments including rickettsia fever, cough and wounds, typhoid fever, infective hepatitis, jaundice, and urinary tract infections. AIM OF THE STUDY: To isolate the antibacterial constituents of the hydro-ethanolic extract of the stem bark of E. chlorantha (ECB) and to evaluate the antibacterial and antibiotic-modifying activities of ECB and its constituents against the multidrug-resistant (MDR) phenotypes. MATERIALS AND METHODS: Chromatographic methods were used to isolate the constituents of ECB and Spectroscopic methods were used to elucidate the chemical structures of the isolated compounds. The antibacterial activity of samples was determined by the broth microdilution method while spectrophotometric methods were used to evaluate the effects of ECB and its most active constituent on bacterial growth. Their effects on bacterial proton-ATPase pumps was assessed through the acidification of the bacterial culture medium. RESULTS: Six protoberberine alkaloids were isolated and identified as columbamine (1), pseudocolumbamine (2), jathrorrhizine (3), palmitine (4), 4,13-dihydroxy-3,9,10-trimethoxyprotoberberine (5), and 13-hydroxy-2,3,9,10-tetramethoxyprotoberberine (6). The crude extract (ECB) inhibited the growth of all the tested MDR bacteria, with the minimal inhibitory concentration (MIC) values below 100 µg/mL obtained against Escherichia coli ATCC 10536, AG 102, Enterobacter aerogenes EA 27, Klebsiella pneumoniae ATCC 11296 and KP 55, Providencia stuartii NEA 16, and Staphylococcus aureus MRSA3 and MRSA6. Compound 1 had the best antibacterial effects with MIC values ranging from 16 to 64 µg/mL. The efflux pump inhibitor (EPI), phenylalanine-arginine-ß naphthylamide (PAßN) significantly improved the activity of compounds 1-6. Compounds 1-3 significantly potentiated the antibacterial activity of antibiotics such norfloxacin (NOR), ciprofloxacin (CIP), and doxycycline (DOX) against the tested MDR bacteria. CONCLUSION: The crude extract (ECB) and its isolated compounds 1-6 are potential antibacterial products from Enantia chlorantha. They could be explored more to develop the antibacterial agents that could be used alone or in combination with antibiotics to overcome MDR phenotypes.

Antibacterial and antibiotic-potentiation activity of the constituents from aerial part of Donella welwitshii (Sapotaceae) against multidrug resistant phenotypes.

BACKGROUND: The rise of multidrug-resistant (MDR) bacteria is a real public health problem worldwide and is responsible for the increase in hospital infections. Donella welwitschii is a liana or shrub belonging to the family Sapotaceae and traditionally used to cure coughs. OBJECTIVE: This study was conducted with the objective to validate the medicinal properties of this plant, the aerial part was studied for its phytochemical composition using column and PTLC chromatography and exploring its antibacterial and antibiotic-modifying activity as well as those of its phytochemicals. METHODS: The structures of the compounds were elucidated from their physical and spectroscopic data in conjunction with literature. The antibacterial activity of the isolated metabolites was performed toward a panel of MDR Gram negative and Gram-positive bacteria. The broth micro-dilution method was used to determine antibacterial activities, efflux pump effect using the efflux pump inhibitor (EPI) (phenylalanine-arginine-ß-naphthylamide (PAßN)), as well as the modulating activity of antibiotics. Monitoring the acidification of the bacterial growth medium was used to study the effects of the samples on the bacterial proton-ATPase pumps and cellular ATP production. RESULTS: Eleven compounds were isolated including pentacyclic triterpenes, C-glucosyl benzophenones. With a MIC value < 10 µg/mL, diospyric acid (7) significantly inhibited the growth of Escherichia coli AG102, Enterobacter aerogenes ATCC13048, Klebsiella pneumoniae KP55, Providencia stuartii NEA16 and Staphylococcus aureus MRSA3. 28-hydroxy-ß-amyrin (8) significantly impaired the growth of Enterobacter aerogenes EA27, Klebsiella pneumoniae ATCC11296 and Staphylococcus aureus MRSA6; and oleanolic acid (9) strongly impaired the growth of Escherichia coli AG 102, Enterobacter aerogenes EA27 and Providencia stuartii PS2636. Diospyric acid (7) and 28-hydroxy-ß-amyrin (8) induced perturbation of H+-ATPase pump and inhibition of the cellular ATP production. Moreover, at MIC/2 and MIC/4, compounds 7, 8, and 9 strongly improved the antibacterial activity of norfloxacin, ciprofloxacin and doxycycline with antibiotic-modulating factors ranging between 2 and 64. CONCLUSION: The overall results of the current work demonstrate that diospyric acid (7), 28-hydroxy-ß-amyrin (8) and oleanolic acid (9) are the major bioactive constituents of Donella welwitschia towards Gram-negative bacteria expressing MDR phenotypes.

Garcinia kola improves cognitive and motor function of a rat model of acute radiation syndrome in the elevated plus maze.

We reported recently that the elevated plus maze is a good tool for evaluating cognitive and motor functional changes in gamma-irradiated rats as a model for new drug evaluation and monitoring. The capacity of Garcinia kola to mitigate radiation-induced brain injury is currently unknown. We therefore assessed the effects of the neuroprotective medicinal plant Garcinia kola, on the cognitive and motor changes in this murine model of acute radiation syndrome. Wistar rats exposed once to an ionizing dose of Tc99m-generated Gamma radiation were treated with an ethyl acetate fraction of methanolic extract of Garcinia kola seeds (content of 100 mg/kg of extract) for 9 weeks. Cognitive and motor function indicators were assessed in the elevated plus maze in these animals and compared with irradiated control groups (vitamin C- and vehicle-treated groups) and the non-irradiated control rats. The irradiated control group displayed cachexia, shaggy and dirty fur, porphyrin deposits around eyes, decreased exploratory activity, reduced social interactions and a loss of thigmotaxis revealed by a marked decrease in rearing episodes and stretch attend posture episodes close to the walls of elevated plus maze closed arm, an increased central platform time, and decreases in open arm time and entries. This group further displayed a decrease in head dips and grooming episodes. Treatment with Garcinia kola, and in a lesser extent vitamin C, significantly prevented the body weight loss (P < 0.001) and mitigated the development of elevated plus maze signs of cognitive and motor affections observed in the irradiated control group (P < 0.05). Altogether, our data suggest for the first time that Garcinia kola seeds have protective properties against the development of cognitive and motor decline in the acute radiation syndrome-like context. Future studies are warranted to characterize the molecular mechanisms and neuronal networks of this action.

Cytotoxicity of botanicals and isolated phytochemicals from Araliopsis soyauxii Engl. (Rutaceae) towards a panel of human cancer cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Araliopsis soyauxii Engl. (Rutaceae) is a Cameroonian medicinal plant traditionally used to treat lung diseases, malaria, and gonorrhea. It has been demonstrated that infectious disease contribute to about 20% of all human tumours. AIMS OF THE STUDY: (1) To perform a phytochemical investigation of the dichloromethane-methanol 1:1 extracts of the bark (ASB), roots (ASR), and leaves (ASL) from Araliopsis soyauxii; (2) to evaluate the cytotoxicity of extracts and isolated compounds; (3) to determine the mode of induction of apoptosis of ASB and kihadanin B (12). MATERIALS AND METHODS: Fourteen constituents of the crude extracts were isolated by column chromatography, while spectroscopic techniques were used for structural elucidation. The resazurin reduction assay (RRA) was applied to determine the cytotoxicity of samples towards a panel of 9 cancer cell lines. For caspases activity, the Caspase-Glo assay was used; flow cytometry was applied to investigate the cell cycle distribution (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP; JC-1 staining), and the reactive oxygen species (ROS; H2DCFH-DA staining). RESULTS: Phytochemical investigations of botanicals (ASB, ASR, and ASL) led to the isolation of 14 compounds. Extract ASB, obacunone (11), kihadanin B (12) as well as doxorubicin (control drug) revealed cytotoxicity towards the 9 cancer cell lines tested. The IC50 values ranged from 11.11 µg/mL (against CCRF-CEM leukemia cells) to 28.18 µg/mL (against HCT116 p53+/+ colon adenocarcinoma cells) for ASB; from 28.25 µM (against MDA-MB-231-pcDNA breast adenocarcinoma cells) to 65.13 µM (against HepG2 hepatocarcinoma cells) for compound 11, and from 5.77 µM (against CCRF-CEM cells) to 43.56 µM (against U87.MGΔEGFR glioblastoma cells) for compound 12. ASB and compound 12 induced apoptosis in CCRF-CEM cells. ASB induced the apoptotic process mediated by MMP alteration and enhanced ROS production, while compound 12 induced apoptosis by caspases activation, MMP alteration, and enhanced ROS production. CONCLUSION: This study demonstrated that Araliopsis soyauxii is a potential source of cytotoxic phytochemicals such as kihadanin B and that ASB and compound 12. Extract and compounds will be explored further to develop anticancer drugs.

Botanicals from the leaves of Acacia sieberiana had better cytotoxic effects than isolated phytochemicals towards MDR cancer cells lines.

The efficiency of cancer chemotherapy is seriously hampered by the development of resistance of neoplastic cells to cytotoxic agents. In the present investigation, the cytotoxicity of the dichloromethane-methanol (1:1) extract of Acacia sieberiana (ASL), fractions (ASLa-c) from the leaves and isolated compounds: chrysoeriol-7-O-rutinoside (1), luteolin-7-O-rutinoside (2), chrysoeriol-7-O-ß-D-glucopyranoside (3), Apigenin-7-O-ß-D-glucopyranoside (4), luteolin-3',4'-dimethoxylether-7-O-ß-D-glucoside (5) and luteolin (6) was investigated. The study was extended to the assessment of the mode of induction of apoptosis by ASL. The resazurin reduction assay (RRA) was used for cytotoxicity studies. Assessments of cell cycle distribution, apoptosis, and reactive oxygen species (ROS) were performed by flow cytometry. A caspase-Glo assay was used to evaluate caspase activities. Botanicals ASL, ASLb and ASLc as well as doxorubicin displayed observable IC50 values towards the nine tested cancer cell lines while ASLa and compounds 1-7 had selective activities. The IC50 values ranged from 13.45 µg/mL (in CCRF-CEM leukemia cells) to 33.20 µg/mL (against MDA-MB-231-BCRP breast adenocarcinoma cells) for ASL, from 16.42 µg/mL (in CCRF-CEM cells) to 29.64 µg/mL (against MDA-MB-231-pcDNA cells) for ASLc, and from 22.94 µg/mL (in MDA-MB-231-BCRP cells) to 40.19 µg/mL (against HCT116 (p53-/-) colon adenocarcinoma cells) for ASLb (Table 1), and from 0.02 µM (against CCRF-CEM cells) to 122.96 µM (against CEM/ADR5000 cells) for doxorubicin. ASL induced apoptosis in CCRF-CEM cells, mediated by ROS production. Acacia sieberiana is a good cytotoxic plant and should be further explored to develop an anticancer phytomedicine to combat both sensitive and drug resistant phenotypes.

Cytotoxicity of a naturally occuring spirostanol saponin, progenin III, towards a broad range of cancer cell lines by induction of apoptosis, autophagy and necroptosis.

This study was aimed to investigate the cytotoxic potential of a natural compound, progenin III on a broad range of cancer cell lines, including various sensitive and drug-resistant phenotypes. The cytotoxicity, progenin III-induced autophagic, ferroptotic and necroptotic cell death were evaluated by the resazurin reduction assay (RRA). Spectrophotometric analysis of caspases activity was performed using caspase-Glo assay. Flow cytometry was applied for cell cycle analysis (PI staining), apoptosis (annexin V/PI staining), mitochondrial membrane potential (MMP) (JC-1) and reactive oxygen species (ROS) (H2DCFH-DA). Progenin III and the reference molecule, doxorubicin exerted cytotoxic effects towards the 18 cancer cell lines tested including animal and human cell lines. The IC50 values obtained ranged from 1.59 µM (towards CCRF-CEM leukemia cells) to 31.61 µM (against the BRAF-V600E homozygous mutant SKMel-28 melanoma cells) for progenin III. Normal sensitivity was achieved with CEM/ADR5000 cells and HCT116p53-/- adenocarcinoma cells respectively compared to their sensitive congeners CCRF-CEM cells and HCT116 p53+/+ cells. Progenin III induced apoptosis in CCRF-CEM cells mediated by caspases 3/7 activation, MMP alteration and increase ROS production, and otherwise autophagy and necroptosis. Progenin III is a potential anticancer molecule that deserves further investigations to develop a novel drug to combat malignant diseases including refractory cancers.

Antistaphylococcal Activity of Extracts, Fractions, and Compounds of Acacia polyacantha Wild (Fabaceae).

Acacia polyacantha is a medicinal plant traditionally used to treat livestock diseases and gastrointestinal infections; our study was undertaken to evaluate the antistaphylococcal activities of the methanolic leaf, bark, and root extracts, fractions, and compounds from Acacia polyacantha against a panel of 14 multidrug-resistant Staphylococcus bacterial strains overexpressing efflux pumps. The study was also extended to investigate two possible modes of action, that is, influence on bacterial growth kinetics and influence on proton-ATPase pumps, of the most active compound against a reference strain. Materials and Methods. The crude extracts after extraction were subjected to column chromatography. Antibacterial assays of extracts, fractions, and compounds alone and in the presence of efflux pump inhibitors were carried out using the broth microdilution method and the study of two mechanisms of action achieved by standard methods with the most active compound. Results. The phytochemical study of Acacia polyacantha leaves leads to the isolation of stigmasterol (1), ß-amyrin (2), 3-O-methyl-D-chiro-inositol (3), epicatechin (4), quercetin-3-O-galactoside (5), 3-O-[ß-D-xylopyranosyl-(1 ⟶ 4)-ß-D-galactopyranosyl]-oleanolic acid (6), 3-O-[ß-galactopyranosyl-(1⟶ 4)-ß-D-galactopyranosyl]-oleanolic acid (7) and that of leaves lead to the isolation of lupeol (8) 2,3-dihydroxypropyltetracosanoate (9), and methyl-gallate (10). Leaf, root, and bark extracts inhibited 92.85% (13/14), 92.85% (13/14), and 71.43 % (10/14) of the tested bacteria strains, respectively, with minimum inhibitory concentration (MIC) varying between 16 and 1024 µg/mL. Fractions exhibited better activities compared to those of their extracts of origin, as their MICs ranged from 16 to 512 µg/mL, with fractions from leaves being more active than those obtained from barks. Compounds had varying activities; MICs varied from 16 to 512 µg/mL with compound 4 presenting the best activity as MICs ≤100 µg/mL were obtained against 11 of the tested bacteria. The activities of extracts, fractions, and compounds were improved in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP) as an efflux pump inhibitor to as much as >128 folds. Meanwhile, in the presence of chlorpromazine as an efflux pump inhibitor, only the activity of compound 10 was improved on 10 of the tested bacteria strains. Compound 4 prolonged the lag phase of the growth kinetic in a concentration-dependent manner and equally inhibited the proton-ATPase pumps of the tested bacteria strains. Conclusion. The present study demonstrates the antistaphylococcal potential of Acacia polyacantha and its constituents to combat bacterial infections alone or in combination with efflux pump inhibitors.

Antibacterial and Antibiotic Modifying Potential of Crude Extracts, Fractions, and Compounds from Acacia polyacantha Willd. against MDR Gram-Negative Bacteria.

The present study aimed to assess the in vitro antibacterial and antibiotic modifying activities of methanol extracts prepared from the leaf (APL) and bark (APB) of Acacia polyacantha, fractions (APLa-d) and compounds isolated from APL against a panel of multidrug resistant (MDR) Gram-negative bacteria. Leaf extract was subjected to column chromatography for compounds isolation; antibacterial assays were performed on samples alone and with an efflux pump inhibitor (EPI), respectively, and several antibiotics on the tested bacteria. The phytochemical investigation of APL led to the isolation of stigmasterol (1), ß-amyrin (2), 3-O-ß-D-glucopyranosylstigmasterol (3), 3-O-methyl-D-chiro-inositol (4), epicatechin (5), quercetin-3-O-glucoside (6), 3-O-[ß-D-xylopyranosyl-(1→4)-ß-D-galactopyranosyl]-oleanolic acid (7), and 3-O-[ß-galactopyranosyl-(1→4)-ß-D-galactopyranosyl]-oleanolic acid (8). APL and APB had minimal inhibitory concentration (MIC) values ≤ 1024 µg/mL on 73.3% and 46.7% of the tested bacteria, respectively. APLb and APLd were effective against 88.9% of tested bacterial species with compound 8 showing the highest activity inhibiting 88.9% of tested bacteria. The EPI, phenylalanine-arginine-ß-naphthylamide (PAßN), strongly improved the activity of APL, APLb, APLd, and compound 8 on all tested bacteria. Synergistic effects were obtained when APL and compounds 7 and 8 were combined with erythromycin (ERY), gentamycin (GEN), ciprofloxacin (CIP), and norfloxacin (NOR). The present study demonstrates the antibacterial potential of Acacia polyacantha and its constituents to combat bacterial infections alone or in combination with EPI.

Cytotoxicity of epunctanone and four other phytochemicals isolated from the medicinal plants Garcinia epunctata and Ptycholobium contortum towards multi-factorial drug resistant cancer cells.

INTRODUCTION: Resistance of cancer cells is a serious impediment to chemotherapy and several phytochemicals are active against multi-drug resistant (MDR) phenotypes. The cytotoxicity of five naturally occurring compounds: betulin (1), mundulea lactone (2), seputhecarpan A (3), seputheisoflavone (4) and epunctanone (5) was evaluated on a panel of 9 cancer cell lines including various sensitive and drug-resistant cell lines. The modes of action of compound 5 were further investigated. METHODS: The resazurin reduction assay was used to evaluate cytotoxicity of samples and ferroptotic cell death induced by compound 5; caspase-Glo assay was used to detect the activation of caspases in CCRF-CEM leukemia cells treated with compound 5. Flow cytometry was used for cell cycle analysis in CCRF-CEM cells treated with compound 5, as well as detection of apoptotic cells by annexin V/PI staining, analysis of mitochondrial membrane potential (MMP) and measurement of reactive oxygen species (ROS). RESULTS: Compounds 1-5 displayed cytotoxic effects in the 9 studied cancer cell lines with IC50 values below 70 µM. The IC50 values varied from 8.20 µM (in HCT116 (p53-/-) colon cancer cells) to 35.10 µM (against HepG2 hepatocarcinoma cells) for 1, from 8.84 µM (in CEM/ADR5000 leukemia cells) to 48.99 µM (in MDA-MB-231 breast adenocarcinoma cells) for 2, from 12.17 µM (in CEM/ADR5000 cells) to 65.08 µM (in MDA-MB-231 cells) for 3, from 23.80 µM (in U87MG.ΔEGFR glioblastoma cells) to 68.66 µM (in HCT116 (p53-/-) cells) for 4, from 4.84 µM (in HCT116 (p53-/-) cells) to 13.12 µM (in HepG2 cells) for 5 and from 0.02 µM (against CCRF-CEM cells) to 122.96 µM (in CEM/ADR5000 cells) for doxorubicin. Compound 5 induced apoptosis in CCRF-CEM cells through alteration of MMP and increase in ROS production. In addition to apoptosis, ferroptosis was also identified as another mode of cell death induced by epunctanone. CONCLUSIONS: Compounds 1-5 are valuable cytotoxic compounds that could be used to combat MDR cancer cells. Benzophenoe 5 is the most active molecule and deserve more investigations to develop new anticancer drugs.

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.

The Croton megalobotrys Müll Arg. traditional medicine in HIV/AIDS management: Documentation of patient use, in vitro activation of latent HIV-1 provirus, and isolation of active phorbol esters.

ETHNOPHARMACOLOGICAL RELEVANCE: Current HIV therapies do not act on latent cellular HIV reservoirs; hence they are not curative. While experimental latency reversal agents (LRAs) can promote HIV expression in these cells, thereby exposing them to immune recognition, existing LRAs exhibit limited clinical efficacy and high toxicity. We previously described a traditional 3-step medicinal plant regimen used for HIV/AIDS management in Northern Botswana that inhibits HIV replication in vitro. Here we describe use of one component of the regimen that additionally contains novel phorbol esters possessing HIV latency-reversal properties. AIM OF THE STUDY: We sought to document experiences of traditional medicine users, assess the ability of traditional medicine components to reverse HIV latency in vitro, and identify pure compounds that conferred these activities. MATERIALS AND METHODS: Experiences of two HIV-positive traditional medicine users (patients) were documented using qualitative interview techniques. Latency reversal activity was assessed using a cell-based model (J-Lat, clone 9.2). Crude plant extracts were fractionated by open column chromatography and reverse-phase HPLC. Compound structures were elucidated using NMR spectroscopy and mass spectrometry. RESULTS: Patients using the 3-step regimen reported improved health over several years despite no reported use of standard HIV therapies. Crude extracts from Croton megalobotrys Müll Arg. ("Mukungulu"), the third component of the 3-step regimen, induced HIV expression in J-lat cells to levels comparable to the known LRA prostratin. Co-incubation with known LRAs and pharmacological inhibitors indicated that the active agent(s) in C. megalobotrys were likely to be protein kinase C (PKC) activator(s). Consistent with these results, two novel phorbol esters (Namushen 1 and 2) were isolated as abundant components of C. megalobotrys and were sufficient to confer HIV latency reversal in vitro. CONCLUSION: We have identified novel LRAs of the phorbol ester class from a medicinal plant used in HIV/AIDS management. These data, combined with self-reported health effects and previously-described in vitro anti-HIV activities of this traditional 3-step regimen, support the utility of longitudinal observational studies of patients undergoing this regimen to quantify its effects on plasma viral loads and HIV reservoir size in vivo.

Cytotoxicity, antimicrobial and antioxidant activity of eight compounds isolated from Entada abyssinica (Fabaceae).

BACKGROUND: Entada abyssinica is a plant traditionally used against gastrointestinal bacterial infections. Eight compounds including three flavonoids, three terpenoids, a monoglyceride and a phenolic compound isolated from E. abyssinica were investigated for their cytotoxicity, antibacterial and antioxidant activity. RESULTS: Compounds 7 and 2 had remarkable activity against Salmonella typhimurium with the lowest respective minimum inhibitory concentration (MIC) values of 1.56 and 3.12 µg/mL. The antioxidant assay gave IC50 values varied from 0.48 to 2.87 µg/mL in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, from 2.53 to 17.04 µg/mL in the 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) assay and from 1.43 to 103.98 µg/mL in the FRAP assay. Compounds had relatively low cytotoxicity (LC50 values ranging from 22.42 to 80.55 µg/mL) towards Vero cells. Ursolic acid had the most potent cytotoxicity against THP-1 and RAW 264.7 cells with LC50 values of 9.62 and 4.56 µg/mL respectively, and selectivity index values of 7.32 and 15.44 respectively. CONCLUSION: Our findings suggest that among the terpenoid and flavonoid compounds studied, entadanin (compound 7) possess tremendous antibacterial activity against S. typhimurium and could be developed for the treatment of bacterial diseases.

Antibacterial and antibiotic-resistance modifying activity of the extracts and compounds from Nauclea pobeguinii against Gram-negative multi-drug resistant phenotypes.

BACKGROUND: Multi-drug resistance of Gram-negative bacteria constitutes a major obstacle in the antibacterial fight worldwide. The discovery of new and effective antimicrobials and/or resistance modulators is necessary to combat the spread of resistance or to reverse the multi-drug resistance. In this study, we investigated the antibacterial and antibiotic-resistance modifying activities against 29 Gram-negative bacteria including multi-drug resistant (MDR) phenotypes of the methanol extracts from Nauclea pobeguiinii leaves (NPL), Nauclea pobeguiinii bark (NPB) and six compounds from the bark extract, identified as 3-acetoxy-11-oxo-urs-12-ene (1), p-coumaric acid (2), citric acid trimethyl ester (3), resveratrol (4), resveratrol ß- D -glucopyranoside (5) and strictosamide (6). METHODS: The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of crude extracts and compounds as well as the antibiotic-resistance modifying effects of MPB and 4. RESULTS: MIC determinations indicate values ranging from 32-1024 µg/mL for NPB and NPL on 89.7 % and 69.0 % of the tested bacterial strains respectively. MIC values below 100 µg/mL were obtained with NPB against Escherichia coli ATCC10536, AG100 and Enterobacter aerogenes CM64 strains. The lowest MIC value for crude extracts of 32 µg/mL was obtained with NPB against E. coli ATCC10536. Compound 4 was active all tested bacteria, whilst 1, 3 and 6 displayed weak and selective inhibitory effects. The corresponding MIC value (16 µg/mL) was obtained with 4 against Klebsiella pneumoniae KP55 strain. Synergistic effects of the combination of NPB with chloramphenicol (CHL), kanamycin (KAN) as well as that of compound 4 with streptomycin (STR) and ciprofloxacin (CIP) were observed. CONCLUSION: The present study provides information on the possible use of Nauclea pobeguinii and compound 4 in the control of Gram-negative bacterial infections including MDR phenotypes. It also indicates that NPB and 4 can be used as naturally occurring antibiotic-resistance modulators to tackle MDR bacteria.

Antibacterial and antibiotic-modulation activity of six Cameroonian medicinal plants against Gram-negative multi-drug resistant phenotypes.

BACKGROUND: Bacterial Infections involving multi-drug resistant (MDR) phenotypes constitute a worldwide health concern. The present work was designed to assess the antibacterial properties of the methanol extracts of six medicinal plants (Anthocleista schweinfurthii, Nauclea latifolia, Boehmeria platyphylla, Caucalis melanantha, Erigeron floribundus and Zehneria scobra) and the effects of their associations with antibiotics on MDR Gram-negative bacteria over-expressing active efflux pumps. METHODS: The antibacterial activities and the ability to potentiate antibiotic effects of the methanol extracts the tested plants were evaluated in vitro against twenty eight Gram-negative bacteria expressing MDR phenotypes, using broth microdilution method. The phytochemical screening of these extracts was also performed using standard methods. RESULTS: All tested extracts displayed moderate to low antibacterial activity on at least 14.3 % of the 28 tested bacteria, with MIC values ranged from 128 to 1024 µg/mL. The best antibacterial spectrum was observed with Naulcea latifolia bark extract. Extracts from A. schweinfurthii fruits, N. latifolia stem bark, Z. scobra and N. latifolia leaves showed synergistic effects with many antibiotics against MDR bacteria. CONCLUSION: The overall results of the present study provide information for the possible use of the studied plants, especially Nauclea latifolia in the control of Gram-negative bacterial infections including MDR species as antibacterials as well as resistance modulators.

Thonningiiflavanonol A and thonningiiflavanonol B, two novel flavonoids, and other constituents of Ficus thonningii Blume (Moraceae).

A phytochemical study of Ficus thonningii has led to the isolation of two previously unreported compounds, thonningiiflavanonol A and thonningiiflavanonol B together with 16 known compounds: shuterin, naringenin, syringic acid, p-hydroxybenzoic acid, genistein, 5,7,3',4',5'-pentahydroxyflavanone, luteolin, methylparaben, aromadendrin, garbanzol, dihydroquercetin, 5,7,3'-trihydroxyflavanone, ß-sitosterol, sitosterolglucoside, lupeol acetate, and taraxerol. Their structures were elucidated on the basis of spectroscopic data. The new compounds and extracts displayed potent antioxidant activity.

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).

Cytotoxicity of three naturally occurring flavonoid derived compounds (artocarpesin, cycloartocarpesin and isobavachalcone) towards multi-factorial drug-resistant cancer cells.

INTRODUCTION: Cancer remains an aggressive deadly disease, if drug resistance develops. This problem is aggravated by the fact that multiple rather than single mechanisms are involved in resistance and that multidrug resistance (MDR) phenomena cause inefficacy of many clinical established anticancer drugs. We are seeking for novel cytotoxic phytochemicals to combat drug-resistant tumour cells. METHODS: In the present study, we investigated the cytotoxicity of three naturally occurring flavonoids including two flavones artocarpesin (1) and cycloartocarpesin (2) and one chalcone, isobavachalcone (3) against 9 drug-sensitive and MDR cancer cell lines. The resazurin reduction assay was used to evaluate the cytotoxicity of these compounds, whilst caspase-Glo assay was used to detect caspase activation. Cell cycle, mitochondrial membrane potential (MMP) and levels of reactive oxygen species (ROS) were all analysed via flow cytometry. RESULTS: Flavones 1 and 2 as well as chalcone 3 displayed cytotoxic effects at various extent on all the 9 tested cancer cell lines with IC50 values respectively below 106 µM, 50 µM and 25 µM. The IC50 values for the three investigational flavonoids ranged from 23.95 µM (towards hepatocarcinoma HepG2 cells) to 105 µM [towards colon carcinoma HCT116 (p53(-/-)) cells] for 1, from 15.51 µM (towards leukemia CCRF-CEM cells) to 49.83 µM [towards glioblastoma U87MG.ΔEGFR cells] for 2 and from 2.30 µM (towards CCRF-CEM cells) to 23.80 µM [towards colon carcinoma HCT116 (p53(+/+)) cells] for 3 and from 0.20 µM (towards CCRF-CEM cells) to 195.12 µM (towards leukemia CEM/ADR5000 cells) for doxorubicin. Compounds 2 and 3 induced apoptosis in CCRF-CEM leukemia cells, mediated by caspase activation and the disruption of MMP. CONCLUSIONS: The three tested flavonoids and mostly chalcone 3 are potential cytotoxic natural products that deserve more investigations to develop novel antineoplastic drugs against multifactorial drug-resistant cancers.

Cytotoxicity of selected Cameroonian medicinal plants and Nauclea pobeguinii towards multi-factorial drug-resistant cancer cells.

BACKGROUND: Malignacies are still a major public concern worldwide and despite the intensive search for new chemotherapeutic agents, treatment still remains a challenging issue. This work was designed to assess the cytotoxicity of six selected Cameroonian medicinal plants, including Nauclea pobeguinii and its constituents 3-acetoxy-11-oxo-urs-12-ene (1), p-coumaric acid (2), citric acid trimethyl ester (3), resveratrol (4), resveratrol ß- D -glucopyranoside (5) and strictosamide (6), against 8 drug-sensitive and multidrug-resistant (MDR) cancer cell lines. METHODS: The resazurin reduction assay was used to evaluate the cytotoxicity of the crude extracts and compounds, whilst column chromatography was used to isolate the constituents of Nauclea pobeguinii. Structural characterization of isolated compounds was performed using nuclear magnetic resonance (NMR) spectroscopic data. RESULTS: Preliminary experiments on leukemia CCRF-CEM cells at 40 µg/mL showed that the leaves and bark extracts from Tragia benthamii, Canarium schweinfurthii, Myrianthus arboreus, Dischistocalyx grandifolius and Fagara macrophylla induced more than 50 % growth of this cell line contrary to the leaves and bark extracts of N. pobeguinii. IC50 values below or around 30 µg/mL were obtained with leaves and bark extracts of N. pobeguinii towards two and five, respectively, of the 8 tested cancer cell lines. The lowest IC50 value was obtained with the bark extract of N. pobeguinii against HCT116 (p53 (-/-) ) colon cancer cells (8.70 µg/mL). Compounds 4 and 6 displayed selective activity on leukemia and carcinoma cells, whilst 1-3 were not active. IC50 values below 100 µM were recorded with compound 5 on all 9 tested cancer cell lines as well as with 4 against 7 out of 8 and 6 against 2 out of 8 cell lines. Collateral sensitivity was observed in CEM/ADR5000 leukemia cells, MDA-MB-231-BCRP breast adenocarcinoma cells (0.53-fold), HCT116 (p53 (+/+) ) cells, human U87MG.ΔEGFR glioblastome multiforme cells to the methanolic bark extract of N. pobeguinii, as well as in MDA-MB-231-BCRP cells and HCT116 (p53 (+/+) ) cells and U87MG.ΔEGFR cells (0.86-fold) to compound 5. CONCLUSIONS: The results of this study demonstrate the cytotoxicity of six Cameroonian medicinal plants, Canarium schweinfurthii, Dischistocalyx grandifolius, Tragia benthamii, Fagara macrophylla, Myrianthus arboreus and Nauclea pobeguinii. We also demonstrated the antiproliferative potential of Nauclea pobeguinii against drug-resistant cancer cell lines. Resveratrol and its glucoside are the major cytotoxic constituents in the bark of Nauclea pobeguinii.