New 21-nordammarane saponins with anti-inflammatory and cytotoxic activities from Lavigeria macrocarpa Oliv.

Chemical investigation of the ethanol extract from the stems and roots of the medicinal plant Lavigeria macrocarpa led to the isolation and structure elucidation of three previously unreported 21-nordammarane-type saponins namely 6α,27-dihydroxy-3,20-dioxo-21-nordammar-24-(Z)-ene 27-O-[α-L-rhamnopyranosyl-(1→2)-ß-D-glucopyranoside] (1), 6α,27-dihydroxy-3-oxo-21-nordammar-24-(Z)-ene 27-O-ß-D-glucopyranoside (2), and 2α,3ß,6α,27-tetrahydroxy-21-nordammar-24-(Z)-ene 27-O-ß-D-glucopyranoside (3) trivially named lavigemacrocarposide A-C, along with eight known secondary metabolites. Acid hydrolysis of lavigemacrocarposide A yielded a new prosapogenin namely 6α,27-dihydroxy-3,20-dioxo-21-nordammar-24-(Z)-ene 27-O-ß-D-glucopyranoside (1a) and the previously unreported artefactual aglycones 1b and 1c. Their structures were elucidated by spectroscopic analyses including mass spectrometry, 1D and 2D NMR as well as chemical evidence. The EtOH extract, some isolated compounds as well as the prosapogenin (1a) and compounds 1b and 1c were evaluated for anti-inflammatory and cytotoxic activity. Icacine (5) exhibited a significant cytotoxicity against both HeLa and MCF-7 cell lines with an IC50 value of 0.78 µg/mL. All the tested compounds showed more that 50% inhibition of NO production, except for 1 and 2.

Anticandidal activity of green synthesised silver nanoparticles and extract loaded chitosan nanoparticles of Euphorbia prostata.

This study aimed to synthesize the silver nanoparticles (SNPs) and loaded chitosan nanoparticles (LCNPs) using Euphorbia prostata based on their anticandidal activity. Antioxidant capacity and the total phenolic and total flavonoid content of plant samples and synthesized nanoparticles (NPs) were also evaluated. SNPs and LCNPs were prepared, respectively using chemical reduction of silver salt solution and ionotropic gelation method. The anticandidal activity was assessed by broth micro-dilution method and the antioxidant activity was determined using free-radical scavenging assays. The synthesized NPs after the optimization process were found to be spherical with sizes ranging from 12 to 100 nm. Spectroscopic analysis of NPs showed the appearance of peaks in prescribed wavelength ranging between 402 and 493 nm. The synthesized NPs showed potent anticandidal activity compared to the free extract. The SNPs formulations NpEPM 7.5 and NpEPMR 7.5, showed significantly low MIC values ranging between 2 and 128 µg/mL. In the case of LCNPs, NpEPM (4:1) and NpEPME (4:1) also showed lower MIC values ranging from 32 to 256 µg/mL. The plant samples as well as NPs showed antioxidant potential. In addition, plant extracts and NPs possess the potent biological potential and can be further investigated through in vivo experiments.

Fractions and isolated compounds from Oxyanthus speciosus subsp. stenocarpus (Rubiaceae) have promising antimycobacterial and intracellular activity.

BACKGROUND: Tuberculosis is a deadly disease caused by Mycobacterium species. The use of medicinal plants is an ancient global practice for the treatment and prevention of diverse ailments including tuberculosis. The aim of this study was to isolate and characterize antimycobacterial compounds by bioassay-guided fractionation of the acetone leaf extract of Oxyanthus speciosus. METHODS: A two-fold serial microdilution method was used to determine the minimum inhibitory concentration (MIC) against mycobacteria. Cytotoxicity and nitric oxide inhibitory activity of the isolated compounds was determined to evaluate in vitro safety and potential anti-inflammatory activity. Intracellular efficacy of the crude extract against Mycobacterium-infected macrophages was also determined. RESULTS: Two compounds were isolated and identified as lutein (1) and rotundic acid (2). These had good antimycobacterial activity against the four mycobacteria tested with MIC values ranging from 0.013 to 0.1 mg/mL. Rotundic acid had some cytotoxicity against C3A human liver cells. Lutein was not cytotoxic at the highest tested concentration (200 µg/mL) and inhibited nitric oxide production in RAW 264.7 macrophages by 94% at a concentration of 25 µg/mL. The acetone crude extract (120 µg/mL) of O. speciosus had intracellular antimycobacterial activity, reducing colony forming units by more than 90%, displaying bactericidal efficacy in a dose and time-dependent manner. CONCLUSION: This study provides good proof of the presence of synergism between different compounds in extracts and fractions. It is also the first report of the antimycobacterial activity of lutein and rotundic acid isolated from Oxyanthus speciosus. The promising activity of the crude extract of O. speciosus both in vitro and intracellularly in an in vitro macrophage model suggests its potential for development as an anti- tuberculosis (TB) herbal medicine.

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.

A New Benzophenanthridine Alkaloid from Caloncoba glauca.

Three alkaloids including a new one, N-formyldihydrochelerythrine (1), together with four other known compounds were isolated from the stem bark of Caloncoba glauca. The structure of the new compound was elucidated from spectroscopic and mass spectrometric evidence. This is the first report of alkaloids from the genus Caloncoba. Sesamin (4) [MIC = 256 µg/mL (Candida albicans) and dihydrochelerythrine (2) [MIC = 32 (C. albicans and C. parapsilosis), and 128 µg/mL (C. krusei)] had moderate to weak antifungal activity.

Extracts of six Rubiaceae species combined with rifampicin have good in vitro synergistic antimycobacterial activity and good anti-inflammatory and antioxidant activities.

BACKGROUND: The Rubiaceae family has played a significant role in drug discovery by providing molecules with potential use as templates for the development of therapeutic drugs. This study was designed to study the in vitro synergistic effect of six Rubiaceae species in combination with a known anti-TB drug. The antioxidant and anti-inflammatory activity of these species were also evaluated to investigate additional benefits in antimycobacterial treatment. METHODS: The checkerboard method was used to determine the antimycobacterial synergistic activity of plant extracts combined with rifampicin. The antioxidant activity of extracts was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Anti-inflammatory activity via inhibition of nitric oxide (NO) production was performed in LPS-activated RAW 264.7 macrophages using the Griess assay. RESULTS: Combination of rifampicin with the crude extracts resulted in a 4 to 256-fold increase of activity of extracts. The crude extract of Cremaspora triflora produced the best synergistic effect with rifampicin, with a fractional inhibitory concentration (FIC) index of 0.08 against Mycobacterium aurum. Extracts of Psychotria zombamontana had the best antioxidant activity with an IC50 value of 1.77 µg/mL, lower than the IC50 of trolox and ascorbic acid (5.67 µg/mL and 4.66 µg/mL respectively). All the extracts tested inhibited nitric oxide (NO) production in a concentration dependent manner with the percentage of inhibition varying from 6.73 to 86.27 %. CONCLUSION: Some of the Rubiaceae species investigated have substantial in vitro synergistic effects with rifampicin and also good free radical scavenging ability and anti-inflammatory activity. These preliminary results warrant further study on these plants to determine if compounds isolated from these species could lead to the development of bioactive compounds that can potentiate the activity of rifampicin even against resistant mycobacteria.

A Novel Ellagic Acid Derivative from Desbordesia glaucescens.

One novel ellagic acid derivative, desglauside (1), was isolated from the leaves of Desbordesia glaucescens together with three known compounds [3',4'-di-O-methylellagic acid (2), oleanolic acid (3) and ß-sitosterol-3-O-ß-D-glucopyranoside (4)]. Their structures were elucidated on the basis of NMR spectroscopic and MS analysis, and by comparison with related published data. The crude extract, fractions and isolated compounds showed no activity against four yeast strains [Candida albicans (ATCC 9002), C. parapsilopsis (ATCC22019), C. tropicalis (ATCC750), Cryptococcus neoformans (IP95026) and one isolate of Candida guilliermondii].

The anti-inflammatory and antioxidant activity of 25 plant species used traditionally to treat pain in southern African.

BACKGROUND: Inflammation is a common risk factor in the pathogenesis of conditions such as infections, arthritis, type 2 diabetes mellitus, obesity and cancer. An ethnobotanical survey of medicinal plants used traditionally to treat inflammation and related disorders such as pain, arthritis and stomach aches in southern Africa led to the selection of 25 plant species used in this study. METHODS: The antioxidant activities of acetone extracts were determined by measuring the free radical scavenging activity and ferric reducing ability, respectively. The anti-inflammatory activities of the extracts were determined by measuring the inhibitory effect of the extracts on the activities of the pro-inflammatory enzyme, lipoxygenase and inducible nitric oxide synthase. RESULTS: Extracts of Peltophorum africanum had good antioxidant activity with IC50 values of 4.67 ± 0.31 µg/mL and 7.71 ± 0.36 µg/mL compared to that of the positive control ascorbic acid (2.92 ± 0.14 µg/mL and 13.57 ± 0.44 µg/mL), using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS) methods, respectively. The metabolism of linoleic acid to leukotriene derivatives by 15-lipoxygenase (15-LOX) was also inhibited by the crude acetone extracts of Peltophorum africanum (IC50 = 12.42 µg/mL), Zanthoxylum capense (IC50 = 14.92 µg/mL) compared to the positive control quercetin (IC50 = 8.75 µg/mL). There was a poor correlation between the flavonoid content and 15-LOX inhibition by the extracts (R(2) = 0.05), indicating that flavonoids are not involved in LOX inhibition. Extracts of Clausena anisata, at a concentration of 6.25 µg/mL inhibited nitric oxide production by RAW 264.7 macrophage cell lines in vitro by 96 %. The extracts of Zanthoxylum capense were the least cytotoxic (IC50 > 1000 µg/mL) when the extract toxicity was determined against Vero (African green Monkey) kidney cell lines. CONCLUSION: Some plant species used traditionally to treat pain have reasonable anti-inflammatory activity and flavonoids are probably not involved in this process.

Some South African Rubiaceae Tree Leaf Extracts Have Antimycobacterial Activity Against Pathogenic and Non-pathogenic Mycobacterium Species.

Tuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Many plant species contain antimycobacterial compounds, which may serve as template molecules for new anti-TB drugs. The Rubiaceae family is the largest family of trees in southern Africa, and preliminary evidence revealed antimycobacterial activity in several species of the genus, motivating further studies. Leaf extracts of 15 tree species from the Rubiaceae family were screened for antimycobacterial activity against pathogenic M. tuberculosis and non-pathogenic Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium bovis BCG (Bacillus Calmette-Guérin) using a twofold serial microdilution assay. Cytotoxicity was determined using a tetrazolium-based colorimetric assay against C3A liver cells and Vero kidney cells. Minimum inhibitory concentration values as low as 0.04 mg/mL against M. smegmatis and M. tuberculosis were recorded. Activity against M. aurum was the best predictor of activity against pathogenic M. tuberculosis (correlation coefficient = 0.9). Bioautography indicated at least 40 different antimycobacterial compounds in the extracts. Cytotoxicity of the extracts varied, and Oxyanthus speciosus had the most promising selectivity index values.

In vitro antibacterial, antioxidant and cytotoxic activity of acetone leaf extracts of nine under-investigated Fabaceae tree species leads to potentially useful extracts in animal health and productivity.

BACKGROUND: The Fabaceae family is the second largest family of medicinal plants, containing more than 490 species which are being used as traditional medicine. The aim of this study was to determine the antioxidant and antibacterial activity as well as the cytotoxicity of acetone leaf extracts of nine tree species from the Fabaceae family that have not been investigated well previously for possible use in animal health and production. METHODS: The antibacterial activity was determined by a serial microdilution method against three Gram-positive and three Gram-negative bacteria. Antioxidant activity was determined using free-radical scavenging assays. The safety of the extracts was ascertained using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on Vero African green monkey kidney cells. RESULTS: Six of the nine acetone extracts had significant antibacterial activity against at least one of the six bacterial species with (MIC 20-80 µg/mL). The Crotalaria capensis extract had the highest activity against Salmonella typhimurium, followed by Indigofera cylindrica with MICs of 20 µg/mL and 40 µg/mL respectively. The Dalbergia nitidula extract had free radical scavenging capacity (IC50 of 9.31±2.14 µg/mL) close to that of the positive control Trolox in the DPPH assay. The Xylia torreana extract also had high activity (IC50 of 14.56±3.96 µg/mL) in the ABTS assay. There was a good correlation between antioxidant activity and total phenolic content (R2 values>0.8). The extracts had weak or no toxicity to Vero cells, compared to the positive control doxorubicin with the LC50 varying from 10.70±3.47 to 131.98±24.87 µg/mL at the concentrations tested. CONCLUSION: Extracts of D. nitidula, X. torreana, C. capensis and I. cylindrica had a low cytotoxicity and high antimicrobial and/or antioxidant activity. These species are therefore promising candidates for the development of useful antimicrobial/antioxidant preparations with a low cytotoxicity that may be useful in promoting animal health and productivity.

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

OBJECTIVE: To evaluate the in vitro antibacterial properties and the ability to potentiate some common antibiotics effects of the methanol extracts of 11 Cameroonian food plants on 29 Gram-negative bacteria expressing multidrug resistant (MDR) phenotypes. METHODS: The antimicrobial activity of the extracts was performed using the broth microdilution method. The phytochemical screening of these extracts was also performed using standard methods. RESULTS: Ocimum basilicum, Gnetum africanum and Eucalyptus robusta extracts possessed an antibacterial activity against all the 29 studied bacteria. The extracts from G. africanum and E. robusta were the most active with the lowest minimal inhibitory concentration of 64 µg/mL on Escherichia coli AG100A for both extracts and also against Klebsiella pneumoniae K24 for G. africanum. When tested in the presence of phenylalanine-arginine ß-Naphtylamide (PAßN), an efflux pump inhibitor, the extract of Thymus vulgaris and E. Robusta showed the best activities on most tested strains. E. Robusta extract showed good synergistic effects, improving the activity of commonly used antibiotics in about 85% of cases. CONCLUSION: The overall results obtained provide the baseline information for the use of the tested plants in the treatment of bacterial infections.

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

BACKGROUND: The present study was designed to investigate the antibacterial activities of the methanol extracts of four Cameroonian edible plants, locally used to treat microbial infections, and their synergistic effects with antibiotics against a panel of twenty nine Gram-negative bacteria including Multi-drug resistant (MDR) phenotypes expressing active efflux pumps. METHODS: The broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of the extracts [alone and in the presence of the efflux pumps inhibitor (EPI) Phenylalanine-Arginine ß-Naphtylamide (PAßN)], and those of antibiotics in association with the two of the most active ones, Piper nigrum and Telfairia occidentalis. The preliminary phytochemical screening of the extracts was conducted according to the standard phytochemical methods. RESULTS: Phytochemical analysis showed the presence of alkaloids and flavonoids in all studied extracts. Other chemical classes of secondary metabolites were selectively present in the extracts. The results of the MIC determination indicated that the crude extracts from P. nigrum and V. amygdalina were able to inhibit the growth of all the twenty nine studied bacteria within a concentration range of 32 to 1024 µg/mL. At a similar concentration range (32 to 1024 µg/mL) the extract from T. occidentalis inhibited the growth of 93.1% of the tested microorganisms. At MIC/2 and MIC/5, synergistic effects were noted between the extracts from P. nigrum and T. occidentalis and seven of the tested antibiotics on more than 70% of the tested bacteria. CONCLUSION: The overall results of the present study provide information for the possible use of the studied edible plants extracts in the control of bacterial infections including MDR phenotypes.

Antibacterial and antibiotic-potentiation activities of the methanol extract of some cameroonian spices against Gram-negative multi-drug resistant phenotypes.

BACKGROUND: The present work was designed to evaluate the antibacterial properties of the methanol extracts of eleven selected Cameroonian spices on multi-drug resistant bacteria (MDR), and their ability to potentiate the effect of some common antibiotics used in therapy. RESULTS: The extract of Cinnamomum zeylanicum against Escherichia coli ATCC 8739 and AG100 strains showed the best activities, with the lowest minimal inhibitory concentration (MIC) of 64 µg/ml. The extract of Dorstenia psilurus was the most active when tested in the presence of an efflux pump inhibitor, phenylalanine Arginine-ß- Naphtylamide (PAßN), a synergistic effect being observed in 56.25 % of the tested bacteria when it was combined with erythromycin (ERY). CONCLUSION: The present work evidently provides information on the role of some Cameroonian spices in the fight against multi-resistant bacteria.

Cytotoxicity and antimicrobial activity of the methanol extract and compounds from Polygonum limbatum.

The present study was designed to investigate the antimicrobial activity and the cytotoxicity of the methanol extract (PLA) as well as fractions (PLA1-4) and compounds [cardamomin (1), (±)-polygohomoisoflavanone (2), (S)-(-)-pinostrobin (3), 2',4'-dihydroxy-3',6'-dimethoxychalcone (4), (2S)-(-)-5-hydroxy-6,7-dimethoxyflavanone (5), and (2S)-(-)-5,7-dimethoxyflavanone (6)] obtained from leaves of Polygonum limbatum. The microbroth dilution was used to determine the minimal inhibitory concentration (MIC) of the samples against 11 microbial strains including Candida albicans, C. krusei, C. tropicalis, Aspergillus fumigatus, Pseudomonas aeruginosa, Escherichia coli, vancomycin-resistant Enterococcus faecalis (VRE), Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), S.epidermidis, and Mycobacterium tuberculosis H37Rv. The sulphorhodamine B cell growth inhibition assay was used to assess the cytotoxicity of the above samples on lung A549 adenocarcinoma, breast carcinoma MCF-7, prostate carcinoma PC-3, cervical carcinoma HeLa, and the acute monocytic leukemia cell line THP-1. The results of the MIC determination indicated that, apart from fraction PLA3, all other fractions as well as PLA and compound 3 were selectively active. MIC values were noted on 100 % of the 11 tested microorganisms for fraction PLA3, 72.7 % for PLA, fraction PLA2, and compound 4, 63.6 % for PLA1, and 54.5 % for fraction PLA4. The results of the cytotoxicity assay revealed that, except for A459 cells, more than 50 % inhibition of the proliferation was obtained with each of the tested samples on at least one of the four other cell lines. IC50 values below 4 µg/mL were obtained with 1 and 4 on THP-1 cells. The overall results of the present study provided baseline information for the possible use of Polygonum limbatum as well as some of the isolated compounds for the control of cancer diseases and mostly leukemia.

Antibacterial Activities of Selected Cameroonian Plants and Their Synergistic Effects with Antibiotics against Bacteria Expressing MDR Phenotypes.

The present work was designed to assess the antibacterial properties of the methanol extracts of some Cameroonian medicinal plants and the effect of their associations with currently used antibiotics on multidrug resistant (MDR) Gram-negative bacteria overexpressing active efflux pumps. The antibacterial activities of twelve methanol extracts of medicinal plants were evaluated using broth microdilution. The results of this test showed that three extracts Garcinia lucida with the minimal inhibitory concentrations (MIC) varying from 128 to 512 µg/mL, Garcinia kola (MIC of 256 to 1024 µg/mL), and Picralima nitida (MIC of 128 to 1024 µg/mL) were active on all the twenty-nine studied bacteria including MDR phenotypes. The association of phenylalanine arginine ß-naphthylamide (PAßN or efflux pumps inhibitor) to different extracts did not modify their activities. At the concentration of MIC/2 and MIC/5, the extracts of P. nitida and G. kola improved the antibacterial activities of some commonly used antibiotics suggesting their synergistic effects with the tested antibiotics. The results of this study suggest that the tested plant extracts and mostly those from P. nitida, G. lucida and G. kola could be used alone or in association with common antibiotics in the fight of bacterial infections involving MDR strains.

Antimicrobial activities of the methanol extract and compounds from Artocarpus communis (Moraceae).

BACKGROUND: Artocarpus communis is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antimicrobial activities of the methanol extract (ACB) and compounds isolated from the bark of this plant, namely peruvianursenyl acetate C (1), α-amyrenol or viminalol (2), artonin E (4) and 2-[(3,5-dihydroxy)-(Z)-4-(3-methylbut-1-enyl)phenyl]benzofuran-6-ol (5). METHODS: The liquid microdilution assay was used in the determination of the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC), against seven bacterial and one fungal species. RESULTS: The MIC results indicated that ACB as well as compounds 4 and 5 were able to prevent the growth of all tested microbial species. All other compounds showed selective activities. The lowest MIC value of 64 µg/ml for the crude extract was recorded on Staphylococcus aureus ATCC 25922 and Escherichia coli ATCC 8739. The corresponding value of 32 µg/ml was recorded with compounds 4 and 5 on Pseudomonas aeruginosa PA01 and compound 5 on E. coli ATCC 8739, their inhibition effect on P. aeruginosa PA01 being more than that of chloramphenicol used as reference antibiotic. CONCLUSION: The overall results of this study provided supportive data for the use of A. communis as well as some of its constituents for the treatment of infections associated with the studied microorganisms.