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1.  Okundoperoxide, A Bicyclic Cyclofarnesylsesquiterpene Endoperoxide from Scleria striatinux with Antiplasmodial Activity 
Journal of natural products  2009;72(2):280-283.
Okundoperoxide (1) was isolated by bioassay-guided fractionation of extracts from Scleria striatinux (syn. S. striatonux) (Cyperaceae). The compound contains a cyclic endoperoxide structural moiety and possesses moderate antimalarial activity.
PMCID: PMC2765531  PMID: 19199815
2.  Antibacterial activities of Beilschmiedia obscura and six other Cameroonian medicinal plants against multi-drug resistant Gram-negative phenotypes 
The rapid spread of bacteria expressing multi-drug resistance propels the search for new antibacterial agents. The present study was designed to evaluate the antibacterial activities of the methanol extracts from Beilschmiedia obscura and six other Cameroonian plants against a panel of twenty nine Gram-negative bacteria including Multi-drug resistant (MDR) phenotypes.
The phytochemical investigations of the extracts were carried out according to the standard methods and the liquid micro-dilution assay was used for all antibacterial assays.
Phytochemical analysis showed the presence of alkaloids in all studied extracts. Other chemical classes of secondary metabolites such as anthocyanines, anthraquinones flavonoids, saponins, tannins, sterols and triterpenes were selectively detected in the extracts. The extract from the fruits of Beilschmiedia obscura, Pachypodanthium staudtii leaves and Peperomia fernandopoiana (whole plant) displayed the best spectrum of activity with MIC values ranging from 16 to 1024 μg/mL against at least 65% and above of the tested bacteria. The extract from Beilschmiedia obscura was the most active with MIC values below 100 μg/mL against ten of the tested bacteria. This extract also showed MBC values below 1024 μg/mL against 55.17% of the studied microorganisms. Phenylalanine arginine β-naphthylamide (PAβN) significantly modulated the activities of extracts from the leaves and fruits of Pachypodanthium staudtii and Beilschmiedia obscura respectively, by increasing their inhibitory activity against Klebsiella pneumoniae KP55 strain at least four fold.
The overall results of the present investigation provide information for the possible use of the methanol extracts of the studied plant species, especially B. obscura to fight infectious diseases caused by Gram-negative bacteria including MDR phenotypes.
PMCID: PMC4223721  PMID: 25023038
Antibacterial activity; Beilschmiedia obscura; Gram-negative bacteria; Multi-drug resistance; Efflux pumps; Medicinal plants
3.  In vitro Antimicrobial Activity of Traditional Plant Used in Mestizo Shamanism from the Peruvian Amazon in Case of Infectious Diseases 
Pharmacognosy Magazine  2015;11(Suppl 4):S625-S633.
Our survey was performed near Iquitos (Peruvian Amazon) and its surroundings and leads us to consider Mestizo ethnomedical practices. The plant species reported here are traditionally used for ailments related to microbial infections. Inhabitants of various ethnic origins were interviewed, and 52 selected plants extracts were evaluated for their antimicrobial properties against a panel of 36 sensitive and multi-resistant bacteria or yeast. The study aimed at providing information on antimicrobial plant extract activities and the ethnomedical context of Mestizo riverine populations from Loreto (Peru).
Material and Method:
The minimum inhibitory concentrations (MICs) of the plant crude extracts were carried out using the agar dilution method and ranged between 0.075 and 5.0 mg/ml.
Of the 40 plants analyzed, 9 species showed MIC ≤0.3 mg/ml (Anacardium occidentale, Couroupita guianensis, Croton lechleri, Davilla rugosa, Erythrina amazonica, Jacaranda copaia subsp. Spectabilis, Oenocarpus bataua, Peperomia macrostachya, and Phyllanthus urinaria) for one or several of the 36 microorganisms and only 6 drug extracts were inactive. Among the 40 plants, 13 were evaluated for the first time for an antibacterial activity.
This evaluation of the antimicrobial activity of 40 plants using an approved standard methodology allowed comparing those activities against various microbes to establish antimicrobial spectra of standardized plant extracts, and give support to the traditional use of these plants. It may also help discovering new chemical classes of antimicrobial agents that could serve against multi-resistant bacteria.
This study leads us to consider Mestizo ethnomedical practices near Iquitos (Peruvian Amazon) and its surroundings. The plant species reported here are traditionally used for ailments related to microbial infections. 52 selected plants extracts were evaluated for their antimicrobial properties against a panel of 36 sensitive and multi resistant bacteria or yeast. The study aimed at providing information on antimicrobial plant extract activities and the ethnomedical context of Mestizo riverine populations from Loreto.
PMCID: PMC4787099  PMID: 27013805
Antimicrobial activity; Iquitos; Loreto; medicinal plant; traditional use
4.  Synergy of antibacterial and antioxidant activities from crude extracts and peptides of selected plant mixture 
A plant mixture containing indigenous Australian plants was examined for synergistic antimicrobial activity using selected test microorganisms. This study aims to investigate antibacterial activities, antioxidant potential and the content of phenolic compounds in aqueous, ethanolic and peptide extracts of plant mixture.
Well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were used to test antibacterial activity against four pathogenic bacteria namely Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa. DPPH (2, 2-diphenyl-1- picrylhydrazyl) and superoxide dismutase (SOD) assays were used to evaluate antioxidant activity. HPLC and gel filtration were used for purification of the peptides. Scanning electron microscope was applied to investigate the mode of attachment of the peptides on target microbial membranes.
Aqueous extraction of the mixture showed no inhibition zones against all the test bacteria. Mean diameter of inhibition zones for ethanol extraction of this mixture attained 8.33 mm, 7.33 mm, and 6.33 mm against S. aureus at corresponding concentrations of 500, 250 and 125 mg/ml while E .coli showed inhibition zones of 9.33 mm, 8.00 mm and 6.66 mm at the same concentrations. B. cereus exhibited inhibition zones of 11.33 mm, 10.33 mm and 10.00 mm at concentrations of 500, 250 and 125 mg/ml respectively. The peptide extract demonstrated antibacterial activity against S. aureus, E. coli and B. cereus. The MIC and MBC values for ethanol extracts were determined at 125 mg/ml concentration against S. aureus and E. coli and B. cereus value was 31.5 mg/ml. MIC and MBC values showed that the peptide extract was significantly effective at low concentration of the Australian plant mixture (APM). Phenolic compounds were detected in hot aqueous and ethanolic extracts of the plant mixture. Hot aqueous, ethanol and peptides extracts also exhibited antioxidant activities.
It was concluded that APM possessed good antibacterial and antioxidant activities following extraction with different solvents. The results suggest that APM provide a new source with antibacterial agents and antioxidant activity for nutraceutical or medical applications.
PMCID: PMC3866934  PMID: 24330547
Indigenous plants; Antibacterial properties; DPPH free radical activity; SOD assay; Pathogenic bacteria
5.  Antimicrobial Activities of a Plethora of Medicinal Plant Extracts and Hydrolates against Human Pathogens and Their Potential to Reverse Antibiotic Resistance 
Microbial infections till date remain a scourge of humanity due to lack of vaccine against some infections, emergence of drug resistant phenotypes, and the resurgence of infections amongst others. Continuous quest for novel therapeutic approaches remains imperative. Here we (i) assessed the effects of extracts/hydrolates of some medicinal plants on pathogenic microorganisms and (ii) evaluated the inhibitory potential of the most active ones in combination with antibiotics. Extract E03 had the highest DZI (25 mm). Extracts E05 and E06 were active against all microorganisms tested. The MICs and MBCs of the methanol extracts ranged from 16.667 × 103 μg/mL to 2 μg/mL and hydrolates from 0.028 to 333333 ppm. Extract E30 had the highest activity especially against S. saprophyticus (MIC of 6 ppm) and E. coli (MIC of 17 ppm). Combination with conventional antibiotics was shown to overcome resistance especially with E30. Analyses of the extracts revealed the presence of alkaloids, flavonoids, triterpenes, steroids, phenols, and saponins. These results justify the use of these plants in traditional medicine and the practice of supplementing decoctions/concoctions with conventional antibiotics. Nauclea pobeguinii (E30), the most active and synergistic of all these extracts, and some hydrolates with antimicrobial activity need further exploration for the development of novel antimicrobials.
PMCID: PMC4477429  PMID: 26180528
6.  In vitro antibacterial activity of selected medicinal plants traditionally used in Vietnam against human pathogenic bacteria 
Medicinal plants are widely used for the treatment of different infectious diseases. Infectious diseases caused by bacteria have a large impact on public health. This study aimed to determine the in vitro antibacterial activity of the medicinal plants traditionally used in Vietnam against the bacterial strains associated with infectious diseases.
Methanol extracts of twelve Vietnamese medicinal plants were tested for their antibacterial activity against five bacterial species including Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) using the broth microdilution method.
All the plant extracts showed antibacterial activity, especially against Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus). Baeckea frutescens extract revealed a potent activity against the Gram-positive bacteria with the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 62.5 μg/ml. High activity against all the three Gram-positive bacteria was also observed for the extracts of Cratoxylum formosum ssp. pruniflorum, Pogostemon cablin, and Pedilanthus tithymaloides with MICs of 125, 125 and 250 μg/ml and MBCs of 125–250, 125–250 and 250–500 μg/ml, respectively. The extracts of C. formosum ssp. pruniflorum and P. tithymaloides showed a broad-spectrum antibacterial activity against all the bacteria tested with the MICs of 125–2,000 μg/ml.
This study indicates clear evidence supporting the traditional use of the plants in treating infectious diseases related to bacteria. In particular, these plant species showed moderate to high antibacterial activity against the Gram-positive bacteria tested.
PMCID: PMC4728873  PMID: 26819218
Antibacterial activity; Infectious diseases; Bacterial infections; Medicinal plants; Vietnam
7.  In vitro antibacterial potency of Butea monosperma Lam. against 12 clinically isolated multidrug resistant bacteria 
To investigate the antibacterial activity, using cold and hot extraction procedures with five solvents, petroleum ether, acetone, ethanol, methanol and water to validate medicinal uses of Butea monosperma Lam (B. monosperma) in controlling infections; and to qualitatively estimate phytochemical constituents of leaf-extracts of the plant.
The antibacterial activity of leaf-extracts was evaluated by the agar-well diffusion method against clinically isolated 12 Gram-positive and -negative multidrug resistant (MDR) pathogenic bacteria in vitro. Values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of leaf-extracts against each bacterium were obtained in a 96-well micro-titre plate, by broth dilution micro-titre plate technique.
The presence of tannins, flavonoids, starch, glycosides and carbohydrates in different leaf extracts was established. Pathogenic bacteria used were, Acinetobacter sp., Chromobacterium violaceum, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella sp., Enterococcus sp., Staphylococcus aureus (S. aureus), methicillin resistant S. aureus and vancomycin resistant S. aureus, along with standard bacterial strains. These MDR bacteria had been recorded to have significant inhibitions by leaf extracts, obtained by cold and hot extraction procedures with five solvents. In addition, the hot aqueous extract against Enterococcus sp. had the highest inhibition zone-size (21 mm). Ciprofloxacin 30 µg/disc was the positive/reference control and the diluting solvent, 10% dimethyl sulphoxide was the negative control. Recorded MIC values of different extracts ranged between 0.23 and 13.30 mg/mL, and MBC values were 0.52 to 30.00 mg/mL, for these bacteria.
Leaf-extracts with hot water and ethanol had shown significant antibacterial activity against all bacteria. B. monosperma leaf-extract could be used in treating infectious diseases, caused by the range of tested bacteria, as complementary and alternate medicine.
PMCID: PMC4027298
Butea monosperma; Gram-positive bacteria; Gram-negative bacteria; Multidrug resistant bacteria; Minimum inhibitory concentration; Antibacterial activity; Phytochemical constituents
8.  The Antibacterial Activity of Cassia fistula Organic Extracts 
Cassia fistula, is a flowering plant and a member of Fabaceae family. Its leaves are compound of 4 - 8 pairs of opposite leaflets. There are many Cassia species around the world which are used in herbal medicine.
This study was designed to examine in vitro anti-bacterial activity of methanolic and ethanolic extracts of C. fistula native to Khuzestan, Iran.
Materials and Methods:
The microbial inhibitory effect of methanolic and ethanolic extracts of C. fistula was tested on 3 Gram positive: Bacillus cereus, Staphylococcus aureus and S. epidermidis and 5 Gram negative: Salmonella Typhi, Kelebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis bacterial species using disc diffusion method at various concentrations. The minimum inhibitory and bactericidal concentrations (MIC and MBC) were measured by the tube dilution assay.
The extract of C. fistula was effective against B. cereus, S. aureus, S. epidermidis, E. coli and K. pneumoniae. The most susceptible microorganisms to ethanolic and methanolic extracts were E. coli and K. pneumoniae, respectively. Also B. cereus and S. aureus showed the least sensitivity to ethanolic and methanolic extracts, respectively. The MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of ethanolic extracts against S. aureus, E. coli, S. epidermidis and K. pneumoniae were also determined.
With respect to the obtained results and regarding to the daily increase of the resistant microbial strains to the commercial antibiotics, it can be concluded that these extracts can be proper candidates of antibacterial substance against pathogenic bacterial species especially S. aureus, E. coli, K. pneumoniae and S. epidermidis.
PMCID: PMC4138669  PMID: 25147664
Cassia fistula; Anti-bacterial Activity; Disc Diffusion Antibacterial Test; Minimum Inhibitory Concentration; Minimum Bactericidal Concentration
9.  Investigation of the possible biological activities of a poisonous South African plant; Hyaenanche globosa (Euphorbiaceae) 
Pharmacognosy Magazine  2010;6(21):34-41.
The present study was undertaken to explore the possible biochemical activities of Hyaenanche globosa Lamb. and its compounds. Two different extracts (ethanol and dichloromethane) of four different parts (leaves, root, stem, and fruits) of H. globosa were evaluated for their possible antibacterial, antityrosinase, and anticancer (cytotoxicity) properties. Two pure compounds were isolated using column chromatographic techniques. Active extracts and pure compounds were investigated for their antioxidant effect on cultured ‘Hela cells’. Antioxidant/oxidative properties of the ethanolic extract of the fruits of H. globosa and purified compounds were investigated using reactive oxygen species (ROS), ferric-reducing antioxidant power (FRAP), and lipid peroxidation thiobarbituric acid reactive substance (TBARS) assays. The ethanolic extract of the leaves and fruits of H. globosa showed the best activity, exhibiting a minimum inhibitory concentration (MIC) of 3.1 mg/ ml and a minimum bactericidal concentration (MBC) of 1.56 and 6.2 mg/ml, respectively, against M. smegmatis. The ethanolic extract of the fruits of H. globosa (F.E) showed the highest percentage of inhibitory activity of monophenolase (90.4% at 200 μg/ml). In addition, F.E exhibited 50% inhibitory concentration (IC50) of 37.7 μg/ml on the viability of ‘HeLa cells’ using cytotoxicity MTT assay. Subsequently, F.E was fractionated using phase-partitioning with n-hexane, ethyl acetate, and n-butanol. The cytotoxicity of these fractions were determined in vitro using different cancer cell lines. The n-hexane fraction exhibited the highest activity of toxicity. Therefore, this fraction was subjected to further separation by chromatographic methods. Two pure compounds known as: ‘Tutin’ and ‘hyenanchin’ were isolated and their structures were determined by NMR spectroscopic methods. Unpredictably, none of them showed significant (P < 0.01) inhibition on cell viability/proliferation at the concentrations that were used. F.E showed significant anti-tyrosinase, antibacterial, and cytotoxicity effects, therefore it can be considered as an effective inhibitor alone or in combination with other plant extracts.
PMCID: PMC2881645  PMID: 20548934
Hyenanche globosa; hyenanchin; tutin; cytotoxicity; antibacterial assay; antioxidant assay; reactive oxygen species
10.  Natural compounds isolated from Brazilian plants are potent inhibitors of hepatitis C virus replication in vitro 
Antiviral Research  2015;115:39-47.
•Antiviral effects of 20 Brazilian natural compounds were investigated.•Four compounds with potent inhibitory activity on HCV replication were identified.•Antiviral activity was independent of HCV genotype.•Antiviral effect was not affected by variants described to confer resistance.•One of the four compounds inhibited HCV IRES-mediated translation.
Compounds extracted from plants can provide an alternative approach to new therapies. They present characteristics such as high chemical diversity, lower cost of production and milder or inexistent side effects compared with conventional treatment. The Brazilian flora represents a vast, largely untapped, resource of potential antiviral compounds. In this study, we investigate the antiviral effects of a panel of natural compounds isolated from Brazilian plants species on hepatitis C virus (HCV) genome replication. To do this we used firefly luciferase-based HCV sub-genomic replicons of genotypes 2a (JFH-1), 1b and 3a and the compounds were assessed for their effects on both HCV replication and cellular toxicity. Initial screening of compounds was performed using the maximum non-toxic concentration and 4 compounds that exhibited a useful therapeutic index (favourable ratio of cytotoxicity to antiviral potency) were selected for extra analysis. The compounds APS (EC50 = 2.3 μM), a natural alkaloid isolated from Maytrenus ilicifolia, and the lignans 3∗43 (EC50 = 4.0 μM), 3∗20 (EC50 = 8.2 μM) and 5∗362 (EC50 = 38.9 μM) from Peperomia blanda dramatically inhibited HCV replication as judged by reductions in luciferase activity and HCV protein expression in both the subgenomic and infectious systems. We further show that these compounds are active against a daclatasvir resistance mutant subgenomic replicon. Consistent with inhibition of genome replication, production of infectious JFH-1 virus was significantly reduced by all 4 compounds. These data are the first description of Brazilian natural compounds possessing anti-HCV activity and further analyses are being performed in order to investigate the mode of action of those compounds.
PMCID: PMC4329992  PMID: 25557602
Brazilian plants; Natural compounds; Antiviral; Hepatitis C virus; Replication
11.  Alkanna tinctoria leaves extracts: a prospective remedy against multidrug resistant human pathogenic bacteria 
Plants are rich source of chemical compounds that are used to accomplish biological activity. Indigenously crude extracts of plants are widely used as herbal medicine for the treatment of infections by people of different ethnic groups. The present investigation was carried out to evaluate the biological potential of Alkanna tinctoria leaves extract from district Charsadda, Pakistan against multidrug resistant human pathogenic bacteria including Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.
Anti-multi-drug resistant bacterial activity of aqueous, chloroform, ethanol and hexane extracts of Alkanna tinctoria leaves were evaluated by well diffusion method. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of different extracts were determined. Moreover qualitative phytochemicals screening of the studied extracts was performed.
All four selected bacteria including A. baumannii, E. coli, P. aeruginosa and S. aureus were categorized as multi-drug resistant (MDR) as they were found to be resistant to 13, 10, 19 and 22 antibiotics belonging to different groups respectively. All the four extract showed potential activity against S. aureus as compare to positive control antibiotic (Imipenem). Similarly among the four extracts of Alkanna tinctoria leaves, aqueous extract showed best activity against A. baumannii (10 ± 03 mm), P. aeruginosa (12 ± 0.5 mm), and S. aureus (14 ± 0.5 mm) as compare to Imipenem. The MICs and MBCs results also showed quantitative concentration of plant extracts to inhibit or kill MDR bacteria. When phytochemicals analysis was performed it was observed that aqueous and ethanol extracts showed phytochemicals with large number as well as volume, especially Alkaloides, Flavonoides and Charbohydrates.
The undertaken study demonstrated that all the four extracts of Alkanna tinctoria leaves exhibited considerable antibacterial activity against MDR isolates. Finding from the current study will be helpful for further elucidation of lead molecules from Alkanna tinctoria leaves for future therapeutic use against MDR pathogens.
PMCID: PMC4410581  PMID: 25902854
Alkanna tinctoria leaves extracts; Anti-MDR bacterial activity; MICs and MBCs; Phytochemicals analysis
12.  Antimicrobial Activity and Phytochemical Study of Vernonia Glabra (Steetz) Oliv. & Hiern. in Kenya 
Infectious diseases are prevalent and life threatening in Kenya. Majority of the sick are seeking herbal remedies in search of effective, safe, and affordable cure. This project aims to investigate the antimicrobial activity and presence of active phytochemical compounds in different parts of Vernonia glabra; a plant used by herbalists in various regions of Kenya, for the treatment of gastrointestinal problems. The plant sample was collected in January 2010 in Machakos, and different parts dried at room temperature under shade, ground into powder and extracted in Dichloromethane: Methanol in the ratio 1:1, and water. These crude extracts were tested against Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger for antimicrobial activity using disc diffusion technique. Minimum inhibitory concentrations (MICs) for active crude extracts were done using disc diffusion technique after the failure of agar and broth dilution methods. It was observed that the organic crude extracts of flower, leaf, stem, root, and/or entire plant, showed activity against at least one of the four micro-organisms screened, and at concentrations lower than the aqueous crude extracts. Organic crude extract of the leaf showed the highest activity against Staphylococcus aureus (mean inhibition zone of 1.85), recording higher activity than the commercially used standard antibiotic (Streptomycin mean inhibition zone of 1.30). The organic crude extract of flower showed significant activity only against S. aureus, with the lowest MIC of 1.5625 mg/100µl, compared to streptomycin with M.I.C of 6.25 mg/100µl. Thin Layer Chromatography-Bioautography Agar-Overlay showed that, flower alkaloids (50% active), root sapogenins (43.8% active), and root terpenoids (38.5% active) were identified as the potential antibacterial compounds against S. aureus. These results suggest that, V. glabra contains phytochemicals of medicinal properties and justify the use of V. glabra in traditional herbal medicine for the treatment of microbial based diseases. However, research on toxicity which is missing in this study is recommended for V. glabra in order to verify, validate and document the safety of this medicinal plant to the society.
PMCID: PMC3746369  PMID: 24082337
Vernonia glabra; Antimicrobial activity; Phytochemicals
13.  Phytochemistry and Preliminary Assessment of the Antibacterial Activity of Chloroform Extract of Amburana cearensis (Allemão) A.C. Sm. against Klebsiella pneumoniae Carbapenemase-Producing Strains 
The chloroform extract of the stem bark of Amburana cearensis was chemically characterized and tested for antibacterial activity.The extract was analyzed by gas chromatography and mass spectrometry. The main compounds identified were 4-methoxy-3-methylphenol (76.7%), triciclene (3.9%), α-pinene (1.0%), β-pinene (2.2%), and 4-hydroxybenzoic acid (3.1%). Preliminary antibacterial tests were carried out against species of distinct morphophysiological characteristics: Escherichia coli, Salmonella enterica Serotype Typhimurium, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus. The minimum inhibitory concentration (MIC) was determinate in 96-well microplates for the chloroform extract and an analogue of themain compound identified, which was purchased commercially.We have shown that plant's extract was only inhibitory (but not bactericidal) at the maximum concentration of 6900 μg/mL against Pseudomonas aeruginosa and Bacillus cereus. Conversely, the analogue 2-methoxy-4-methylphenol produced MICs ranging from215 to 431 μg/mL against all bacterial species.New antibacterial assays conducted with such chemical compound against Klebsiella pneumoniae carbapenemase-producing strains have shown similarMICresults and minimumbactericidal concentration (MBC) of 431 μg/mL.We conclude that A. cearensis is a good source of methoxy-methylphenol compounds,which could be screened for antibacterial activity againstmultiresistant bacteria fromdifferent species
PMCID: PMC3977124  PMID: 24772183
14.  Activity of Aristolochia bracteolata against Moraxella catarrhalis 
A bioassay-guided fractionation of methanol extract of Aristolochia bracteolata whole plant was carried out in order to evaluate its antimicrobial activity and to identify the active compounds in this extract. Antibacterial and antifungal activities of methanol extract against gram-positive, gram-negative, and fungal strains were investigated by the agar disk diffusion method. Among the strains tested, Moraxella catarrhalis and sea urchin-derived Bacillus sp. showed the highest sensitivity towards the methanol extract and hence they are used as test organisms for the bioassay-guided fractionation. From this extract, aristolochic acid 1 (AA-1) has been isolated and has showed the greatest antibacterial activity against both standard strain and clinical isolates of Moraxella catarrhalis with equal minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 25 and 50 μg/mL. Modification of the AA-1 to AA-1 methyl ester completely abolished the antibacterial activity of the compound and the piperonylic acid moiety of AA-1 which suggested that the coexistence of phenanthrene ring and free carboxylic acid is essential for AA-1 antibacterial activity.
PMCID: PMC4745564  PMID: 26904734
15.  Evaluation of Antimicrobial Activity of the Methanol Extracts from 8 Traditional Medicinal Plants 
Toxicological Research  2011;27(1):31-36.
The methanol extract of 12 medicinal plants were evaluated for its antibacterial activity against Gram-positive (5 strains) and Gram-negative bacteria (10 strains) by assay for minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) . The antibacterial activity was determined by an agar dilution method (according to the guidelines of Clinical and Laboratory Standard Institute) . All the compounds (12 extracts) of the 8 medicinal plants (leaf or root) were active against both Gram-negative and Gram-positive bacteria. Gram-negative showed a more potent action than Gram positive bacteria. The MIC concentrations were various ranged from 0.6 μg/ml to 5000 μg/ml. The lowest MIC (0.6 μg/ml) and MBC (1.22 μg/ml) values were obtained with extract on 4 and 3 of the 15 microorganisms tested, respectively.
PMCID: PMC3834511  PMID: 24278548
Antimicrobial activity; traditional medicinal plants; minimum inhibitory concentration (MIC) ; minimum bacterial concentration (MBC) ; methanol extract; agar dilution method .
16.  Antibacterial constituents of three Cameroonian medicinal plants: Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis 
Multidrug resistance is a worrying cause of treatment failure in bacterial infections. The search of bioactive constituents from medicinal plants against multidrug resistant (MDR) bacteria has significantly evolved in the two last decades. In the present study, twenty-two compounds (three terpenoids, eleven phenolics and eight alkaloids) isolated from three Cameroonian medicinal plants, namely Garcinia nobilis, Oricia suaveolens and Balsamocitrus camerunensis, as well as the crude extracts were tested for their antibacterial activities against Mycobacterium tuberculosis and Gram-negative bacteria amongst which were MDR active efflux pumps expressing phenotypes.
The microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of the studied samples.
The results of the MIC determinations indicate that, the best crude extract was that from G. nobilis (GNB), its inhibitory effects being noted against 12 of the 14 tested bacteria. The extract of GNB also exhibited better anti-tuberculosis (MIC of 128 μg/ml M. tuberculosis against ATCC 27294 strain) and antibacterial (MIC of 64 μg/ml against Escherichia coli ATCC10536) activities compared to the extracts of O. suaveolens and B. camerunensis. Interestingly, 4-prenyl-2-(3,7-dimethyl-2,6-octadienyl)-1,3,5,8-tetrahydroxyxanthone (2), isolated from the most active extract GNB, also showed the best activity amongst compounds, inhibiting the growth of all the fourteen tested microorganisms. The lowest MIC value obtained with compound 2 was 8 μg/ml against M. tuberculosis ATCC 27294 and M. tuberculosis clinical MTCS2 strains. Other compounds showed selective activities with 11 of the 14 tested bacteria being sensitive to the xanthone, morusignin I (5) and the alkaloid, kokusaginine (13).
The results of the present investigation provide evidence that the crude extract from G. nobilis, O. suaveolens and B. camerunensis as well as some of their compounds, and mostly compound 2 (isolated from G. nobilis,) could be considered as interesting natural antibacterial products.
PMCID: PMC3637112  PMID: 23574627
Antimycobacterial; Antibacterial; Cameroon; Compounds; Garcinia nobilis; Oricia suaveolens; Balsamocitrus camerunensis
17.  Divergent Chemical Cues Elicit Seed Collecting by Ants in an Obligate Multi-Species Mutualism in Lowland Amazonia 
PLoS ONE  2010;5(12):e15822.
In lowland Amazonian rainforests, specific ants collect seeds of several plant species and cultivate them in arboreal carton nests, forming species-specific symbioses called ant-gardens (AGs). In this obligate mutualism, ants depend on the plants for nest stability and the plants depend on ant nests for substrate and nutrients. AG ants and plants are abundant, dominant members of lowland Amazonian ecosystems, but the cues ants use to recognize the seeds are poorly understood. To address the chemical basis of the ant-seed interaction, we surveyed seed chemistry in nine AG species and eight non-AG congeners. We detected seven phenolic and terpenoid volatiles common to seeds of all or most of the AG species, but a blend of the shared compounds was not attractive to the AG ant Camponotus femoratus. We also analyzed seeds of three AG species (Anthurium gracile, Codonanthe uleana, and Peperomia macrostachya) using behavior-guided fractionation. At least one chromatographic fraction of each seed extract elicited retrieval behavior in C. femoratus, but the active fractions of the three plant species differed in polarity and chemical composition, indicating that shared compounds alone did not explain seed-carrying behavior. We suggest that the various AG seed species must elicit seed-carrying with different chemical cues.
PMCID: PMC3012710  PMID: 21209898
18.  Introducing Urtica dioica, A Native Plant of Khuzestan, As an Antibacterial Medicinal Plant 
Urtica dioica is a flowering plant with long history of use in folk medicine and as a food source.
This study examined in vitro antibacterial potential of alcoholic extracts of U. dioica.
Materials and Methods:
Hydroalcoholic extracts from aerial parts were prepared using aqueous solution of ethanol and methanol and their inhibitory effects against clinical isolates was examined by disc diffusion method at different doses. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) indexes were also investigated. The scanning electron microscopy (SEM) analysis was also performed to find structural changes of affected bacteria consequent to exposing with extracts.
Both extracts were active against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli with respectively 16, 10, 18, and 14 mm (methanolic) and 11, 9, 17, and 16 mm (ethanolic) inhibition zone. The MIC of ethanolic extract against S. epidermidis and E. coli was respectively 10 and 40 mg/mL. The MIC of methanolic extract against S. aureus and S. epidermidis was 40 and 10 mg/mL, respectively. The MBC was found only for S. epidermidis (20 mg/mL). In SEM analysis the round shape of S. epidermidis was changed and irregular shapes were appeared, which suggest that the main target of these extracts was cell wall.
Extracts of U. dioica showed significant antibacterial effect against some clinically important pathogenic bacteria. Based on the obtained results it can be concluded that U. dioica is useful as antibacterial and bactericidal agent in treating infectious diseases.
PMCID: PMC4302403  PMID: 25625045
Urtica dioica; Medicinal Plant; Antibacterial Agent; Natural Product; Phytotherapy
19.  Antibacterial Activity of a Cardanol from Thai Apis mellifera Propolis 
Background: Propolis is a sticky, dark brown resinous residue made by bees that is derived from plant resins. It is used to construct and repair the nest, and in addition possesses several diverse bioactivities. Here, propolis from Apis mellifera from Nan province, Thailand, was tested for antibacterial activity against Gram+ve (Staphylococcus aureus and Paenibacillus larvae) and Gram-ve (Escherichia coli) bacteria.
Materials and methods: The three bacterial isolates were confirmed for species designation by Gram staining and analysis of the partial sequence of 16S rDNA. Propolis was sequentially extracted by methanol, dichloromethane and hexane. The antibacterial activity was determined by agar well diffusion and microbroth dilution assays using streptomycin as a positive control. The most active crude extract was further purified by quick column and adsorption chromatography. The apparent purity of each bioactive fraction was tested by thin layer chromatography. The chemical structure of the isolated bioactive compound was analyzed by nuclear magnetic resonance (NMR).
Results: Crude methanol extract of propolis showed the best antibacterial activity with a minimum inhibition concentration (MIC) value of 5 mg/mL for S. aureus and E. coli and 6.25 mg/mL for P. larvae. After quick column chromatography, only three active fractions were inhibitory to the growth of S. aureus and E. coli with MIC values of 6.25 and 31.3 µg/mL, respectively. Further adsorption chromatography yielded one pure bioactive fraction (A1A) with an IC50 value of 0.175 µg/mL for E. coli and 0.683 µg/mL for P. larvae, and was determined to be cardanol by NMR analysis. Scanning and transmission electron microscopy analysis revealed unusual shaped (especially in dividing cells), damaged and dead cells in cardanol-treated E. coli.
Conclusion: Thai propolis contains a promising antibacterial agent.
PMCID: PMC3936026  PMID: 24578609
Antibacterial activity; Apis mellifera; Cardanol; Propolis; Nan province; Pathogen.
20.  In vitro control of Staphylococcus aureus (NCTC 6571) and Escherichia coli (ATCC 25922) by Ricinus communis L. 
To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L (R. communis) against Staphylococcus aureus (S. aureus) (NCTC 6571) and Escherichia coli (E. coli) (ATCC 25922).
Leaf powder of R. communis L. was extracted with hot (in Soxhlet) and cold ethanol and methanol, separately. The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods. The extracts were also subjected to phytochemical analysis.
All the four test extracts showed inhibition on both S. aureus and E. coli. Hot and cold ethanol extracts revealed significantly (P<0.05) higher inhibition on S. aureus than methanol extracts, and the hot ethanol extract had the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values (5 mg/mL and 10 mg/mL, respectively). E. coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL, respectively. Phytochemical analysis revealed the presence of saponins, cardiac glycosides, tannins, flavonoids and terpenoids in all test extracts.
This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S. aureus and E. coli. Especially, the hot and cold extracts of ethanol are more inhibitive against S. aureus even at lower concentration. Further study is needed to identify the specific bioactive compounds, their mode of action and their nontoxic nature in vivo condition.
PMCID: PMC3609375  PMID: 23570001
Ricinus communis; Antibacterial activity; Staphylococcus aureus; Escherichia coli; Extract; Minimum inhibitory concentration; Minimum bactericidal concentration
21.  Antibacterial, antibiofilm and cytotoxic activities of Terminalia fagifolia Mart. extract and fractions 
The methicillin resistance of bacteria from the genus Staphylococcus and its ability to form biofilms are important factors in pathogenesis of these microorganisms. Thus, the search for new antimicrobials agents, especially from plants, has been intensified. In this context, Terminalia species have been the subject of research for many pharmacological activities. In this study we evaluated the antibacterial, antibiofilm and cytotoxic activities of the ethanol extract (EtE) from Terminalia fagifolia stem bark as well as that of three fractions of the extract (AqF, HaF and WSF).
We determined the minimum inhibitory concentration (MIC) by microdilution in 96-well plates, where the strains were exposed to serial dilutions of the ethanol extract and fractions, ranging from 12.5 to 400 μg/mL. We then determined the minimum bactericidal concentration (MBC), seeding the inoculum (10 μL) with concentrations equal to or greater than the MIC in Mueller-Hinton agar. To test the antibiofilm activity biofilm formation was induced in the presence of concentrations equivalent to 1/2, 1/4 and 1/8 of the MIC extract or fraction tested. In addition, the effect of the EtE and the fractions on cell viability was tested by the MTT assay on human MCF-7 breast cancer and mouse fibroblast NIH/3T3. To obtain high-resolution images of the effect of the aqueous fraction on the bacterial morphology, atomic force microscopy (AFM) imaging of treated S. aureus cells was performed.
We observed antibacterial activity of EtE and fractions with MICs ranging from 25–200 μg/mL and MBCs ranging from 200–400 μg/mL. Regarding antibiofilm activity, both the EtE as the AqF, HaF and WSF fractions showed significant inhibition of the biofilm formation, with inhibition of biofilms formation of over 80% for some strains. The EtE and fractions showed a moderate cytotoxicity in cell line NIH/3T3 viability and potential antitumoral activity on human breast cancer cell line MCF-7. The microscopic images obtained revealed morphological changes to the S. aureus ATCC 29213 surface caused by AqF, as well as significant size alterations.
The results show potential antibacterial, antibiofilm and antitumoral activities of the ethanol extract and fractions of T. fagifolia.
PMCID: PMC4406121  PMID: 25902872
Terminalia; Staphylococcus; Antibacterial; Antibiofilm; Cytotoxicity
22.  Anti-nociceptive properties in rodents and the possibility of using polyphenol-rich fractions from sida urens L. (Malvaceae) against of dental caries bacteria 
Sida urens L. (Malvaceae) is in flora of Asian medicinal herbs and used traditionally in West of Burkina Faso for the treatment of infectious diseases and particularly used against, dental caries bacteria, fever, pain and possesses analgesic properties. This study was conducted to reveal the antibacterial effect against dental caries bacteria on the one hand, and evaluate their analgesic capacity in experimental model with Swiss mice and on the other hand, with an aim to provide a scientific basis for the traditional use of this plant for the management of dental caries bacteria.
The antibacterial assays in this study were performed by using inhibition zone diameters, MIC (Minimum inhibitory concentration) and MBC (Minimal bactericidal concentration) methods. On the whole the dental caries bacteria (Gram-positive and Gram-negative bacterial strains) were used. Negative control was prepared using discs impregnated with 10% DMSO in water and commercially available Gentamicin from Alkom Laboratories LTD was used as positive reference standards for all bacterial strains. In acute toxicity test, mice received doses of extract (acetone/water extract) from Sida urens L. by intraperitoneal route and LD50 was determined in Swiss mice. As for analgesic effects, acetic acid writhing method was used in mice. The acetic acid-induced writhing method was used in mice with aim to study analgesic effects.
The results showed that the highest antibacterial activities were founded with the polyphenol-rich fractions against all bacterial strains compared to the standard antibiotic. About preliminary study in acute toxicity test, LD50 value obtained was more than 5000 mg/kg b.w. Polyphenol-rich fractions produced significant analgesic effects in acetic acid-induced writhing method and in a dose-dependent inhibition was observed.
These results validate the ethno-botanical use of Sida urens L. (Malvaceae) and demonstrate the potential of this herbaceous as a potential antibacterial agent of dental caries that could be effectively used for future health care purposes.
PMCID: PMC3699430  PMID: 23787152
23.  Antimicrobial Constituents of the Leaves of Mikania micrantha H. B. K 
PLoS ONE  2013;8(10):e76725.
To isolate plant-derived compounds with antimicrobial activity from the leaves of Mikania micrantha, to determine the compounds configuration, and to evaluate their antimicrobial activity against eight plant pathogenic fungi (Exserohilum turcicum, Colletotrichum lagenarium, Pseudoperonispora cubensis, Botrytis cirerea, Rhizoctonia solani, Phytophthora parasitica, Fusarium solani, and Pythium aphanidermatum,) and four plant pathogenic bacteria (gram negative bacteria: Ralstonia dolaanacearum, Xanthomonas oryzae pv. Oryzae, Xanthomonas Campestris pv. Vesicatoria, and Xanthomonas campestris pv. Citri), and four bacteria (gram positive bacteria: Staphyloccocus aureus, Bacillus subtilis, Micrococcus luteus, and Bacillus cereus).
Methods and Results
Antimicrobial constituents of the leaves of M. micrantha were isolated using bioactivity- guided fractionation. The antifungal activity of the isolated compounds was evaluated by the inhibit hypha growth method and inhibit spore germination method. Characterization of antibacterial activity was carried out using the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs). MIC and MBC were determined by the broth microdilution method. Six compounds – deoxymikanolide, scandenolide, dihydroscandenolide, mikanolide, dihydromikanolide, and m - methoxy benzoic acid – have been isolated from leaves of Mikania micrantha H. B. K. Deoxymikanolide, scandenolide, and dihydroscandenolide were new compounds. The result of bioassay showed that all of isolated compounds were effective against tested strains and deoxymikanolide showed the strongest activity.
Conclusions and Significance
The leaves of M. micrantha may be a promising source in the search for new antimicrobial drugs due to its efficacy and the broadest range. Meanwhile, adverse impact of M. micrantha will be eliminated.
PMCID: PMC3788719  PMID: 24098556
24.  Host Plant Associations and Parasitism of South Ecuadorian Eois Species (Lepidoptera: Geometridae) Feeding on Peperomia (Piperaceae) 
Journal of Insect Science  2015;15(1):119.
The very species-rich tropical moth genus Eois Hübner (Lepidoptera: Geometridae) is a promising model group for studying host plant specialization and adaptive radiation. While most Eois species are assumed to be specialized herbivores on Piper L. species, records on other plant taxa such as Peperomia Ruiz & Pavón (Piperaceae) are still relatively scarce. Moreover, little is known about life history traits of most species, and only a few caterpillars have been described so far. We collected caterpillars associated with Peperomia (Piperaceae) host plants from June 2012 to January 2013 in three elevational bands of montane and elfin rainforests on the eastern slopes of the Andes in southern Ecuador. Caterpillars were systematically searched and reared to the adult stage. We were able to delimitate ten species of Eois on Peperomia by comparison of larval and adult morphology and by using 658 bp fragments of the mitochondrial COI gene (barcode sequences). Three of these species, Eois albosignata (Dognin), Eois bolana (Dognin), and Eois chasca (Dognin), are validly described whereas the other seven taxa represent interim morphospecies, recognized unequivocally by their DNA barcodes, and their larval and adult morphology. We provide information about their host plants, degree of parasitism, and describe the larval stages in their last instar. Additionally, caterpillars and moths are illustrated in color plates. This is the first comparative study dealing with Eois moths whose caterpillars feed on Peperomia hosts.
PMCID: PMC4672213  PMID: 26286230
Andes; caterpillars; host plants; larval morphology; mountain rainforest
25.  Biocidal effects of stem bark extract of Chrysophyllum albidium G. Don on vancomycin-resistant Staphylococcus aureus 
Staphylococcus aureus causes variety of infections in humans and animals worldwide and predominates in surgical wound infections. This study assessed the antimicrobial potential of the stem bark extract of Chrysophyllum albidum against an array of vancomycin resistant Staphylococcus aureus (VRSA) isolated from clinical samples.
The methanolic crude extract of the plant was preliminary screened for the presence of phytochemicals; after then, the extract was partitioned into n-hexane, chloroform, ethyl acetate and butanol fractions. A range of concentrations of the plant extract fractions was prepared to assess its antimicrobial potency; the minimum inhibitory concentrations (MICs); the minimum bactericidal concentrations (MBCs); the rate of killing; the potassium ion leakage potential and nucleotides leakage ability against the VRSAs.
The phytochemical screening revealed the presence of tannins, alkaloids, flavonoids, saponins, steroids, reducing sugars and terpenoids as major phytoconstituents resident in the crude plant extract. The two active fractions (n-hexane and butanol) at a concentration of 10 mg/ml exhibited antibacterial activities with the MIC and MBC values for the fractions ranged between 0.63–10 mg/ml and 1.25–10 mg/ml respectively. The time kill assay revealed that the antibacterial action of the two fractions are time and concentration dependent; the n-hexane and butanol fractions achieved 100 % kill on the test isolates at a concentration of 3 × MIC and 2 × MIC respectively after 120 min of reaction time. Varying amount of potassium ions as well as nucleotides were leaked from the test cells by n-hexane and butanol fractions.
This study has established the possibility of developing antimicrobial agents of natural origin to manage possible infection from vancomycin resistant Staphylococcus aureus that are now developing multi-resistance against many antibiotics.
PMCID: PMC4802705  PMID: 27004526
Chrysophyllum albidum; Vancomycin resistant Staphylococcus aureus; Clinical samples; Methanolic extract; Phytochemicals; Minimum inhibitory concentrations; Minimum bactericidal concentrations; Time kill; Potassium ion; Nucleotide

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