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1.  Anti-nociceptive properties in rodents and the possibility of using polyphenol-rich fractions from sida urens L. (Malvaceae) against of dental caries bacteria 
Background
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.
Method
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.
Results
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.
Conclusion
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.
doi:10.1186/1476-0711-12-14
PMCID: PMC3699430  PMID: 23787152
2.  Antibacterial activity against β- lactamase producing Methicillin and Ampicillin-resistants Staphylococcus aureus: fractional Inhibitory Concentration Index (FICI) determination 
Background
The present study reports the antibacterial capacity of alkaloid compounds in combination with Methicillin and Ampicillin-resistants bacteria isolated from clinical samples. The resistance of different bacteria strains to the current antibacterial agents, their toxicity and the cost of the treatment have led to the development of natural products against the bacteria resistant infections when applied in combination with conventional antimicrobial drugs.
Method
The antibacterial assays in this study were performed by using inhibition zone diameters, MIC, MBC methods, the time-kill assay and the Fractional Inhibitory Concentration Index (FICI) determination. On the whole, fifteen Gram-positive bacterial strains (MRSA/ARSA) were used. Negative control was prepared using discs impregnated with 10 % DMSO in water and commercially available Methicillin and Ampicillin from Alkom Laboratories LTD were used as positive reference standards for all bacterial strains.
Results
We noticed that the highest activities were founded with the combination of alkaloid compounds and conventional antibiotics against all bacteria strains. Then, results showed that after 7 h exposition there was no viable microorganism in the initial inoculums.
Conclusion
The results of this study showed that alkaloid compounds in combination with conventional antibiotics (Methicillin, Ampicillin) exhibited antimicrobial effects against microorganisms tested. These results validate the ethno-botanical use of Cienfuegosia digitata Cav. (Malvaceae) in Burkina Faso. Moreover, this study demonstrates the potential of this herbaceous as a source of antibacterial agent that could be effectively used for future health care purposes.
doi:10.1186/1476-0711-11-18
PMCID: PMC3464800  PMID: 22716026
3.  Free radical scavenging capacity, anticandicidal effect of bioactive compounds from Sida Cordifolia L., in combination with nystatin and clotrimazole and their effect on specific immune response in rats 
Background
Infectious diseases caused by fungi are still a major threat to public health, despite numerous efforts by researchers. Use of ethnopharmacological knowledge is one attractive way to reduce empiricism and enhance the probability of success in new drug-finding efforts. In this work, the total alkaloid compounds (AC) from Sida cordifolia L. (Malvaceae) have been investigated for their free radical scavenging capacity, antifungal and immunostimulatory properties.
Method
The antifungal activity was investigated against five candida strains using the microplate dilution method and the Fractional Inhibitory Concentration Index (FICI) of compounds was evaluated. The antioxidant activity of the samples was evaluate using three separate methods, at last, the immunostimulatory effect on immunosuppressed wistar rats was performed.
Results
As for the antifungal activity, result varied according to microorganism. The results obtained in this antifungal activity were interesting and indicated a synergistic effect between alkaloid compounds and the antifungal references such as Nystatin and Clotrimazole. Antioxidant capacity noticed that the reduction capacity of DPPH radicals obtained the best result comparatively to the others methods of free radical scavenging. Our results showed a low immunostimulatory effect and this result could be explained by the lack of biologically active antioxidants such as polyphenol compounds lowly contained in the alkaloid compounds.
Conclusion
The results of this study showed that alkaloid compounds in combination with antifungal references (Nystatin and Clotrimazole) exhibited antimicrobial effects against candida strains tested. The results supported the utilization of these plants in infectious diseases particularly in treatment of candida infections.
doi:10.1186/1476-0711-11-33
PMCID: PMC3576270  PMID: 23268761
4.  Daptomycin-Resistant Enterococcus faecalis Diverts the Antibiotic Molecule from the Division Septum and Remodels Cell Membrane Phospholipids 
mBio  2013;4(4):e00281-13.
ABSTRACT
Treatment of multidrug-resistant enterococci has become a challenging clinical problem in hospitals around the world due to the lack of reliable therapeutic options. Daptomycin (DAP), a cell membrane-targeting cationic antimicrobial lipopeptide, is the only antibiotic with in vitro bactericidal activity against vancomycin-resistant enterococci (VRE). However, the clinical use of DAP against VRE is threatened by emergence of resistance during therapy, but the mechanisms leading to DAP resistance are not fully understood. The mechanism of action of DAP involves interactions with the cell membrane in a calcium-dependent manner, mainly at the level of the bacterial septum. Previously, we demonstrated that development of DAP resistance in vancomycin-resistant Enterococcus faecalis is associated with mutations in genes encoding proteins with two main functions, (i) control of the cell envelope stress response to antibiotics and antimicrobial peptides (LiaFSR system) and (ii) cell membrane phospholipid metabolism (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase). In this work, we show that these VRE can resist DAP-elicited cell membrane damage by diverting the antibiotic away from its principal target (division septum) to other distinct cell membrane regions. DAP septal diversion by DAP-resistant E. faecalis is mediated by initial redistribution of cell membrane cardiolipin-rich microdomains associated with a single amino acid deletion within the transmembrane protein LiaF (a member of a three-component regulatory system [LiaFSR] involved in cell envelope homeostasis). Full expression of DAP resistance requires additional mutations in enzymes (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase) that alter cell membrane phospholipid content. Our findings describe a novel mechanism of bacterial resistance to cationic antimicrobial peptides.
IMPORTANCE  The emergence of antibiotic resistance in bacterial pathogens is a threat to public health. Understanding the mechanisms of resistance is of crucial importance to develop new strategies to combat multidrug-resistant microorganisms. Vancomycin-resistant enterococci (VRE) are one of the most recalcitrant hospital-associated pathogens against which new therapies are urgently needed. Daptomycin (DAP) is a calcium-decorated antimicrobial lipopeptide whose target is the bacterial cell membrane. A current paradigm suggests that Gram-positive bacteria become resistant to cationic antimicrobial peptides via an electrostatic repulsion of the antibiotic molecule from a more positively charged cell surface. In this work, we provide evidence that VRE use a novel strategy to avoid DAP-elicited killing. Instead of “repelling” the antibiotic from the cell surface, VRE diverts the antibiotic molecule from the septum and “traps” it in distinct membrane regions. We provide genetic and biochemical bases responsible for the mechanism of resistance and disclose new targets for potential antimicrobial development.
IMPORTANCE 
The emergence of antibiotic resistance in bacterial pathogens is a threat to public health. Understanding the mechanisms of resistance is of crucial importance to develop new strategies to combat multidrug-resistant microorganisms. Vancomycin-resistant enterococci (VRE) are one of the most recalcitrant hospital-associated pathogens against which new therapies are urgently needed. Daptomycin (DAP) is a calcium-decorated antimicrobial lipopeptide whose target is the bacterial cell membrane. A current paradigm suggests that Gram-positive bacteria become resistant to cationic antimicrobial peptides via an electrostatic repulsion of the antibiotic molecule from a more positively charged cell surface. In this work, we provide evidence that VRE use a novel strategy to avoid DAP-elicited killing. Instead of “repelling” the antibiotic from the cell surface, VRE diverts the antibiotic molecule from the septum and “traps” it in distinct membrane regions. We provide genetic and biochemical bases responsible for the mechanism of resistance and disclose new targets for potential antimicrobial development.
doi:10.1128/mBio.00281-13
PMCID: PMC3735187  PMID: 23882013
5.  Antimicrobial Activity of Carpolobia Lutea Extracts and Fractions 
Carpolobia lutea (G. Don) (Polygalaceae) is a tropical medicinal plant putative in traditional medicines against gonorrhea, gingivitis, infertility, antiulcer and malaria. The present study evaluated the antimicrobial, antifungal and antihelicobacter effects of extracts C. lutea leaf, stem and root. The extracts were examined using the disc-diffusion and Microplates of 96 wells containing Muller-Hinton methods against some bacterial strains: Eschericia coli (ATCC 25922), E. coli (ATCC10418), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Staphyllococus aureus (ATCC 6571), Enterococcus faecalis (ATCC 29212) and Bacillus subtilis (NCTC 8853) and four clinical isolates: one fungi (Candida albican) and three bacteria (Salmonella, Sheigella and staphylococcus aureus). The Gram-positive bacteria: Staphylococcus aureus (ATCC 25923), Enterococcus faecalis (ATCC 29212), Bacillus subtilis (ATCC 19659) and the Gram-negative bacteria: Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Cândida albicans (ATCC 18804) and Helicobacter pylori (ATCC 43504). Some of these extracts were found to be active against some tested strains but activity against H. pylori was >1000mg/ml and good fungistatic activity against C. albican. The MIC against C. albican is in the order n-HF > CHF > ETF= EAF.The order of potency of fraction was the ethanol root > n-HF leaf > ethanol fraction stem > chloroform fraction leaf = ethyl acetate fraction leaf. Polyphenols were demonstrated in ethanol fraction, ethyl acetate fraction, crude ethyl acetate extract and ethanol extract, respectively. These polyphenols isolated may partly explain and support the use of C. lutea for the treatment of infectious diseases in traditional Ibibio medicine of Nigeria.
PMCID: PMC3746663  PMID: 23983362
Carpolobia lutea; Polygalaceae; antimicrobial; antifungal; antihelicobacter; Polyphenols
6.  In vitro antibacterial activity and acute toxicity studies of aqueous-methanol extract of Sida rhombifolia Linn. (Malvaceae) 
Background
Many bacteria among the Enterobacteria family are involved in infectious diseases and diarrhoea. Most of these bacteria become resistant to the most commonly used synthetic drugs in Cameroon. Natural substances seem to be an alternative to this problem. Thus the aim of this research was to investigate the in vitro antibacterial activity of the methanol and aqueous-methanol extracts of Sida rhombifolia Linn (Malvaceae) against seven pathogenic bacteria involved in diarrhoea. Acute toxicity of the most active extract was determined and major bioactive components were screened.
Methods
The agar disc diffusion and the agar dilution method were used for the determination of inhibition diameters and the Minimum Inhibitory Concentration (MICs) respectively. The acute toxicity study was performed according WHO protocol.
Results
The aqueous-methanol extract (1v:4v) was the most active with diameters of inhibition zones ranging from 8.7 - 23.6 mm, however at 200 μg/dic this activity was relatively weak compared to gentamycin. The MICs of the aqueous-methanol extract (1v:4v) varied from 49.40 to 78.30 μg/ml. Salmonella dysenteriae was the most sensitive (49.40 μg/ml). For the acute toxicity study, no deaths of rats were recorded. However, significant increase of some biochemical parameters such as aspartate amino-transferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and creatinine (CRT) were found. The phytochemical analysis of the aqueous methanol extract indicated the presence of tannins, polyphenols, alkaloids, glycosides, flavonoids and saponins
Conclusion
The results showed that the aqueous-methanol extract of S. rhombifolia exhibited moderate antibacterial activity. Some toxic effects were found when rats received more than 8 g/kg bw of extract.
Antibacterial; Enterobacteria; Acute toxicity; Phytochemical analysis
doi:10.1186/1472-6882-10-40
PMCID: PMC2922083  PMID: 20663208
7.  Antimicrobial activity and phytochemical analyses of Polygonum aviculare L. (Polygonaceae), naturally growing in Egypt 
Polygonum aviculare (Polygonaceae) is an herb commonly distributed in Mediterranean coastal regions in Egypt and used in folkloric medicine. Organic and aqueous solvent extracts and fractions of P. aviculare were investigated for antimicrobial activities on several microorganisms including bacteria and fungi. Phytochemical constituents of air-dried powered plant parts were extracted using aqueous and organic solvents (acetone, ethanol, chloroform and water). Antimicrobial activity of the concentrated extracts was evaluated by determination of the diameter of inhibition zone against both Gram-negative and Gram-positive bacteria and fungi using paper disc diffusion method.
Results of the phytochemical studies revealed the presence of tannins, saponins, flavonoids, alkaloids and sesquiterpenes and the extracts were active against both Gram-negative and Gram-positive bacteria. Chloroform extract gave very good and excellent antimicrobial activity against all tested bacteria and good activity against all tested fungi except Candida albicans. Structural spectroscopic analysis that was carried out on the active substances in the chloroform extract led to the identification of panicudine (6-hydroxy-11-deoxy-13 dehydrohetisane).
Evaluation of the antimicrobial activity of panicudine indicated significant activity against all tested Gram-negative and Gram-positive organisms. Panicudine displayed considerable activity against the tested fungi with the exception of C. albicans. Antimicrobial activity of the extracts was unaffected after exposure to different heat treatments, but was reduced at alkaline pH. Studies of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of panicudine on the tested organisms showed that the lowest MIC and the MBC were demonstrated against Salmonella paratyphi, Bacillus subtilis and Salmonella typhi and the highest MIC and MBC were against Staphylococcus aureus.
doi:10.1016/j.sjbs.2009.12.009
PMCID: PMC3730555  PMID: 23961059
Polygonum aviculare; Antimicrobial activity; Phytochemical analysis; Minimum inhibitory concentration; Minimum bactericidal concentration
8.  Antimicrobial and toxicological activities of five medicinal plant species from Cameroon Traditional Medicine 
Background
Infectious diseases caused by multiresistant microbial strains are on the increase. Fighting these diseases with natural products may be more efficacious. The aim of this study was to investigate the in vitro antimicrobial activity of methanolic, ethylacetate (EtOAc) and hexanic fractions of five Cameroonian medicinal plants (Piptadeniastum africana, Cissus aralioides, Hileria latifolia, Phyllanthus muellerianus and Gladiolus gregasius) against 10 pathogenic microorganisms of the urogenital and gastrointestinal tracts.
Methods
The fractions were screened for their chemical composition and in vivo acute toxicity was carried out on the most active extracts in order to assess their inhibitory selectivity.
The agar well-diffusion and the micro dilution methods were used for the determination of the inhibition diameters (ID) and Minimum inhibitory concentrations (MIC) respectively on 8 bacterial species including two Gram positive species (Staphylococcus aureus, Enterococcus faecalis), and six Gram negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Shigella flexneri, Salmonella typhi) and two fungal isolates (Candida albicans, Candida krusei). The chemical composition was done according to Harbone (1976), the acute toxicity evaluation according to WHO protocol and the hepatic as well as serum parameters measured to assess liver and kidney functions.
Results
The chemical components of each plant's extract varied according to the solvent used, and they were found to contain alkaloids, flavonoids, polyphenols, triterpens, sterols, tannins, coumarins, glycosides, cardiac glycosides and reducing sugars. The methanolic and ethylacetate extracts of Phyllanthus muellerianus and Piptadeniastum africana presented the highest antimicrobial activities against all tested microorganisms with ID varying from 8 to 26 mm and MIC from 2.5 to 0.31 mg/ml. The in vivo acute toxicity study carried out on the methanolic extracts of Phyllanthus muellerianus and Piptadeniastrum africana indicated that these two plants were not toxic. At the dose of 4 g/kg body weight, kidney and liver function tests indicated that these two medicinal plants induced no adverse effect on these organs.
Conclusion
These results showed that, all these plant's extracts can be used as antimicrobial phytomedicines which can be therapeutically used against infections caused by multiresistant agents.
Phyllanthus muellerianus, Piptadeniastum africana, antimicrobial, acute toxicity, kidney and liver function tests, Cameroon Traditional Medicine
doi:10.1186/1472-6882-11-70
PMCID: PMC3182953  PMID: 21867554
Phyllanthus muellerianus; Piptadeniastum africana; antimicrobial; acute toxicity; kidney and liver function tests; Cameroon Traditional Medicine
9.  Screening Togolese medicinal plants for few pharmacological properties 
Pharmacognosy Research  2012;4(2):116-122.
Background:
Terminalia macroptera Guill. et Perr. (Combretaceae), Sida alba L. (Malvaceae), Prosopis africana Guill et Perr. Taub. (Mimosaceae), Bridelia ferruginea Benth. (Euphorbiaceae), and Vetiveria nigritana Stapf. (Asteraceae) are traditionally used in Togolese folk medicine to treat several diseases including microbial infections.
Objective:
This study aimed to investigate the antimicrobial, antioxidant, and hemolytic properties of the crude extracts of the above-mentioned plants.
Materials and Methods:
The antimicrobial and the antioxidant activities were assayed using the NCCLS microdilution method and the DPPH free radical scavenging, respectively. Human A+ red blood cells were used to perform the hemolytic assay. Phenolics were further quantified in the extracts using spectrophotometric methods.
Results:
Minimal inhibitory concentrations in the range of 230-1800 μg/ml were recorded in the NCCLS broth microdilution for both bacterial and fungal strains with methanol extracts. The DPPH radical scavenging assay yielded interesting antioxidant activities of the extracts of P. africana and T. macroptera (IC50 values of 0.003 ± 0.00 μg/ml and 0.05 ± 0.03 μg/ml, respectively). These activities were positively correlated with the total phenolic contents and negatively correlated with the proanthocyanidin content of the extracts. The hemolytic assay revealed that great hemolysis occurred with the methanol extracts of T. macroptera, S. longepedunculata, and B. ferruginea.
Conclusion:
These results support in part the use of the selected plants in the treatment of microbial infections. In addition, the plant showed an interesting antioxidant activity that could be useful in the management of oxidative stress.
doi:10.4103/0974-8490.94737
PMCID: PMC3326758  PMID: 22518084
Antimicrobial; antioxidant; hemolytic; phenolics
10.  Evaluation of Aromatic Plants and Compounds Used to Fight Multidrug Resistant Infections 
Traditional medicine plays a vital role for primary health care in India, where it is widely practiced to treat various ailments. Among those obtained from the healers, 78 medicinal plants were scientifically evaluated for antibacterial activity. Methanol extract of plants (100 μg of residue) was tested against the multidrug resistant (MDR) Gram-negative and Gram-positive bacteria. Forty-seven plants showed strong activity against Burkholderia pseudomallei (strain TES and KHW) and Staphylococcus aureus, of which Tragia involucrata L., Citrus acida Roxb. Hook.f., and Aegle marmelos (L.) Correa ex Roxb. showed powerful inhibition of bacteria. Eighteen plants displayed only a moderate effect, while six plants failed to provide any evidence of inhibition against the tested bacteria. Purified compounds showed higher antimicrobial activity than crude extracts. The compounds showed less toxic effect to the human skin fibroblasts (HEPK) cells than their corresponding aromatic fractions. Phytochemical screening indicates that the presence of various secondary metabolites may be responsible for this activity. Most of the plant extracts contained high levels of phenolic or polyphenolic compounds and exhibited activity against MDR pathogens. In conclusion, plants are promising agents that deserve further exploration. Lead molecules available from such extracts may serve as potential antimicrobial agents for future drug development to combat diseases caused by the MDR bacterial strains as reported in this study.
doi:10.1155/2013/525613
PMCID: PMC3816052  PMID: 24223059
11.  In vitro antimicrobial activity of mangrove plant Sonneratia alba 
Objective
To investigate the antimicrobial property of mangrove plant Sonneratia alba (S. alba).
Methods
The antimicrobial activity was evaluated using disc diffusion and microdilution methods against six microorganisms. Soxhlet apparatus was used for extraction with a series of solvents, n-hexane, ethyl acetate and methanol in sequence of increasing polarity.
Results
Methanol extract appeared to be the most effective extract while n-hexane extract showed no activity. The antimicrobial activities were observed against the gram positive bacteria Staphylococcus aureus (S. aureus) and Bacillus cereus (B. cereus), the gram negative Escherichia coli (E. coli) and the yeast Cryptococcus neoformans. Pseudomonas aeruginosa and Candida albicans appeared to be not sensitive to the concentrations tested since no inhibition zone was observed. E. coli (17.5 mm) appeared to be the most sensitive strain followed by S. aureus (12.5 mm) and B. cereus (12.5 mm).
Conclusions
From this study, it can be concluded that S. alba exhibits antimicrobial activities against certain microorganisms.
doi:10.1016/S2221-1691(12)60069-0
PMCID: PMC3609317  PMID: 23569943
Antibacterial; Antifungal; Sonneratia alba; Mangroves; Antimicrobial activity
12.  Studies on the antimicrobial activity and brine shrimp toxicity of Zeyheria tuberculosa (Vell.) Bur. (Bignoniaceae) extracts and their main constituents 
Background
Due to the indiscriminate use of antimicrobial drugs, the emergence of human pathogenic microorganisms resistant to major classes of antibiotics has been increased and has caused many clinical problems in the treatment of infectious diseases. Thus, the aim of this study was to evaluate for the first time the in vitro antimicrobial activity and brine shrimp lethality of extracts and isolated compounds from Zeyheria tuberculosa (Vell.) Bur., a species used in Brazilian folk medicine for treatment of cancer and skin diseases.
Methods
Using the disc diffusion method, bioautography assay and brine shrimp toxicity test (Artemia salina Leach), we studied the antimicrobial activity and lethality of extracts and isolated compounds against three microorganisms strains, including Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria and yeasts (Candida albicans).
Results
In this study, the extracts inhibited S. aureus (8.0 ± 0.0 to 14.0 ± 0.0 mm) and C. albicans (15.3 ± 0.68 to 25.6 ± 0.4 mm) growth. In the brine shrimp test, only two of them showed toxic effects (LC50 29.55 to 398.05 μg/mL) and some extracts were non-toxic or showed weak lethality (LC50 705.02 to > 1000 μg/mL). From these extracts, four flavones [5,6,7,8-tetramethoxyflavone (1), 5,6,7-trimethoxyflavone (2), 4'-hydroxy-5,6,7,8-tetramethoxyflavone (3), and 4'-hydroxy-5,6,7-trimethoxyflavone (4)] were isolated through bioassay-guided fractionation and identified based on the 1D and 2D NMR spectral data. By bioautography assays, compounds 1 [S. aureus (16.0 ± 0.0 mm) and C. albicans (20.0 ± 0.0 mm)] and 3 [S. aureus (10.3 ± 0.6 mm) and C. albicans (19.7 ± 0.6 mm)] inhibited both microorganisms while 2 inhibited only S. aureus (11.7 ± 0.6 mm). Compound 4 did not restrain the growth of any tested microorganism.
Conclusion
Our results showed that extracts and isolated flavones from Z. tuberculosa may be particularly useful against two pathogenic microorganisms, S. aureus and C. albicans. These results may justify the popular use this species since some fractions tested had antimicrobial activity and others showed significant toxic effects on brine shrimps. However, in order to evaluate possible clinical application in therapy of infectious diseases, further studies about the safety and toxicity of isolated compounds are needed.
doi:10.1186/1476-0711-8-16
PMCID: PMC2691395  PMID: 19450272
13.  Effect of ethnomedicinal plants used in folklore medicine in Jordan as antibiotic resistant inhibitors on Escherichia coli 
Background
Escherichia coli occurs naturally in the human gut; however, certain strains that can cause infections, are becoming resistant to antibiotics. Multidrug-resistant E. coli that produce extended-spectrum β lactamases (ESBLs), such as the CTX-M enzymes, have emerged within the community setting as an important cause of urinary tract infections (UTIs) and bloodstream infections may be associated with these community-onsets. This is the first report testing the antibiotic resistance-modifying activity of nineteen Jordanian plants against multidrug-resistant E. coli.
Methods
The susceptibility of bacterial isolates to antibiotics was tested by determining their minimum inhibitory concentrations (MICs) using a broth microdilution method. Nineteen Jordanian plant extracts (Capparis spinosa L., Artemisia herba-alba Asso, Echinops polyceras Boiss., Gundelia tournefortii L, Varthemia iphionoides Boiss. & Blanche, Eruca sativa Mill., Euphorbia macroclada L., Hypericum trequetrifolium Turra, Achillea santolina L., Mentha longifolia Host, Origanum syriacum L., Phlomis brachydo(Boiss.) Zohary, Teucrium polium L., Anagyris foetida L., Trigonella foenum-graecum L., Thea sinensis L., Hibiscus sabdariffa L., Lepidium sativum L., Pimpinella anisum L.) were combined with antibiotics, from different classes, and the inhibitory effect of the combinations was estimated.
Results
Methanolic extracts of the plant materials enhanced the inhibitory effects of chloramphenicol, neomycin, doxycycline, cephalexin and nalidixic acid against both the standard strain and to a lesser extent the resistant strain of E. coli. Two edible plant extracts (Gundelia tournefortii L. and Pimpinella anisum L.) generally enhanced activity against resistant strain. Some of the plant extracts like Origanum syriacum L.(Labiateae), Trigonella foenum- graecum L.(Leguminosae), Euphorbia macroclada (Euphorbiaceae) and Hibiscus sabdariffa (Malvaceae) did not enhance the activity of amoxicillin against both standard and resistant E. coli. On the other hand combinations of amoxicillin with other plant extracts used showed variable effect between standard and resistant strains. Plant extracts like Anagyris foetida (Leguminosae) and Lepidium sativum (Umbelliferae) reduced the activity of amoxicillin against the standard strain but enhanced the activity against resistant strains. Three edible plants; Gundelia tournefortii L. (Compositae) Eruca sativa Mill. (Cruciferae), and Origanum syriacum L. (Labiateae), enhanced activity of clarithromycin against the resistant E. coli strain.
Conclusion
This study probably suggests possibility of concurrent use of these antibiotics and plant extracts in treating infections caused by E. coli or at least the concomitant administration may not impair the antimicrobial activity of these antibiotics.
doi:10.1186/1472-6882-10-9
PMCID: PMC2839964  PMID: 20187978
14.  Colon-available raspberry polyphenols exhibit anti-cancer effects on in vitro models of colon cancer 
Background
There is a probable association between consumption of fruit and vegetables and reduced risk of cancer, particularly cancer of the digestive tract. This anti-cancer activity has been attributed in part to anti-oxidants present in these foods. Raspberries in particular are a rich source of the anti-oxidant compounds, such as polyphenols, anthocyanins and ellagitannins.
Methods
A "colon-available" raspberry extract (CARE) was prepared that contained phytochemicals surviving a digestion procedure that mimicked the physiochemical conditions of the upper gastrointestinal tract. The polyphenolic-rich extract was assessed for anti-cancer properties in a series of in vitro systems that model important stages of colon carcinogenesis, initiation, promotion and invasion.
Results
The phytochemical composition of CARE was monitored using liquid chromatography mass spectrometry. The colon-available raspberry extract was reduced in anthocyanins and ellagitannins compared to the original raspberry juice but enriched in other polyphenols and polyphenol breakdown products that were more stable to gastrointestinal digestion. Initiation – CARE caused significant protective effects against DNA damage induced by hydrogen peroxide in HT29 colon cancer cells measured using single cell microgelelectrophoresis. Promotion – CARE significantly decreased the population of HT29 cells in the G1 phase of the cell cycle, effectively reducing the number of cells entering the cell cycle. However, CARE had no effect on epithelial integrity (barrier function) assessed by recording the trans-epithelial resistance (TER) of CACO-2 cell monolayers. Invasion – CARE caused significant inhibition of HT115 colon cancer cell invasion using the matrigel invasion assay.
Conclusion
The results indicate that raspberry phytochemicals likely to reach the colon are capable of inhibiting several important stages in colon carcinogenesis in vitro.
doi:10.1186/1477-3163-6-4
PMCID: PMC1868020  PMID: 17442116
15.  Antibacterial activities of the extracts, fractions and compounds from Dioscorea bulbifera 
Background
Dioscorea bulbifera is an African medicinal plant used to treat microbial infections. In the present study, the methanol extract, fractions (DBB1 and DBB2) and six compounds isolated from the bulbils of D. bulbifera, namely bafoudiosbulbins A (1), B (2), C (3), F (4), G (5) and 2,7-dihydroxy-4-methoxyphenanthrene (6), were tested for their antimicrobial activities against Mycobacteria and Gram-negative bacteria involving multidrug resistant (MDR) phenotypes expressing active efflux pumps.
Methods
The microplate alamar blue assay (MABA) and the broth microdilution methods were used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples.
Results
The results of the MIC determinations indicated that when tested alone, the crude extract, fractions DBB1 and DBB2 as well as compounds 2 to 5 were able to prevent the growth of all the fifteen studied microorganisms, within the concentration range of 8 to 256 μg/mL. The lowest MIC value for the methanol extract and fractions (16 μg/mL) was obtained with DBB1 and DBB2 on E, coli AG100A and DBB2 on Mycobacterium tuberculosis MTCS2. The lowest value for individual compounds (8 μg/mL) was recorded with compound 3 on M. smegmatis and M. tuberculosis ATCC and MTCS2 strains respectively. The activity of the samples on many MDR bacteria such as Enterobacter aerogenes EA289, CM64, Klebsiella pneumoniae KP63 and Pseudomonas aeruginosa PA124 was better than that of chloramphenicol. When tested in the presence of the efflux pump inhibitor against MDR Gram-negative bacteria, the activity of most of the samples increased. MBC values not greater than 512 μg/mL were recorded on all studied microorganisms with fraction DBB2 and compounds 2 to 5.
Conclusions
The overall results of the present investigation provided evidence that the crude extract D. bulbifera as well as some of the compounds and mostly compounds 3 could be considered as potential antimicrobial drugs to fight against MDR bacteria.
doi:10.1186/1472-6882-12-228
PMCID: PMC3528471  PMID: 23176193
Diterpenoids; Antimycobacterial; Antibacterial; Dioscorea bulbifera; Dioscoreaceae
16.  Attenuation of oxidative stress in U937 cells by polyphenolic-rich bark fractions of Burkea africana and Syzygium cordatum 
Background
Oxidative stress has been implicated in the progression of various diseases, which may result in the depletion of endogenous antioxidants. Exogenous supplementation with antioxidants could result in increased protection against oxidative stress. As concerns have been raised regarding synthetic antioxidant usage, the identification of alternative treatments is justified. The aim of the present study was to determine the antioxidant efficacy of Burkea africana and Syzygium cordatum bark extracts in an in vitro oxidative stress model.
Methods
Cytotoxicity of crude aqueous and methanolic extracts, as well as polyphenolic-rich fractions, was determined in C2C12 myoblasts, 3T3-L1 pre-adipocytes, normal human dermal fibroblasts and U937 macrophage-like cells using the neutral red uptake assay. Polyphenolic content was determined using the Folin-Ciocalteau and aluminium trichloride assays, and antioxidant activity using the Trolox Equivalence Antioxidant Capacity and DPPH assays. The extracts efficacy against oxidative stress in AAPH-exposed U937 cells was assessed with regards to reactive oxygen species generation, cytotoxicity, apoptosis, lipid peroxidation and reduced glutathione depletion.
Results
B. africana and S. cordatum showed enrichment of polyphenols from the aqueous extract, to methanolic extract, to polyphenolic-rich fractions. Antioxidant activity followed the same trend, which correlated well with the increased concentration of polyphenols, and was between two- to three-fold stronger than the Trolox antioxidant control. Both plants had superior activity compared to ascorbic acid in the DPPH assay. Polyphenolic-rich fractions were most toxic to the 3T3-L1 (IC50’s between 13 and 21 μg/ml) and C2C12 (IC50’s approximately 25 μg/ml) cell lines, but were not cytotoxic in the U937 and normal human dermal fibroblasts cultures. Free radical-induced generation of reactive oxygen species (up to 80%), cytotoxicity (up to 20%), lipid peroxidation (up to 200%) and apoptosis (up to 60%) was successfully reduced by crude extracts of B. africana and the polyphenolic-rich fractions of both plants. The crude extracts of S. cordatum were not as effective in reducing cytotoxic parameters.
Conclusion
Although oxidative stress was attenuated in U937 cells, cytotoxicity was observed in the 3T3-L1 and C2C12 cell lines. Further isolation and purification of polyphenolic-fractions could increase the potential use of these extracts as supplements by decreasing cytotoxicity and maintaining antioxidant quality.
doi:10.1186/1472-6882-13-116
PMCID: PMC3680320  PMID: 23714009
Antioxidant; Apoptosis; Burkea africana; Cytotoxicity; Free radicals; Glutathione; Lipid peroxidation; Oxidative stress; Polyphenols; Syzygium cordatum
17.  tabAnti-HER2 (erbB-2) oncogene effects of phenolic compounds directly isolated from commercial Extra-Virgin Olive Oil (EVOO) 
BMC Cancer  2008;8:377.
Background
The effects of the olive oil-rich Mediterranean diet on breast cancer risk might be underestimated when HER2 (ERBB2) oncogene-positive and HER2-negative breast carcinomas are considered together. We here investigated the anti-HER2 effects of phenolic fractions directly extracted from Extra Virgin Olive Oil (EVOO) in cultured human breast cancer cell lines.
Methods
Solid phase extraction followed by semi-preparative high-performance liquid chromatography (HPLC) was used to isolate phenolic fractions from commercial EVOO. Analytical capillary electrophoresis coupled to mass spectrometry was performed to check for the composition and to confirm the identity of the isolated fractions. EVOO polyphenolic fractions were tested on their tumoricidal ability against HER2-negative and HER2-positive breast cancer in vitro models using MTT, crystal violet staining, and Cell Death ELISA assays. The effects of EVOO polyphenolic fractions on the expression and activation status of HER2 oncoprotein were evaluated using HER2-specific ELISAs and immunoblotting procedures, respectively.
Results
Among the fractions mainly containing the single phenols hydroxytyrosol and tyrosol, the polyphenol acid elenolic acid, the lignans (+)-pinoresinol and 1-(+)-acetoxypinoresinol, and the secoiridoids deacetoxy oleuropein aglycone, ligstroside aglycone, and oleuropein aglycone, all the major EVOO polyphenols (i.e. secoiridoids and lignans) were found to induce strong tumoricidal effects within a micromolar range by selectively triggering high levels of apoptotic cell death in HER2-overexpressors. Small interfering RNA-induced depletion of HER2 protein and lapatinib-induced blockade of HER2 tyrosine kinase activity both significantly prevented EVOO polyphenols-induced cytotoxicity. EVOO polyphenols drastically depleted HER2 protein and reduced HER2 tyrosine autophosphorylation in a dose- and time-dependent manner. EVOO polyphenols-induced HER2 downregulation occurred regardless the molecular mechanism contributing to HER2 overexpression (i.e. naturally by gene amplification and ectopically driven by a viral promoter). Pre-treatment with the proteasome inhibitor MG132 prevented EVOO polyphenols-induced HER2 depletion.
Conclusion
The ability of EVOO-derived polyphenols to inhibit HER2 activity by promoting the proteasomal degradation of the HER2 protein itself, together with the fact that humans have safely been ingesting secoiridoids and lignans as long as they have been consuming olives and OO, support the notion that the stereochemistry of these phytochemicals might provide an excellent and safe platform for the design of new HER2-targeting agents.
doi:10.1186/1471-2407-8-377
PMCID: PMC2626601  PMID: 19094209
18.  Anti-Ulcer and Wound Healing Activities of Sida Corymbosa in Rats 
Background
There are strong beliefs in the efficacy of traditional medical systems worldwide. Many herbs have been acclaimed to possess antiulcer effects and could be unexplored sources of new lead compounds. Sida corymbosa R. E. Fries (Malvaceae) is used in Northern Nigeria to treat ulcers and wounds. This work aimed to investigate the usefulness of Sida corymbosa in treatments of stomach ulcers and wounds in traditional medicine.
Materials and Methods
Effect of the aqueous extract was determined on gastric ulceration, rate of wound healing and inflammation using ethanol-induced and diclofenac-induced ulceration, wound excision model and albumin-induced inflammation respectively in rats.
Results
The study demonstrated the anti-ulcer activity of Sida corymbosa as the extract (250, 500 and 1000 mg/kg) showed a dose-dependent, significant (P<0.05) reduction of ulcer indices against gastric ulcers induced by both ethanol and diclofenac. Topical application of a formulation prepared with the extract of Sida corymbosa on surgically created incisions produced an increase in the rate of healing of the wounds. The extract of Sida corymbosa exhibited a significant (P < 0.05), dose-related decrease in inflammation induced by fresh egg albumin. This study showed that Sida corymbosa has constituents with the ability to reduce the severity of haemorrhagic gastric lesions, promote wound healing and reduce inflammation. These actions may be attributed to any one of the active constituents or as a result of synergistic effects of these phytoconstituents.
Conclusion
This study validates the use of the plant in traditional medicine for the treatment of stomach ulcers and wounds.
PMCID: PMC3957246  PMID: 24653558
Sida corymbosa; Anti-Ulcer; Wound Healing
19.  Studies of the in vitro cytotoxic, antioxidant, lipase inhibitory and antimicrobial activities of selected Thai medicinal plants 
Background
Traditional folk medicinal plants have recently become popular and are widely used for primary health care. Since Thailand has a great diversity of indigenous (medicinal) plant species, this research investigated 52 traditionally used species of Thai medicinal plants for their in vitro cytotoxic, antioxidant, lipase inhibitory and antimicrobial activities.
Methods
The 55 dried samples, derived from the medicinally used parts of the 52 plant species were sequentially extracted by hexane, dichloromethane, ethanol and water. These 220 extracts were then screened for in vitro (i) cytotoxicity against four cell lines, derived from human lung (A549), breast (MDA-MB-231), cervical (KB3-1) and colon (SW480) cancers, using the MTT cytotoxicity assay; (ii) antioxidant activity, analyzed by measuring the scavenging activity of DPPH radicals; (iii) lipase inhibitory activity, determined from the hydrolytic reaction of p-nitrophenyllaurate with pancreatic lipase; and (iv) antimicrobial activity against three Gram-positive and two Gram-negative bacteria species plus one strain of yeast using the disc-diffusion method and determination of the minimum inhibitory concentration by the broth micro-dilution assay.
Results
The crude dichloromethane and/or ethanol extracts from four plant species showed an effective in vitro cytotoxic activity against the human cancer cell lines that was broadly similar to that of the specific chemotherapy drugs (etoposide, doxorubicin, vinblastine and oxaliplatin). In particular, this is the first report of the strong in vitro cytotoxic activity of Bauhinia strychnifolia vines. The tested tissue parts of only six plant species (Allium sativum, Cocoloba uvifera, Dolichandrone spathacea, Lumnitzera littorea, Sonneratia alba and Sonneratia caseolaris) showed promising potential antioxidant activity, whereas lipase inhibitory activity was only found in the ethanol extract from Coscinum fenestratum and this was weak at 17-fold lower than Orlistat, a known lipase inhibitor. The highest antimicrobial activity was observed in the extracts from S. alba and S. caseolaris against Pseudomonas aeruginosa and Candida albicans, respectively.
Conclusion
The Thai medicinal plant B. strychnifolia is first reported to exert strong in vitro cytotoxic activities against human cancer cell lines and warrants further enrichment and characterization. The broad spectrum of the biological activities from the studied plant extracts can be applied as the guideline for the selection of Thai medicinal plant species for further pharmacological and phytochemical investigations.
doi:10.1186/1472-6882-12-217
PMCID: PMC3519510  PMID: 23145786
Antimicrobial; Antioxidant; Cytotoxic; Lipase inhibitory; Thai medicinal plants
20.  Antimicrobial activity, antibiotic susceptibility and virulence factors of Lactic Acid Bacteria of aquatic origin intended for use as probiotics in aquaculture 
BMC Microbiology  2013;13:15.
Background
The microorganisms intended for use as probiotics in aquaculture should exert antimicrobial activity and be regarded as safe not only for the aquatic hosts but also for their surrounding environments and humans. The objective of this work was to investigate the antimicrobial/bacteriocin activity against fish pathogens, the antibiotic susceptibility, and the prevalence of virulence factors and detrimental enzymatic activities in 99 Lactic Acid Bacteria (LAB) (59 enterococci and 40 non-enterococci) isolated from aquatic animals regarded as human food.
Results
These LAB displayed a broad antimicrobial/bacteriocin activity against the main Gram-positive and Gram-negative fish pathogens. However, particular safety concerns based on antibiotic resistance and virulence factors were identified in the genus Enterococcus (86%) (Enterococcus faecalis, 100%; E. faecium, 79%). Antibiotic resistance was also found in the genera Weissella (60%), Pediococcus (44%), Lactobacillus (33%), but not in leuconostocs and lactococci. Antibiotic resistance genes were found in 7.5% of the non-enterococci, including the genera Pediococcus (12.5%) and Weissella (6.7%). One strain of both Pediococcus pentosaceus and Weissella cibaria carried the erythromycin resistance gene mef(A/E), and another two P. pentosaceus strains harboured lnu(A) conferring resistance to lincosamides. Gelatinase activity was found in E. faecalis and E. faecium (71 and 11%, respectively), while a low number of E. faecalis (5%) and none E. faecium exerted hemolytic activity. None enterococci and non-enterococci showed bile deconjugation and mucin degradation abilities, or other detrimental enzymatic activities.
Conclusions
To our knowledge, this is the first description of mef(A/E) in the genera Pediococcus and Weissella, and lnu(A) in the genus Pediococcus. The in vitro subtractive screening presented in this work constitutes a valuable strategy for the large-scale preliminary selection of putatively safe LAB intended for use as probiotics in aquaculture.
doi:10.1186/1471-2180-13-15
PMCID: PMC3574848  PMID: 23347637
Lactic Acid Bacteria; Aquatic animals; Aquaculture probiotics; Anti-fish pathogens activity; Antibiotic resistance and virulence factors; Qualified Presumption of Safety
21.  The Aspergillus fumigatus Siderophore Biosynthetic Gene sidA, Encoding l-Ornithine N5-Oxygenase, Is Required for Virulence  
Infection and Immunity  2005;73(9):5493-5503.
Aspergillus fumigatus is the leading cause of invasive mold infection and is a serious problem in immunocompromised populations worldwide. We have previously shown that survival of A. fumigatus in serum may be related to secretion of siderophores. In this study, we identified and characterized the sidA gene of A. fumigatus, which encodes l-ornithine N5-oxygenase, the first committed step in hydroxamate siderophore biosynthesis. A. fumigatus sidA codes for a protein of 501 amino acids with significant homology to other fungal l-ornithine N5-oxygenases. A stable ΔsidA strain was created by deletion of A. fumigatus sidA. This strain was unable to synthesize the siderophores N′,N",N‴-triacetylfusarinine C (TAF) and ferricrocin. Growth of the ΔsidA strain was the same as that of the wild type in rich media; however, the ΔsidA strain was unable to grow in low-iron defined media or media containing 10% human serum unless supplemented with TAF or ferricrocin. No significant differences in ferric reduction activities were observed between the parental strain and the ΔsidA strain, indicating that blocking siderophore secretion did not result in upregulation of this pathway. Unlike the parental strain, the ΔsidA strain was unable to remove iron from human transferrin. A rescued strain (ΔsidA + sidA) was constructed; it produced siderophores and had the same growth as the wild type on iron-limited media. Unlike the wild-type and rescued strains, the ΔsidA strain was avirulent in a mouse model of invasive aspergillosis, indicating that sidA is necessary for A. fumigatus virulence.
doi:10.1128/IAI.73.9.5493-5503.2005
PMCID: PMC1231119  PMID: 16113265
22.  THE ANTIBACTERIAL ACTIVITY OF HEMOGLOBIN 
Low concentrations of hemoglobin (0.1 µg./ml. or less) exert a lethal action on some Gram-negative bacteria under certain conditions in vitro. Hemoglobins from various mammals and the distinct genetic types of human hemoglobin all manifest similar bactericidal activity. The bactericidal effect is a function of the globin moiety of the molecule; native and acid or acid-alcohol denatured globins have the same degree of activity. Hemoglobins kill enterobacteriaceae only under precisely controlled conditions. The test medium must be low in ionic concentration and acid in reaction. Various strains of Escherichia and Salmonella are susceptible to the lethal effect of hemoglobin, while the few strains of Shigella, Klebsiella, and Proteus examined were resistant. Certain acid polysaccharides and basic amines or proteins block the bactericidal effect when incorporated in the test in low concentration. Present evidence also suggests that exposure of the microorganisms to certain cations such as magnesium renders them resistant to the lethal action of globin. Hemoglobin loses its bactericidal power when complexed with haptoglobin, and serum fractions rich in free haptoglobin protect otherwise susceptible bacteria from killing by hemoglobin. The reaction appears to be a bactericidal rather than a bacteriostatic one. At 38°C. maximal killing requires approximately 30 minutes; at temperatures of 28°C. or 0°C. the bactericidal action does not take place. The minimal concentration of hemoglobin required to kill 50 per cent of the microorganisms in the test is unrelated to the size of the bacterial inoculum. Under conditions suitable for bactericidal action, hemoglobin is adsorbed onto heat-killed susceptible strains of coliform bacteria; material possessing bactericidal activity can be eluted with dilute mineral acid.
PMCID: PMC2136794  PMID: 13491755
23.  Antibacterial activities of the methanol extracts of seven Cameroonian dietary plants against bacteria expressing MDR phenotypes 
SpringerPlus  2013;2:363.
The morbidity and mortality caused by bacterial infections significantly increased with resistance to commonly used antibiotics. This is partially due to the activation of efflux pumps in Gram-negative bacteria. The present work designed to assess the in vitro antibacterial activities of seven Cameroonian dietary plants (Sesamum indicum, Sesamum radiatum, Cinnamomum zeylanicum, Corchous olitorius, Cyperus esculentus, Adansonia digitata, Aframomum kayserianum), against multidrug resistant (MDR) Gram-negative bacteria over expressing active efflux pumps. The standard phytochemical methods were used to detect the main classes of secondary metabolites in the extracts. The antibacterial activities of the studied extracts in the absence or presence of an efflux pump inhibitor (PAβN) were evaluated using liquid microbroth dilution method. The results obtained indicated that apart from the extract of C. esculentus, all other samples contained alkaloids, phenols and polyphenols meanwhile other classes of chemicals were selectively present. The studied extracts displayed antibacterial activities with minimal inhibitory concentrations (MICs) values ranged from 64 to 1024 μg/mL on the majority of the 27 tested microbial strains. The extract of S. indicum was active against 77.77% of the tested microorganisms whilst the lowest MIC value (64 μg/mL) was recorded with that of A. kayserianum against E. aerogenes EA294. The results of the present work provide baseline information on the possible used of the tested Cameroonian dietary plants in the treatment of bacterial infections including multi-drug resistant phenotypes.
doi:10.1186/2193-1801-2-363
PMCID: PMC3738912  PMID: 23961425
Antibacterial activity; Cameroon; Dietary plants; Efflux pumps; Gram-negative bacteria; Multi-drug resistant
24.  Antimicrobial activity of some medicinal plants from the cerrado of the centralwestern region of Brazil 
Brazilian Journal of Microbiology  2012;43(4):1302-1308.
Ethanol extracts from six selected species from the Cerrado of the Central-Western region of Brazil, which are used in traditional medicine for the treatment of infectious diseases and other medical conditions, namely Erythroxylum suberosum St. Hil. (Erythroxylaceae), Hyptis crenata Pohl. ex Benth. (Lamiaceae), Roupala brasiliensis Klotz. (Proteaceae), Simarouba versicolor St. Hil. (Simaroubaceae), Guazuma ulmifolia Lam. (Sterculiaceae) and Protium heptaphyllum (Aubl.) March. (Burseraceae), as well as fractions resulting from partition of these crude extracts, were screened in vitro for their antifungal and antibacterial properties. The antimicrobial activities were assessed by the broth microdilution assay against six control fungal strains, Candida albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis and Cryptococcus neoformans, and five control Gram-positive and negative bacterial strains, Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Toxicity of the extracts and fractions against Artemia salina was also evaluated in this work. All plants investigated showed antimicrobial properties against at least one microorganism and two species were also significantly toxic to brine shrimp larvae. The results tend to support the traditional use of these plants for the treatment of respiratory and gastrointestinal disorders and/or skin diseases, opening the possibility of finding new antimicrobial agents from these natural sources. Among the species investigated, Hyptis crenata, Erythroxylum suberosum and Roupala brasiliensis were considered the most promising candidates for developing of future bioactivity-guided phytochemical investigations.
doi:10.1590/S1517-83822012000400009
PMCID: PMC3769025  PMID: 24031956
Antifungal; Antibacterial; Antimicrobial; Artemia salina; Cerrado
25.  In Vitro Antibacterial Properties of Pexiganan, an Analog of Magainin 
Pexiganan, a 22-amino-acid antimicrobial peptide, is an analog of the magainin peptides isolated from the skin of the African clawed frog. Pexiganan exhibited in vitro broad-spectrum antibacterial activity when it was tested against 3,109 clinical isolates of gram-positive and gram-negative, anaerobic and aerobic bacteria. The pexiganan MIC at which 90% of isolates are inhibited (MIC90) was 32 μg/ml or less for Staphylococcus spp., Streptococcus spp., Enterococcus faecium, Corynebacterium spp., Pseudomonas spp., Acinetobacter spp., Stenotrophomonas spp., certain species of the family Enterobacteriaceae, Bacteroides spp., Peptostreptococcus spp., and Propionibacterium spp. Comparison of the MICs and minimum bactericidal concentrations (MBCs) of pexiganan for 143 isolates representing 32 species demonstrated that for 92% of the isolates tested, MBCs were the same or within 1 twofold difference of the MICs, consistent with a bactericidal mechanism of action. Killing curve analysis showed that pexiganan killed Pseudomonas aeruginosa rapidly, with 106 organisms/ml eliminated within 20 min of treatment with 16 μg of pexiganan per ml. No evidence of cross-resistance to a number of other antibiotic classes was observed, as determined by the equivalence of the MIC50s and the MIC90s of pexiganan for strains resistant to oxacillin, cefazolin, cefoxitin, imipenem, ofloxacin, ciprofloxacin, gentamicin, and clindamicin versus those for strains susceptible to these antimicrobial agents. Attempts to generate resistance in several bacterial species through repeated passage with subinhibitory concentrations of pexiganan were unsuccessful. In conclusion, pexiganan exhibits properties in vitro which make it an attractive candidate for development as a topical antimicrobial agent.
PMCID: PMC89207  PMID: 10103181

Results 1-25 (986627)