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PubMed2006

Proteinase-activated receptors induce nonoxidative, antimicrobial peptides and increased antimicrobial activity in human mononuclear phagocytes.

As thrombin and SFLLRNPNDKYEPF (SFLLRN-14), a synthetic ligand, mainly of the proteinase-activated receptor-1 (PAR-1), induce in monocytes the synthesis and secretion of chemokines, the PAR pathway can be viewed as a mononuclear phagocyte-activating principle. Classically, antimicrobial activity of mononuclear phagocytes is the measure for activation. Here, we investigated whether thrombin or SFLLRN-14 increases the antimicrobial activity of human monocytes and compared these effects to those of IFN-gamma. Furthermore, we measured the effects of these agents on the secretion of reactive oxygen intermediates and the antimicrobial activity of acid peptide extracts from monocytes. Human monocytes were exposed to maximally active concentrations of thrombin, SFLLRN-14, and IFN-gamma. Human monocytes treated with thrombin or SFLLRN-14 and then challenged with Salmonella enterica serovar typhimurium, including its attenuated mutant phoP, or Listeria monocytogenes killed, within 3 h, significantly more bacteria than control cells, an effect comparable with or surpassing the effect of IFN-gamma. This finding establishes the proteinase-PAR pathway as a potent, alternate activation pathway of mononuclear phagocytes. Thrombin and SFLLRN-14 had no significant effects on the amount of H(2)O(2) secreted by monocytes. This was in contrast to IFN-gamma, which as expected, increased the secretion of H(2)O(2) by approximately fourfold. Thrombin and SFLLRN-14, but not IFN-gamma, however, significantly increased the antimicrobial activity of acid peptide extracts of monocytes in a radial diffusion assay. Taken together, these findings suggest that IFN-gamma and thrombin differentially regulate oxidative and nonoxidative killing systems of human monocytes.

Anti-Bacterial Agents↗
PubMed2006

Comparison of the concentrations of phenolic compounds in olive oils and other plant oils: correlation with antimicrobial activity.

The antimicrobial activity of different edible vegetable oils was studied. In vitro results revealed that the oils from olive fruits had a strong bactericidal action against a broad spectrum of microorganisms, this effect being higher in general against Gram-positive than Gram-negative bacteria. Thus, olive oils showed bactericidal activity not only against harmful bacteria of the intestinal microbiota (Clostridium perfringens and Escherichia coli) also against beneficial microorganisms such as Lactobacillus acidophilus and Bifidobacterium bifidum. Otherwise, most of the foodborne pathogens tested (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, Yersinia sp., and Shigella sonnei) did not survive after 1 h of contact with olive oils. The dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons, hydroxytyrosol and tyrosol, were the phenolic compounds that statistically correlated with bacterial survival. These findings were confirmed by testing each individual phenolic compound, isolated by HPLC, against L. monocytogenes. In particular, the dialdehydic form of decarboxymethyl ligstroside aglycon showed a potent antimicrobial activity. These results indicate that not all oils classified as "olive oil" had similar bactericidal effects and that this bioactivity depended on their content of certain phenolic compounds.

Anti-Infective Agents↗
PubMed2006

Deletion of all cysteines in tachyplesin I abolishes hemolytic activity and retains antimicrobial activity and lipopolysaccharide selective binding.

Tachyplesin I is a cyclic beta-sheet antimicrobial peptide isolated from the hemocytes of Tachypleus tridentatus. The four cysteine residues in tachyplesin I play a structural role in imparting amphipathicity to the peptide which has been shown to be essential for its activity. We investigated the role of amphipathicity using an analogue of tachyplesin I (TP-I), CDT (KWFRVYRGIYRRR-NH(2)), in which all four cysteines were deleted. Like TP-I, CDT shows antimicrobial activity and disrupts Escherichia coli outer membrane and model membranes mimicking bacterial inner membranes at micromolar concentrations. The CDT peptide does not cause hemolysis up to 200 microg/mL while TP-I showed about 10% hemolysis at 100 microg/mL and about 25% hemolysis at 150 microg/mL. Peptide-into-lipid titrations under isothermal conditions reveal that the interaction of CDT with lipid membranes is an enthalpy-driven process. Binding assays performed using fluorometry demonstrate that the peptide CDT binds and inserts into only negatively charged membranes. The peptide-induced thermotropic phase transition of MLVs formed of DMPC and the DMPC/DMPG (7:3) mixture suggests specific lipid-peptide interactions. The circular dichroism study shows that the peptide exists as an unordered structure in an aqueous buffer and adopts a more ordered beta-structure upon binding to negatively charged membrane. The NMR data suggest that CDT binding to negatively charged bilayers induces a change in the lipid headgroup conformation with the lipid headgroup moving out of the bilayer surface toward the water phase, and therefore, a barrel stave mechanism of membrane disruption is unlikely as the peptide is located near the headgroup region of lipids. The lamellar phase (31)P chemical shift spectra observed at various concentrations of the peptide in bilayers suggest that the peptide may function neither via fragmentation of bilayers nor by promoting nonlamellar structures. NMR and fluorescence data suggest that the presence of cholesterol inhibits the peptide binding to the bilayers. These properties help to explain that cysteine residues may not contribute to antimicrobial activity and that the loss of hemolytic activity is due to lack of hydrophobicity and amphipathicity.

Anti-Infective Agents↗
PubMed1985

[The suitability of propylene glycol (1,2-propanediol) as an active antimicrobial adjuvant in ointments].

Propylene glycol was tested for its antimicrobial activity as well as its possible irritant effect in ointments. With regard to the antimicrobial effect, vehicles containing more than 5% propylene glycol proved to be superior to those containing glycerol. 269 volunteers with or without eczema who had been treated with 10% propylene glycol under occlusion and by means of the Duhring chamber method, showed very few irritations; there was almost none observed in patients tested with an ointment containing glycerol instead. We did not find any allergic sensitization against propylene glycol.

Adjuvants, Pharmaceutic↗
PubMed2001

Lipopeptaibols, a novel family of membrane active, antimicrobial peptides.

Lipopeptaibols are members of a novel group of naturally occurring, short peptides with antimicrobial activity, characterized by a lipophilic acyl chain at the N-terminus, a high content of the turn/helix forming alpha-aminoisobutyric acid and a 1,2-amino alcohol at the C-terminus. The amino acid sequences range from 6 to 10 residues and the fatty acyl moieties from 8 to 15 carbon atoms. The peptide portion of lipopeptaibols can be shorter than those of the nonlipidated peptaibols that range from 10 to 19 amino acid residues. The longest peptides fold into a mixed 3(10)/alpha helix, whereas the shortest peptides tend to adopt a beta-turn/sheet structure. Using solution methodologies, a series of analogues of trichogin GA IV was synthesized which allowed determination of the minimal lipid chain and peptide main-chain lengths for the onset of membrane activity and exploitation of a number of spectroscopic techniques aimed at determining its preferred conformation under a variety of conditions and investigating in detail its mode of interaction with, and its effect on, the phospholipid membranes.

Amino Acid Sequence↗
PubMed2001

Induction of direct antimicrobial activity through mammalian toll-like receptors.

The mammalian innate immune system retains from Drosophila a family of homologous Toll-like receptors (TLRs) that mediate responses to microbial ligands. Here, we show that TLR2 activation leads to killing of intracellular Mycobacterium tuberculosis in both mouse and human macrophages, through distinct mechanisms. In mouse macrophages, bacterial lipoprotein activation of TLR2 leads to a nitric oxide-dependent killing of intracellular tubercle bacilli, but in human monocytes and alveolar macrophages, this pathway was nitric oxide-independent. Thus, mammalian TLRs respond (as Drosophila Toll receptors do) to microbial ligands and also have the ability to activate antimicrobial effector pathways at the site of infection.

Animals↗
PubMed2000

Microemulsions are membrane-active, antimicrobial, self-preserving systems.

Microemulsions are physically stable oil/water systems that have potential use as delivery systems for many pharmaceuticals which are normally of limited use due to their hydrophobicity, toxicity or inability to access the site of action. It has been suggested that microemulsions are self-preserving antimicrobials in their own right, although there is little evidence to support this. In this experiment, microemulsions of various compositions were formulated and tested for their stability and antimicrobial action. The physical stability of the different microemulsions was assessed by centrifugation at 4000g and by storage in a water bath at 37 degrees C for one month, during which no phase separation was observed. The antimicrobial activity of the microemulsions was tested using the compendial method, observation of the kinetics of killing, and transmission electron microscopy (TEM) of microemulsion-exposed cultures of Pseudomonas aeruginosa PA01. These latter experiments on Ps. aeruginosa indicated distinct signs of membrane disruption. The results indicated that the microemulsions are self-preserved, and that their killing of microbial cultures is very rapid and may be the result of membrane activity.

Anti-Bacterial Agents↗
PubMed1995

Synthetic approaches and biological evaluation of some new sulfonate ester-containing quinazoline derivatives as potentially active antimicrobial agents.

Several sulfonate ester-containing quinazolinone derivatives that are substituted with, isolated or fused, aryl, hetaryl or hetarylphenyl ring systems were synthesized with a view to evaluate their efficacy as new bactericidal and/or fungicidal agents. Synthesis of these products involved prior preparation of the 2-[4'-(benzenesulfonyloxy)phenyl]-3,1- 4(H)-benzoxazin-4-one derivative (2) and subsequent reaction with several nitrogen nucleophiles. The structure of these products were established from elemental and spectral analyses. Most of the prepared compounds showed high antimicrobial activity, comparable to standard chemotherapeutic agents, when screened against different microorganisms.

4-Quinolones↗
PubMed1995

Potentially active antimicrobial agents from 2-benzenesulfonyloxyphenyl-3,1-benzoxazine-4-one derivative.

Fourteen of nitrogeneous heterocyclic compounds that accommodate the sulfonate-ester moiety were synthesized through interaction of 2-benzenesulfonylo xyphenyl-3,1-benzoxazine-4-one with some nucleophilic reagents. The assigned structures for the prepared new compounds were confirmed on the basis of elemental and spectral data. Evaluation of the antimicrobial activity of these products, relative to standard antibiotics was tested and discussed.

Anti-Bacterial Agents↗
PubMed1998

Biologically active polymers: synthesis and antimicrobial activity of modified glycidyl methacrylate polymers having a quaternary ammonium and phosphonium groups.

Polymers with antibacterial activity have been synthesized by chemical modification of poly(glycidyl methacrylate). The glycidyl methacrylate was polymerized by the free radical polymerization technique. The poly(glycidyl methacrylate) was hydrolyzed and was chloroacetylated using chloroacetyl chloride. The chloroacetylated product was modified to yield polymers with either quaternary ammonium or phosphonium salts. The antimicrobial activity of the modified glycidyl methacrylate polymers has been examined against a variety of test microorganisms by the cut plug and the viable cell counting methods using shake flask of ten times diluted nutrient broth medium. All three polymers obtained were inhibitory to the growth of Gram negative bacteria (Escherichia coli, Pseudomones aeruginosa, Shigella sp. and Salmonella typhae) and Gram positive bacteria (Bacillus subtilis and B. cereus) as well as the fungus (Trichophytun rubrum). It was found that the growth inhibitory effect varied according to the structure of the polymer and the composition of the active group and increased with increasing the concentration of the polymer. The tested polymers showed more antimicrobial activity against Gram negative bacteria and the fungus, whereas were less active against Gram positive bacteria.

Anti-Bacterial Agents↗
PubMed2005

Synthesis and antimicrobial activity of some novel derivatives of benzofuran: part 1. Synthesis and antimicrobial activity of (benzofuran-2-yl)(3-phenyl-3-methylcyclobutyl) ketoxime derivatives.

The reaction of salicylaldehyde with 1-phenyl-1-methyl-3-(2-chloro-1-oxoethyl) cyclobutane (1) and potassium carbonate was used to prepare (benzofuran-2-yl)(3-methyl-3-phenylcyclobutyl) methanone (2) for the starting reagent purposes. (benzofuran-2-yl)(3-phenyl-3-methyl cyclobutyl) ketoxime (3) was synthesized from the reaction of the compound (2) with hidroxylamine. New derivatives of (benzofuran-2-yl)(3-phenyl-3-methyl cyclobutyl) ketoxime (3) such as, O-glycidylketoxime (4) and O-phenylacylketoxime (5a-c) were obtained very high yields. Alkyl, allyl and aryl substituted N-oxime ethers (6a-e) were obtained from the reaction compound 3 and various halogen contained compounds. The syntheses of the compounds (7a-f) were carried out from the reaction of the compound (4) and different amines such as, isopropyl amine, natrium azide, morpholine and piperazine. All of the synthesized compounds were tested for antimicrobial activity against Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 8739, Klebsiella pneumoniae ATCC 4352, Pseudomonas aeruginosa ATCC 1539, Salmonella typhi, Shigella flexneri, Proteus mirabilis ATCC 14153 and Candida albicans ATCC 10231. Among the synthesized compounds (benzofuran-2-yl)(3-phenyl-3-methyl cyclobutyl)-O-[2-hydroxy-3-(N-methylpiperazino)] propylketoxime (7d) was found the most active derivative against S. aureus ATCC 6538. The compounds 2, 5b, 6b, 6c, 7b and 7f showed very strong and the same antimicrobial effect against C. albicans ATCC 10231. Similarly (benzofuran-2-yl)(3-phenyl-3-methylcyclobutyl)-O-benzylketoxime 6a showed good antimicrobial effect against C. albicans ATCC 10231. None of the other compounds exhibited activity against the other test microorganisms.

Anti-Infective Agents↗
PubMed2006

Human angiogenin lacks specific antimicrobial activity.

The antimicrobial activities of commercially available human angiogenin were studied against two pathogens, namely, Candida albicans and Streptococcus pneumoniae. In contrast to the data published earlier, antimicrobial action of angiogenin was rather limited and comparable to that of bovine serum albumin.

Animals↗
PubMed2003

C-terminal domain of a hevein-like protein from Wasabia japonica has potent antimicrobial activity.

An antimicrobial protein, designated WjAMP-1, was purified from leaves of Wasabia japonica L. WjAMP-1 showed antimicrobial activity against both fungi and bacteria. The deduced amino acid sequence of cDNA of WjAMP-1 showed 60% and 70% identity with a hevein from Hevea brasiliansis and a hevein-like protein from Arabidopsis thaliana, respectively. However, matured WjAMP-1 lacked the hevein domain and may correspond to the C-terminal domain of hevein. Southern blot analysis showed that one or two copies of the WjAMP-1 gene were presented in the genome of wasabi. Expression of WjAMP-1 was detected in all organs tested, and was especially strong in petioles. Expression of WjAMP-1 was induced by the inoculation with fungal pathogens and treatment with methyl jasmonate. Recombinant WjAMP-1 expressed in Nicotiana benthamiana using potato virus X vector also inhibited not only growth of fungi but also bacteria. These results suggest that WjAMP-1 may be the C-terminal domain of hevein and one of the defense gene in W. japonica. WjAMP-1 gene may be useful genes to generate resistant plants against fungal and bacterial pathogens.

Alternaria↗
PubMed1991

Pharmacological properties of Moringa oleifera. 1: Preliminary screening for antimicrobial activity.

The antimicrobial activities of Moringa oleifera leaves, roots, bark and seeds were investigated in vitro against bacteria, yeast, dermatophytes and helminths pathogenic to man. By a disk-diffusion method, it was demonstrated that the fresh leaf juice and aqueous extracts from the seeds inhibit the growth of Pseudomonas aeruginosa and Staphylococcus aureus and that extraction temperatures above 56 degrees C inhibited this activity. No activity was demonstrated against four other pathogenic Gram-positive and Gram-negative bacteria and Candida albicans. By a dilution method, no activity was demonstrated against six pathogenic dermatophytes. A method was standardized for studying the effect of aqueous extracts on Ascaris lumbricoides eggs, but no activity was exhibited by any part of the tree in contrast to Chenopodium ambrosioides leaf extracts.

Animals↗
PubMed1996

Screening of some Cuban medicinal plants for antimicrobial activity.

The antimicrobial activities of 23 extracts of 12 Cuban plant species reported in traditional medicine were tested. The agar diffusion method was used to assess the activity against four bacteria and one yeast: Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The results, evaluated as the diameter of the inhibition zone of microbial growth, showed that nine extracts were active against Gram-positive bacteria but only two of these proved to be also active against Gram-negative bacteria. None of the extracts inhibited the growth of the yeast. The most susceptible bacterium was Staphylococcus aureus and the best antibacterial activity was shown by Schinus terebenthifolius.

Anti-Bacterial Agents↗
PubMed1985

Antimicrobial activity, bacterial resistance, and antimicrobial pharmacology. Is it possible to use new agents cost-effectively?

Perusal of the various journals devoted to antimicrobial agents and to the chemotherapy of infectious diseases reveals an increasing number of articles devoted to the analysis of the pharmacology of antimicrobial agents and the relationships of antimicrobial activity and pharmacologic properties. However, most attention to the pharmacokinetic properties of antimicrobial agents in the past decade has focused on the toxic properties of these agents, and there has been little work devoted to improving methods of administration. The availability of nontoxic antibiotics that are extremely active at low concentrations and of agents with markedly extended half-lives should cause us to reevaluate some of our current dosing practices. In many ways, a major adverse influence on appropriate antimicrobial therapy of ordinary infections has been the febrile neutropenic patient. Lessons learned from the care of these patients are inappropriately applied to the treatment of other patients. The neutropenic patient requires frequent administration of antibiotics at maximally tolerated doses. Many patients at risk for infection do not require antimicrobial therapeutic programs in which the antibiotic always exceeds the minimal inhibitory concentration. Indeed, the concept that the drug must be present in the serum well above the minimal inhibitory concentration for the entire interval of infection is derived from studies of neutropenic patients infected with Pseudomonas aeruginosa. Increasing resistance of hospital-acquired bacteria to older antibacterial agents will alter the initial and subsequent selection of antimicrobial agent. Combination drug therapy, which has a prominent role in the neutropenic patient, frequently results in greater cost to the health care system than is seen with single agents that are active against resistant bacteria. There are clear areas in which new antibacterial agents will be beneficial. We may be at a stage in which use of the older agents can no longer be viewed as the best clinically and economically. Better use of twice- or once-daily dosing programs of new agents coupled with use of intramuscular and oral administration of antibiotics can help reduce nosocomial infections that contribute to rising health costs.

Anti-Bacterial Agents↗