Sub-MICs of Mentha piperita essential oil and menthol inhibits AHL mediated quorum sensing and biofilm of Gram-negative bacteria

Bacterial quorum sensing (QS) is a density dependent communication system that regulates the expression of certain genes including production of virulence factors in many pathogens. Bioactive plant extract/compounds inhibiting QS regulated gene expression may be a potential candidate as antipathogenic drug. In this study anti-QS activity of peppermint (Menthe piperita) oil was first tested using the Chromobacterium violaceum CVO26 biosensor. Further, the findings of the present investigation revealed that peppermint oil (PMO) at sub-Minimum Inhibitory Concentrations (sub-MICs) strongly interfered with acyl homoserine lactone (AHL) regulated virulence factors and biofilm formation in Pseudomonas aeruginosa and Aeromonas hydrophila. The result of molecular docking analysis attributed the QS inhibitory activity exhibited by PMO to menthol. Assessment of ability of menthol to interfere with QS systems of various Gram-negative pathogens comprising diverse AHL molecules revealed that it reduced the AHL dependent production of violacein, virulence factors, and biofilm formation indicating broad-spectrum anti-QS activity. Using two Escherichia colt biosensors, MG4/pKDT17 and pEAL08-2, we also confirmed that menthol inhibited both the las and pqs QS systems. Further, findings of the in vivo studies with menthol on nematode model Caenorhabditis elegans showed significantly enhanced survival of the nematode. Our data identified menthol as a novel broad spectrum QS inhibitor.

Estudo dos mecanismos de resistência e virulência de isolados de Cryptococcus neoformans e Cryptococcus gattii e quantificação de genes de bomba de efluxo pós tratamento com Galatos de Alquila

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fungitoxic non-glycosidic iridoids from Alibertia macrophylla

The aqueous alcohol extract of the leaves of Alibertia macrophylla afforded two epimeric pairs of iridoid aglycones and one of them showed high inhibitory activity against Aspergillus niger, Cladosporium sphaerospermum, C. cladosporioides and Colletotrichum gloesporioides. Three of the compounds are reported for the first time from natural sources. Their structures were established on the basis of spectroscopic studies, mainly through 13C NMR analysis. © 1992.

Caracterização dos compostos derivados de furoxano como inibidores da atividade de bombas de efluxo em Mycobacterium tuberculosis e estudo da influência do efluxo e da halotolerância nos perfis de resistência do bacilo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Allelopathic potential of Equisetum giganteum L. and Nephrolepis exaltata L. on germination and growth of cucumber and lettuce

Nephrolepis exaltata L. Schott "Bostoniensis" family Davalliaceae and Equisetum giganteum L. family Equisetaceae, Phylum Pteridophyta, exhibit a strong mechanism of dominance in the areas in which they live. Have secondary compounds with allelopathic activity. The objective of this article was evaluate allelopathic potential of two ferns species, using bioassay applying aqueous extracts of dried fronds, in cucumber and lettuce seeds, and observing germination and initial development. To observe the influence on germination was analyze the percentage of germinated seeds and germination speed index (GSI). To observe initial development was analyzed shoot and root growth of the seedlings. The bioassays revealed that no concentration significantly inhibited the germination, but germination speed was delayed gradually in two species tested, as increased the extract concentration. In initial development, all the extracts showed a tendency to inhibit the growth, and an increase in extract concentration decreasing growth of radicle and hypocotyl axis. We conclude that the aqueous extract has inhibitory activity more pronounced in early development than in seed germination, affecting the primary structures of the tested plants, corroborating with the observations of occurrences of the species in natural places where dominate and suppress the growth of other species.

Avaliação in vitro da eficácia de extratos de plantas medicinais do Cerrado frente Staphylococcus aureos isolado de difetentes fontes de propriedades leiteiras

The objective of this study is to evaluate the potencial microbial activity in-vitro from the extract of some endemic plants from Cerrado such as Baccharis dracunculifolia, Cochlospermum regium, Croton antisyphiliticus, Eugenia dysenterica and Lippia sidoides, against the agent Staphylococcus aureus isolated from bovine mastitic milk, osteo from cow’s teat, milker equipament, nasal cavitites and milker’s gullet. The extracts were prepared from aerial parts as well as the reticular systems of plants using the solvents methanol, hexane and chloroform at a concentration of 10%. To evaluate the antimicrobial activity, the technique of microdilution in broth was used for determining the Minimal Inibitory Concentration (MIC) followed by the determination of Minimal Bactericidal Concentration (MBC). The extracts from Baccharis dracunculifolia and Croton antisyphiliticus, followed by extracts from Lippia sidoides, reported respectively, presented better inhibitory activity against the multiplication of the bacteria Staphylococcus aureus. Furthermore, the results demonstrate that the isolated strains from the milk and nasal cavities of the milker showed strong resistance against gentamicin, active agent commonly applied to combat mastitis bovine. However, there was sensitivity against extracts from the reported plants, reinforcing the importance of the medicinal plants as a therapeutic resource and its aplicability.

Bioprospecção do fungo endofítico Hypoxylon investiens associado à alga marinha Asparagopsis taxiformis: potencial antifúngico, anticolinesterásico e antitumoral

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potencial do uso do ácido cafeico em formulações cosméticas: atividade antioxidante, atividade despigmentante e citotoxicidade

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Potencial do uso do ácido cafeico em formulações cosméticas: atividade antioxidante, atividade despigmentante e citotoxicidade

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antioxidant, anti-acetylcholinesterase and cytotoxic activities of ethanol extracts of peel, pulp and seeds of exotic Brazilian fruits Antioxidant, anti-acetylcholinesterase and cytotoxic activities in fruits

Ethanol extracts of powdered genipap (Genipa americana L), umbu (Spondia tuberosa A.) and siriguela (Spondia purpurea L) prepared from separate pulp, seeds and peel were investigated for their (i) antioxidant capacity, which was evaluated by various known methods; (ii) acetylcholinesterase (AChE) inhibitory activity; and (iii) cytotoxic effect on corneal epithelial cells of sheep. The highest values of total phenolic content were obtained with peel and seed extracts. Siriguela and umbu (seeds and peel) extracts displayed the highest antioxidant activities. Lipid peroxidation assays using mimetic biomembranes and mouse liver homogenates indicated that genipap pulp is a promising antioxidant. The investigation of phenols and organic acid contents revealed the presence of quercetin, citric and quinic acids, chlorogenic acid derivatives, among others, in several extracts, with the highest amount found in siriguela seeds. Genipap pulp and siriguela seed ethanol extracts presented an AChE inhibition zone similar to that of the positive control, carbachol. AChE inhibition assay with chlorogenic acid, one of the main constituents of siriguela seeds, revealed that this acid showed activity similar to that of the control physostigmine. These data suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries. (C) 2012 Elsevier Ltd. All rights reserved.

Design, synthesis and the effect of 1,2,3-triazole sialylmimetic neoglycoconjugates on Trypanosoma cruzi and its cell surface trans-sialidase

This work describes the synthesis of a series of sialylmimetic neoglycoconjugates represented by 1,4-disubstituted 1,2,3-triazole-sialic acid derivatives containing galactose modified at either C-1 or C-6 positions, glucose or gulose at C-3 position, and by the amino acid derivative 1,2,3-triazole fused threonine-3-O-galactose as potential TcTS inhibitors and anti-trypanosomal agents. This series was obtained by Cu(I)-catalysed azide-alkyne cycloaddition reaction ('click chemistry') between the azido-functionalized sugars 1-N(3)-Gal (commercial), 6-N(3)-Gal, 3-N(3)-Glc and 3-N(3)-Gul with the corresponding alkyne-based 2-propynyl-sialic acid, as well as by click chemistry reaction between the amino acid N(3)-ThrOBn with 3-O-propynyl-GalOMe. The 1,2,3-triazole linked sialic acid-6-O-galactose and the sialic acid-galactopyranoside showed high Trypanosoma cruzi trans-sialidase (TcTS) inhibitory activity at 1.0 mM (approx. 90%), whilst only the former displayed relevant trypanocidal activity (IC(50) 260 mu M). These results highlight the 1,2,3-triazole linked sialic acid-6-O-galactose as a prototype for further design of new neoglycoconjugates against Chagas' disease. (C) 2011 Elsevier Ltd. All rights reserved.

Pyridine Alkaloids from Senna multijuga As Acetylcholinesterase Inhibitors

As part of an ongoing research project on Senna and Cassia species, five new pyridine alkaloids, namely, 12'-hydroxy-7'-multijuguinol (1), 12'-hydroxy-8'-multijuguinol (2), methyl multijuguinate (3), 7'-multijuguinol (4), and 8'-multijuguinol (5), were isolated from the leaves of Senna multijuga (syn. Cassia multijuga). Their structures were elucidated on the basis of spectroscopic data analysis. Mass spectrometry was used for confirmation of the positions of the hydroxy groups in the side-chains of 1, 2, 4, and 5. All compounds exhibited weak in vitro acetylcholinesterase inhibitory activity as compared with the standard compound physostigmine.

Lactobacillus sakei 2a and its Concentrated Acid Extract on Inhibition of Food-Borne Salmonella strains

Lactic acid bacteria are used in food production to provide desirable organoleptic characteristics, and can also act as biopreservatives, controlling the growth of undesirable microorganisms. In this study, we examined the antimicrobial action of Lactobacillus sakei 2a and its concentrated acid extract against food-borne Salmonella spp. The extract was obtained by acid extraction from culture broth of L. sakei 2a and was designated extract 2a. We determined that extract 2a had significant activity (approximately 500 AU ml(-1)). We used different antimicrobial substances alone or in combination with extract 2a to evaluate the inhibitory activity of the various treatments on a pool of five Salmonella strains. The pathogen Listeria monocytogenes Scott A Cm-r Em(r) was used as an indicator strain of inhibitory activity. In summary, all antimicrobials substances that were tested showed an inhibitory effect against the growth of Salmonella, andthis action was enhanced in the presence of extract 2a. Moreover, among the treatments applied, the combination of extract 2a and 0.1% lactic acid exhibited the most potent inhibitory effect towards the pool of Salmonella strains. Our findings indicate that L. sakei 2a and extract 2a, especially in combination with other antimicrobials, present potential technological application in the control of salmonellae in foods.

A tellurium-based cathepsin B inhibitor: Molecular structure, modelling, molecular docking and biological evaluation

The crystallographically determined structure of biologically active 4,4-dichloro-1,3-diphenyl-4-telluraoct-2-en-1-one, 3, shows the coordination geometry for Te to be distorted psi-pentagonal bipyramidal based on a C2OCl3(lone pair) donor set. Notable is the presence of an intramolecular axial Te center dot center dot center dot O (carbonyl) interaction, a design element included to reduce hydrolysis. Raman and molecular modelling studies indicate the persistence of the Te center dot center dot center dot O(carbonyl) interaction in the solution (CHCl3) and gasphases, respectively. Docking studies of 3' (i.e. original 3 less one chloride) with Cathepsin B reveals a change in the configuration about the vinyl C = C bond. i.e. to E from Z (crystal structure). This isomerism allows the optimisation of interactions in the complex which features a covalent Te-SGCys29 bond. Crucially, the E configuration observed for 3' allows for the formation of a hypervalent Te center dot center dot center dot O interaction as well as an O center dot center dot center dot H-O hydrogen bond with the Gly27 and Glu122 residues, respectively. Additional stabilisation is afforded by a combination of interactions spanning the S1, S2, S1' and S2' sub-sites of Cathepsin B. The greater experimental inhibitory activity of 3 compared with analogues is rationalised by the additional interactions formed between 3' and the His110 and His111 residues in the occluding loop, which serve to hinder the entrance to the active site. (C) 2012 Elsevier B.V. All rights reserved.

Characterization of suramin binding sites on the human group IIA secreted phospholipase A(2) by site-directed mutagenesis and molecular dynamics simulation

Suramin is a polysulphonated naphthylurea with inhibitory activity against the human secreted group IIA phospholipase A(2) (hsPLA2GIIA), and we have investigated suramin binding to recombinant hsPLA2GIIA using site-directed mutagenesis and molecular dynamics (MD) simulations. The changes in suramin binding affinity of 13 cationic residue mutants of the hsPLA2GIIA was strongly correlated with alterations in the inhibition of membrane damaging activity of the protein. Suramin binding to hsPLA2GIIA was also studied by MD simulations, which demonstrated that altered intermolecular potential energy of the suramin/mutant complexes was a reliable indicator of affinity change. Although residues in the C-terminal region play a major role in the stabilization of the hsPLA2GIIA/suramin complex, attractive and repulsive hydrophobic and electrostatic interactions with residues throughout the protein together with the adoption of a bent suramin conformation, all contribute to the stability of the complex. Analysis of the h5PLA2GIIA/suramin interactions allows the prediction of the properties of suramin analogues with improved binding and higher affinities which may be candidates for novel phospholipase A(2) inhibitors. (C) 2012 Elsevier Inc. All rights reserved.