RESUMO

The competitive colonization of bacteria on similar ecological niches has a significant impact during their establishment. The synthesis speeds of different chemical classes of molecules during early competitive colonization can reduce the number of competitors through metabolic effects. In this work, we demonstrate for the first time that Kosakonia cowanii Cp1 previously isolated from the seeds of Capsicum pubescens R. P. produced volatile organic compounds (VOCs) during competitive colonization against Pectobacterium aroidearum SM2, affecting soft rot symptoms in serrano chili (Capsicum annuum L.). The pathogen P. aroidearum SM2 was isolated from the fruits of C. annuum var. Serrano with soft rot symptoms. The genome of the SM2 strain carries a 5,037,920 bp chromosome with 51.46% G + C content and 4925 predicted protein-coding genes. It presents 12 genes encoding plant-cell-wall-degrading enzymes (PCDEWs), 139 genes involved in five types of secretion systems, and 16 genes related to invasion motility. Pathogenic essays showed soft rot symptoms in the fruits of C. annuum L., Solanum lycopersicum, and Physalis philadelphica and the tubers of Solanum tuberosum. During the growth phases of K. cowanii Cp1, a mix of VOCs was identified by means of HS-SPME-GC-MS. Of these compounds, 2,5-dimethyl-pyrazine showed bactericidal effects and synergy with acetoin during the competitive colonization of K. cowanii Cp1 to completely reduce soft rot symptoms. This work provides novel evidence grounding a better understanding of bacterial interactions during competitive colonization on plant tissue, where VOC synthesis is essential and has a high potential capacity to control pathogenic microorganisms in agricultural systems.

RESUMO

Aim: To evaluate antifungal potential of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine hybrids based on thiosemicarbazones and thiazolidinediones against pathogenic Sporothrix species. Methods: Antifungal activity of nine compounds were assessed by broth microdilution. Interactions between active compounds and itraconazole were evaluated by the checkerboard assay using non-wild-type isolates. Cytotoxicity of the compounds was determined. Results: Four C-3 substituted analogs showed antifungal activity, unrelated to thiosemicarbazone or thiazolidinedione functions. Synergistic interactions between the four compounds and itraconazole, and low toxicity on mouse fibroblast cells were observed. Activity of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine hybrids against Sporothrix depended on the substitution on the imidazopyrazine ring. Conclusion: Antifungal potential, overcoming itraconazole resistance and low toxicity indicate the possible use of that series of compounds in a therapeutic alternative for treatment of sporotrichosis.

Assuntos

RESUMO

Poly(ADP-ribosyl)polymerase (PARP) synthesizes poly(ADP-ribose) (PAR), which is anchored to proteins. PAR facilitates multiprotein complexes' assembly. Nuclear PAR affects chromatin's structure and functions, including transcriptional regulation. In response to stress, particularly genotoxic stress, PARP activation facilitates DNA damage repair. The PARP inhibitor Olaparib (OLA) displays synthetic lethality with mutated homologous recombination proteins (BRCA-1/2), base excision repair proteins (XRCC1, Polß), and canonical nonhomologous end joining (LigIV). However, the limits of synthetic lethality are not clear. On one hand, it is unknown whether any limiting factor of homologous recombination can be a synthetic PARP lethality partner. On the other hand, some BRCA-mutated patients are not responsive to OLA for still unknown reasons. In an effort to help delineate the boundaries of synthetic lethality, we have induced DNA damage in VERO cells with the radiomimetic chemotherapeutic agent bleomycin (BLEO). A VERO subpopulation was resistant to BLEO, BLEO + OLA, and BLEO + OLA + ATM inhibitor KU55933 + DNA-PK inhibitor KU-0060648 + LigIV inhibitor SCR7 pyrazine. Regarding the mechanism(s) behind the resistance and lack of synthetic lethality, some hypotheses have been discarded and alternative hypotheses are suggested.

Assuntos

RESUMO

The structures of a new hybrid terpyridine-pyrazine ligand, namely 4'-[4-(pyrazin-2-yl)phenyl]-4,2':6',4''-terpyridine (L2), C25H17N5, and its one-dimensional coordination polymer catena-poly[[bis(acetylacetonato-κ2O,O')zinc]-µ-4'-[4-(pyrazin-2-yl-κN4)phenyl]-4,2':6',4''-terpyridine-κN1], [Zn(C5H7O2)2(C25H17N5)]n or [Zn(acac)2(L2)]n (Hacac is acetylacetone), are reported. Packing interactions in both crystal structures are analyzed using Hirshfeld surface and enrichment ratio techniques. For the simpler structure of the monomeric ligand, further studies on the interaction hierarchy using the energy framework approach were made. The result was a complete picture of the intermolecular interaction landscape, which revealed some subtle details, for example, that some weak (at first sight negligible) C-H...N interactions in the structure of free L2 play a relevant role in the crystal stabilization.

RESUMO

Hybrid organic-inorganic materials have been seen as a promising approach to produce sensors for the detection and/or recognition of heterocyclic aromatic amines (HAAs). This work shows the synthesis of a hybrid film as a result of the incorporation of [Fe(CN)5(NH3)]3- into chitosan (CS); CS-[(CN)5Fe(NH3)]3-. The sensitivity of CS-[(CN)5Fe(NH3)]3- toward HAA-like species was evaluated by using pyrazine (pz) as probe molecule in vapor phase by means of electrochemistry and spectroscopic techniques. The crystallinity (SEM-EDS and XRD) decrease of CS-[(CN)5Fe(NH3)]3- in comparison to CS was assigned to the disturbance of the hydrogen bond network within the polymer. Such conclusion was reinforced by the water contact angle measurements. The results presented in this work indicate physical and intermolecular interactions, mostly hydrogen bond, between [Fe(CN)5(NH3)]3- and CS, where the complex is likely trapped in the polymer with its sixth coordination site available for substitution reactions.

Assuntos

RESUMO

A series of 11 pairs of substituted pyrazine N-oxides, differing in the substituent position, were examined using electrospray ionization mass spectrometry (ESI-MS) in order to use spectra to assess the differentiation of positional isomers. For each compound, mass spectra were recorded with three different metal cations, namely calcium (II), copper (II) and aluminum (III), with characterization of the observed peaks. Differentiation between regioisomeric N-oxides has been achieved by comparison of the identity and relative intensities of the peaks originating from the adduct ions formed with the metal ions. Principal component analysis (PCA) has been employed to assist in the interpretation of the results obtained with each metal ion, exploring possible trends according to the nature and position of the substituent in the pyrazine N-oxide.

Assuntos