Dihydroeugenol derivatives associated with blue LED light: A different form to face multidrug resistant (MDR) bacteria.

Eugenol has already had its pharmacological properties elucidated in previous studies, including antibacterial and antifungal properties. Based on such information, this study aimed to evaluate the antibacterial and modulatory activity of coumarin compounds prepared from dihydroeugenol and to associate them with blue LED light for the same activity. For this study, five of the substances available: compound 1 (C1), 8-methoxy-2-oxo-6-propyl-2H-chromen-3-carboxylic acid, compound (C2), 3-(hydroxy(4-nitrophenyl)methyl)-8- methoxy-6-propyl-2H-chromen-2-one, compound 7 (C3), 8-hydroxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one, compound 8 (C4), 3-(4-aminobenzoyl)-8-methoxy-6-propyl-2H-chromen-2-one and Compound 9 (C5), 8-methoxy-3-(4-nitrobenzoyl)-6-propyl-2H-chromen-2-one 2-one. To determine the MIC, the broth microdilution technique was used. The products were evaluated for their potential to modulate the activity of antibiotics. Afterward, the plates were submitted to blue LED light for 20 min. When exposed to LED, C3 exhibited a decrease in MIC for SA ATCC and C5 for EC ATCC, with an average of 645.08 µg/mL for both cases. C2 and C4 exhibited synergism in a greater number of situations. However, C3 showed promising activity against S. aureus. C1 and C2 already acted better against E. coli, with the difference that C1 acted better against these bacteria when associated with LED. In general, the compounds studied here exhibited good antibacterial activity when associated with LED.

Evaluation of the antibacterial and inhibitory activity of NorA and MepA efflux pumps from Staphylococcus aureus by diosgenin.

The increase in bacterial resistance to available antibiotics has driven several researchers to search for new agents with therapeutic properties. Diosgenin is a naturally occurring steroidal saponin that has demonstrated several pharmacological properties. In the present study, we report the antimicrobial activity of diosgenin against the standard and multidrug-resistant bacteria of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, in addition to the efflux pump inhibitory activity against Staphylococcus aureus strains carrying NorA and MepA pumps. For this purpose, the broth microdilution method was used, from which the value of the Minimum Inhibitory Concentration (MIC) was obtained, and this was associated with subinhibitory concentration (MIC/8) with antibiotic of clinical use and ethidium bromide for strains carrier by efflux pump. Diosgenin showed antimicrobial activity for standard S. aureus bacteria and potentiating activity in association with gentamicin and ampicillin for P. aeruginosa multidrug-resistant bacteria, it also showed potentiation in association with norfloxacin against the E. coli strain and gentamicin against the S. aureus strain. Antimicrobial activity against efflux pump-bearing strains revealed that saponin did not interfere with the efflux pump mechanism or intervened antagonistically. Thus, saponin has shown to be very promising against bacterial resistance in association with aminoglycoside, fluoroquinolones and beta-lactam, however additional studies should be carried out to better elucidate the mechanism of action of diosgenin.

Inhibition of the MepA efflux pump by limonene demonstrated by in vitro and in silico methods.

Bacterial resistance is a natural process carried out by bacteria, which has been considered a public health problem in recent decades. This process can be triggered through the efflux mechanism, which has been extensively studied, mainly related to the use of natural products to inhibit this mechanism. To carry out the present study, the minimum inhibitory concentration (MIC) tests of the compound limonene were performed, through the microdilution methodology in sterile 96-well plates. Tests were also carried out with the association of the compound with ethidium bromide and ciprofloxacin, in addition to the ethidium bromide fluorimetry, and later the molecular docking. From the tests performed, it was possible to observe that the compound limonene presented significant results when associated with ethidium bromide and the antibiotic used. Through the fluorescence emission, it was observed that when associated with the compound limonene, a greater ethidium bromide fluorescence was emitted. Finally, when analyzing the in silico study, it demonstrated that limonene can efficiently fit into the MepA structure. In this way, it is possible to show that limonene can contribute to cases of bacterial resistance through an efflux pump, so that it is necessary to carry out more studies to prove its effects against bacteria carrying an efflux pump and assess the toxicity of the compound.

Structural studies of a vasorelaxant lectin from Dioclea reflexa Hook seeds: Crystal structure, molecular docking and dynamics.

The three-dimensional structure of Dioclea reflexa seed lectin (DrfL) was studied in detail by a combination of X-ray crystallography, molecular docking and molecular dynamics. DrfL was purified by affinity chromatography using Sephadex G-50 matrix. Its primary structure was obtained by mass spectrometry, and crystals belonging to orthorhombic space group P212121 were grown by the vapor diffusion method at 293K. The crystal structure was solved at 1.765Å and was very similar to that of other lectins from the same subtribe. The structure presented Rfactor and Rfree of 21.69% and 24.89%, respectively, with no residues in nonallowed regions of Ramachandran plot. Similar to other Diocleinae lectins, DrfL was capable of relaxing aortic rings via NO induction, with CRD participation, albeit with low intensity (32%). In silico analysis results demonstrated that DrfL could strongly interact with complex N-glycans, components of blood vessel glycoconjugates. Despite the high similarity among Diocleinae lectins, it was also reported that each lectin has unique CRD properties that influence carbohydrate binding, resulting in different biological effects presented by these molecules.

A lectin from Dioclea violacea Interacts with midgut surface of Lutzomyia migonei, unlike its homologues, Cratylia floribunda lectin and Canavalia gladiata lectin.

Leishmaniasis is a vector-borne disease transmitted by phlebotomine sand fly. Susceptibility and refractoriness to Leishmania depend on the outcome of multiple interactions that take place within the sand fly gut. Promastigote attachment to sand fly midgut epithelium is essential to avoid being excreted together with the digested blood meal. Promastigote and gut sand fly surface glycans are important ligands in this attachment. The purpose of the present study was to evaluate the interaction of three lectins isolated from leguminous seeds (Diocleinae subtribe), D-glucose and D-mannose-binding, with glycans on Lutzomyia migonei midgut. To study this interaction the lectins were labeled with FITC and a fluorescence assay was performed. The results showed that only Dioclea violacea lectin (DVL) was able to interact with midgut glycans, unlike Cratylia floribunda lectin (CFL) and Canavalia gladiata lectin (CGL). Furthermore, when DVL was blocked with D-mannose the interaction was inhibited. Differences of spatial arrangement of residues and volume of carbohydrate recognition domain (CRD) may be the cause of the fine specificity of DVL for glycans in the surface on Lu. migonei midgut. The findings in this study showed the presence of glycans in the midgut with glucose/mannose residues in its composition and these residues may be important in interaction between Lu. migonei midgut and Leishmania.

Vasorelaxant activity of Canavalia grandiflora seed lectin: A structural analysis.

Lectins are comprised of a large family of proteins capable of the specific and reversible recognition of carbohydrates. Legume lectins, the most studied plant lectins, show high structural similarity, but with modifications that imply a variation in the intensity of some biological activities. In this work, the primary and tertiary structures of Canavalia grandiflora (ConGF) were determined. ConGF, a lectin isolated from C. grandiflora seeds, is able to induce relaxant activity in rat aortic rings. The complete sequence of ConGF comprises 237 amino acids. This particular protein has primary sequence variations commonly found in lectins from Dioclea and Canavalia genera. The protein structure was solved at 2.3 Å resolution by X-ray crystallography. An X-Man molecule was modeled into the carbohydrate recognition domain. Still, ConGF (30 and 100 µg mL(-1)) elicited 25% of vasorelaxation (IC50=34.48 ± 5.07 µg mL(-1)) in endothelialized aortic rings. A nonselective inhibitor of nitric oxide blocked ConGF relaxant effect, showing mediation by nitric oxide. Key distances between ConGF carbohydrate recognition domain residues were determined in order to explain this effect, in turn revealing some structural aspects that could differentiate lectins from the Canavalia genera with respect to different efficacy in vasorelaxant effect.

Purification, partial characterization and immobilization of a mannose-specific lectin from seeds of Dioclea lasiophylla mart.

Lectin from the seeds of Dioclea lasiophylla (DlyL) was purified in a single step by affinity chromatography on a Sephadex® G-50 column. DlyL strongly agglutinated rabbit erythrocytes and was inhibited by monosaccharides (D-mannose and α-methyl-D-mannoside) and glycoproteins (ovalbumin and fetuin). Similar to other Diocleinae lectins, DlyL has three chains, α, ß and γ, with mass of 25,569 ± 2, 12,998 ± 1 and 12,588 ± 1 Da, respectively, and has no disulfide bonds. The hemagglutinating activity of DlyL was optimal in pH 8.0, stable at a temperature of 70 °C and decreased in EDTA solution, indicating that lectin activity is dependent on divalent metals. DlyL exhibited low toxicity on Artemia sp. nauplii, but this effect was dependent on the concentration of lectin in solution. DlyL immobilized on cyanogen bromide-activated Sepharose® 4B bound 0.917 mg of ovalbumin per cycle, showing the ability to become a tool for glycoproteomics studies.

Homologous Canavalia lectins elicit different patterns of antinociceptive responses.

Canavalia gladiata (CGL), C. maritima (ConM) and C. brasiliensis (ConBr) lectins were evaluated in nociception models. ConBr inhibited first (32%) and second (100%) phases of the formalin test; CGL inhibited only the first (74%) and ConM only the second (59%) phase. Hypernociception evaluated in the Von Frey test was inhibited by ConM (55%), CGL (41%) and ConBr (38%). Acetic acid-induced abdominal writhing was reduced by ConBr (66%), CGL (52%) and ConM (60%). ConBr and CGL effects were reversed by the lectin association with its ligand sugar. The antinociceptive activity of the structural homologous lectins was differentiated by potency, efficacy and mechanisms.

Toxicity and binding profile of lectins from the Genus canavalia on brine shrimp.

Lectins are sugar-binding proteins widely distributed in nature with many biological functions. Although many lectins have a remarkable biotechnological potential, some of them can be cytotoxic. Thus, the aim of this study was to assess the toxicity of five lectins, purified from seeds of different species of Canavalia genus. In order to determine the toxicity, assays with Artemia nauplii were performed. In addition, a fluorescence assay was carried out to evaluate the binding of lectins to Artemia nauplii. In order to verify the relationship between the structure of lectins and their cytotoxic effect, structural analysis was carried out to evaluate the volume of the carbohydrate recognition domain (CRD) of each lectin. The results showed that all lectins exhibited different toxicities and bound to a similar area in the digestive tract of Artemia nauplii. Concerning the structural analysis, differences in spatial arrangement and volume of CRD may explain the variation of the toxicity exhibited by each lectin. To this date, this is the first study that establishes a link between toxicity and structure of CRD from Diocleinae lectins.

Purification and characterization of a mannose/N-acetyl-D-glucosamine-specific lectin from the seeds of Platymiscium floribundum Vogel.

Platymiscium floribundum lectin (PFL), a mannose/N-acetyl-D-glucosamine-specific lectin, was isolated from P. floribundum seeds using Sepharose-mannose affinity media chromatography. PFL is a glycoprotein that is a potent agglutinin for rabbit erythrocytes. In addition, PFL is highly stable because it is able to maintain its hemagglutinating activity after exposure to temperatures of up to 60 °C for 1 h and exposure to a wide pH range. The PFL purification process was monitored using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the results showed that the purified lectin consists of a single band with a molecular mass of approximately 29 kDa in either the presence or the absence of a reducing agent. The analysis of purified PFL by electrospray ionization-mass spectrometry showed that most ions had a molecular weight of 27,053 ± 2 Da, and other less abundant ions had similar molecular weights. Gel filtration shows that the lectin exists as a dimer in solution with mass at approximately 65 kDa. Sixteen peptides were sequenced, and as a result, a total of 130 amino acids were identified and resulted in a coverage of approximately 65% of the PFL sequence. The partial sequence of PFL was aligned with sequences of other lectins from evolutionarily related species, and PFL showed considerable similarity to the other lectins.

Protein crystal content analysis by mass spectrometry and preliminary X-ray diffraction of a lectin from Canavalia grandiflora seeds with modulatory role in inflammation.

RATIONALE: Lectins are a family of proteins capable of deciphering the glycan code. Several authors have published works about crystallization and mass spectrometry analyses of ConA-like lectins. However, mass spectrometry has never been used to characterize lectin crystal content. In this study, Canavalia grandiflora lectin (ConGF), a ConA-like lectin, was crystallized, part of its primary structure sequenced and the pro-inflammatory activity evaluated. In addition, the crystal content was analyzed by mass spectrometry. METHODS: ConGF was crystallized in the presence of X-Man by hanging-drop vapor diffusion at 293 K and the protein crystal content was analyzed by electrospray ionization in a SYNAPT HDMS mass spectrometer. Partial sequence was obtained by protein digestion with several proteolytic enzymes and the peptides sequenced by liquid chromatography/tandem mass spectrometry (LC/MS/MS). The pro-inflammatory potential of ConGF was also evaluated in the model of rat paw edema. RESULTS: The protein crystals consist of mature α chain and ß and γ fragments measuring 25 612 ± 2 Da, 12 962 ± 2 Da and 12 667 ± 2 Da, respectively. The crystal belongs to the orthorhombic space group I222 (unit cell parameters: a = 67.70, b = 55.90, c = 107.46 Å), assuming a monomer in the asymmetric unit. The solvent content was calculated as 43.50% and the protein content as 2.5 µg. Furthermore, a significant part of the primary structure (65.8%) was determined by mass spectrometry. CONCLUSIONS: As far as we know this is the first report of lectin crystal content characterized by mass spectrometry. Like other ConA-like lectins, GonGF induced paw edema however differing in potency and duration. The observed pro-inflammatory activity suggests that ConGF might be a useful tool in the study of inflammation processes and structure/function relationships.