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There has been growing effort in the scientific community to develop new antibiotics to address the major threat of bacterial resistance. One promising approach is the use of metal complexes that provide broader opportunities. Among these systems, polypyridine-ruthenium(II) complexes have received particular attention as drug candidates. Here, we prepared two new ruthenium(II) complexes with the formulation [Ru(DFO)(phtpy-R)Cl](PF 6 ), where phtpy = 4'-phenyl-2,2':6',2''-terpyridine; R = -H(MPD1), -CH 3 (MPD2); and DFO = 4,5-diazafluoren-9-one, and investigated their chemical, biochemical and antibacterial activities. These compounds exhibit photoreactivity and produce reactive oxygen species (ROSs). Photogeneration of singlet oxygen ( 1 O 2 ) was measured in acetonitrile with significant quantum yields using blue light, Φ = 0.40 and 0.39 for MDP1 and MPD2, respectively. Further studies have shown that MPD1 and MPD2 can generate superoxide radicals. Antibacterial assays demonstrated a significant enhancement in MIC (minimum inhibitory concentration) upon blue light irradiation (>32-fold), with MICs of 15.6 μg mL -1 ( S. aureus , ATCC 700698) and 3.9 μg mL -1 ( S. epidermidis , ATCC 35984) for both metal complexes. Interestingly, an MIC of 15.6 μg mL -1 for MPD1 and MPD2 was observed against S. epidermidis ATCC 12228 under red light irradiation. The latter results are encouraging, considering that red light penetrates deeper into the skin. In addition, no significant cytotoxicity was observed in some mammalian cells, even upon light irradiation, supporting their potential safety. Altogether, these data show evidence of the potential use of these compounds as antimicrobial photodynamic therapeutic agents, enriching our arsenal to combat this worldwide bacterial threat.

In this study, we purified a lectin isolated from the seeds of Dioclea bicolor (DBL) via affinity purification. Electrophoresis analysis revealed that DBL had three bands, α, β, and γ chains, with molecular masses of approximately 29, 14, and 12 kDa, respectively. Gel filtration chromatography revealed that the native form of DBL had a molecular mass of approximately 100 kDa, indicating that it is a tetramer. Interestingly, DBL-induced hemagglutination was inhibited by several glucosides, mannosides, ampicillin, and tetracycline with minimum inhibitory concentration (MIC) values of 1.56-50 mM. Analysis of the complete amino acid sequence of DBL revealed the presence of 237 amino acids with high similarity to other Diocleinae lectins. Circular dichroism showed the prominent β-sheet secondary structure of DBL. Furthermore, DBL structure prediction revealed a Discrete Optimized Protein Energy (DOPE) score of -26,642.69141/Normalized DOPE score of -1.84041. The DBL monomer was found to consist a β-sandwich based on its 3D structure. Molecular docking showed the interactions between DBL and α-D-glucose, N-acetyl-D-glucosamine, α-D-mannose, α-methyl-D-mannoside, ampicillin, and tetracycline. In addition, DBL showed antimicrobial activity with an MIC of 125 μg/mL and exerted synergistic effects in combination with ampicillin and tetracycline (fractional inhibitory concentration index ≤ 0.5). Additionally, DBL significantly inhibited biofilm formation and showed no toxicity in murine fibroblasts (p < 0.05). These results suggest that DBL exhibits antimicrobial activity and works synergistically with antibiotics., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Oxidative stress on cysteine (Cys)-containing proteins has been associated with physiological disorders, as suggested for the human cofilin-1 (CFL-1) protein, in which the oxidized residues are likely implicated in the aggregation process of α-synuclein, leading to severe neuronal injuries. Considering the relevance of the oxidation state of cysteine, quantification of thiols may offer a guide for the development of effective therapies. This work presents, for the very first time, thiol quantification within CFL-1 in solution and on the surface following classic and adapted versions of Ellman's assay. The 1:1 stoichiometric Ellman's reaction occurs between 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB), and the free thiol of the cysteine residue, producing two 2-nitro-5-thiobenzoate (TNB 2- ) ions, one of which is released into the medium. While in solution, the thiol concentration was determined by the absorbance of the released TNB 2- , on the surface, the mass of the attached TNB 2- ion to the protein allowed the quantification by means of the multiparametric surface plasmon resonance (MP-SPR) technique. The SPR angle change after the interaction of DTNB with immobilized CFL-1 gave a surface coverage of 26.5 pmol cm -2 for the TNB 2- ions (Γ TNB2- ). The ratio of this value to the surface coverage of CFL-1, Γ CFL-1 = 6.5 ± 0.6 pmol cm -2 (also determined by MP-SPR), gave 4.1 as expected for this protein, i.e., CFL-1 contains four Cys residues in its native form (reduced state). A control experiment with adsorbed oxidized protein showed no SPR angle change, thus proving the reliability of adapting Ellman's assay to the surface using the MP-SPR technique. The results presented in this work provide evidence of the heterogenization of Ellman's assay, offering a novel perspective for studying thiol-containing species within proteins. This may be particularly useful to ensure further studies on drug-like molecules that can be carried out with validated oxidized or reduced CFL-1 or other analogous systems.

Health care-associated infections (HAIs) contribute to a significant rate of morbidity, mortality, and financial burden on health systems. These infections are caused by multidrug-resistant bacteria that produce biofilm as the main virulence factor. This study aimed to evaluate the effect of the copper-based metallic compounds [Cu(phen)(pz)NO 2 ]Cl (I), [Cu(bpy)(pz)(NO 2 )]Cl (II), and [Cu(phen)(INA)NO 2 ]Cl (III), where phen = phenanthroline, bpy = bipyridine, pz = pyrazinamide, and INA = isonicotinic acid, against planktonic cells and biofilms formation of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. The susceptibility of the microorganisms was evaluated by minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), and time-kill curve assay on planktonic cells. The biofilm formation was evaluated by biomass quantification through staining with crystal violet (CV), colony-forming units (CFUs) quantification, and biofilm metabolic activity determination by XTT assay. The compounds showed bacteriostatic and bactericidal activity on all microorganisms analyzed. Regarding the antibiofilm activity, all metallic compounds were able to reduce significantly the biofilm biomass, colony-forming units, and the metabolic activity of remaining cells, varying the efficient concentration according to the strain analyzed. Interestingly, compounds (I), (II) and (III) did not exhibit DNA degradation activity even with up to 100 µM of these metal complexes. On the other hand, complexes (I) and (III) showed a remarkable capacity to cleave DNA upon addition of glutathione, a reducing agent (Cu II /Cu I ) that leads to reactive oxygen species (ROS) formation. The results presented in this study showed promising antimicrobial and antibiofilm effects., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Tuberculosis is one of the oldest known infectious diseases, responsible for millions of deaths annually around the world. The ability of Mycobacterium tuberculosis (Mtb) to enter into a dormant state has been considered integral to the success of this bacterium as a human pathogen. One of the key systems involved in regulating the entrance into dormancy is the differentially expressed in virulent strain sensor protein (DevS) [(dormancy survival sensor protein (DosS)]. However, the physiological signal for DevS has remained unclear since it was first shown to be a heme-based sensor with conflicting reports on whether it is a redox or an oxygen sensor. To address this question and provide a better understanding of the electronic properties of this protein, we present here, for the first time, a series of spectroelectrochemistry measurements of the full-length holo DevS in anaerobic conditions as well as bound to CO, NO, imidazole (Imz), cyanide, and O 2 . An interesting feature of this protein is its ability to bind Imz even in the ferrous state, implying small-molecule analogues could be designed as potential regulators. Nonetheless, a midpoint potential (E m ) value of +10 mV [vs normal hydrogen electrode (NHE)] for DevS as measured under anaerobic conditions is much higher than the expected cytosolic potential for Mtb or even within stimulated macrophages (~ -270 mV vs NHE), indicating this sensor works in a reduced ferrous state. These data, along with the high oxygen affinity and very slow auto-oxidation rate of DevS, provides evidence that it is not a redox sensor. Overall, this study validates the biological function of DevS as an oxygen sensor directly involved in the dormancy/latency of Mtb., (© 2019 Federation of European Biochemical Societies.)

Complexes with general formula [RuCl(η6-p-cymene)(P-NR-P)]X (R = CH2Py (Py = pyridine) - [1a]+, CH2Ph (Ph = phenyl) - [1b]+, Ph - [1c] and p-tol (p-tol = p-tolyl) - [1d]+; X = PF6- or BF4-) were evaluated as cytotoxic agents against two cancer cell lines (HeLa and MDA-MB-231). All metal complexes are active in the range of concentrations tested (up to 100 μmol L-1). The IC50 (μmol L-1) values for the metal complexes are lower than that found for cisplatin. The activities are up to 6- and 15-fold higher than cisplatin for HeLa and MDA-MB-231 cancer cell lines, respectively. Studies of DNA binding and DNA cleavage were performed. DNA binding studies revealed a modest hypochromic shift in the metal complexes electronic spectra, indicating a weak interaction with Kb values in the range of 1.7 × 103-1.6 × 104. Although the cleavage tests revealed that in the dark DNA is not a biological target for these metal complexes, upon blue light irradiation they are activated causing DNA cleavage. Electrochemical studies showed the presence of two independent redox processes, one attributed to the oxidation process of Ru2+ → Ru3+ (EC process) and the other one to the reduction of Ru2+ → Ru1+, which is further reduced to Ru0 (ECE mechanism). In both processes, coupled chemical reactions were observed. DFT calculations were performed to support the electrochemical/chemical behavior of the complexes. The reactivity of complex [1b]BF4 with CH3CN was evaluated and two complexes were isolated [2b]BF4 and [3b]BF4. The complex mer-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4 ([2b]BF4) was isolated after refluxing the precursor [1b]BF4 in CH3CN. Isomerization of [2b]BF4 in CH3CN resulted in the formation of fac-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4. An attempt to isolate the fac-isomer by adding diethyl ether was unsuccessful, and the complex [3b]BF4 was observed as the major component. The complex [Ru2(μ-Cl3)(CH3CN)2(P-NCH2Ph-P)2]BF4 ([3b]BF4) proved to be very stable and can be obtained from both the mer- and the fac-isomers. The molecular structures of [1b]BF4 and [3b]BF4 were solved by single-crystal X-ray diffraction.

The cis-[Ru(bpy) 2 (Met)](PF 6 ) 2 complex, where Met = L-methionine and bpy = 2,2'-bipyridine, was prepared and fully characterized. This complex was subjected to blue and green light photolysis (453 and 505 nm, respectively) in aqueous solution, leading to the release of methionine and formation of the cis-[Ru(bpy) 2 (H 2 O) 2 ] 2+ ion. This latter photoproduct was shown to subsequently interact with DNA, while DNA photocleavage was noticed. In agreement with these reactivities, this compound exhibited an exciting antibacterial action, particularly against Gram-positive bacteria Staphylococcus aureus and Staphylococcus epidermidis, which was enhanced upon blue light irradiation. Altogether, these results showed that our strategy was successful in producing light-triggered DNA-binding agents with pharmacological potential and a likely blocking reagent for efficient peptide chemistry formation.

The aim of this study was to investigate the antibacterial activity, antibiotic-associated synergy, and anti-biofilm activity of the ruthenium complex, cis -[RuCl 2 (dppb) (bqdi)] 2+ (RuNN). RuNN exhibited antimicrobial activity against Gram-positive bacteria with minimum inhibitory concentration (MIC) values ranging from 15.6 to 62.5 µg ml -1 and minimum bactericidal concentration (MBC) values ranging from 62.5 to 125 µg ml -1 . A synergistic effect against Staphylococcus spp. was observed when RuNN was combined with ampicillin, and the range of associated fractional inhibitory concentration index (FICI) values was 0.187 to 0.312. A time-kill curve indicated the bactericidal activity of RuNN in the first 1-5 h. In general, RuNN inhibited biofilm formation and disrupted mature biofilms. Furthermore, RuNN altered the cellular morphology of S. aureus biofilms. Further, RuNN did not cause hemolysis of erythrocytes. The results of this study provide evidence that RuNN is a novel therapeutic candidate to treat bacterial infections caused by Staphylococcus biofilms.

A major challenge to the control and eventual eradication of Mycobacterium tuberculosis infection is this pathogen's prolonged dormancy. The heme-based oxygen sensor protein DevS (DosS) plays a key role in this phenomenon, because it is a major activator of the transcription factor DevR. When DevS is active, its histidine protein kinase region is ON and it phosphorylates and activates DevR, which can induce the transcription of the dormancy regulon genes. Here, we have investigated the mechanism by which the ligation of molecular oxygen to a heme-binding domain in DevS switches OFF its histidine protein kinase region. To shed light on the oligomerization states of this protein and possible protein-surfaces of interaction, we used analytical gel filtration, together with dynamic light scattering, fluorescence spectroscopy and chemical crosslinking. We found that DevS exists as three major species: an octamer, a tetramer and a dimer. These three states were observed for the concentration range between 0.5 and 20 μm DevS, but not below 0.1 μm. Levels of DevS in M. tuberculosis are expected to range from 5 to 26 μm. When this histidine protein kinase was OFF, the DevS was mainly tetrameric and dimeric; by contrast, when the kinase was ON, the protein was predominantly octameric. The changes in quaternary structure were rapid upon binding to the physiological signal. This finding represents a novel strategy for switching the activity of a two-component heme-based sensor. An enhanced understanding of this process might potentially lead to the design of novel regulatory agents that target the multimer interfaces for treatment of latent tuberculosis., (© 2018 Federation of European Biochemical Societies.)

Brazil has one of the largest biodiversities in the world. The search for new natural products extracted from the Brazilian flora may lead to the discovery of novel drugs with potential to treat infectious and other diseases. Here, we have investigated 9 lectins extracted and purified from the Northeastern Brazilian flora, from both leguminous species: Canavalia brasiliensis (ConBr), C. maritima (ConM), Dioclea lasiocarpa (DLasiL) and D. sclerocarpa (DSclerL), and algae Amansia multifida (AML), Bryothamniom seaforthii (BSL), Hypnea musciformis (HML), Meristiella echinocarpa (MEL) and Solieria filiformis (SfL). They were exposed to a panel of 18 different viruses, including HIV and influenza viruses. Several lectins showed highly potent antiviral activity, often within the low nanomolar range. DSclerL and DLasiL exhibited EC 50 values (effective concentration of lectin required to inhibit virus-induced cytopathicity by 50%) of 9 nM to 46 nM for HIV-1 and respiratory syncytial virus (RSV), respectively, DLasiL also inhibited feline corona virus at an EC 50 of 5 nM, and DSclerL, ConBr and ConM showed remarkably low EC 50 values ranging from 0.4 to 6 nM against influenza A virus strain H3N2 and influenza B virus. For HIV, evidence pointed to the blockage of entry of the virus into its target cells as the underlying mechanism of antiviral action of these lectins. Overall, the most promising lectins based on their EC 50 values were DLasiL, DSclerL, ConBr, ConM, SfL and HML. These novel findings indicate that lectins from the Brazilian flora may provide novel antiviral compounds with therapeutic potential.

Nitric oxide has been involved in many key biological processes such as vasodilation, platelet aggregation, apoptosis, memory function, and this has drawn attention to the development of exogenous NO donors. Metallonitrosyl complexes are an important class of these compounds. Here, two new ruthenium nitrosyl complexes containing a thiocarbonyl ligand, with the formula cis-[Ru(phen) 2 (L)(NO)](PF 6 ) 3 (phen = phenantroline, L = thiourea or thiobenzamide), were synthesized and characterized by electronic spectroscopy, FTIR, NMR , mass spectrometry and voltammetric techniques. Theoretical calculations using Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) were also used and further supported the characterizations of these complexes. An efficient release of nitric oxide by blue light was validated using a NO/HNO probe: 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, known as cPTIO. Interestingly, the complex containing thiourea cleaved DNA even in the dark, while both complexes showed great DNA photocleavage activity in blue light. This process might work mainly through NO and hydroxyl radical production. Additionally, these complexes showed promising vasodilator activity, whose mechanism of action was investigated using N-Nitro-l-arginine methyl ester hydrochloride (L-NAME) and 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and compared to sodium nitroprusside. Both compounds were indeed NO-mediated heme-dependent activators of soluble guanylate cyclase. Additionally, they did not show any significant cytotoxicity against cancer cell lines U87 and GBM02. Altogether, these results supported both complexes having potential pharmacological applications that deserve further studies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The lectin DLasiL was isolated from seeds of the Dioclea lasiocarpa collected from the northeast coast of Brazil and characterized for the first time by mass spectrometry, DNA sequencing, inductively coupled plasma-mass spectrometry, electron paramagnetic resonance, and fluorescence spectroscopy. The structure of DLasiL lectin obtained by homology modelling suggested strong conservation of the dinuclear Ca/Mn and sugar-binding sites, and dependence of the solvent accessibility of tryptophan-88 on the oligomerisation state of the protein. DLasiL showed highly potent (low nanomolar) antiproliferative activity against several human carcinoma cell lines including A2780 (ovarian), A549 (lung), MCF-7 (breast) and PC3 (prostate), and was as, or more, potent than the lectins ConBr (Canavalia brasiliensis), ConM (Canavalia maritima) and DSclerL (Dioclea sclerocarpa) against A2780 and PC3 cells. Interestingly, DLasiL lectin caused a G2/M arrest in A2780 cells after 24h exposure, activating caspase 9 and delaying the on-set of apoptosis. Confocal microscopy showed that fluorescently-labelled DLasiL localized around the nuclei of A2780 cells at lectin doses of 0.5-2× IC 50 and gave rise to enlarged nuclei and spreading of the cells at high doses. These data reveal the interesting antiproliferative activity of DLasiL lectin, and suggest that further investigations to explore the potential of DLasiL as a new anticancer agent are warranted., (Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.)

Ruthenium polypyridine complexes have shown promise as agents for photodynamic therapy (PDT) and tools for molecular biology (chromophore-assisted light inactivation). To accomplish these tasks, it is important to have at least target selectivity and great reactive oxygen species (ROS) photogeneration: two properties that are not easily found in the same molecule. To prepare such new agents, we synthesized two new ruthenium complexes that combine an efficient DNA binding moiety (dppz ligand) together with naphthyl-modified (1) and anthracenyl-modified (2) bipyridine as a strong ROS generator bound to a ruthenium complex. The compounds were fully characterized and their photophysical and photochemical properties investigated. Compound 2 showed one of the highest quantum yields for singlet oxygen production ever reported (Φ Δ = 0.96), along with very high DNA binding (log K b = 6.78). Such photochemical behavior could be ascribed to the lower triplet state involving the anthracenyl-modified bipyridine, which is associated with easier oxygen quenching. In addition, the compounds exhibited moderate selectivity toward G-quadruplex DNA and binding to the minor groove of DNA, most likely driven by the pendant ligands. Interestingly, they also showed DNA photocleavage activity even upon exposure to a yellow light-emitting diode (LED). Regarding their biological activity, the compounds exhibited an exciting antibacterial action, particularly against Gram-positive bacteria, which was enhanced upon blue LED irradiation. Altogether, these results showed that our strategy succeeded in producing light-triggered DNA binding agents with pharmacological and biotechnological potential.

FixL from Rhizobium etli (ReFixL) is a hybrid oxygen sensor protein. Signal transduction in ReFixL is effected by a switch off of the kinase activity on binding of an oxygen molecule to ferrous heme iron in another domain. Cyanide can also inhibit the kinase activity upon binding to the heme iron in the ferric state. The unfolding by urea of the purified full-length ReFixL in both active pentacoordinate form, met-FixL(Fe III ) and inactive cyanomet-FixL (Fe III -CN - ) form was monitored by UV-visible absorption spectroscopy, circular dichroism (CD) and fluorescence spectroscopy. The CD and UV-visible absorption spectroscopy revealed two states during unfolding, whereas fluorescence spectroscopy identified a three-state unfolding mechanism. The unfolding mechanism was not altered for the active compared to the inactive state; however, differences in the ΔG H2O were observed. According to the CD results, compared to cyanomet-FixL, met-FixL was more stable towards chemical denaturation by urea (7.2 vs 4.8kJmol -1 ). By contrast, electronic spectroscopy monitoring of the Soret band showed cyanomet-FixL to be more stable than met-FixL (18.5 versus 36.2kJmol -1 ). For the three-state mechanism exhibited by fluorescence, the ΔG H2O for both denaturation steps were higher for the active-state met-FixL than for cyanomet-FixL. The overall stability of met-FixL is higher in comparison to cyanomet-FixL suggesting a more compact protein in the active form. Nonetheless, hydrogen bonding by bound cyanide in the inactive state promotes the stability of the heme domain. This work supports a model of signal transduction by FixL that is likely shared by other heme-based sensors., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Two new metal complexes containing the ligand thiobenzamide (TBz), with the formula cis-[RuCl(TBz)(L)2]PF6, where L = 2,2'-bipyridine (bpy) or o-phenanthroline (phen), were synthesized and characterized by cyclic voltammetry and spectroscopic techniques (UV–Vis, IR, 1H and 13C NMR). These compounds showed cytotoxic activity in all cancer cell lines studied. The HL-60 strain was the most sensitive to both metal complexes, with IC50 ranging from 1.5 µmol L−1 to 5.7 µmol L−1. Interestingly, [RuCl(TBz)(bpy)2]PF6 exhibited a significant selectivity index of 6.6 for the cytotoxicity ratio between normal cells (MRC-5) and cancer cells (HL-60). In addition, this metal complex promoted mitochondrial membrane depolarization and increased mitochondrial superoxide production. Finally, synergism was observed between [RuCl(TBz)(bpy)2]PF6 and doxorubicin in combination against a cell model with HL-60 cells. A combinatorial index of 0.27 was observed in this study. In addition, an isobologram study showed points below the isobolographic line, indicating a synergistic effect. These results show promising pharmacological potential for these compounds which deserve further biological investigation. [ABSTRACT FROM AUTHOR]

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Symbiotic nitrogen fixation (SNF) by rhizobium, a Gram-negative soil bacterium, is an essential component in the nitrogen cycle and is a sustainable green way to maintain soil fertility without chemical energy consumption. SNF, which results from the processes of nodulation, rhizobial infection, bacteroid differentiation and nitrogen-fixing reaction, requires the expression of various genes from both symbionts with adaptation to the changing environment. To achieve successful nitrogen fixation, rhizobia and their hosts cooperate closely for precise regulation of symbiotic genes, metabolic processes and internal environment homeostasis. Many researches have progressed to reveal the ample information about regulatory aspects of SNF during recent decades, but the major bottlenecks regarding improvement of nitrogen-fixing efficiency has proven to be complex. In this mini-review, we summarize recent advances that have contributed to understanding the rhizobial regulatory aspects that determine SNF efficiency, focusing on the coordinated regulatory mechanism of symbiotic genes, oxygen, carbon metabolism, amino acid metabolism, combined nitrogen, non-coding RNAs and internal environment homeostasis. Unraveling regulatory determinants of SNF in the nitrogen-fixing protagonist rhizobium is expected to promote an improvement of nitrogen-fixing efficiency in crop production. [ABSTRACT FROM AUTHOR]

Solieria spp. (Solieriaceae, Gigartinales, Rhodophyta) can be found in various habitats ranging from the marine environment to low-salinity estuarine environments. Of the commercially exploited carrageenophytes, some of the most abundant belong to the Solieriaceae family as, Kappaphycus, Eucheuma and Solieria. The supply of these seaweeds is ensured by their mastered culture and by large quantities of stranded wild seaweeds which are harvested. Rich in carrageenans, i.e., in linear sulfated galactans, these red macroalgae are widely used for their gelling, thickening, and stabilizing properties in food, cosmetic, or pharmaceutical industries. In addition, Solieria spp. provide scientific potential as a model for the development of cultures in Integrated Multitrophic Aquaculture (IMTA), for innovation in extraction and purification processes and in biorefineries to access to bioactive compounds. The genus Solieria was described using the species Solieria chordalis as the type species in 1842. Today, this species is found in large quantities on the beaches of the western Atlantic just like Solieria filiformis found on the other side of the Ocean on some beaches in Mexico. Due to its abundance, several scientific teams from France and from Mexico study these algae with high potential in nutrition, health and for environmental applications. Eight other species of the genus Solieria have been inventoried, the last one in 2018. Nevertheless, their abundance is lower as well as the number of scientific studies mentioning them. Therefore, in this review, we focus on the biology, ecophysiology, biochemical composition, and applications of Solieria spp. based mainly on the two species widely studied, namely Solieria chordalis and Solieria filiformis. [ABSTRACT FROM AUTHOR]

The Dalbergieae lectin group encompasses several lectins with significant differences in their carbohydrate specificities and biological properties. The current work reports on the purification and characterization of a GalNAc/Gal-specific lectin from Vataireopsis araroba (Aguiar) Ducke, designated as VaL. The lectin was purified from the seeds in a single step using guar gum affinity chromatography. The lectin migrated as a single band of about 35 kDa on SDS-PAGE and, in native conditions, occurs as a homodimer. The purified lectin is stable at temperatures up to 60 °C and in a pH range from 7 to 8 and requires divalent cations for its activity. Sugar-inhibition assays demonstrate the lectin specificity towards N-acetyl-D-galactosamine, D-galactose and related sugars. Furthermore, glycan array analyses show that VaL interacts preferentially with glycans containing terminal GalNAc/Galβ1-4GlcNAc. Biological activity assays were performed using three insect cell lines: CF1 midgut cells from the spruce budworm Choristoneura fumiferana, S2 embryo cells from the fruit fly Drosophila melanogaster, and GutAW midgut cells from the corn earworm Helicoverpa zea. In vitro assays indicated a biostatic effect for VaL on CF1 cells, but not on S2 and GutAW cells. The lectin presented a biostatic effect by reducing the cell growth and inducing cell agglutination, suggesting an interaction with glycans on the cell surface. VaL has been characterized as a galactoside-specific lectin of the Dalbergieae tribe, with sequence similarity to lectins from Vatairea and Arachis. [ABSTRACT FROM AUTHOR]

The designing of efficient macrocyclic complexes for the alteration in nucleic acids and understanding is still in debate. Herein, to study the deoxyribonucleic acid (DNA) interaction with MN5-complexes, two macrocyclic complexes, A (MnII) and B (FeII), have been synthesized and characterized using multiple analytical techniques. The electronic absorption, fluorescence, and electrochemical methods were utilized to examine the binding ability of both complexes with calf thymus-DNA (ct-DNA). The spectral results were found to be in good agreement with the interaction of both complexes with ct-DNA, as also supported by the remarkable decrease in both anodic peak current (ipa) and cathodic peak current (ipc) during cyclic voltammetric analysis in the presence of ct-DNA. The spectral investigations clearly indicated the higher binding affinity of complex A as compared to complex B towards ct-DNA. Additionally, both complexes were also found to be potential antibacterial agents. [ABSTRACT FROM AUTHOR]

Lectins participate in the defense against microorganisms and in signaling the damage caused by pathogens to the cell surface and/or intracellular in plants. This study aims to analyze the antifungal potential of lectins extracted from seeds of Canavalia ensiformis (L.) DC and Canavalia rosea (Sw.) DC, against Candida albicans and Candida tropicalis. The antimicrobial tests were performed by microdilution against Candida spp. The test to verify the combined lectin/fluconazole effect was performed using subinhibitory concentrations of lectins and with antifungal ranging from 0.5 to 512 µg/mL. The ability to inhibit the morphological transition of Candida spp. was evaluated by microcultivation in a moist chamber. The results of the minimum inhibitory concentration revealed no antifungal activity against the tested strains. However, lectins modified the action of fluconazole, reducing the IC50 of the drug against C. albicans. Lectins were also able to discretely modulate the morphological transition of the tested strains. [ABSTRACT FROM AUTHOR]

Lectins are widely distributed proteins having ability of binding selectively and reversibly with carbohydrates moieties and glycoconjugates. Although lectins have been reported from different biological sources, the legume lectins are the best-characterized family of plant lectins. Legume lectins are a large family of homologous proteins with considerable similarity in amino acid sequence and their tertiary structures. Despite having strong sequence conservation, these lectins show remarkable variability in carbohydrate specificity and quaternary structures. The ability of legume lectins in recognizing glycans and glycoconjugates on cells and other intracellular structures make them a valuable research tool in glycomic research. Due to variability in binding with glycans, glycoconjugates and multiple biological functions, legume lectins are the subject of intense research for their diverse application in different fields such as glycobiology, biomedical research and crop improvement. The present review specially focuses on structural and functional characteristics of legume lectins along with their potential areas of application. [ABSTRACT FROM AUTHOR]

A large number of infections are caused by Gram-positive and Gram-negative multi-resistant bacteria worldwide, adding up to a figure of around 700,000 deaths per year. The indiscriminate uses of antibiotics, as well as their misuse, resulted in the selection of bacteria resistant to known antibiotics, for which it has little or no treatment. In this way, the strategies to combat the resistance of microorganisms are extremely important and, essential oils of Croton species have been extensively studied for this purpose. The aim of this study was to carry the evaluation of antibacterial, antibiofilm, antioxidant activities, and spectroscopic investigation of essential oil from Croton piauhiensis (EOCp). The EOCp exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria with required MICs ranging from 0.15 to 5% (v/v). In addition, the MBC of the EOCp for Staphylococcus aureus ATCC 25923 and ATCC 700698, were 0.15 and 1.25%, respectively. Moreover, the EOCp significantly reduced significantly the biofilm production and the number of viable cells from the biofilm of all bacterial strains tested. The antioxidant potential of the EOCp showed EC50 values ranging from 171.21 to 4623.83 μg/mL. The EOCp caused hemolysis (>45%) at the higher concentrations tested (1.25 to 5%), and minor hemolysis (17.6%) at a concentration of 0.07%. In addition, docking studies indicated d-limonene as a phytochemical with potential for antimicrobial activity. This study indicated that the EOCp may be a potential agent against infections caused by bacterial biofilms, and act as a protective agent against ROS and oxidative stress. [ABSTRACT FROM AUTHOR]

The emergence of a new human coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has imposed great pressure on the health system worldwide. The presence of glycoproteins on the viral envelope opens a wide range of possibilities for the application of lectins to address some urgent problems involved in this pandemic. In this work, we discuss the potential contributions of lectins from nonmammalian sources in the development of several fields associated with viral infections, most notably COVID-19. We review the literature on the use of nonmammalian lectins as a therapeutic approach against members of the Coronaviridae family, including recent advances in strategies of protein engineering to improve their efficacy. The applications of lectins as adjuvants for antiviral vaccines are also discussed. Finally, we present some emerging strategies employing lectins for the development of biosensors, microarrays, immunoassays and tools for purification of viruses from whole blood. Altogether, the data compiled in this review highlight the importance of structural studies aiming to improve our knowledge about the basis of glycan recognition by lectins and its repercussions in several fields, providing potential solutions for complex aspects that are emerging from different health challenges. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis (Mtb) has an old history as a human pathogen and still kills over one million people every year. One key feature of this bacterium is its dormancy: a phenomenon responsible for major changes in its metabolism and replication that have been associated with the need for a lengthy therapy for Mtb. This process is regulated by key heme-based sensors, particularly DosT and DevS (DosS), among other co-regulators, and also linked to nitrogen utilization (nitrate/nitrite) and stringent responses. In face of the current threat of tuberculosis, there is an urgent need to develop new therapeutic agents capable of targeting the dormant state, associated with the need for a lengthy therapy. Interestingly, many of those key proteins are indeed metallo-containing or metallo-dependent biomolecules, opening exciting bioinorganic opportunities. Here, we critically reviewed a series of small molecules targeting key proteins involved in these processes, including DosT/DevS/DevR, RegX3, MprA, MtrA, NarL, PknB, Rel, PPK, nitrate and nitrite reductases, GlnA1, aiming for new opportunities and alternative therapies. In the battle against Mycobacterium tuberculosis, new drug targets must be searched, in particular those involved in dormancy. A series of exciting cases for drug development involving metallo-containing or metallo-dependent biomolecules are reviewed, opening great opportunities for the bioinorganic chemistry community. [ABSTRACT FROM AUTHOR]

Mistletoes are semiparasite plants containing pharmaceutical proteins with applications in cancer treatment. Previous research has demonstrated that somaclonal variation can lead to the biosynthesis of novel proteins from mistletoe callus cultures. The protein content of Viscum album subsp. abietis tissues and biotechnologically propagated calluses, was analyzed to identify proteins with putative anticancer properties. In addition, evolutionary relations among linked species to Viscum were studied. Calluses were propagated from stem explants. The protein extracts mass spectra were processed with Proteome Discoverer and a search was performed using as reference the Uniprot V. album reviewed database. A phylogenetic tree was reconstructed using the LG amino acid substitution model by homologous sequences for Beta galactoside-specific lectin 2. The homology modeling of the Beta-galactoside-specific lectin 2 was carried out using Modeller software. Considerable differences were observed by comparing the protein content of the calluses and the maternal tissues. Four mistletoe lectins, six viscotoxins and the chitin binding lectin-cbML were identified within the species tissues. An in silico phylogenetic and structural study provides insights to the role of these lectins and the mechanism of semiparasite survival and evolution, towards a novel anticancer and immune system modulation pipeline. Callogenesis exhibited protein biosynthesis alterations and novel protein isoforms expression. Phyllogenetic analysis revealed evolutionary relations primarily within the Viscum genus and other species containing 2-ribosome inactivating proteins. The homology modeling of the mistletoe lectin 2 revealed possible structure related anticancer properties. In conclusion, mistletoe calluses were shown to possess a unique protein biosynthetic profile compared to donor plant tissues. Key message: Protein identification within V. album tissues and calluses highlighted evolutionary relations in species containing 2-RIP lectins and proteins with putative anti-malignant properties. [ABSTRACT FROM AUTHOR]

The discovery of an increasing number of proteins that function in the detoxification and sensing of gaseous ligands has renewed interest in hemeproteins. It is critical to measure the affinities of these proteins for ligands like O 2 , CO, and NO, know with confidence when a protein is fully saturated with a specific ligand, and be able to estimate how well a ligand will compete against other ligands for a specific protein. Below we describe how to obtain an intact O 2 -binding hemeprotein with a full complement of heme, how to evaluate the factors that can impact its affinity for O 2 , and how to determine accurately the equilibrium and kinetic parameters K d , k on , and k off for O 2 binding., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Kinetoplastid parasites are responsible for serious diseases in humans and livestock such as Chagas disease and sleeping sickness (caused by Trypanosoma cruzi and Trypanosoma brucei , respectively), and the different forms of cutaneous, mucocutaneous and visceral leishmaniasis (produced by Leishmania spp). The limited number of antiparasitic drugs available together with the emergence of resistance underscores the need for new therapeutic agents with novel mechanisms of action. The use of agents binding to surface glycans has been recently suggested as a new approach to antitrypanosomal design and a series of peptidic and non-peptidic carbohydrate-binding agents have been identified as antiparasitics showing efficacy in animal models of sleeping sickness. Here we provide an overview of the nature of surface glycans in three kinetoplastid parasites, T. cruzi , T. brucei and Leishmania. Their role in virulence and host cell invasion is highlighted with the aim of identifying specific glycan–lectin interactions and carbohydrate functions that may be the target of novel carbohydrate-binding agents with therapeutic applications. [ABSTRACT FROM AUTHOR]

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Lectins are diverse group of carbohydrate binding proteins distributed ubiquitously in plant species. Lectins are the subject of intense investigation. Therefore, in the past few years studies on legume lectins with respect to their biochemical and pharmacological properties have been extensively carried out. Legume lectins are reported to contain antifungal, mitogenic, immunomodulatory, and antitumor properties. Some of the lectin also display anti-HIV-1 reverse transcriptase and antineoplastic activities. Plant lectins are expected to open new vistas for the design and development of drugs to be used against different serious diseases. This article aims to review up-to-date advances of legume lectins vis-à-vis structure, biological properties, and their practical applications. [ABSTRACT FROM AUTHOR]

Susceptibility to chlorimuron varies according to soybean genotype. STS® (sulfonylurea-tolerant soybean) presents a high tolerance to some sulfonylureas; this feature is determined by semi-dominants alleles, Als1 and Als2. Experiments were conducted in the field for four seasons with two cultivars for season to evaluate the selectivity of chlorimuron rates in post-emergency (V4) of glyphosate-tolerant and sulfonylurea-tolerant soybean. Data analysis made it possible to infer that there was no significant effect on the productivity of the cultivars when they received application in post-emergency, of chlorimuron at the doses used (0, 15, 30, 45, 60, 75, and 90 g ai ha-1). The maximum recommended rate for non-STS cultivars of chlorimuron is 20 g ai ha-1, or 4.5 times less than the maximum rate employed in this study. The soybean cultivars CD 250 RR/STS, CD 236 RR/STS, CD 2630 RR/STS, and BMX Turbo RR/STS were tolerant to the application, in post-emergency (V4) of the herbicide chlorimuron, until the rate of 90 g ai ha-1. [ABSTRACT FROM AUTHOR]

A selection of cobalt (III)/(II) macrobicyclic 'sarcophagine' (sar) cage complexes with NS mixed donor sets but differing in a single apical substituent has been chosen to span a redox potential range of +150 to −150 mV vs the normal hydrogen electrode and thus acts as redox buffers in protein spectroelectrochemistry and redox potentiometry. The cobalt(III) cage complexes are all based on the same parent structure [Co( XMeNSsar)], where X, the variable apical substituent, is -NO, -Cl, -OH, -NH or -NMe, and a methyl group occupies the opposite apical position. The X-ray crystal structures of selected members of this series are reported. Changes to the apical substituent X enable the Co redox potential to be tuned across a range of more than 200 mV by the inductive effects of the functional group. The pH dependence of the redox potential enabled the p K values of some functional groups to be determined. The complexes were successfully employed as electron transfer mediators in the spectroelectrochemical investigation of a variety of heme proteins. Graphical abstract: [ABSTRACT FROM AUTHOR]

Corynebacterium glutamicum, a gram-positive and facultative anaerobic bacterium, is widely used for the industrial production of amino acids, such as L-glutamate and L-lysine. C. glutamicum grows and produces amino acids under aerobic conditions. When restricted under anaerobic conditions, it produces organic acids, such as L-lactate and succinate, through metabolic shift. With the increasing threat of global warming, these organic acids have drawn considerable attention as bio-based plastic monomers. In addition to the organic acids, the anaerobic bioprocess is also used to produce other value-added compounds, including isobutanol, ethanol, 3-methyl-1-butanol, 2,3-butanediol, L-alanine, and L-valine. Therefore, C. glutamicum is now a versatile cell factory for producing a wide variety of useful chemicals under both aerobic and anaerobic conditions. The growth and metabolism of the bacterium depend on the oxygen levels, which modulate the rearrangement of the carbon flux by reprogramming gene expression patterns and intracellular redox states. Anaerobic cell growth and L-lysine production as well as aerobic succinate production have been demonstrated by engineering the metabolic pathways or supplying a terminal electron acceptor instead of oxygen. In this review, we discuss the physiological and metabolic changes in C. glutamicum associated with its application as a cell factory under different oxygen states. Physiological switching in bacteria is initiated with the sensing of oxygen availability. While such a sensor has not been identified in C. glutamicum yet, the molecular mechanism for oxygen sensing in related bacteria is also discussed. KEY POINTS: • C. glutamicum produces a wide variety of useful compounds under anaerobic conditions. • C. glutamicum is a versatile cell factory under both aerobic and anaerobic conditions. • Metabolic fate can be overcome by engineering metabolic pathways., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A lectin from seeds of Dioclea lasiocarpa (DLL) was purified in a single step by affinity chromatography in a Sephadex G-50 column. DLL haemagglutinated rabbit erythrocytes showing stability even after 1 h of exposure to a different pH values (optimal between pH 6.0 and 8.0) but was inhibited after incubation with d-mannose and d-glucose. The pure protein possessed a molecular weight of 25 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and 25,410Da by mass spectrometry. The results analyzed by the software SELCON 3 indicate that β-sheet secondary structures are predominant in DLL (approximately 40.2% antiparallel β-sheet, 4.6% parallel β-sheet, 7.2% α-helices, 17.3% turns, and 28.7% unordered structures). Mechanical activity of isolated aorta from rat measured by cumulative concentration curves of DLL, performed at the contraction plateau induced by phenylephrine in either endothelium-intact or denuded aorta. DLL (IC50 = 34.12 ± 3.46 µg/ml) relaxed precontracted endothelized aortic rings by 34.61 ± 9.06%, 55.19 ± 11.9%, and 81.33 ± 14.35%, respectively, at 10 µg/ml (initial concentration), 30 µg/ml, and 100 µg/ml (maximum effect). All effects occurred via interaction with lectin domains and participation of nitric oxide. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bauhinia variegata lectins (BVL-I and BVL-II) are single chain lectins isolated from the plant Bauhinia variegata. Single chain lectins undergo post-translational processing on its N-terminal and C-terminal regions, which determines their physiological targeting, carbohydrate binding activity and pattern of quaternary association. These two lectins are isoforms, BVL-I being highly glycosylated, and thus far, it has not been possible to determine their structures. The present study used prediction and validation algorithms to elucidate the likely structures of BVL-I and -II. The program Bhageerath-H was chosen from among three different structure prediction programs due to its better overall reliability. In order to predict the C-terminal region cleavage sites, other lectins known to have this modification were analysed and three rules were created: (1) the first amino acid of the excised peptide is small or hydrophobic; (2) the cleavage occurs after an acid, polar, or hydrophobic residue, but not after a basic one; and (3) the cleavage spot is located 5-8 residues after a conserved Leu amino acid. These rules predicted that BVL-I and –II would have fifteen C-terminal residues cleaved, and this was confirmed experimentally by Edman degradation sequencing of BVL-I. Furthermore, the C-terminal analyses predicted that only BVL-II underwent α-helical folding in this region, similar to that seen in SBA and DBL. Conversely, BVL-I and -II contained four conserved regions of a GS-I association, providing evidence of a previously undescribed X4+unusual oligomerisation between the truncated BVL-I and the intact BVL-II. This is the first report on the structural analysis of lectins from Bauhinia spp. and therefore is important for the characterisation C-terminal cleavage and patterns of quaternary association of single chain lectins. [ABSTRACT FROM AUTHOR]