Degradation of xanthene-based dyes by photoactivated persulfate: experimental and computational studies.

Dyes are naked-eye detectable even at low concentration levels and can cause environmental damage when released into aquatic effluents; therefore, methods for removing the residual color from the aquatic media are always a current issue. In this paper, degradation of three xanthene dyes, Rhodamine B, Eosin Y, and Sodium Fluorescein, using photoactivated persulfate was evaluated at pH 3.0 and 11.0. The dyes' degradation followed a pseudo-first-order reaction. Although the solution is completely decolorized in 40 min at pH 3.0, achieving 75% mineralization requires a longer reaction time of 180 min. Furthermore, GC-MS analyses indicate that degradation products are mainly low-molecular weight acids, CO2 and H2O. Experiments carried out in dark and under UV irradiation showed substantial contribution of radical (SO4•- and HO•) and non-radical pathways to dye degradation in both pH. Additionally, to get more insights into the degradation pathways, HOMO-LUMO energy gaps of the dyes were calculated by DFT using MPW1PW91/MidiXo level of theory and, in general, the lower the bandgap, the faster the degradation. Fukui functions revealed that the preferential sites to radical attack were the xanthene or the benzoate portion depending on the pH, wherein attack to the xanthene ring provided better kinetic and mineralization results.

Effect of Crotalus basiliscus snake venom on the redox reaction of myoglobin.

In this work, we have studied the effect of Crotalus basiliscus snake venom on the redox reaction of myoglobin (Mb), and by means of electrochemical techniques, we have shown that this reaction is undoubtedly affected following the interaction with the venom. Surface plasmon resonance, electrophoresis, UV-Vis, and circular dichroism showed that the interaction involves the attachment of some constituent of the venom to the protein, although not affecting its first and secondary structures. Mass spectra support this suggestion by showing the appearance of signals assigned to the Mb dimer and to a new species resulting from the interaction between Mb and the venom proteins. In addition, the mass spectra suggest the aromatic amino acids of myoglobin, mainly tryptophan and phenylalanine, are more exposed to the solvent medium upon the exposure to the venom solution. The results altogether indicate that the harmful effects of the venom of Crotalus basiliscus snake are likely connected to the blocking of the redox site of Mb.

Cyclic lipopeptide signature as fingerprinting for the screening of halotolerant Bacillus strains towards microbial enhanced oil recovery.

Cyclic lipopeptides (CLPs) are non-ribosomal biosurfactants produced by Bacillus species that exhibit outstanding interfacial activity. The synthesis of CLPs is under genetic and environmental influence, and representatives from different families are generally co-produced, generating isoforms that differ in chemical structure and biological activities. This study to evaluate the effect of low and high NaCl concentrations on the composition and surface activity of CLPs produced by Bacillus strains TIM27, TIM49, TIM68, and ICA13 towards microbial enhanced oil recovery (MEOR). The strains were evaluated in mineral medium containing NaCl 2.7, 66, or 100 g L-1 and growth, surface tension and emulsification activity were monitored. Based on the analysis of 16S rDNA, gyrB and rpoB sequences TIM27 and TIM49 were assigned to Bacillus subtilis, TIM68 to Bacillus vallismortis, and ICA13 to Bacillus amyloliquefaciens. All strains tolerated up to 100-g L-1 NaCl, but only TIM49 and TIM68 were able to reduce surface tension at this concentration. TIM49 also showed emulsification activity at concentrations up to 66-g L-1 NaCl. ESI-MS analysis showed that the strains produced a mixture of CLPs, which presented distinct CLP profiles at low and high NaCl concentrations. High NaCl concentration favored the synthesis of surfactins and/or fengycins that correlated with the surface activities of TIM49 and TIM68, whereas low concentration favored the synthesis of iturins. Taken together, these findings suggest that the determination of CLP signatures under the expected condition of oil reservoirs can be useful in the guidance for choosing well-suited strains to MEOR.

Antiulcer activity of Mauritia flexuosa L.f. (Arecaceae) pulp oil: An edible Amazonian species with functional properties.

Mauritia flexuosa, known as buriti in Brazil, is a widespread palm tree in Amazonia. It has many ethnobotanical uses, including food, oil, and medicine. The oil obtained from buriti's fruit pulp has high levels of monounsaturated fatty acids, carotenoids, and tocopherols, and is used in the food, cosmetic, and pharmaceutical industries for its antioxidant properties. Many biological activities have been reported for buriti oil, such as antioxidant, antimicrobial, chemopreventive, and immunomodulatory. Due to its high content of bioactive compounds, buriti oil is considered a functional ingredient with possible benefits in preventing oxidative stress and chronic diseases, particularly in the gastrointestinal tract. Peptic ulcer disease is a multifactorial disorder, involving lesions in the stomach and duodenum mucosa, which has a complex healing process. In this context, some nutrients and bioactive compounds help the maintenance of gastrointestinal mucosal integrity and function, such as carotenoids, tocopherols, and unsaturated fatty acids, which makes buriti oil an interesting candidate to be used in the prevention and management of gastrointestinal diseases. This study aimed to evaluate the gastroprotective and antiulcer effects of buriti oil and its possible mechanisms of action. Buriti oil reduced the ulcerative area and lipid peroxidation induced by ethanol. The gastroprotective activity of buriti oil partially depends on nitric oxide and sulfhydryl compounds. In acetic acid-induced gastric ulcers, buriti oil accelerated healing and stimulated the formation of new gastric glands. These results demonstrated the potential of buriti oil as a functional ingredient to promote health benefits in the gastrointestinal tract.

Unraveling the antifungal composition of bitter orange decoction against the melon pathogen Fusarium jinanense.

Bitter orange (Citrus aurantium) is an important source of essential oils with high antimicrobial activities, however the composition and antifungal potential of the decoction peels is little explored. This study assessed the peel decoction's chemical profile at the secondary metabolism level and its antifungal activity against the melon phytopathogen Fusarium jinanense. The decoction's antifungal potential was investigated using a bioassay-guided fractionation approach based on Solid-Phase Extraction (SPE) and LC-HRMS/MS analysis. Coumarins and flavones were the most abundant classes of compounds in the high-value fractions responsible for up to 61% of the mycelial inhibition of F. jinanense. Overall, this study has presented for the first time the chemical composition, the antifungal potential of the decoction of C. aurantium peels and the compounds associated with these results. This strategy can guide the exploration of under-explored food sources and add value to compounds or fractions enriched with bioactive compounds.

Harvestman phenols and benzoquinones: characterisation and biosynthetic pathway.

Benzoquinones are usually present in arthropod defence exudates. Here, we describe the chemical profiles of 12 harvestman species belonging to the neotropical family Gonyleptidae. Nine of the studied species produced benzoquinones, while three produced alkyl phenols. Two benzoquinones and one phenol exhibited biological activity against bacteria and fungi. We also studied the biosynthesis of 2-ethyl-1,4-benzoquinone by feeding Magnispina neptunus individuals with ¹³C-labelled precursors; the benzoquinones were biosynthesised through a polyketide pathway using acetate and propionate building blocks.

Effect of pulsed light on postharvest disease control-related metabolomic variation in melon (Cucumis melo) artificially inoculated with Fusarium pallidoroseum.

Pulsed light, as a postharvest technology, is an alternative to traditional fungicides, and can be used on a wide variety of fruit and vegetables for sanitization or pathogen control. In addition to these applications, other effects also are detected in vegetal cells, including changes in metabolism and secondary metabolite production, which directly affect disease control response mechanisms. This study aimed to evaluate pulsed ultraviolet light in controlling postharvest rot, caused by Fusarium pallidoroseum in 'Spanish' melon, in natura, and its implications in disease control as a function of metabolomic variation to fungicidal or fungistatic effects. The dose of pulsed light (PL) that inhibited F. pallidoroseum growth in melons (Cucumis melo var. Spanish) was 9 KJ m-2. Ultra-performance liquid chromatography (UPLC) coupled to a quadrupole-time-of-flight (QTOF) mass analyzer identified 12 compounds based on tandem mass spectrometry (MS/MS) fragmentation patterns. Chemometric analysis by Principal Components Analysis (PCA) and Orthogonal Partial Least Squared Discriminant Analysis (OPLS-DA) and corresponding S-Plot were used to evaluate the changes in fruit metabolism. PL technology provided protection against postharvest disease in melons, directly inhibiting the growth of F. pallidoroseum through the upregulation of specific fruit biomarkers such as pipecolic acid (11), saponarin (7), and orientin (3), which acted as major markers for the defense system against pathogens. PL can thus be proposed as a postharvest technology to prevent chemical fungicides and may be applied to reduce the decay of melon quality during its export and storage.

Nitro-imidazole-based ruthenium complexes with antioxidant and anti-inflammatory activities.

Inflammation is a physiological process triggered in response to tissue damage, and involves events related to cell recruitment, cytokines release and reactive oxygen species (ROS) production. Failing to control the process duration lead to chronification and may be associated with the development of various pathologies, including autoimmune diseases and cancer. Considering the pharmacological potential of metal-based compounds, two new ruthenium complexes were synthesized: cis-[Ru(NO2)(bpy)2(5NIM)]PF6 (1) and cis-[RuCl(bpy)2(MTZ)]PF6 (2), where bpy = 2,2'-bipyridine, 5NIM = 5-nitroimidazole and MTZ = metronidazole. Both products were characterized by spectroscopic techniques, followed by Density Functional Theory (DFT) calculations in order to support experimental findings. Afterwards, their in vitro cytotoxic, antioxidant and anti-inflammatory activities were investigated. Compounds 1 and 2 presented expressive in vitro antioxidant activity, reducing lipid peroxidation and decreasing intracellular ROS levels with comparable effectiveness to the standard steroidal drug dexamethasone or α-tocopherol. These complexes showed no noticeable cytotoxicity on the tested cancer cell lines. Bactericidal assay against metronidazole-resistant Helicobacter pylori, a microorganism able to disrupt oxidative balance, unraveled compound 1 moderate activity over that strain. Besides this, it was able to inhibit interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) production as well as interleukin-1ß (IL-1ß) and cyclooxygenase-2 (COX-2) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. This latter activity is remarkable, which has not been reported for other ruthenium-based complexes. Altogether, these results suggest cis-[Ru(NO2)(bpy)2(5NIM)]PF6 complex has potential pharmacological application as an anti-inflammatory agent that deserve further biological investigation.

Thiocarbonyl-bound metallonitrosyl complexes with visible-light induced DNA cleavage and promising vasodilation activity.

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)](PF6)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.

A Brazilian social bee must cultivate fungus to survive.

The nests of social insects provide suitable microenvironments for many microorganisms as they offer stable environmental conditions and a rich source of food [1-4]. Microorganisms in turn may provide several benefits to their hosts, such as nutrients and protection against pathogens [1, 4-6]. Several examples of symbiosis between social insects and microorganisms have been found in ants and termites. These symbioses have driven the evolution of complex behaviors and nest structures associated with the culturing of the symbiotic microorganisms [5, 7, 8]. However, while much is known about these relationships in many species of ants and termites, symbiotic relationships between microorganisms and social bees have been poorly explored [3, 4, 9, 10]. Here, we report the first case of an obligatory relationship between the Brazilian stingless bee Scaptotrigona depilis and a fungus of the genus Monascus (Ascomycotina). Fungal mycelia growing on the provisioned food inside the brood cell are eaten by the larva. Larvae reared in vitro on sterilized larval food supplemented with fungal mycelia had a much higher survival rate (76%) compared to larvae reared under identical conditions but without fungal mycelia (8% survival). The fungus was found to originate from the material from which the brood cells are made. Since the bees recycle and transport this material between nests, fungus would be transferred to newly built cells and also to newly founded nests. This is the first report of a fungus cultivation mutualism in a social bee.

Produção de biossurfactantes: manoproteínas intracelulares e soforolipídios extracelulares por Saccharomyces cerevisiae / Biosurfactant production: intracellular manoproteins and extracellular sophorolipids by Saccharomyces cerevisiae

RESUMO Os biossurfactantes apresentam inúmeras aplicações ambientais e são produzidos por diversos microrganismos. Os provenientes da levedura Saccharomyces cerevisiae são pouco estudados para fins ambientais, sendo atóxicos. Objetivou-se o estudo da produção de biossurfactantes intra e extracelular por essa levedura, desenvolvida em meio de cultivo contendo 0,5% de extrato de levedura e 1% de peptona, além de concentrações variadas de sacarose e indutores oleosos - glicerol e óleos de soja e diesel. Os experimentos foram realizados durante 96 horas, e a produção de biossurfactantes foi avaliada diariamente, por meio da redução da tensão superficial e de estabilização de emulsões. O biossurfactante extracelular foi extraído da biomassa obtida, com posterior precipitação e caracterização química por intermédio de espectrometria de massa. As maiores produtividades de emulsificantes extracelulares foram obtidas com glicerol (0,20 UE.h-1) e óleo de soja (0,21 UE.h-1), em 48 horas de cultivo. Em ensaios posteriores, realizados com aumento da concentração de indutor, foi verificado um aumento das produtividades extracelulares para 0,45 UE.h-1 para o glicerol e 0,30 UE.h-1 para o óleo de soja. A maior redução da tensão superficial foi de 9,89%, em 72 horas, para o indutor óleo diesel. A diminuição dessa tensão, aliada ao aumento das atividades emulsificantes, é um importante indicativo da utilização do substrato hidrofóbico pelo microrganismo. O estudo comprova aumento na produção de biossurfactantes extracelulares quando realizada otimização de cultivo. Para a produção dos intracelulares, a necessidade de processo de rompimento celular aumenta os custos do bioprocesso.

ABSTRACT Biosurfactants implicate many environmental applications, being produced by a wide range of microorganisms. Those from the Saccharomyces cerevisiae yeast are still poorly studied for environmental purposes and are non-toxic. The aim of the study was the production of intra- and extracellular biosurfactants by the Saccharomyces cerevisiae yeast. The yeast was grown in cultured medium containing 0.5% yeast extract, 1% peptone and variable concentrations of sucrose and oily inducers. Inducers used were glycerol, soybean oil and diesel oil. Experiments were conducted for 96 h, and the daily production of biosurfactants was evaluated by reducing surface tension and stabilizing emulsions. Extracellular biosurfactant was extracted from the obtained biomass, with subsequent precipitation and chemical characterization by mass spectrometry. The highest extracellular emulsifier yields were achieved with glycerol inductor (0.20 UE h-1) and soybean oil (0.21 UE h-1) in 48h of cultivation. In later tests performed with increasing concentration of inducer, an increase in extracellular yields was noticed in these experiments (0.45 UE h-1 for glycerol and 0.30 UE h-1 for the soybean oil). The greatest reduction in surface tension was 9.89% in 72 h for diesel oil inducer. The reduction of surface tension combines with the increase of emulsifying activities in an important indicator of the use of hydrophobic substrate by the microorganism. The study confirms an increase in the production of extracellular biosurfactants when optimizing cultivation. The production of intracellular biosurfactants has also been verified, however the process of cellular disruption increases the cost of the bioprocess.

Microorganisms in cryopreserved semen and culture media used in the in vitro production (IVP) of bovine embryos identified by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS).

Commercial cattle breeders produce their own herd offspring for the dairy and beef market using artificial insemination. The procedure involves sanitary risks associated with the collection and commercialization of the germplasm, and the in vitro production and transfer of the bovine embryos must be monitored by strict health surveillance. To avoid the spreading of infectious diseases, one must rely on using controlled and monitored germplasm, media, and reagents that are guaranteed free of pathogens. In this article, we investigated the use of a new mass spectrometric approach for fast and accurate identification of bacteria and fungi in bovine semen and in culture media employed in the embryo in vitro production process. The microorganisms isolated from samples obtained in a commercial bovine embryo IVP setting were identified in a few minutes by their conserved peptide/protein profile, obtained applying matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), matched against a commercial database. The successful microorganisms MS identification has been confirmed by DNA amplification and sequencing. Therefore, the MS technique seems to offer a powerful tool for rapid and accurate microorganism identification in semen and culture media samples.