Solvent-free synthesis of nitrone-containing template as a chemosensor for selective detection of Cu(II) in water.

A state-of-the-art method was developed for repurposing nitrone-containing compounds in the chemosensory field, the ability of the designed molecules to chelate metal cations was evaluated, and their unprecedented solubility in water was confirmed. A facile, rapid, and solvent-free method of synthesizing small molecular mass chemosensors was developed by using a modulative α-aryl-N-aryl nitrone template. α-(Z)-Imidazol-4-ylmethylen-N-phenyl nitrone (Nit1) and α-(Z)-2-pyridyl-N-phenyl nitrone (Nit2) were prepared in 15 min, isolated in less than 60 min with ca. 90% yield, and screened against nine metal cations. Nit1 is a small-molecular-mass compound (188 g mol-1) that is water-soluble and has specificity for sensing Cu2+ with an association constant of K = 1.53 × 1010 and a limit of detection (LOD) of 0.06 ppm. These properties make Nit1 a competitive chemosensor for the detection of Cu2+ in aqueous solution. The nitrone-containing template used in this study is a step forward for new and small chemosensory entities.

Mass Spectrometry-Guided Genome Mining as a Tool to Uncover Novel Natural Products.

The chemical space covered by natural products is immense and widely unrecognized. Therefore, convenient methodologies to perform wide-ranging evaluation of their functions in nature and potential human benefits (e.g., for drug discovery applications) are desired. This protocol describes the combination of genome mining (GM) and molecular networking (MN), two contemporary approaches that match gene cluster-encoded annotations in whole genome sequencing with chemical structure signatures from crude metabolic extracts. This is the first step towards the discovery of new natural entities. These concepts, when applied together, are defined here as MS-guided genome mining. In this method, the main components are previously designated (using MN), and structurally related new candidates are associated with genome sequence annotations (using GM). Combining GM and MN is a profitable strategy to target new molecule backbones or harvest metabolic profiles in order to identify analogues from already known compounds.

Molecular networking-based dereplication of strictosidine-derived monoterpene indole alkaloids from the curare ingredient Strychnos peckii.

RATIONALE: Monoterpene indole alkaloids (MIAs) are a large group of biologically active compounds produced by hundreds of plant species in numerous plant families, such as Apocynaceae, Loganiaceae and Rubiaceae. Although this diversity is biosynthetically intermediated by strictosidine, there are no works focused on the fragmentation patterns under collision-induced dissociation of strictosidine-derived alkaloids. METHODS: Initially, the alkaloid fingerprint of Strychnos peckii was established using leaf spray with tandem mass spectrometry (LS-MS/MS). Then, high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC/MS/MS) analyses were carried out to focus on the patterns of neutral losses in product ion scan experiments with the leaf aqueous extract. Finally, the product ion spectra from a set of presumable strictosidine-type derivatives were analyzed and organized via molecular networking (MN), and dereplicated by manual interpretation of MS/MS spectra. RESULTS: LS-MS/MS allowed the tentative identification of strictosidine-derived alkaloids in the leaves of S. peckii, showing useful neutral losses for the dereplication of strictosidine analogues by HPLC/MS/MS experiments. The use of MN combined with manual interpretation of the fragmentation patterns highlighted characteristic fragmentation pathways, and allowed the tentative identification of strictosidine, desoxycordifoline, strictosidinic acid, 10-hydroxystrictosidine, 5-carboxystrictosidine, lyaloside, 3,4-dehydrostrictosidine and strictosidine lactam. CONCLUSIONS: The use of MN combined with the analysis of the fragmentation patterns proved to be a useful strategy for the dereplication of strictosidine-derived MIAs from S. peckii, highlighting known and unprecedented structures, as well as useful diagnostic product ions. Therefore, this workflow is an effective approach for the characterization of strictosidine-type alkaloids in future dereplication works.

The Intermediates in Lewis Acid Catalysis with Lanthanide Triflates.

Lanthanide triflates are effective Lewis acid catalysts in reactions involving carbonyl compounds due to their high oxophilicity and water stability. Despite the growing interest, the identity of the catalytic species formed in lanthanide catalysed reactions is still unknown. We have therefore used mass spectrometry and ion spectroscopy to intercept and characterize the intermediates in a reaction catalysed by ytterbium and dysprosium triflates. We were able to identify a number of lanthanide intermediates formed in a simple condensation reaction between a C-acid and an aldehyde. Results show correlation between the reactivity of lanthanide complexes and their charge state and suggest that the triply charged complexes play a key role in lanthanide catalysed reactions. Spectroscopic data of the gaseous ions accompanied by theoretical calculations reveal that the difference between catalytic efficiencies of ytterbium and dysprosium ions can be explained by their different electrophilicity.

Influence of different types of acids and pH in the recovery of bioactive compounds in Jabuticaba peel (Plinia cauliflora).

Jabuticaba peel presents a high content of bioactive compounds such as phenolic acids, flavonoids, and anthocyanins, normally considered as a food residue. Nowadays, there is a great interesting in the recovery of bioactive compounds from food residue due to health benefits of the ingredients produced, environmental issues and economic aspects. For the success of phenolic compounds extraction, the solvent and pH influence recovery of these compounds. However, studies that evaluate the use of different weak acids bioactive compounds recovery are scarce. Thus, the aim of the present work was to evaluate the effect of formic, acetic, and phosphoric acids addition in the extraction solvent, to adjust the pH to 1.0, 2.0 and 3.0, in bioactive compounds recovery and antioxidant capacity of jabuticaba peel. The extracts were analyzed as antioxidant capacity (ORAC, FRAP), total phenols content monomeric anthocyanin's and a qualitative analysis of phenolics by Liquid Chromatography with mass spectrometry (LC-MS). The kind of acid used in the extraction process affected mainly in the extraction of anthocyanins. The acid that presented a better recovery of anthocyanin (3.4 mg/g raw material) and a better antioxidant capacity (ORAC) (841 µmol TE/g raw material) was formic acid in pH 1.0.

Structure-Based Molecular Networking for the Target Discovery of Oxahomoaporphine and 8-Oxohomoaporphine Alkaloids from Duguetia surinamensis.

In addition to seven known alkaloids (2, 6-11) and 1,2,4-trimethoxybenzene (1), three isoquinoline-derived alkaloids (3-5), namely, duguetinine (3), a compound based on an unprecedented oxahomoaporphine scaffold, and two new 8-oxohomoaporphine alkaloids, duguesuramine (4) and 11-methoxyduguesuramine (5), and a new asarone-derived phenylpropanoid (10) were isolated from the bark of Duguetia surinamensis. The isolation workflow was guided by HPLC-HRESIMS/MS and molecular networking-based analyses. Twenty-four known alkaloids were dereplicated from the D. surinamensis alkaloid-rich fraction network and were assigned by manual MS/MS interpretation. Their cytotoxic potential was evaluated.

Vinyl-1,2,4-oxadiazoles Behave as Nucleophilic Partners in Morita-Baylis-Hillman Reactions.

We describe that vinyl-oxadiazoles function as a new and efficient nucleophilic partner for the Morita-Baylis-Hillman (MBH) reaction. The reaction between 5-vinyl-3-aryl-1,2,4-oxadiazoles and aromatic and aliphatic aldehydes, catalyzed by DABCO in the absence of solvent, showed high efficiency to afford a new class of heterocyclic MBH adducts with potential biological activity on yields up to 99% and short reaction times. These synthetically attractive adducts bear a heterocyclic scaffold of large pharmaceutical and commercial interest associated with a plethora of biological effects and technological applications. We also demonstrate their synthetic usefulness by a photoinduced addition reaction to a polyfunctionalized amino alcohol.

Remela de cachorro (Clavija lancifolia Desf.) fruits from South Amazon: Phenolic composition, biological potential, and aroma analysis.

Remela de cachorro (Clavija lancifolia Desf.) is an Amazonian native fruit consumed specially in the Purus microregion. Because of its rarity, restricted consumption, and the lack of knowledge about its chemical composition, remela de cachorro fruit was studied in relation to its phenolic and aroma constitution. Using liquid chromatography tandem mass spectrometry (LC-MS/MS), 11 compounds (flavonoids and its glucosides along with organic acids) were tentatively identified by fragmentation patterns. A previously validated method was applied to quantify common antioxidant compounds in the raw pulps, for which kaempferol was the main compound. Gas chromatography mass spectrometry (GC-MS) with headspace solid-phase microextraction (HS-SPME) was employed to assess the aroma composition of remela de cachorro fruit. A total of 27 volatile organic compounds (VOCs) were identified for this fruit, for which benzaldehyde and linalool were the main VOCs. Furthermore, biological activities, such as antioxidant capacity (ABTS, DPPH, and ORAC methods), cytotoxicity, and α-glucosidase and lipase inhibitions of the hydroalcoholic extract of remela de cachorro fruit were evaluated. In vitro biological assays revealed the potential of this fruit as a bioactive food that should be further studied and explored in Amazonian products.

Statistical mixture design investigation for extraction and quantitation of aporphine alkaloids from the leaves of Unonopsis duckei R.E. Fr. by HPLC-MS/MS.

INTRODUCTION: Alkaloids-derived drugs are a billionaire world-market and several phytochemical investigations aim the identification of new sources and/or structures. Thus, improving the way of extracting and methods to quantify them are of utmost importance. OBJECTIVE: To quantify isoquinoline-derived alkaloids in Unonopsis duckei R.E. Fr. through a new validated high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method in combination with a statistical mixture design that aimed a proper direct extraction of these compounds from leaves. METHODOLOGY: Extracts were obtained with acetone, methanol, chloroform, and n-hexane in different combinations and proportions. Chemometrics were applied in order to compare peak areas, and therefore evaluate synergism and antagonism effects between the solvents. After selection of extraction solvent, the quantification was validated and applied in the best solvent combination to quantify the main alkaloids in U. duckei. RESULTS: Chemometrics indicated a synergistic effect between chloroform and methanol solvents, thus improving alkaloid extraction and extract yield. Analytes were quantified in a 15-min method, with limits of detection (LODs) between 0.5 and 5.2 ng/mL and limits of quantification (LOQs) between 1.6 and 17.2 ng/mL. The accuracy ranged between 80 and 120%. Coefficients of variation were lower than 17.42% at all concentrations. Concentrations of the alkaloids in U. duckei varied from 6.79 to 131.10 µg/g of dried leaf and glaziovine was found to be the main compound. CONCLUSION: The integration of simplex centroid model and quantification by HPLC-MS/MS is promising. Statistical optimisation of the alkaloid extraction and application of selective, sensitive and robust HPLC-MS/MS method will contribute to quality control applications in phytotherapeutic medicines.

Antioxidative, Antiproliferative and Antimicrobial Activities of Phenolic Compounds from Three Myrcia Species.

Myrcia bella Cambess., Myrcia fallax (Rich.) DC. and Myrcia guianensis (Aubl.) DC. (Myrtaceae) are trees found in Brazilian Cerrado. They have been widely used in folk medicine for the treatment of gastrointestinal disorders, hemorrhagic and infectious diseases. Few reports have been found in the literature connecting their phenolic composition and biological activities. In this regard, we have profiled the main phenolic constituents of Myrcia spp. leaves extracts by ESI(−)Q-TOF-MS. The main constituents found were ellagic acid (M. bella), galloyl glucose isomers (M. guianensis) and hexahydroxydiphenic (HHDP) acid derivatives (M. fallax). In addition, quercetin and myricetin derivatives were also found in all Myrcia spp. extracts. The most promising antioxidant activity, measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, was found for M. fallax extracts (EC50 8.61 ± 0.22 µg·mL−1), being slightly less active than quercetin and gallic acid (EC50 2.96 ± 0.17 and 2.03 ± 0.02 µg·mL−1, respectively). For in vitro antiproliferative activity, M. guianensis showed good activity against leukemia (K562 TGI = 7.45 µg·mL−1). The best antimicrobial activity was observed for M. bella and M. fallax to Escherichia coli (300 and 250 µg·mL−1, respectively). In conclusion, the activities found are closely related to the phenolic composition of these plants.

Petroleomics via Orbitrap mass spectrometry with resolving power above 1 000 000 at m/z 200.

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches. Pertinent parameters that underpin the main figures of merit, that is, signal to noise ratios, dynamic range, spectral error, scan speed, mass accuracy and mass resolving power = R p, and provide subsidies to develop these analyzers were tested. Comparisons are made with data obtained using the most common petroleomics instrument, which is a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), that has been used in the last decade in our laboratory for crude oil analysis providing R p of 340 000 at m/z 400 with transients of 3 s duration, and has been extensively demonstrated to fulfill all major requirements for precise petroleomics investigations. The high-field compact MegaOrbitrap mass analyzer, when operated at an R p = 840 000 at m/z 400 (R p > 1 000 000 at m/z 200) with a detection time of 3 s, was found to be well suited for adequate characterization of crude oil. Accurate class classification and mass accuracy below 1 ppm was obtained leading to proper, comprehensive petroleomics characterization.

An Aminocatalyzed Michael Addition/Iron-Mediated Decarboxylative Cyclization Sequence for the Preparation of 2,3,4,6-Tetrasubstituted Pyridines: Scope and Mechanistic Insights.

A novel, scalable strategy for the preparation of 2,3,4,6-tetrasubstituted pyridines is described. This protocol has two steps: an aminocatalyzed addition of ketones to alkylidene isoxazol-5-ones, followed by an iron-mediated decarboxylative cyclization event. Mechanistic insights for both steps are provided based on HRMS-ESI(+) studies.

Lipidomic alterations of in vitro macrophage infection by L. infantum and L. amazonensis.

Particular lipid profiles have been found in two different protozoa of the Leishmania genus. Leishmania infantum, a visceral leishmaniasis causative agent and Leishmania amazonensis, a cutaneous leishmaniasis, reveal distinctive lipid contents of phosphatidylethanolamine and phosphatidylserine plasmalogens, sphingolipids, phosphatidylinositols, phosphatidylcholine, and phosphatidylethanolamine, which have been shown to be related to species, life-cycle of the parasite, and macrophage infection. L. infantum displayed a higher content of phosphatidylethanolamine plasmalogens than L. amazonensis, which may help to differentiate their unique clinical manifestations. Phosphatidylserines plasmalogens are also found to be an important lipid class for the intracellular form of the parasite. Our findings also reveal lipid classes that may be involved in visceralization pathways and parasite differentiation.

Identification of oxidoreductases from the petroleum Bacillus safensis strain.

A gram-positive bacterium, denominated CFA-06, was isolated from Brazilian petroleum in the Campos Basin and is responsible for the degradation of aromatic compounds and petroleum aromatic fractions. The CFA-06 strain was identified as Bacillus safensis using the 16S rRNA and gyrase B sequence. Enzymatic assays revealed the presence of two oxidoreductases: a catalase and a new oxidoreductase. The oxidoreductases were enzymatically digested and analyzed via ESI-LTQ-Orbitrap mass spectrometry. The mass data revealed a novel oxidoreductase (named BsPMO) containing 224 amino acids and 89% homology with a hypothetic protein from B. safensis (CFA-06) and a catalase (named BsCat) with 491 amino acids and 60% similarity with the catalase from Bacillus pumilus (SAFR-032). The new protein BsPMO contains iron atom(s) and shows catalytic activity toward a monooxygenase fluorogenic probe in the presence of cofactors (NADH, NADPH and NAD). This study enhances our knowledge of the biodegradation process of petroleum by B. safensis.

Genome Sequence of Bacillus safensis CFA06, Isolated from Biodegraded Petroleum in Brazil.

Bacillus safensis is a microorganism recognized for its biotechnological and industrial potential due to its interesting enzymatic portfolio. Here, as a means of gathering information about the importance of this species in oil biodegradation, we report a draft genome sequence of a strain isolated from petroleum.

Searching for monooxygenases and hydrolases in bacteria from an extreme environment.

Microbial oxidation potentials of extremophiles recovered from Pampo Sul oil field, Campos Basin, Brazil, in pure culture or in consortia, were investigated using high-throughput screening (HTS) and multibioreactions. Camphor (1), cis-jasmone (2), 2-methyl-cyclohexanone (3), 1,2-epoxyoctane (4), phenylethyl acetate (5), phenylethyl propionate (6), and phenylethyl octanoate (7) were used to perform multibioreaction assays. Eighty-two bacterial isolates were recovered from oil and formation water samples and those presenting outstanding activities in HTS assays were identified by sequencing their 16S rRNA genes. These results revealed that most microorganisms belonged to the genus Bacillus and presented alcohol dehydrogenase, monooxygenase, epoxide hydrolase, esterase, and lipase activities.