Elisane Longhinotti

Brazilian fruit pulps as functional foods and additives: Evaluation of bioactive compounds

Eight tropical fruit pulps from Brazil were simultaneously characterised in terms of their antioxidant and antimicrobial properties. Antioxidant activity was screened by DPPH radical scavenging activity (126-3987 mg TE/100g DW) and ferric reduction activity power (368-20819 mg AAE/100g DW), and complemented with total phenolic content (329-12466 mg GAE/100g DW) and total flavonoid content measurements (46-672 mg EE /100g DW), whereas antimicrobial activity was tested against the most frequently found food pathogens. Acerola and açaí presented the highest values for the antioxidant-related measurements. Direct correlations between these measurements could be observed for some of the fruits. Tamarind exhibited the broadest antimicrobial potential, having revealed growth inhibition of Pseudomonas aeruginosa. Escherichia coli, Listeria monocytogenes, Salmonella sp. and Staphylococcus aureus. Açaí and tamarind extracts presented an inverse relationship between antibacterial and antioxidant activities, and therefore, the antibacterial activity cannot be attributed (only) to phenolic compounds.

Isoniazid metal complex reactivity and insights for a novel anti-tuberculosis drug design

For over a decade, tuberculosis (TB) has been the leading cause of death among infectious diseases. Since the 1950s, isoniazid has been used as a front-line drug in the treatment of TB; however, resistant TB strains have limited its use. The major route of isoniazid resistance relies on KatG enzyme disruption, which does not promote an electron transfer reaction. Here, we investigated the reactivity of isoniazid metal complexes as prototypes for novel self-activating metallodrugs against TB with the aim to overcome resistance. Reactivity studies were conducted with hydrogen peroxide, hexacyanoferrate(III), and aquopentacyanoferrate(III). The latter species showed a preference for the inner-sphere electron transfer reaction pathway. Additionally, electron transfer reaction performed with either free isoniazid or (isoniazid)pentacyanoferrate(II) complex resulted in similar oxidized isoniazid derivatives as observed when the KatG enzyme was used. However, upon metal coordination, a significant enhancement in the formation of isonicotinic acid was observed compared with that of isonicotinamide. These results suggest that the pathway of a carbonyl-centered radical might be favored upon coordination to the Fe(II) owing to the π-back-bonding effect promoted by this metal center; therefore, the isoniazid metal complex could serve as a potential metallodrug. Enzymatic inhibition assays conducted with InhA showed that the cyanoferrate moiety is not the major player involved in this inhibition but the presence of isoniazid is required in this process. Other isoniazid metal complexes, [Ru(CN)5(izd)]3− and [Ru(NH3)5(izd)]2+ (where izd is isoniazid), were also unable to inhibit InhA, supporting our proposed self-activating mechanism of action. We propose that isoniazid reactivity can be rationally modulated by metal coordination chemistry, leading to the development of novel anti-TB metallodrugs.Graphical abstract

A novel and simple synthetic route for a piperazine derivative

Um novo derivado da piperazina, 5-oxopiperazinio-3-sulfonato monohidratado, foi produzido a partir de uma rota sintetica simples como resultado da adicao do ion bisulfito, HSO3-, ao anel e do ataque nucleofilico de moleculas de agua a moleculas de pirazina. O material isolado foi caracterizado por RMN, espectrometria de massa, infravermelho e difracao de raios-X.

Synthesis, characterization and catalytic properties of nanostructured porous carbon

Abstract MCM-41, MCM-48 and FAU molecular sieves were used as template to prepare carbon nitrides (CN). The amine-functionalized CN were characterized by XRD, Raman and infrared (FTIR) spectroscopy, N 2 adsorption isotherms as well as the catalytic activity in a fine chemistry reaction was evaluated. MCM-41 is the best matrix to obtain ordered materials with a graphitic character. Also, sucrose is the best carbon precursor to obtain a pore filling of 32 wt.% compared with naphthalene and carbon tetrachloride. The nanoporous carbons studied are potentially of great importance because of their textural features and high catalytic performance. It must be correlated to the basic active sites that provide active, selective and stable catalysts to the target reaction.

Role of Cu, Ni and Co metals in the acidic and redox properties of Mo catalysts supported on Al2O3 spheres for glycerol conversion

The combined acid–base and redox properties of active Cu, Ni and Co-promoted Mo catalysts supported on Al2O3 spheres have been investigated for the gas-phase dehydration of glycerol. Al2O3 spheres used as supports were impregnated with an aqueous resin containing metal precursors that was synthesized by the polymeric precursor method. The supports and catalysts were characterized by means of chemical analysis, XRD, H2-TPR, N2-physisorption isotherms, SEM-EDS, CO2-TPD, TG/DTA and pyridine adsorption isotherms. The results show differences in morphological, textural and acid–base properties, whereas the XRD and H2-TPR analyses point to a good dispersion of the metal precursors. The H2-TPR analysis shows that the addition of Co, Cu or Ni affects the reducibility of the Mo6+ species, which results in a shift of the H2 consumption peaks to a lower temperature. The addition of Mo resulted in a higher catalytic conversion, particularly for the sample containing Cu (CuMoAl). This improvement in the catalytic performance is possibly related to the presence of active Cu1+/Cu0 and Mo5+/Mo4+ redox species. Although all catalysts favour glycerol dehydration with higher acrolein selectivity, it was found that the redox properties of the Mo species play an important role in the product distribution, which leads to allyl alcohol production with decreased hydroxyacetone yield.

Adsorption of Safranin on Pseudostem Banana Fibers

Adsorption assays indicated that the pseudostem banana fibers are an efficient sorbent for the removal of safranin from aqueous solution being dependent on pH, dye concentration, and temperature. Kinetics and thermodynamic studies indicated Sips isotherm as the most suitable model to describe the studied adsorption process, which occurs through a pseudo second-order process. The thermodynamic parameters indicated that the sorption of safranin dye onto pseudostem banana fiber is spontaneous (ΔGads ≅ –30 kJ mol−1) and exothermic (ΔHads ≅ –17 kJ mol−1).

Prevalent fatty acids in cashew nuts obtained from conventional and organic cultivation in different stages of processing

Brazil is one of the three largest producers of fruits in the world, and among those fruit trees, the cashew tree stands out due to the high nutritional and commercial value of its products. During its fruit processing, there are losses in some compounds and few studies address this issue. Over the last decade the conventional system of food production has been substituted for the organic cultivation system, which is a promising alternative source of income given the global demand for healthy food. Therefore, this research aimed to characterize and quantify the prevalent fatty acids found in cashew nuts obtained from conventional and organic cultivation during various stages of processing. The prevalent fatty acids found were palmitic, linoleic, oleic, and stearic acid. The average of these fatty acids were 6.93 ± 0.55; 16.99 ± 0.61; 67.62 ± 1.00 and 8.42 ± 0.55 g/100 g, respectively. There was no reduction in the palmitic, oleic and stearic fatty acid contents during processing. Very little difference was observed between the nuts obtained from conventional and organic cultivation, indicating that the method of cultivation used has little or no influence on the content of cashew nut fatty acids.

On the correlation between electronic intramolecular delocalization and Au-S bonding strength of ruthenium tetraammine SAMs

Trans-[Ru(L)(NH3)4(L’)](PF6)n type complexes, where L = 4-cyanopyridine (CNpy), NCS-, CN-, and L’ = CNpy, 1,4-dithiane (1,4-dt), 4-mercaptopyridine (pyS) and thionicotinamide (tna), were synthesized and characterized. SAMs on gold of the complexes containing sulfur were studied by reductive desorption and SERS spectroscopy. Depending on the nature of L’, the withdrawing capability of the CNpy ligand is strong enough to partially oxidize the ruthenium atom and, as a consequence, delocalize the s electronic density from the trans located ligand. The reductive desorption results showed that the stability of the SAMs is directly related to this effect.

Volatile Organic Compounds from Filamentous Fungi: a Chemotaxonomic Tool of the Botryosphaeriaceae Family

Volatile organic compounds (VOCs) from ten endophytic fungal species belonging to the Botryosphaeriaceae family were extracted by headspace-solid phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). Thirty-four VOCs were identified. Most of the compounds are sesquiterpenes (14 non-oxygenated and 10 oxygenated), and two linear ketones and eight alcohols were also identified. Multivariate data analysis (PCA and HCA) allowed the differentiation of all investigated species, and proved to be efficient for the differentiation of Neofusicocum parvum and N. ribis, which are considered very similar species. α-Bisabolol, α-selinene, α-cedrene epoxide and guaiol acetate were suggested as biomarkers.

Chitosan Film Containing an Iron Complex: Synthesis and Prospects for Heterocyclic Aromatic Amines (HAAs) Recognition

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