Reactivity assessment of oligomeric systems associated with crystalline and amorphous cellulose for bioethanol production: a DFT study.

Context: The production of bioethanol from renewable raw materials is a decisive factor in the economic development of many countries. However, the complexity of the processes and the numerous experimental variables involved require a deeper understanding of the chemical reactions that take place during bioethanol production to define optimal parameters. Here, we have employed density functional theory-based calculations to investigate the local reactivity of oligomeric systems by considering crystalline and amorphous cellulose models to better understand some details regarding pulp pretreatment processes.

Reactivity of amino acids and short peptide sequences: identifying bioactive compounds via DFT calculations.

Bioactive peptides are short amino acid sequences that play important roles in various physiological processes, including antioxidant and protective effects. These compounds can be obtained through protein hydrolysis and have a wide range of potential applications in a variety of areas. However, despite the potential of these compounds, more in-depth knowledge is still necessary to better understand details regarding their chemical reactivity and electronic properties.

Date fruit melanin is primarily based on (-)-epicatechin proanthocyanidin oligomers.

Plant-based melanin seems to be abundant, but it did not receive scientific attention despite its importance in plant biology and medicinal applications, e.g. photoprotection, radical scavenging, antimicrobial properties, etc.

Antiviral Action against SARS-CoV-2 of a Synthetic Peptide Based on a Novel Defensin Present in the Transcriptome of the Fire Salamander ().

The potential emergence of zoonotic diseases has raised significant concerns, particularly in light of the recent pandemic, emphasizing the urgent need for scientific preparedness. The bioprospection and characterization of new molecules are strategically relevant to the research and development of innovative drugs for viral and bacterial treatment and disease management. Amphibian species possess a diverse array of compounds, including antimicrobial peptides.

Exploring the antiviral activity of α-ketoamides compounds through electronic structure calculations: a structure-activity relationship study.

In recent years, the scientific community has worked intensively in the search and development of new drugs to suppress viral infections, such as COVID-19. In fact, a number of active compounds have been tested; however, the absence of significant structure-activity relationships hinders the production of optimized drugs. In this study, molecular modeling techniques were employed to investigate the electronic, structural and chemical reactivity properties of a set α-ketoamides whose antiviral activities have been reported in the literature, aiming to propose new promising derivatives.

Natural cordiaquinones as strategies to inhibit the growth and biofilm formation of methicillin-sensitive and methicillin-resistant Staphylococcus spp.

Aims: The aim of this study was to investigate the antibacterial and antibiofilm potential of cordiaquinones B, E, L, N, and O against different Staphylococci strains, in addition to analyzing in silico the observed effect.

Methods And Results: The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined according to CLSI guidelines. The inhibition of biofilm formation was investigated at sub-MICs.

Antioxidant and Neuroprotective Effects of the First Tryptophyllin Found in Snake Venom ().

In this study, we report the isolation, characterization, and synthesis of the peptide BmT-2 belonging to the tryptophyllins family, isolated from the venom of the snake . This is the first time a tryptophyllin is identified in snake venom. We tested whether BmT-2 had cytotoxic effects and antioxidant activity in a set of experiments that included both in vitro and cell-based assays.

Visible Light Photoelectrochemical Sensor for Dopamine: Determination Using Iron Vanadate Modified Electrode.

This study reports a facile approach for constructing low-cost and remarkable electroactivity iron vanadate (Fe-V-O) semiconductor material to be used as a photoelectrochemical sensor for dopamine detection. The structure and morphology of the iron vanadate obtained by the Successive Ionic Adsorption and Reaction process were critically characterized, and the photoelectrochemical characterization showed a high photoelectroactivity of the photoanode in visible light irradiation. Under best conditions, dopamine was detected by chronoamperometry at +0.

Neuroprotective effects on microglia and insights into the structure-activity relationship of an antioxidant peptide isolated from Pelophylax perezi.

Tryptophyllins constitute a heterogeneous group of peptides that are one of the first classes of peptides identified from amphibian's skin secretions. Here, we report the structural characterization and antioxidant properties of a novel tryptophyllin-like peptide, named PpT-2, isolated from the Iberian green frog Pelophylax perezi. The skin secretion of P.

Effects of Mechanical Deformation on the Opto-Electronic Responses, Reactivity, and Performance of Conjugated Polymers: A DFT Study.

The development of polymers for optoelectronic applications is an important research area; however, a deeper understanding of the effects induced by mechanical deformations on their intrinsic properties is needed to expand their applicability and improve their durability. Despite the number of recent studies on the mechanochemistry of organic materials, the basic knowledge and applicability of such concepts in these materials are far from those for their inorganic counterparts. To bring light to this, here we employ molecular modeling techniques to evaluate the effects of mechanical deformations on the structural, optoelectronic, and reactivity properties of traditional semiconducting polymers, such as polyaniline (PANI), polythiophene (PT), poly (-phenylene vinylene) (PPV), and polypyrrole (PPy).

Revisiting the hydroxylation phenomenon of SiO: a study through "hard-hard" and "soft-soft" interactions.

Surface hydroxylation has been extensively studied over the years for a variety of applications, and studies involving hydroxylation of different silica surfaces are still carried out due to the interesting properties obtained from those modified surfaces. Although a number of theoretical studies have been employed to evaluate details on the hydroxylation phenomenon on silica (SiO) surfaces, most of these studies are based on computationally expensive models commonly based on extended systems. In order to circumvent such an aspect, here we present a low-cost theoretical study on the SiO hydroxylation process aiming to evaluate aspects associated with water-SiO interaction.

Sulfonated melanin derivatives: theoretical evaluation of local reactivities and chemical structures.

Melanins are natural macromolecules present in several organisms responsible for photoprotection, photosensitivity, ion chelation, and thermoregulation. Such materials have attracted attention due to their interesting electronic properties, which suggest their possible application in biocompatible devices. However, the low typical solubility of traditional melanins does not allow the production of good quality thin films.

The peptide secreted at the water to land transition in a model amphibian has antioxidant effects.

In addition to the morphophysiological changes experienced by amphibians during metamorphosis, they must also deal with a different set of environmental constraints when they shift from the water to the land. We found that secretes a single peptide ([M + H]+ = 658.38 Da) at the developmental stage that precedes the onset of terrestrial behaviour.

Ibuprofen-loaded biocompatible latex membrane for drug release: Characterization and molecular modeling.

The incorporation of drugs and bioactive compounds in the natural rubber latex (NRL) matrix has been an alternative for the development of transdermal release membranes. Ibuprofen (IBF) is known to be used to treat inflammatory diseases, but when administered orally, high concentrations can cause some adverse problems. In this work, the incorporation of IBF in the NRL membranes was evaluated by physical-chemical, permeation, hemocompatibility and molecular modeling assays.

Polythiophene derivatives as chemical sensors: a DFT study on the influence of side groups.

Conjugated polymers have been considered promising candidates for applications in chemical sensors, mainly due to their high versatility of synthesis, low cost, light weight, and suitable optoelectronic properties. In this context, polythiophene (PT) derivatives have been successfully employed. However, at the same time that the versatility of the synthesis allows the production of varied derivatives, the complexity of interactions with analytes hinders an efficient design of compounds with improved sensing properties.

Reactivity of eumelanin building blocks: A DFT study of monomers and dimers.

Melanins are natural pigments with important biological properties and have been considered promising materials for several bio-electronic applications. In spite of it, until now there is no satisfactory understanding of the macromolecular structure of these compounds. In this work, we have employed electronic structure calculations to evaluate the local reactivity on monomeric building blocks of eumelanin and on a varied combination of these units (dimers).

The Antioxidant Peptide Salamandrin-I: First Bioactive Peptide Identified from Skin Secretion of Salamandra Genus (Salamandra salamandra).

Amphibian skin is a multifunctional organ that plays key roles in defense, breathing, and water balance. In this study, skin secretion samples of the fire salamander (Salamandra salamandra) were separated using RP-HPLC and de novo sequenced using MALDI-TOF MS/MS. Next, we used an in silico platform to screen antioxidant molecules in the framework of density functional theory.

Polypyrrole derivatives for optoelectronic applications: a DFT study on the influence of side groups.

Conjugated organic polymers have been considered interesting materials for various technological applications, mainly due to their unique optoelectronic properties and the variety of methods employed in their synthesis. In this context, polypyrrole (PPy) derivatives have been widely employed. The great versatility of synthesis of this material allows the production of a number of derivatives with distinct properties, allowing their application in several areas.

Reactivity of lignin subunits: the influence of dehydrogenation and formation of dimeric structures.

Lignin is one of the most abundant natural materials around the world, accounting for about a quarter of the woody tissue. In general, it is well known that these highly branched aromatic bio-polymers are formed from the polymerization of p-coumaryl, coniferyl, and sinapyl alcohols; however, the connection between these structures are still not known in detail. In this work, we have employed electronic structure calculations to investigate local reactivities and details regarding the connectivity between the basic structures of lignin (unmodified mono and dilignols as well as dehydrogenated monolignols).

Antifungal and anti-inflammatory potential of eschweilenol C-rich fraction derived from Terminalia fagifolia Mart.

Ethnopharmacological Relevance: Folk knowledge transmitted between generations allows traditional populations to maintain the use of medicinal plants for the treatment of several diseases. In this context, the species Terminalia fagifolia Mart., native to Brazil, is used for the treatment of chronic and infectious diseases.

Acetylated cashew gum-based nanoparticles for the incorporation of alkaloid epiisopiloturine.

The natural alkaloid epiisopiloturine has recently become the focus of study for various medicinal properties, particularly for its anti-inflammatory and antischistosomal effect. The incorporation of active molecules in natural polymeric matrices has garnered increasing interest during recent decades. A new derivative of cashew gum successfully obtained by gum acetylation has shown great potential as a carrier in controlled drug release systems.

Identification of Common Resonant Lines in the EPR Spectra of Melanins.

Melanins are natural pigments with promising bioelectronic applications. Among their unique properties, the existence of a persistent paramagnetic signal can be considered one of the most intriguing and controversial features. Additionally, the possible influence of such centers on charge transport accentuates the need for a better understanding of their origin and specific characteristics.

Chemical sensors based on N-substituted polyaniline derivatives: reactivity and adsorption studies via electronic structure calculations.

Conjugated organic polymers represent an important class of materials for varied technological applications including in active layers of chemical sensors. In this context, polyaniline (PANI) derivatives are promising candidates, mainly due to their high chemical stability, good processability, versatility of synthesis, polymerization, and doping, as well as relative low cost. In this study, electronic structure calculations were carried out for varied N-substituted PANI derivatives in order to investigate the potential sensory properties of these materials.

Modeling of Open-Circuit Voltage of Phenyl-C61-Butyric Acid Methyl Ester-Like Based Bulk-Heterojunction Solar Cells.

New materials are currently being sought for use in active layers of bulk-heterojunction organic solar cells, and computational modeling plays an important role in this search. Although open circuit voltage (V(oc)) is one of the fundamental quantities that determine the efficiency of a solar cell, there is no consensus on the best way to estimate this magnitude for new materials from calculations of the electronic structure. In this paper, we compare ways of predicting V(oc) values employing a diverse group of blends and conclude that it is possible to have a good prediction tool for organic solar cells based on phenyl-C61-butyric acid methyl ester (PCBM) acceptor molecules.