In this study, we discussed the impact of multicomponent reactions (MCRs), with a special focus on the Biginelli MCR and its variations. We observed a growing problem concerning the increasing number of published articles and the lack of reproducibility in MCRs, mainly due to the insufficient characterization of the synthesized products, with only melting points commonly reported. Within the scope of this study, we conducted a meticulous analysis of the articles describing a variant of the Biginelli MCR for the synthesis of chromenopyrimidinones (CPDs). During this analysis, we found conflicting characterization data presented for the proposed structure, which motivated us to investigate various methodologies for CPD synthesis. However, we discovered that the CPD was not synthesized in the literature articles, nor in the reproductions of the described methodologies, nor in the new methodologies tested. Under all experimental conditions, the obtained product was dicumarol (DC-01). Furthermore, we performed a mechanistic study of the reaction, which confirmed that the CPD cannot be obtained under the tested reaction conditions.

Persistent organic pollutants, polycyclic aromatic hydrocarbons (PAH) have widespread presence in all environmental compartments, even in food, been considered ubiquitous. Being originated by petroleum compounds or pyrolysis reactions, PAH are a very alarming substances for the air quality maintenance once these chemicals can be found at gaseous form or associated to particles at the atmosphere. Those compounds are well known in the literature because of their carcinogenic and mutagenic potential and, once at the atmospheric layers, can be converted by other chemicals as ozone and nitrogen dioxide, creating new possibly toxic compounds. Despite having a periodic particulate patter (PM) monitoring, the capital region, Brazilian Federal District (FD), has no profound studies about the composition and chemical characteristics of this pollutant, without sampling fine fractions, like PM2.5, nowadays. Lacking PAH works at the DF region, using PM local monitoring as source to make an assessment to understand the particulate coarse fractions, that might have these compounds, is the beginning of knowing more about them at the region. Objective of this work was to adapt and validate an analytical method to quantify and identify PAH in PM through Gas Chromatography and Mass Spectrometry, to obtain a routine method that could be used at Chemometrics and Environmental Chemistry Laboratory (LQQA) of the University of Brasilia (UnB). First the method was adapted and after it was implemented for the analysis of the 16 EPA priority PAH, 1-methylnaphthalene and 2-methylnaphthalene bonded to PM. A 2³ Factorial planning was used to optimize the solvent evaporation process after extraction. Tests to the analyte recovery in certified reference material was caried in a sediment and a dust (PM10 like) material. A total 26 samples of 2018, 40 samples of 2022 and 4 samples of 2023 were analyzed. Those samples were obtained from two sites, one at Brasília central zone and other near to 2 cement industrial plants. All 18 compounds were quantified in samples, but some samples had results below LoQ and LoD. Diagnosis ratios, that is used for other works in literature, were calculated and sources were assessed. Seasonal variations were also assessed, with result that vary through the months and between the sample sites. There are different patterns to the dry season and the rainy season, so characteristics for the local weather. Sum concentrations (∑PAH) obtained ranged from 0.05 and 4.24 ηg.m-3 (m/v) considering all sites and periods.

Copper oxide nanoparticles (CuO-NPs) are currently nanomaterials of great technological interest due to their catalytic and bactericidal activities. In these applications, their performance depends on size, shape, and preparation methods. With the expectation of extensive use, the impacts of CuO-NPs on the environment and human health have been increasingly studied. Thus, this master's dissertation focuses on the synthesis of CuO-NPs and characterization of their structure, morphology, and toxicity, evaluated through embryotoxicological and biochemical tests using zebrafish embryos as model organisms. Specifically, the influence of the shape and coating of CuO-NPs on their toxicity is evaluated. To this end, four CuO-NPs were synthesized and characterized, in spherical and rod shapes, with and without citrate coating (functionalization). Synthesis was carried out by the precipitation method using copper chloride (CuCl2) or copper acetate (Cu(CH3COO)2.H2O) as precursors and sodium hydroxide as a hydrolysis/precipitation agent. Nanostructure characterization was performed using various techniques: X-ray diffractometry (XRD), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-Vis), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, emission/photoluminescence spectroscopy (FL), thermogravimetric analysis (TGA), and dynamic light scattering (DLS). Embryotoxicological assays were conducted using the OECD protocol, 2013, in which organisms were exposed to different concentrations of the nanostructures diluted in water to assess toxic effects. XRD measurements showed that nanoparticles have average crystallite sizes ranging from about 5 nm to 35 nm for rod and spherical particles with and without citrate. This result is corroborated by Raman and UV-Vis spectra. Citrate coating was confirmed by FTIR spectra, TGA curves, and zeta potential measurements, ranging from -45 mV to -30 mV. Morphological analysis by TEM revealed CuO-NPs in two distinct shapes: rods and spheres, with well-defined nanocrystalline structure. Rods have an average length of 29 nm while spheres have an average diameter of 3.32 nm. Embryotoxicological studies showed that spherical nanostructures are less toxic than rod-shaped ones. Citrate coating reduces the toxicity of both CuO-NP shapes by 30% compared to uncapped nanoparticles. Biochemical assays supported previous observations, indicating that both shapes increase cellular oxidative stress and inhibit acetylcholinesterase activity. It is concluded that the shape and coating of CuO-NPs play a crucial role in determining their toxicity, highlighting the need to consider nanoparticle shape when assessing environmental risks associated with these nanomaterials.

The search for new molecules with antibiotic activity is of fundamental importance given the emergence of new multiresistant strains. However, new strategies, which involve reducing the pathogenicity of a bacterial infection, are proving to be powerful tools in the treatment of people afflicted by such illnesses. Quorum sensing (QS) is a population density perception mechanism that regulates the expression of virulence genes in bacteria, among other factors. This strategy allows the bacteria to behave as a multicellular organism and only express virulence factors when the population reaches a certain threshold, facilitating the attack on the host's immune system. QS is based on the production of chemical signals, called autoinducers. In Gram-negative bacteria, the autoinducers responsible for checking population density are N-acyl homoserine lactones. A sensor strain widely used in QS assays is Chromobacterium subtsugate CV026 ATCC 31532, which is deleted for two genes: 1 – the cviI gene, responsible for the synthesis of the autoinducer; and 2 – the vioS gene, repressor of the CviI/R system. This sensor strain, in the presence of an autoinducer supplied by an external source, forms a purple pigment, known as violacein, being an indicator of the occurrence of the QS mechanism. Therefore, the search for compounds that are capable of reducing violacein production represents the first step in the search for molecules that promote interference in the bacterial pathogenicity process, without compromising the growth of the strain and reducing the chances of mutation to a specific type more resistant. Different classes of compounds are capable of interfering with the QS of CV026. In this work, different sub-collections of Morita-Baylis-Hillman (MBHA) adducts have their ability to interfere with violacein biosynthesis evaluated. The choice of these compounds is based on structural similarities with that of the cognate N-acyl homoserine lactone autoinducer. Molecular docking, competition assay and RT-qPCR data suggest that interference occurs at the transcriptional level. The work also addresses the synthesis of a class of compounds previously evaluated for their QS inhibitory capacity in CV026, the tetrahydrochromenones. The attempt to promote the separation of the R and S isomers of a tetrahydrochromenone led to the formation of the tetrahydrochromenimine nucleus. Different and unprecedented analogues of these were obtained using hydrazones and oximes.

Artisanal small-scale gold mining (ASGM), an increasingly prevalent activity in South America, generates mercury-contaminated tailings that are often disposed of in the environment, leading to the introduction of mercury into ecosystems and the food web, where it bioaccumulates. Therefore, studying the geochemical processes involved in the desorption and dissolution of mercury in these tailings is essential for critical risk evaluations in the short and long term. For this purpose, sequential extraction procedures (SEPs) can be useful because they help to identify the phases to which Hg is associated, although they also have limitations such as a lack of selectivity and specificity. In this work, we propose a modified four-step SEP: exchangeable mercury (F1), oxidizable mercury (F2), mercury bound to Fe oxides (F3), and strongly bound mercury (F4). To test this adapted sequential extraction method, we evaluated the Hg contamination in mercury-contaminated tailings of the Amazon basin. The results revealed a total mercury concentration of 103 ± 16 mg.kg−1 in the tailings, with a significant portion in F1 (28% of the total), where Hg was bioavailable. The large Hg concentration in F3 (36%) suggested that Fe oxides likely contribute to mercury retention. Together, the SEP results emphasize the urgent need for improved surveillance of gold mining activities and responsible tailings management practices to mitigate environmental contamination and safeguard the health of the Amazon ecosystem.

Biodegradable polymers synthesized from renewable raw materials have become very attractive, due to the increasing number of inappropriately discarded materials with high degradation time. This way, poly(lactic acid) emerges as one of the most promising materials, being a product based on renewable raw material, biodegradable with properties similar to polymers based on fossil raw material, thus being able to replace them in different types of applications. This work aims at the synthesis of poly(L-lactic acid) from a process of direct polycondensation of lactic acid, evaluating the products obtained in the process with the use of organometallic catalysts. The analyzes of the obtained polymers were made through the acid index, infrared spectroscopy, viscosity, thermogravimetry (TGA) and differential scanning calorimetry (DSC) and the obtained results showed that there was a process of polyesterification of the monomers, obtaining different types of products in each reaction.

Concerns regarding personal health have been taking consumers (especially those with diabetes and other disease comorbidities that depend of dietary) to replace sugar with natural sweeteners. Among this group, stevia along with the polyols xylitol and erythritol stands on for its benefits such as cariostatic properties, satiety prolongation and antioxidant properties. With the increased demand and high market prices, these products are easy targets for adulteration, by illicit addition of low-cost artificial sweeteners in the product. Thus, the aim of this project is to determine natural sweeteners in tabletop commercial samples using near and mid infrared spectroscopy and a DD-SIMCA classification model in order to attest the authenticity of the products. The results showed the model was capable of classify correctly most of the validation samples (natural sweeteners), among these were samples of other classes and samples adulterated with saccharin, sucrose and acesulfame. The efficiency rate of the DD-SIMCA model reached 90% for most of training sets. The use of infrared spectroscopy combined with the DD-SIMCA algorithm provides a promising alternative to verification of authenticity of erythritol, stevia and xylitol.

Paper devices (PAD) are simple, low cost and use small amounts of reagent, the use of digital imaging to perform determinations in this medium is usually done through colorimetry, requiring multiple steps between signal acquisition and results. Aluminium chlorohydrate is an active ingredient of most commercially available antiperspirants, and the determination of aluminum is one way to perform quality control of these products, since the analyte is potentially harmful to human health. For this purpose, a fluorimeter capable of performing fluorescence determinations in an agile manner using PAD and digital images, with control and reading done by smartphone, using an app developed for this purpose, was developed. Aluminium chlorohydrate determinations were performed in commercial antiperspirant samples using the proposed instrument, and the results obtained were then compared with a reference method. The developed method for aluminum determinations was effective in determining the samples with errors less than 8.2% and no difference at the 95% confidence level for eight samples compared to the reference method.

Membrane-active peptides (MAPs) exhibit a broad biotechnological potential, both as alternatives to conventional drugs in combating multidrug-resistant microorganisms (MDR), and as carriers of conjugated drugs. However, their application relies on the selectivity with which these molecules recognize their targets, prokaryotic membranes, in relation to host membranes. Antimicrobial peptides (AMPs) and intragenic antimicrobial peptides (IAPs), the last-mentioned found in the primary structure of various proteins, are often poorly selective, being both antimicrobial and cytotoxic. The peptide Hs02 is an example of an IAP, consisting of 16 amino acid residues, a positive net charge, and an α-helix structure when adsorbed onto membranes. Nonetheless, while Hs02 is a potent and broad-spectrum antimicrobial agent, it exhibits moderate selectivity towards eukaryotic cells. With the purpose of enhancing this IAP’s selectivity, two generations of Hs02 analogs were synthesized, purified, and characterized. In one of these series, three shortened analogs were synthesized, followed by three others with point mutations at critical sites. The evaluation of their structures was carried out through Circular Dichroism spectroscopy, in the presence of large unilamellar vesicles (LUVs) with neutral and negative charges, as well as lipopolysaccharides (LPS). Furthermore, antimicrobial activities were tested against Gram-positive and Gram-negative bacteria, and cytotoxicities were measured using MTT cell viability assays with BV-2 microglial cells as a model. The obtained results demonstrated a significant increase in the therapeutic index (TI) of all second-generation analogs against the tested Gram-negative bacteria, particularly in the case of 16.3. Regarding Gram-positive bacteria, the developed analogs exhibited a decrease in their TI, suggesting that the cell wall composition of these bacteria might hinder the passage of cationic antimicrobial peptides. Despite this reduction, 16.3 showed an almost 5-fold increase in the Therapeutic Index against E. coli and P. aeruginosa, attributed to reduced cytotoxicity and maintained antimicrobial activity compared to the original peptide. The findings of this study indicate that the balance between Hs02's cationicity and minimal hydrophobicity was optimized, significantly altering the TI of this MAP.

In this master’s thesis, the synthesis of novel carba-isoflavonoids is described. They were formed through the reaction between an aryl bromide and a tetralone, enhancing the α-arylation method of tetralones using a palladium catalytic system with a bulky ligand, a strong base, and a solvent to establish a new (sp²―sp³) bond between aryl groups and the α position of tetralones. Microwave-assisted heating was employed to reduce the reaction time to 25 and 30 minutes. This represents a simple and efficient strategy for the formation of α-aryl carbonyl compounds. Through this work, 10 previously unreported compounds were obtained with varying yields (30-84%). A synthesis of carba-pterocarpens from the products of α-arylation of tetralones was achieved using the BBr3-promoted cyclization method. The results were promising as it proved to be a rapid and practical reaction for obtaining the desired products. The substances prepared in this study were spectroscopically characterized using ¹H NMR, ¹³C NMR, 2D-NMR, MS and IV (FTIR).

It is known that the use of plastic bags has made it more practical for moving goods, as well as storage, but polyethylene is obtained from petroleum, fossil and finite source. The use of plastic bags to collect domestic sink garbage does not allow organic matter to decompose correctly, leading to an increase in waste, in addition to the pollution already caused by the improper disposal of plastic. A possibly viable alternative proposal is the use of kraft paper, which is rich in cellulose and resistant, coated with a layer of latex, composed mainly of natural rubber (polyisoprene) and water and stabilized with an anticoagulant, preferably natural, such as tannin, which allows the temporary waterproofing of the container, allowing the bag to receive domestic organic waste, be stored for a limited time, and be disposed of for composting along with the food waste inside. Tests were carried out to determine the most adequate treatment, which would allow the best water repellency with the surface, but which would maintain the temporary characteristic of waterproofing. Then, it was determined the capacity to retain larger amounts of water of the treatments with the best results of water repellency. The temporarily waterproofed kraft paper was tested also for its possibility to develop microorganisms under appropriate conditions in petri dishes. Finally, the latex-tannin protected kraft paper samples were submitted to destructibility in a degrading environment based on ground earth with earthworms. Of the various treatments performed, the best result was kraft paper coated with two layers of 1% latex-tannin.

The current work reports the synthesis and investigation by physical-chemistry and spectroscopic methods of four dithiocarbazates HL¹, HL² H₂L³ and H₂L⁴ and eight novel metal complexes, which four complexes are derived from 2-acetylpyridine [Cu(L¹)Cl] (1), [Cu(L¹)Br] (2), [Cu(L²)Cl] (3) and [Cu(L²)Br] (4), explored in detail in section 1; and four complexes are derived from 1,1,1-trifluoro-2,4-pentanedione, [Ni(L³)PPh₃] (5), [Ni(L³)Py] (6), [Ni(L⁴)PPh₃] (7) and [Ni(L⁴)Py] (8), explored in detail in section 2. The crystal structures of Cu(II) complexes were elucidated by single crystal X-ray diffraction, which showed distorted square planar geometry to the metal centers, which tridentate ligands coordinated by NNS system and an additional halogen (Cl^- or Br^-) complete the coordination sphere. Mass spectrometry data indicated the presence of [Cu(L¹)(DMF)]⁺ and [Cu(L²)(DMF)]⁺ and characteristic fragmentation of the compounds. The Density Functional Theory (DFT) B97-3c method was used to optimize the geometries, and indicated that the results are in agreement with the experimental data. Hydrogen bonds and π-π stacking interactions were observed by the Hirshfeld surface, and the main interactions are attributed to the H---H contacts. In addition, the compounds were characterized by FT-IR and by ultraviolet–visible spectroscopy, which showed good agreement with the proposed structures. The biological activity of the compounds was evaluated against human glioma cells (U251) and the results revealed that free dithiocarbazates present high antitumor activity in vitro, which is increased after complexation with copper. The measurement of the cytotoxicity of the compounds also showed activity in a low concentration range, which indicates the high efficiency of the complexes as potential drugs. In section 2, the crystal structures of the H₂L³ and the (5)-(8) complexes are described after being elucidated by single crystal X-ray diffraction. Additionally, all compounds were characterized by a set of techniques that corroborate the proposed structures. In general, the results showed square planar geometry to the metal centers, which dithiocarbazates tridentate and a triphenylphosphine or pyridine molecule as coligand. The mass spectrometry data indicated the presence of the molecular ions [M+ H]⁺ and characteristic fragmentations of the compounds, which indicated the same behavior of the compounds as a solid and in solution. The ligands and complexes in this section were tested against four cell lines (MDA-MB-231 - breast cancer; U251 - glioma; NALM-6 and 697 - leukemia), furthermore, a molecular docking study was made to evaluate the predominant mode of binding of each compound with proteins of known 3D structures.

The present work concerns pioneer studies about the preparation of carbon-supported Mo-based catalysts and their use in the production of hydrocarbon biofuels through the hydroprocessing of lipidic feedstocks. A starting mesopore-rich activated carbon (AC) was prepared by chemical activation of dried coconut shell with H3PO4. This AC was used as obtained or after being treated with HNO3 or under an H2 atmosphere at elevated temperature, which permitted to increase or reduce the content of surface acidic groups, respectively. Preparation conditions were searched in order to give rise to catalysts with improved activity for the hydodeoxygenation (HDO) of lipidic feedstocks. HDO tests were carried out in a batch system having dodecanoic acid (a model compound) or coconut oil as substrate. Efficient catalysts were obtained, which promoted complete feedstock deoxygenation. The best results were verified for the catalyst prepared using the unmodified AC as support, adding Ni as activating agent, and depositing Mo and Ni successively from individual solutions by wet impregnation. It is valid to highlight that the prepared catalysts presented good stability in successive HDO cycles. Due to the low acidity of the carbon supports, the occurrence of isomerization reactions was not significant, so that the obtained biofuels were basically constituted by n-alkanes. The produced biofuels present a great potential to be used as drop-in substitutes for fossil fuels like diesel and jet fuel.

Cope and Claisen rearrangements are thermally activated [3,3] sigmatropic rearrangements that occur through cyclic six-membered transition states. Despite extensive investigation over the years, the magnetochemistry of these rearrangements still poses questions. In light of this, an investigation was conducted based on chemical-computational models to unravel the mechanistic and magnetochemical aspects of Cope and Claisen rearrangements using Density Functional Theory (DFT), CBS-QB3, Atoms in Molecules (AIM) theory, Multicenter Bond Order, Noncovalent Interaction (NCI), GIAO, and GIMIC methods. It was found that the Cope and Claisen rearrangements proceed via concerted mechanisms and cyclic six-membered aromatic transition states. The molar and anisotropic susceptibility (𝜒), NICS(1), and NICSzz exhibited a good correlation with J(nA.T-1), yet these descriptors proved insufficient to estimate the aromatic character of these transition states. Among the magnetic and topological descriptors employed in this study, magnetically induced current density (J) emerged as an excellent strategy for estimating the aromatic character of the transition states involved in the investigated rearrangements. Comparing the chair conformations of Cope rearrangement (RCO) and Claisen rearrangement (RCL), it was observed that greater aromatic character is associated with less-favored kinetics. For the chair conformations, RCL (TS2) exhibited 𝐽=8.63 nA.T-1, while RCO (TS4) showed 𝐽=10.43 nA.T-1. By utilizing the J(nA.T-1) index, the following aromatic character order was established: TS4 > TS2 > TS3 > TS1 for the analyzed structures, with boat conformations displaying high paramagnetic currents, which decrease the overall current in the ring. This result suggests that the aromatic character and thermodynamics in RCO and RCL cannot be directly correlated since the most stable transition states are not necessarily the most aromatic ones.

The synthesis of new selective fluorescent markers, with specific photophysical and biological properties, is highly desirable, and this area is growing more and more. In this sense, this work presents the synthesis of a fluorescent derivative called BTD-CHO, with the objective of being used in cellular bioimaging. The architecture of the derivative was intuitive to obtain a marker capable of selectively detecting hydrazine. The characterization of the compound controlled that the systemic occurred effectively. Photophysical studies appreciate large Stokes shifts and good stability in the excited state. The addition of hydrazine showed a shift in fluorescence from the green to the blue region, evidencing effective and selective labeling, even in the presence of other ions. Biological studies approved that the use of BTD-CHO can be performed both in living cells and in fixed cells, in addition to having been successfully employed in multicellular models, such as C. elegans and Zebrafish. Bioimaging revealed that the derivative was able to cross the cell membrane and selectively mark lipid bodies, showing strong fluorescence intensity, higher than that observed with the commercial marker Bodipy®, and also specificity for lipids that are not marked by the commercial marker. Furthermore, the derivative was superior to the commercial marker in terms of cytotoxicity and solubility in aqueous media. Such results demonstrate and consolidate the BTD core as an excellent and promising alternative for cellular bioimaging applications.

The presence of polycyclic aromatic hydrocarbons (PAHs) in firefighters' personal protective equipment is a concern. PAHs are compounds that have two or more condensed aromatic rings and are considered carcinogenic, mutagenic, and teratogenic. Several studies have shown that occupational exposure of these professionals to toxic compounds increases the risk of developing lung cancer, trachea, and leukemia, in addition to cardiovascular diseases. Some habits, such as adequate storage, washing method and washing frequency, can reduce this risk. With that in mind, we developed a form to assess attitudes and working practices of firefighters from Distrito Federal and Pernambucorelated to the presence of these pollutants in personal protective equipment. [iW1] The results show good awareness level from firefighters related to health attitudes, but, on the other hand, it was evidenced the lack of structure inside fire departments, making more difficult to adopt good habits that could reduce the exposure to carcinogenic compounds.

Besides that, we also evaluated the presence of PAHs deposited in firefighters' personal protective equipment during training exercise. To the best of our knowledge, this is the first study regarding the theme performed with Brazilian firefighters. Samples were collected after a firefighting training exercise and analysis were done with gas chromatography coupled to mass spectrometry. A set of 16 target compounds were searched and 8 were found in samples that were collected on the sleeve, chest, shoulder, and glove of firefighters’ suits. The highest concentration and variety of pollutants was found at an instructor, very probably due to the higher exposure frequency compared to those firefighters who carry out one-off combats.

Finally, we in we have evaluated some methods to decontaminating firefighters' fire-fighting suits. It is important to quote that it is mandatory that decontamination remove PAHs while maintaining the integrity of the suits. Photolysis with an ultraviolet and white lamp were evaluated, as well as the addition of an oxidizing agent (H₂O₂) to oxidize two probe PAHs. Regarding the fibers, damage was verified by scanning electron microscopy, optical microscopy and attenuated total reflection Fourier transform infrared spectroscopy. In addition, a tear resistance test (ASTM D2261) was performed on the outer layer fabric of the jacket, before and after treatment.

Best result was achieved using white lamp photolysis (WLP), when it was possible to remove more than 83% of the pyrene and 9-methylanthracene previously deposited on the fabric outer layer firefighting suit. The WLP was compared with the most used techniques (washing in a washing machine and brushing with soap and water) and showed better results. The experiment was also carried out on real samples, with the three layers of the fabric. Photolysis presented a superior result to the other techniques, removing 73% of PAHs, while washing and brushing promoted a reduction of 44% and 32%, respectively.

With this, it was possible to develop a simple and inexpensive method of decontamination based on an advanced oxidative process, photolysis, which is effective in the degradation of PAHs, in addition to maintaining the integrity of Kevlar® and Nomex® fibers.

Some proteins may present internal segments with shape and physical-chemical properties compatible with antimicrobial peptides (AMPs), such that, when synthesized as individual entities, present similar biological activities. Normally, the prospection of those is done based on helical AMPs, which results in the identification of protein segments compatible with cationic and amphiphilic α-helices. The present work explores a new form for encrypted antimicrobial peptides in proteins based on cationic and amphiphilic β-sheets and aims to evaluate their activity as antibacterial and anti-inflammatory molecules. For such, 6 putative short intragenic antimicrobial peptides (IAPs) were prospected from the human proteome by the software Kamal, and 4 of these were synthetized and purified with success, named Hs11, Hs12, Hs13, Hs14. One control peptide, the HsCtrl1, also was synthetized. Peptides Hs11 and Hs12 presented wide antimicrobial activity against bacteria, presenting a minimum inhibitory concentration between 8 and 128 µM. Furthermore, it was verified that none of the tested peptides reduced the cellular viability of murine macrophages (BMDM) after 24 hours of incubation in concentrations up to 100 µM. All the peptides reduced, in different ways, the biogenesis of lipid bodies in BMDM treated or not with lipopolysaccharides (LPS). Hs11, Hs12, Hs13 and Hs14 decreased the secretion of TNF-α and IL-6 in BMDM not stimulated with

LPS. The peptide Hs11 reduced the secretion of TNF-α to basal levels in cells that were previously incubated with LPS. At last, nuclear magnetic resonance studies were conducted to investigate the interaction between LPS aggregates and the peptide Hs11. In conclusion, short amphiphilic peptides ranging from 8 to 9 amino acid residues are interesting new small molecules, as they present antibacterial and anti-inflammatory activity that is comparable to previously known AMPs. The methodology described herein has the potential to generate alternatives in the combat of bacterial infections caused by resistant microorganisms, which are expected to victimize more people than cancer per year by 2050.

Micro-pollutants of emerging concern have imposed a major technological challenge: pesticides, drugs and other anthropogenic substances are increasingly found in aquatic and atmospheric environments and even in water supplies, being related to adverse effects on biota and human health. Overcoming this challenge requires understanding the behavior of these species in the environment and the development of technologies that allows for minimizing their dissemination. Viable alternatives applied in this thesis include the use of radical-based oxidation processes using both experimental – via the competition kinetics method – and theoretical protocols – blend of kinetic, quantum chemistry and machine learning calculations. In a first study, the mechanisms, kinetics, and an evaluation of the toxicity of picloram degradation – a pesticide widely used in the world - initiated by OH radicals indicate that: i) two favorable pathways occur by addition to the pyridine ring, ii) picloram and the majority of degradation products are estimated as harmful; however, ii) these compounds can suffer photolysis by sunlight. However, the competition kinetic method and the quantum chemistry description make the degradation analyses a formidable enterprise, considering the costs of ad hoc instrumental equipment’s and dedicated computational efforts. To overcome the demanding conventional procedures, we developed a free and user-friendly web application (www.pysirc.com.br) based on holistic machine learning combined with molecular fingerprints models that permits compilation of kinetic parameters and mechanistic interpretation of radical-based oxidation attacks according to the OECD principles. Machine learning algorithms were implemented, and all models provided high goodness-of-fit for radical-based degradation in aquatic and atmospheric environment. The models were interpreted using the SHAP (SHapley Additive exPlanations) method: the results showed that the model developed made the prediction based on a reasonable understanding of how electron-withdrawing/donating groups interfere in the reactivity of the radicals. We argue that our models and web interface can stimulate and expand the application and interpretation of kinetic research on contaminants in water and air treatment units based on advanced oxidative technologies.

Statistical learning models that use machine learning methods like GSA have been used for decades in chemistry for a variety of tasks. With these techniques, our research groups are mainly dedicated to the kinetic and mechanistic study of reactive and non-reactive processes allied to the development of new models and techniques for carrying out these researches. With the current increase in the processing capacity of computers and the advent of sophisticated methods of machine learning, such as deep learning, it has become increasingly necessary to create new analysis techniques as well as the development of platforms and tools that systematize these techniques. Accordingly, the present work makes three proposals for theoretical models that will be presentend with the development of codes for their use, with graphical and intuitive interfaces: 𝑖) We propose here the transitivity plot: a new perspective under Arrhenius plot that is able to linearize non-Arrhenius curvatures and thus observe regime changes. Its application was able to linearize the curvature of the propylene carbonate relaxation process and revealed a break in the regime at the temperature of 198K, with changes in phenomenological parameters such as the barrier height. In addition, the Transitivity code systematizes tools developed over the last 10 years to deal with the kinetics of non-Arrhenius processes, providing options for phenomenological estimation of the reaction kinetic constant in liquid and gas phases and perform model fitting with experimental kinetic data using GSA. As an example of its application, a publication on the free energy surface topography of the Claisen-Schmidt reaction was carried out and will be shown in this work. 𝑖𝑖) we also propose the generalized model of the temperature coefficient Qd10, used to evaluate the degree of dependence of biological processes as a function of temperature. The model was applied to a series of biological processes present in recent literature and unified the conflicting results obtained by the different researchers: the quality of the fits reinforced the initial hypothesis that the temperature coefficient must be described using deformed exponentials (Qd10) instead of the usual Arrhenius model (Q10). Furthermore, the standard model Q10 is a particular case of the proposed model, as it is retrieved when the deformed parameter is equal to zero, thus validating its general justification. The Qd10-GSA interface was developed and it estimates parameters related to the Arrhenius and AquilantiMundim formulations from experimental data, thus drawing a parallel between the usual model Q10 and the model proposed here Qd10. 𝑖𝑖𝑖) We also propose deep learning models that use artificial neural networks and learn from a spectral database, obtained from NIST, to make inferences about structural properties of molecules and perform spectra reconstructions from molecular featurizers. CNN ResNet34 and the proposed tabular model performed well in the classification of molecular structural properties using infrared and mass spectra, with F1-Score values between 0.83 and 0.88 and accuracies of 96%. The reconstruction models showed a mean square error of 0.005 and 0.007 in the reconstruction of the mass and infrared spectra, respectively. Thus, it is concluded that the development of these models suggests that neural networks are suitable for the search for new spectral analysis techniques and represent a step towards the creation of autonomous analysis techniques. Finally, the codes developed here present very intuitive and user-friendly interfaces in order to disseminate the proposed new concepts and the authors hope that they can also be used as powerful research tools and didactic tools for teaching thermodynamics, process kinetics and related issues.