Resumo em Português:

Cyclodextrins (CDs) are cyclic oligosaccharides, products of the intramolecular transglycosylation reaction promoted by the enzyme cyclomaltodextrin glucanotransferase (CGTase). The most commonly produced CDs are α-CD, β-CD and γ-CD, composed of 6, 7 and 8 glucose molecules, respectively. They form non-covalent inclusion complexes with several molecules, increasing their stability and/or solubility. Due to the importance of CDs and the various industrial applications, this work aimed to use the commercial enzyme Toruzyme® to obtain CDs and direct its production to α-CD or β-CD through the use of ethanol and complexing agents in the reaction medium. The reaction medium added with ethanol and cyclohexanecarboxylic acid directed the production to β-CD, reaching 47.09 mg mL-1 of this molecule. The production medium containing ethanol and stearic acid proved to be more advantageous for the production of α-CD and, after 48 h of reaction, the production of α-CD reached 19.57 mg mL-1, a value six times greater than that of amount of β-CD produced. With this study it was possible to prove that with the use of ethanol and complexing agents in the reaction medium it is possible to direct the production of a certain CD and, thus, make different CGTases economically viable for industrial use.

Resumo em Português:

Contamination of natural resources by dyes present in industrial effluents causes serious impacts to the environment. Research on efficient methods to remove these contaminants has intensified in recent years. A promising method is adsorption, as it uses effective and low-cost adsorbents, such as biomass. In this study, the adsorptive capacity of carbon chemically activated with phosphoric acid (H3PO4) obtained from monkfish (Enterolobium contortisiliquum) shells was investigated for the removal of methylene blue (MB) dye in aqueous medium. UV-Visible was used to quantify the dye removed from the experimental batch method. Adsorption tests at different temperatures suggest that the Langmuir isotherm model (R2 = 0.9967) and the pseudo-second order kinetic model better fit the experimental data. The negative values of ∆Hads and ∆Gads express that the adsorption dynamics is exothermic and spontaneous. The positive value of ∆Sads suggests an increase in disorder at the solid-solution interface during the process. Under these conditions, TCA (monkfish activated charcoal) presented a qe of 525.15 mg g-1, reaching a removal percentage of 82.67%. The treatment carried out to obtain activated carbon allowed the SEM, BET and FT-IR analyses to reveal a porous surface with the presence of micro and mesopores and acid groups on the TCA surface.

Resumo em Português:

Hop (Humulus lupulus L.) is a plant widely used as raw material in global beer production, valued for its aroma, flavor and bittering components. Despite Brazil’s third-place position in global beer production, the country still relies on imported hops. Thus, this study describes the chemical composition and volatile oil content of Cascade and Chinook hop cultivars grown in a tropical area in São Paulo state during 2020 and 2021, as well as imported commercial pellets. Hydrodistillation was employed to extract the oils, which were analyzed using GC-FID and GC-MS techniques. Approximately 40% of the cultivated hop plants exhibited volatile oil content within the expected range. Among the 55 identified compounds, β-myrcene, β-caryophyllene, and α-humulene were the major constituents, and several key compounds contributing to hop aroma were detected. Principal component analysis revealed distinct clustering patterns based on cultivar and harvest year. This study reports the first comparative analysis of hops harvested in different years and the volatile oil composition and content of Chinook hops cultivated in Brazil, making a significant contribution to the fields of agronomy and national beer market. These findings highlight Brazil’s potential to become a major hop producer by implementing proper management practices and suitable technologies.

Resumo em Inglês:

Phytochemical study of Psychotria schlechtendaliana (Rubiaceae) aerial parts resulted in the isolation of alkaloids 4 N oxide harmane (1) and strictosidinic acid (2), and the terpenoids sitosterol, estigmasterol, α-amyrin, β-amyrin and betulinic acid. The crude extract (CE), its fractions (hexane FH, chloroform FC, ethyl acetate FEA, hydromethanolic FHM, alkaloidal chloroform FCOH, alkaloidal aqueous FAq) and majority alkaloid (1) were investigated for their antiproliferative potential against nine human tumor cells lines and one non-tumoral human cell line (HaCat). CE, FH and FEA fractions exhibited strong growth inhibition for ovary cells (OVCAR-3, GI50 = 5.89; 1.36 and 6.59 μg mL-1, respectively) and FC, FH and FAq fractions showed potent activity on the growth of leukemia cell lines (K562, GI50 = 1.92; 7.23 and 8.81 μg mL-1, respectively). Compound 1 exhibited selective antiproliferative activity to breast cancer (MCF-7, GI50 = 32.7 μg mL-1) and was non-toxic to HaCat cells. To evaluate the anti-inflammatory effect, models of ear edema induced by croton oil and the enzyme myeloperoxidase (MPO) were used. FH and FC fractions exhibited anti-inflammatory effect and reduce ear edema compared to the control group. These fractions showed results superior to those exhibited by indomethacin (75.1%), FH (97.5%) and FC (95.5%) fractions.

Resumo em Inglês:

A method was developed for quantifying the concentrations of Ca, Fe, Mg, and Zn in star fruit. An in vitro assay was used to evaluate the bioaccessibility of these elements after a simulated gastrointestinal digestion. The results showed that the total elemental concentration in star fruit were 78-186.2 mg kg-1 for Ca, 92.1-148.1 mg kg-1 for Mg, below the limit of detection for Fe and Zn. The bioaccessibility of Ca and Mg was 40 and 58%, respectively. These bioaccessibility percentages were attributed to the presence of an antinutrient in star fruit that promotes precipitation of insoluble compounds during the in vitro assay. Based on the data from gastrointestinal digestion assay, it is possible to conclude that star fruit intake can supply 1.6-2.04% and 11.2-19.6% of the recommended dietary allowance (RDA) of Ca and Mg, respectively.

Resumo em Inglês:

Various aniline sensing materials have excellent properties based on quartz crystal microbalance (QCM) transducer, but their synthesis processes are complex. Herein, commercial calcium silicate hydrate nanosheets (CSH-S) was utilized for facile fabrication of aniline sensor based on QCM platform. This sensor was capable of detecting 0.1 ppm aniline, and the response time (14 s) and recovery time (16 s) were short. Besides, the devices could restore sensitivity after 30 days, demonstrating excellent stability. In addition, variable temperature experiment combined with simulation calculation methods were carried out to study the adsorption of aniline on CSH-S surfaces, then the sensing mechanism was revealed. This work opens up a rapid and convenient method for detecting gaseous aniline.

Resumo em Inglês:

Scaffolds are devices with interconnected pores that favor cell interaction and proliferation. They play a significant role in tissue engineering, as they mimic the conditions of tissue production in vivo. The aim of this study was to synthesize scaffolds of chitosan, collagen, and Jatropha mollissima by lyophilization and characterize their chemical/biodegradability and morphological properties. For that, techniques of optical microscopy, infrared spectrometry, biodegradation test, and degree of swelling were performed. A 2% (m/v) chitosan/collagen (1:9) in lactic acid solution was produced. Then, Jatropha mollissima crude extract was added to this solution in different proportions of mass (5, 10, and 15%). Optical microscope images indicated the three-dimensional network formation with interconnected pores and predominantly lamellar shape. Through infrared spectrometry, characteristic bands indicated a physical mixture. Also, the swelling degree of all samples was proportional to the amount of Jatropha mollissima extract with the highest percentage of 1852%. Biodegradation test also revealed a proportional ratio between the amount of sap used and the degraded percentage with the lowest value of around 35% in 28 days. In conclusion, it can be inferred that the scaffolds produced show potential to be used in tissue engineering as dressings.

Resumo em Português:

Solid tumors are frequently affected by the presence of hypoxic cells, originating anomalous and disordered cell growth. This subpopulation presents resistance to conventional chemotherapy agents and radiotherapy, due to the difficulties of reaching the target region, the permanence in the G0 phase of cell cycle and the low local concentration of oxygen. The use of hypoxia activated prodrugs becomes, in this scenario, an effective and selective alternative in cancer therapy, though not yet available for clinical use in solid tumor treatment. Twenty years after the publication of the paper intitled “Agentes Antineoplásicos Biorredutíveis: Uma Nova Alternativa para o Tratamento de Tumores Sólidos” in the Química Nova journal (2002), the current essay aims to identify the advances in the pre-clinical and clinical studies regarding the development of new hypoxia-directed drugs and the improvement of the molecules previously studied. Moreover, to clarify the main challenges for the implementation and success of this drug class, in order to identify the hindrances for the preparation of a bioavailable, safe and selective drug.

Resumo em Inglês:

The structure of food webs is a fundamental attribute of ecosystems, and their characterization provides an intrinsic knowledge of the trophic interactions among organisms and of nutrient and energy transfer within ecosystems. Over the last few decades, several chemical and biogeochemical approaches have been proposed to explore different aspects of food webs. In this sense, this study reviews the application of stable isotopes and mercury as main auxiliary tools to the characterization and modeling of aquatic food webs, including analytical and modeling advances, strengths and limitations. The metanalysis performed showed that the most used tools for trophic ecology studies are stable isotopes, and that they can provide better results when combined with mercury and specific chemical molecules such as amino and fatty acids. In addition, the statistical methods applied in the interpretation of results, such as isotope mixing models, have witnessed significant advances in the last two decades. All approaches have premises and limitations when applied to aquatic ecosystems, which must be well understood prior to results interpretation. The use of multiple tracers in trophic studies provides complementary information and in many cases is an appropriate alternative to overcome some limitations, allowing to expand the knowledge of the food webs.

Resumo em Inglês:

Coulometry is a well-established technique for certified reference materials (CRM). However, commercial coulometers are currently expensive and utilize outdated software. The National Metrology Institute of Colombia (INMC) has developed a cheaper and modular coulometer with powerful software capable of controlling the instrument, and acquiring pH, the potential difference between generator electrodes, and the electrical current at any stage of the coulometric titration. The results obtained from this new coulometer align well with the novel method for calculating the amount of substance content of potassium hydrogen phthalate (KHP). This method involves the experimental data fitting with the theoretical titration curve TC(NLR), also developed by the INMC. TC(NLR) replaces the traditional empirical W-function (eWf), which has no chemical basis and does not account for CO2 as an impurity. The KHP content of the CRM KHP 84L from NIST was measured using the developed coulometer, resulting in 4.9069 ± 0.0090 mol kg-1 with a bias of 0.21% for the eWf, and a more accurate result of 4.8983 ± 0.0047 mol kg-1 with a bias of 0.041% for the TC(NLR). The challenges during the development of the coulometer, particularly in terms of instrumentation, as well as their impact on uncertainty, are also discussed.

Resumo em Português:

Despite being responsible for many essential products in our daily lives, the chemical industries have not given proper attention to environmental issues for a long time. In the late 90’s, Green Chemistry (GC) emerged as a field of chemistry responsible for dealing with the relationship between the products used and their effects on human health and the environment. However, the employability of GC, in practice, is still incipient due to the little importance given to this field during the training of professionals. In Brazil, without a legislation that collaborates for its insertion, GC struggles to be part of the contents studied and the curricular matrices of higher education courses. This work aimed at revisiting the subject through an analysis of whether Brazilian higher educational institutions are working on disciplines related to Green Chemistry in their courses and how they are doing so. Based on the data obtained, it was noticed that this topic is more present in elective and theoretical disciplines, mainly for postgraduate and teaching training courses, taught predominantly in public institutions located substantially in the Southeast region. Although there are interesting proposals, the number of educational institutions that promote GC in their disciplines is still considered low.

Resumo em Português:

The relationship between syphilis and chemistry is remarkable due to its being the first example in western history of a comprehensive attempt by researchers from many countries and cultures to direct their efforts to tackle a serious health problem by means of chemical science. This effort started to take place at the time when the science of chemistry was already beginning to emerge, apart from alchemy. Thus, the fight against syphilis was closely linked to the emergence of iatrochemistry, or medicinal chemistry, which eventually gave rise, centuries later, to chemotherapy. Many of the early iatrochemical compounds in the XVIth century were of mineral origin, and often also synthetic. One of the pioneers of this trend was Paracelsus, who occupies a prominent place in the process. Along the centuries a number of different chemical approaches were attempted to cure syphilis until the advent of antibiotics in the mid-twentieth century, after so much time in which syphilis remained a physical and moral scourge of humankind, challenging all those that endeavoured to find its cure. In this article we recount many fascinating aspects of the application of chemistry in this quest, showing its development in the world as well as in Brazil, throughout its entire history.