Isolation and characterization of reference standard candidates for cocaine and benzoylecgonine obtained from illicit substances seized.

The area of forensic chemistry has been growing and developing as a line of research due to the high demands of public safety that require increasingly reliable results due to their importance in criminalistics. In this way, the development of new technologies that help this area, whether in the identification and quantification of drugs or the fight against fraud, becomes promising. In this context, the present work explored the production of reference standards from the purification of cocaine/crack samples seized by the Civil Police of the State of Espírito Santo. Cocaine was purified using chromatographic techniques, and benzoylecgonine was synthesized from purified cocaine. All substances were characterized by ultra-high-resolution mass spectrometry and nuclear magnetic resonance. Homogeneity and stability studies were also performed with benzoylecgonine, and the results were evaluated using analysis of variance (ANOVA). Cocaine and benzoylecgonine showed purities of 98.37% and 96.34%, respectively. The homogeneity of the batch, short-term stability, and other parameters were also evaluated, which together indicate this proposal as promising in the development of reference standards for drugs of abuse from samples seized by the Brazilian forensic police.

Anti-Candida, docking studies, and in vitro metabolism-mediated cytotoxicity evaluation of Eugenol derivatives.

The high morbidity and mortality rates of Candida infections, especially among immunocompromised patients, are related to the increased resistance rate of these species and the limited therapeutic arsenal. In this context, we evaluated the anti-Candida potential and the cytotoxic profile of eugenol derivatives. Anti-Candida activity was evaluated on C. albicans and C. parapsilosis strains by minimum inhibitory concentration (MIC), scanning electron microscopy (SEM), and molecular docking calculations at the site of the enzyme lanosterol-14-α-demethylase active site, responsible for ergosterol formation. The cytotoxic profile was evaluated in HepG2 cells, in the presence and absence of the metabolizing system (S9 system). The results indicated compounds 1b and 1d as the most active ones. The compounds have anti-Candida activity against both strains with MIC ranging from 50 to 100 µg ml-1 . SEM analyses of 1b and 1d indicated changes in the envelope architecture of both C. albicans and C. parapsilosis like the ones of eugenol and fluconazole, respectively. Docking results of the evaluated compounds indicated a similar binding pattern of fluconazole and posaconazole at the lanosterol-14-α-demethylase binding site. In the presence of the S9 system, compound 1b showed the same cytotoxicity profile as fluconazole (1.08 times) and compound 1d had 1.23 times increase in cytotoxicity. Eugenol and other evaluated compounds showed a significant increase in cytotoxicity. Our results suggest compound 1b as a promising starting point candidate to be used in the design of new anti-Candida agent prototypes.

Lactose quantification in bovine milk by nuclear magnetic resonance without deuterated solvent (No-D qNMR).

Milk is a homogeneous mixture of substances such as lactose, proteins, and glycerides. Among carbohydrates, lactose is a disaccharide composed of glucose and galactose, and it is present in bovine milk at a level of 4.6%. According to resolution no. 135 of the National Health Surveillance Agency (ANVISA) from Brazil, dairy products labeled "lactose-free" must contain 1.0 mg mL-1 or less of this disaccharide. Thus, this work aims to develop and validate a method for quantifying the lactose content by quantitative nuclear magnetic resonance without the use of deuterated solvent (No-D qMNR). The validation of the developed method followed the norms provided by ANVISA resolution RDC no. 166, based on the figures of merit such as selectivity, linearity, the limit of detection (LOD) and quantification (LOQ), accuracy, precision, and robustness. The obtained results validated the method due to excellent linearity, demonstrated by the value of R > 0.990 and the homoscedasticity of the results, as well as precision, accuracy, and robustness values lower than 5%. Furthermore, LOD and LOQ values around 0.1345 mg mL-1 and 0.4076 mg mL-1, respectively, were obtained, which are lower than those required by legislation. The No-D qNMR technique was also able to quantify lactose content in commercial lactose-free milk.

Synthesis of Coumarin Derivatives as Versatile Scaffolds for GSK-3ß Enzyme Inhibition.

BACKGROUND: Glycogen synthase kinase-3 (GSK-3) is involved in the phosphorylation and inactivation of glycogen synthase. GSK-3 inhibitors have been associated with a variety of diseases, including Alzheimer´s disease (AD), diabetes type II, neurologic disorders, and cancer. The inhibition of GSK-3ß isoforms is likely to represent an effective strategy against AD. OBJECTIVE: The present work aimed to design and synthesize coumarin derivatives to explore their potential as GSK-3ß kinase inhibitors. METHODS: The through different synthetic methods were used to prepare coumarin derivatives. The GSK-3ß activity was measured through the ADP-Glo™ Kinase Assay, which quantifies the kinasedependent enzymatic production of ADP from ATP, using a coupled-luminescence-based reaction. A docking study was performed by using the crystallographic structure of the staurosporine/GSK-3ß complex [Protein Data Bank (PDB) code: 1Q3D]. RESULTS: The eleven coumarin derivatives were obtained and evaluated as potential GSK-3ß inhibitors. Additionally, in silico studies were performed. The results revealed that the compounds 5c, 5d, and 6b inhibited GSK-3ß enzymatic activity by 38.97-49.62% at 1 mM. The other coumarin derivatives were tested at 1 mM, 1 µM, and 1 nM concentrations and were shown to be inhibitor candidates, with significant IC50 (1.224-6.875 µM) values, except for compound 7c (IC50 = 10.809 µM). Docking simulations showed polar interactions between compound 5b and Lys85 and Ser203, clarifying the mechanism of the most potent activity. CONCLUSION: The coumarin derivatives 3a and 5b, developed in this study, showed remarkable activity as GSK-3ß inhibitors.

Stereoelectronic interaction and their effects on conformational preference for 2-substituted methylenecyclohexane: an experimental and theoretical investigation.

Conformational preferences for 2-substituted methylenecyclohexanes were determined using (3) J H 2 H 3 spin-spin coupling constants, while stereoelectronic interactions were obtained by means of theoretical calculations and NBO analysis. The conformational equilibrium of compounds studied can be represented by their axial and equatorial conformers, the axial conformers being the most stable form in polar and nonpolar solvents. These conformational preferences were attributed to the hyperconjugative interactions between the pi C-C-->sigma* C-Xax. and sigma C-H-->sigma* C-Xax. orbitals, and the repulsive steric interaction observed between sigma C-H-->n Xeq..

Structural assignment of Diels-Alder adducts: an experimental and theoretical approach.

A detailed NMR analysis with total assignment of (1)H and (13)C NMR data for the endo and the exo adducts, obtained by Diels-Alder reaction between 2-cyclohexenone and cyclopentadiene, is described. The unequivocal assignment of the endo and exo structures was performed by (1)H and (13)C NMR. These assignments were supported by theoretical chemical shift calculations at GIAO/HF level using 6-311 + g(2d, p) from optimized structures at the B3LYP/6-31g(d) level.

Heavy Halogen Atom Effect on (13)C NMR Chemical Shifts in Monohalo Derivatives of Cyclohexane and Pyran. Experimental and Theoretical Study.

As a first step, a qualitative analysis of the spin-orbit operator was performed to predict the kind of organic compounds, where it could be expected that the SO/FC (spin-orbit/Fermi contact) and SO/SD (spin-orbit/spin dipolar) yield unusually small contributions to the "heavy atom effect" on (13)C SCSs (substituent chemical shifts). This analysis led to the conclusion that compounds presenting strong hyperconjugative interactions involving the σ*C-X orbital (X = halogen) are good examples where such effects can be expected to take place. On the basis of such results, the following set of model compounds was chosen: 2-eq-halocyclohexane (2-eq), 2-ax-halocyclohexane (2-ax), and 2-ax-halopyran (3), to measure (13)C SCSs. Such experimental values, as well as those of methane and halomethanes taken from the literature, were compared to calculated values at a nonrelativistic approach using B3LYP, and at a relativistic approach with BP86 using scalar ZORA, spin-orbit ZORA, scalar PAULI, and spin-orbit PAULI. Results from relativistic calculations are in agreement with the trends predicted by the qualitative model discussed in this work.

Electronic interactions and their influence on the conformational stability of trans-2-halocyclopentanol.

Conformational preferences and electronic interactions of trans-2-fluorocyclopentanol (1), trans-2-chlorocyclopentanol (2), and trans-2-bromocyclopentanol (3) were analyzed using experimental and theoretical (3)J(HH) coupling constants, theoretical calculations, and natural bond orbital (NBO) analysis. The conformational equilibria of compounds 1-3 can be represented by their diaxial and diequatorial conformers as supported by theoretical calculations. From (3)J(HH) coupling constant values, it can be found that the diequatorial conformer is present in the equilibrium as 55% for compound 1 and as 60% for compounds 2 and 3. This behavior is in agreement with orbital interaction analyses obtained from NBO.