This review deals with two-dimensional liquid chromatography (2D-LC) separations encompassing target heart-cut (LC-LC), multiple heart-cut (mLC-LC), non-targeted comprehensive (LC × LC), and selective comprehensive (sLC × LC) analysis. It presents an overview of basic concepts and emphasizes the versatility of the applications gained by going from one-(1D) to two-dimensional (2D) separations. This review also discusses target analysis of achiral and chiral drugs for different applications and the use of 2D-LC in zonal bioaffinity chromatography. Advances in instrumental and column technologies have widened the application of LC × LC and sLC × LC separations, and we will discuss some of them.

We describe an on-flow zonal affinity-based chromatography assay to screen ligands for the nucleoside diphosphate kinase B enzyme (NME2) from Homo sapiens. For the first time, we have covalently immobilized NME2 on the surface of an open fused silica capillary reactor (NME2-ICER) and placed the reactor before the analytical column, which resulted in a two-dimensional liquid chromatography-based system. We evaluated the pH effect on immobilized NME2 activity and carried out steady-state kinetic studies to compare free and immobilized NME2. Steady-state kinetic studies with the substrates adenosine 5’-triphosphate di(tris) salt dihydrate (ATP) and guanosine 5’-diphosphate sodium salt (GDP) resulted in apparent Michaelis-Menten constant values of 1136 and 713 mmol L-1, respectively. The ping-pong catalysis mechanism and substrate specificity were preserved after NME2 immobilization. By employing a reference inhibitor, (-)-epicatechin gallate (ECG), we verified the potential application of this method in NME2 ligand screening and NME2 inhibitor identification. The half maximum inhibitory concentration (IC50) for ECG was 161.3 ± 1.0 μmol L-1.

The methodology developed in this study through the acquisition of fingerprint chromatograms by liquid chromatography-diode array detector (LC-DAD), aided by principal component analysis, made it possible to assess, in a rational way, the chemical differences between six accessions of Lippia alba and to verify the influence of the method of extraction, the seasonality and the individuality of each accession on chemical composition of its extracts. Among all extracts analyzed against cancer cell lines, eight of them showed to be more promising against a human leukemia cell line (HL-60), displaying cell growth inhibition percentage ranging between 40.0 and 52.0%. In the inhibitory activity assays against acetylcholinesterase enzyme, all extracts showed weak inhibitory effect, with highlight only for six of them, which displayed inhibition ranging between 27.0 and 32.0%.

A new series of Mannich bases derived from 2-hydroxy-1,4-naphthoquinone (lawsone), substituted benzaldehydes and two primary amines, and their Cu2+ complexes were synthesized and evaluated for their potential as selective cholinesterase inhibitors (ChEIs). Immobilized capillary enzyme reactors (ICERs) bearing butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) were used not only for the on-flow screening assay but also for determining the inhibitory potency and equilibrium binding constants of the lead inhibitors. Eight copper complexes were identified and characterized as potent reversible and selective ChEIs with inhibitory potencies (IC50) and constants of inhibition (Ki) ranging from 1.24 to 11.5 µmol L-1. One of the compounds was particularly promising, showing IC50 and Ki values of 1.24 ± 0.01 and 1.06 ± 0.01 µmol L-1, respectively, for huAChE. These values were lower than those for the standard inhibitor galanthamine (IC50 = 206 ± 30.0 and Ki = 126 ± 18.0 µmol L-1). Even though, it is showing noncompetitive inhibition of huAChE and linear mixed-type inhibition of eeAChE. These complexes showed a promising cholinesterase inhibitory activity and can be used as model inhibitors.

O objetivo deste estudo foi avaliar os níveis de estresse transitório e o estado de ansiedade em crianças submetidas à anestesia dental convencional e computadorizada. Vinte crianças (7 a 12 anos de idade) foram randomicamente designadas para receber anestesia dental convencional e computadorizada. Para investigar a hipótese que o estresse transitório poderia ser menor após a anestesia computadorizada, comparada à anestesia convencional, os níveis de cortisol na saliva foram medidos antes e depois de cada técnica. A ansiedade também foi avaliada individualmente por meio do State-Trait Anxiety Inventory for Children (STAIC). Os dados numéricos foram analisados estatisticamente pelo teste não paramétrico de Mann-Whitney (nível de significância de 5%). Os níveis salivares de cortisol aumentaram em 8 (40%) pacientes após anestesia convencional e em 9 (45%) pacientes após anestesia computadorizada, sem diferença estatisticamente significante entre os dois tipos (p=0,34). Da mesma maneira, não foi encontrada diferença estatisticamente significante entre as técnicas (p=0,39) com relação à análise psicológica baseada nos escores STAIC. Anestesia local usando tanto a anestesia convencional quanto o sistema de aplicação computadorizado produziu nível similar de estresse/ansiedade em pacientes infantis, utilizando análises quantitativa e qualitativa.

The aim of this study was to evaluate the transitory stress levels and the anxiety state in children submitted to conventional and computerized dental anesthesia. Twenty children (7 to 12 years) were randomly assigned to receive conventional and computerized dental anesthesia. To investigate the hypothesis that transitory stress could be lower after using computerized anesthesia compared to conventional anesthesia, cortisol levels in saliva were measured before and after each technique. Anxiety was also evaluated individually by answering the State-Trait Anxiety Inventory for Children (STAIC). Numerical data were analyzed statistically by the Mann-Whitney non-parametric test (5% significance level). Salivary cortisol levels increased in 8 (40%) patients after conventional anesthesia and in 9 (45%) patients after computerized anesthesia, with no statistically significant difference between the two types (p=0.34). In the same way, no statistically significant difference was found between the techniques (p=0.39) related to the psychological analysis based on the STAIC scores. Local anesthesia using either conventional anesthesia or a computerized delivery system produced similar level of stress/anxiety in pediatric patients, using both quantitative and qualitative analyses.

O desenvolvimento de métodos rápidos e eficazes para a identificação de novas moléculas bioativas é fundamental para o processo de descoberta e planejamento de fármacos. A integração de um sistema de cromatografia liquida de alta eficiência (CLAE), com biorreatores como fase estacionária (IMER) é uma estratégia atrativa e versátil para a triagem de coleções de compostos visando à identificação de novos agentes terapêuticos. Os parâmetros cinéticos da enzima imobilizada gliceraldeído-3-fosfato desidrogenase (GAPDH) de Trypanosoma cruzi e humana foram determinados (T. cruzi: K M G3P = 0.50 mmol L-1; K M NAD+ = 0.67 mmol L-1; humana: K M G3P = 3.7 mmol L-1; K M NAD+ = 0.75 mmol L-1) e comparados com aqueles observados em solução (T. cruzi: K M G3P = 0.42 mmol L-1; K M NAD+ = 0.26 mmol L-1; humana: K M G3P = 0.16 mmol L-1; K M NAD+ = 0.18 mmol L-1). Os resultados indicaram uma diminuição na afinidade das enzimas imobilizadas, entretanto, os elementos estruturais necessários para o processo de reconhecimento molecular e atividade biológica permaneceram inalterados, aumentando a estabilidade das enzimas. Além disso, a análise estrutural forneceu dados moleculares importantes envolvidos nos efeitos da imobilização sobre as interações entre ligante e receptor e, consequentemente, sobre a atividade enzimática e parâmetros cinéticos.

The development of fast and reliable methods for the identification of new bioactive compounds is of utmost importance to boost the process of drug discovery and development. Immobilized enzyme reactors (IMERs), integrated with high performance liquid chromatography (HPLC), are attractive and versatile tools for screening collections consisting of natural products and synthetic small molecules. Standard kinetic parameters of the immobilized enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from both Trypanosoma cruzi de and human have been determined (T. cruzi: K M G3P = 0.50 mmol L-1; K M NAD+ = 0.67 mmol L-1; humana: K M G3P = 3.7 mmol L-1; K M NAD+ = 0.75 mmol L-1), and comparisons of these values with those of the parasite and human free enzymes indicate a decrease in the affinity for the immobilized system (T. cruzi: K M G3P = 0.42 mmol L-1; K M NAD+ = 0.26 mmol L-1; humana: K M G3P = 0.16 mmol L-1; K M NAD+ = 0.18 mmol L-1). Interestingly, despite the kinetic differences between the two systems, the immobilized GAPDHs retained the required structural requirements for molecular recognition and biological activity, increasing the stability the enzyme. In the present work, we described an integrated structural analysis which has provided important insights into the molecular basis underlying the effects of immobilization on the ligand-receptor interactions and consequent enzymatic activity and kinetics parameters.

A utilização de parâmetros apenas morfológicos para posicionar taxonomicamente diversas espécies em sub-famílias e tribos na família Rubiaceae é bastante problemática devido à falta de informações sobre a distribuição geográfica e de características morfoanatômicas nos níveis hierárquicos mais baixos, como por exemplo, o gênero Chimarrhis. O perfil micromolecular de diferentes espécies pode auxiliar na delimitação de tribos indicando tendências filogenéticas mais completas entre as tribos das sub-famílias, já que os metabólitos secundários são expressões de adaptação, regulação e evolução de um determinado táxon. Nesse contexto, os alcalóides indólicos monoterpênicos isolados de Chimarrhis turbinata foram bastante úteis para embasar a classificação taxonômica feita por Robbrecht, em que posiciona Chimarrhis como um gênero da tribo Condamineae e subfamília Cinchonoideae.

The morphological parameters used to establish close connections among species taxonomically different into the Rubiaceae family is complex, mainly due to the lack of information on habitat and morphoanatomical characters in the lower hierarchic groups, for example, Chimarrhis genus. The micromolecular profile of delimited species into determined taxa can be useful to establish the boundaries among close taxonomic groups, and to indicate evolutionary phylogenetic trends into the taxa. Several indole alkaloids isolated from C. turbinata showed to be a valuable tool to support the taxonomic classification performed by Robbrecht, who established the most recent taxonomy for Rubiaceae, based on morphological characters, and concluded that Chimarrhis belong to Condamineae, and subfamily Cinchonoideae.

As células estão continuamente expostas a uma série de fatores que exercem estresse oxidativo o qual gera várias patologias que estão relacionadas a fatores de senescência tais como doenças coronárias, artrites reumática, e câncer. Para combater esse efeito, os organismos vivos desenvolveram uma rede complexa de antioxidantes que agem contra essas espécies radicalares nocivas à vida. Com o intuito de fazer uma bioprospecção de espécies vegetais da Mata Atlântica e Cerrados brasileiros estabelecemos uma metodologia para detetar compostos com atividade antioxidante. A combinação de CLAE a um detetor eletroquímico permitiu a detecção de micromoléculas antioxidantes nos extratos brutos das folhas de Chimmarhis turbinata (DC). Foi possível detectar e identificar nas matrizes naturais os compostos responsáveis após comparação com padrões isolados da mesma espécie.

Living cells are continuously exposed to a variety of challenges that exert oxidative stress and are directly related with senescence and the onset of various pathological conditions such as coronary heart disease, rheumatoid arthritis and cancer. Nevertheless, living organisms have developed a complex antioxidant network to counteract reactive species that are detrimental to life. With the aim of bio-prospecting plant species from the Brazilian Cerrado and Atlantic Forest, we have established a methodology to detect secondary antioxidant metabolites in crude extracts and fractions obtained from plant species. Combining HPLC with an electrochemical detector allowed us to detect micromolecules that showed antioxidant activities in Chimarrhis turbinata (DC) leaf extracts. Comparison with purified flavonoid standards led us to identify the compounds in their natural matrices giving valuable information on their antioxidant capacity.