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Abstract Background Schizophrenia (SCZ) is a severe mental disorder of multifactorial origin in which the role of amino acids is relatively unknown. Based on the hypothesis that there is an imbalance in amino acid levels in individuals with SCZ compared with healthy controls (HCs), the aim of this study was to identify the 20 proteinogenic amino acids involved in protein synthesis. Methods This study included 43 sex‐ and age‐matched individuals: 20 HCs and 23 with SCZ diagnosed using the Diagnostic and Statistical Manual of Mental Disorders criteria. Using proton nuclear magnetic resonance, we identified the serum levels of the 20 amino acids proteinogenic. We perform multivariate statistical exploratory analyzes to identify compounds, quantify, and identify the main biomarkers of SCZ. Results We identified the serum levels of 19 of the 20 amino acids. Cysteine, the main precursor of glutathione, was not detected. Multivariate exploratory analysis identified lysine, Tryptophan (TRP), and glutamate as possible biomarkers of SCZ. Both lysine and TRP levels were lower and glutamate levels were higher in individuals with SCZ than in HCs. The observed reduction in plasma TRP levels in SCZ was attributed to the activation of the kynurenine pathway and has implications for serotonin synthesis. A strong positive correlation was observed between lysine and TRP, and a weak negative correlation between lysine and glutamate. This result is consistent with the lysine catalysis process because lysine degradation generates glutamate and favors an increase in dopamine. Conclusions The results are consistent with the lysine catalysis process because lysine degradation generates glutamate and favors an increase in dopamine. We were unable to identify any studies suggesting a relationship between lysine catabolism and SCZ pathophysiology, but we recognize this association as innovative.

Propolis is a resinous bee product with a very complex composition, which is dependent upon the plant sources that bees visit. Due to the promising antimicrobial activities of red Brazilian propolis, it is paramount to identify the compounds responsible for it, which, in most of the cases, are not commercially available. The aim of this study was to develop a quick and clean preparative-scale methodology for preparing fractions of red propolis directly from a complex crude ethanol extract by combining the extractive capacity of counter-current chromatography (CCC) with preparative HPLC. The CCC method development included step gradient elution for the removal of waxes (which can bind to and block HPLC columns), sample injection in a single solvent to improve stationary phase stability, and a change in the mobile phase flow pattern, resulting in the loading of 2.5 g of the Brazilian red propolis crude extract on a 912.5 mL Midi CCC column. Three compounds were subsequently isolated from the concentrated fractions by preparative HPLC and identified by NMR and high-resolution MS: red pigment, retusapurpurin A; the isoflavan 3(R)-7-O-methylvestitol; and the prenylated benzophenone isomers xanthochymol/isoxanthochymol. These compounds are markers of red propolis that contribute to its therapeutic properties, and the amount isolated allows for further biological activities testing and for their use as chromatographic standards.

This study applied qNMR spectroscopy and chemometrics to metabolically profile polyfloral honey samples collected in southeastern (São Paulo - SP) and southern (Santa Catarina - SC) Brazil, over the 2019–2020 and 2020–2021 harvest seasons. Both 1D and 2D NMR experiments were carried out to identify and quantify metabolites, followed by descriptive statistical analysis, heatmap, and principal component analysis (PCA), considering geographic and botanical origins. Twenty-one metabolites were detected, encompassing carbohydrates, amino acids, organic acids, ketones, alcohols, esters, and alkaloids. The heatmap and the PCA allowed for distinguishing the geographical and botanical origin. Regarding the botanical origin, three clusters were detected, i.e., Hovenia dulcis (SC), Citrus spp. (SP), and Eucalyptus spp. (SC and SP). The analytical approach proved to be effective for determining the geographic and botanical origins of Brazilian polyfloral honey, even though the country has a huge floral diversity and, accordingly, different types of honey.

Abstract The nucleocapsid (N) protein plays critical roles in coronavirus genome transcription and packaging, representing a key target for the development of novel antivirals, and for which structural information on ligand binding is scarce. We used a novel fluorescence polarization assay to identify small molecules that disrupt the binding of the N protein to a target RNA derived from the SARS-CoV-2 genome packaging signal. Several phenolic compounds, including L-chicoric acid (CA), were identified as high-affinity N-protein ligands. The binding of CA to the N protein was confirmed by isothermal titration calorimetry, 1H-STD and 15N-HSQC NMR, and by the crystal structure of CA bound to the N protein C-terminal domain (CTD), further revealing a new modulatory site in the SARS-CoV-2 N protein. Moreover, CA reduced SARS-CoV-2 replication in cell cultures. These data thus open venues for the development of new antivirals targeting the N protein, an essential and yet underexplored coronavirus target.