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Molecular docking, in silico studies and NMR show that the new guanylhydrazone is a promising compound for the treatment of Alzheimer's disease.

Six quinoline-piperonal hybrids were synthesized and evaluated as potential drugs against Alzheimer’s disease (AD). Theoretical analysis of the pharmacokinetic and toxicological properties of the compounds suggest that they present good oral bio-availability and are also capable of penetrating the blood–brain barrier, qualifying as leads for new drugs against AD. Evaluation of their inhibitory capacity against acetyl- and butyrilcholinesterases (AChE and BChE) through Ellmann’s test showed that three compounds present promising results with one of them being capable of inhibiting both enzymes. Further docking studies of the six compounds synthesized helped to elucidate the main interactions that may be responsible for the inhibitory activities observed.

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Two new compounds (E)-2-(5,7-dibromo-3,3-dimethyl-3,4-dihydroacridin-1(2H)-ylidene)hydrazinecarbothiomide (3) and (E)-2-(5,7-dibromo-3,3-dimethyl-3,4-dhihydroacridin-1(2H)-ylidene)hydrazinecarboxamide (4) were synthesized and evaluated for their anticholinesterase activities. In vitro tests performed by NMR and Ellman's tests, pointed to a mixed kinetic mechanism for the inhibition of acetylcholinesterase (AChE). This result was corroborated through further docking and molecular dynamics studies, suggesting that the new compounds can work as gorge-spanning ligands by interacting with two different binding sites inside AChE. Also, in silico toxicity evaluation suggested that these new compounds can be less toxic than tacrine.

Bees are becoming more and more valued for the extremely important role they play in ecological communities, especially for their pollinating action. The state of Roraima, Brazil has areas of native vegetation and variety of stingless bees, and this potential is still untapped. The objective of this study was to determine the chemical composition of materials collected from the nests of Frieseomelitta silvestrii (FRIESE, 1902), identified in São Luiz, in Roraima state, Brazil) The chemical composition of the collected material was determined by gas chromatography coupled to mass spectrometry (GC-MS). The dichloromethane extracts of propolis, cerumen threads and resin present in the stingless bee nest presented differentiated profiles with the occurrence of low polarity compounds.

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