5-Fluorocytosine (5-FC) was investigated for the controlled synthesis of cocrystals by applying the pK a rule. Five cocrystals were designed and developed with adipic, succinic, terephtalic, benzoic, and malic acids, all exhibiting negative ΔpK a values ranging from close to zero up to roughly −1. The synthesized cocrystals were analyzed by single crystal X-ray diffraction, and the observed supramolecular synthons were compared to the reported structures containing 5-FC. In the first four cocrystals, the intermolecular interactions between adjacent 5-FC molecules form two different homodimers showing R 2 2 (8) motifs and assembled via complementary N−H···O and N−H···N hydrogen bonds, respectively. However, in the cocrystal with malic acid (ΔpK a = −0.1), an intermediate supramolecular synthon pattern between salts and cocrystals is observed. In this crystal packing, the homodimer of 5-FC molecules held by the N−H···O interactions is preserved, but a new heterodimer is formed between 5-FC and the acid molecule, such as the ones observed for 5-FC salts. These differences were analyzed using UNI Force Field Calculations to establish the intermolecular potentials of the synthons. As an application, we synthesized a cocrystal of 5-FC with 5-fluorouracil. This can be considered the first step toward the application of 5-FC for the design of new tailor-made drugs.

: Cyclin-dependent kinases (CDKs) comprise a family of about 20 serine/threonine kinases whose catalytic activity requires a regulatory subunit known as cyclin; these enzymes play several roles in the cell cycle and transcription. PCTAIRE kinases (PCTKs) are a CDK subfamily, characterized by serine to cysteine mutation in the consensus PSTAIRE motif, involved in binding to the cyclin. One member of this class is PCTK3, which has two isoforms (a and b) and is also known as CDK18. After being activated by cyclin A2 or phosphorylation at Ser12 by PKA, PCTK3 can perform several functions. Among these functions, we may highlight the following: modulation of cargo transport in membrane traffic, p53-responsive gene, regulation of genome integrity. According to different studies, PCTK3 dysfunction is related to a wide range of diseases, such as metabolic diseases, cerebral ischemia, depression, cancer, neurological disorders, and Alzheimer's disease. Although this protein participates in different biological events, we may say that PCTK3 has received far less attention than other CDKs. There are thousands of published articles about other CDKs and less than two hundred articles related to PCTK3. The main objective of this review is to present the selected published studies about this protein. Our focus is on PCTK3 particularities compared to other CDKs. Here we give an overview of the biological functions of PCTK3 and explore its potential as a target for drug design.

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Desenvolvimento de géis e esponjas de quitosana e blendas quitosana/gelatina em ácido adípicoChitosan is a natural polymer studied in various fields such as environmental, food, pharmaceutical, biomedical and biotechnology. It can be obtained from different polymorphic forms of chitin, of which the form β has proven advantageous because it promotes more homogeneous and chemical modifications leads to a final product less allergenic. Chitosan can be combined with other compounds and thus further improve its properties. The aim of this study was to analyze how the use of adipic acid, replacing acetic acid affects the properties of gels and sponges of chitosan and chitosan/gelatin, which were subsequently crosslinked with EDC/NHS. The techniques used for these studies were: rheology, FTIR, SEM, absorption in PBS and cytotoxicity assays. In rheology, it was observed that increasing the concentration of chitosan was possible to prepare more elastic and viscous gels. The same occurs in the presence of gelatin or EDC/NHSO. The effect of the use of adipic acid to replace the acetic acid was also shown on rheological measurements, because the gels with 2% chitosan or chitosan/gelatin without EDC/NHS were more elastic and more viscous when the adipic acid has been used. The FTIR spectra showed the presence of interactions between chitosan and gelatin and the formation of amide II Bonds after crosslinking with EDC/NHS. In the preparation of the sponges it was observed that the gels of chitosan with adipic acid generated unstable sponges crumbled during neutralization, but this instability does not occur with the blend. Sponges prepared with the blend were studied after neutralization and SEM showed that the use of EDC/NHS altered the morphology leading to the formation of interconnected pores. The use of acetic acid increases the absorption in PBS for sponges without EDC/NHS, while for sponges with EDC/NHS the absorption is greater when adipic acid was used. All sponges were non-cytotoxic making them promising materials to be studied for applications in the medical field, such as dressing materials, implants, controlled drug release.