Alzheimer's (AD) and Parkinson's (PD) diseases are the main neurodegenerative disorders of the central nervous system, affecting millions of people worldwide. The absence of effective and curative therapies to slow down the progression of neurodegenerative processes constitutes a serious medical concern. In this sense, the development of new neuroprotective therapies becomes imperative. Glypromate is an endogenous neuropeptide with the sequence of Gly-Pro-Glu which displays evidence of neuroprotective activity in many in vitro models of AD and PD. Despite its neuroprotective potential use in the clinical, this neuropeptide exhibits low intestinal absorption, liability towards enzymatic proteolysis, and reduced blood-brain barrier permeability. In fact, clinical trials led by Neuren Pharmaceuticals with Glypromate failed in phase III. The use of constrained proline mimetics and capping strategies have been employed in the assembly of bioactive Glypromate analogues to improve lipophilicity and enhance enzymatic stability. Considering this rationale, the NeuroPro project aims at the design, synthesis, and biological evaluation of novel constrained Glypromate analogues. NeuroPro also explores the chemical conjugation of these constrained peptidomimetics with relevant active pharmaceutical ingredients (APIs) used in AD and PD therapy. This approach is expected to deliver new neuroprotective hits with higher metabolic resistance while exploring synergism between Glypromate analogues and APIs. In this work, the synthesis of 52 new Glypromate conjugates with Amantadine, Memantine, and Aminoindane is disclosed. These peptide-conjugates are currently undergoing biological evaluation to assess their cytotoxicity in human differentiated SH-SY5Y cells. The conjugates with the lowest cytotoxicity will be selected to proceed with neuroprotection studies.

Vaccinia H1-related phosphatase (VHR) is a dual-specific phosphatase that is a promising potential target for the treatment of many human diseases. In this work, we have proposed a series of 6-(4-chlorophenyl)-N-aryl-4-(trichloromethyl)-4H-1,3,5-oxadiazin-2-amines as potential VHR inhibitors. The SuperPred online server predicts VHR inhibition for the studied compounds with a probability of 88.88-98.51%. To establish the efficiency of binding of 4H-1,3,5-oxadiazine derivatives to the active site of VHR (PDB ID: 3F81) in the AutoDock Vina program, we have carried out molecular docking studies. According to its results, the studied compounds effectively interact with the hydrophobic region of the VHR active site due to aromatic rings and the trichloromethyl group, but the polar catalytic cavity is not involved, and therefore inhibition cannot be effective. In this regard, we have built a number of model compounds containing a sulfate group and its derivatives (methyl ester and amide) in the para-position of the arylamine fragment. According to the results of molecular docking, these compounds effectively bind to the polar catalytic cavity of the enzyme due to hydrogen bonds, but due to the relative rigidity of their molecules, hydrophobic interactions are not fully realized. Therefore, in these model compounds between the arylamine fragment and the sulfo group, we introduced a spacer with a length of one to three methylene groups. Hit compounds have been selected - 2-(4-((6-(4-chlorophenyl)-4-(trichloromethyl)-4H-1,3,5-oxadiazin-2-yl)amino)phenyl)ethane-1-sulfonic acid and its amide.

Currently, there is a growing interest in the development of bimodal systems that have a signal for more than one diagnostic imaging technique, such as magnetic resonance imaging (MRI). MRI is able to distinguish pathological from healthy tissues, however, in some cases, a high local concentration of the contrast agents (CAs) is necessary to improve the contrast in the images. Nanoparticulate CAs are able to concentrate several CAs molecules into one nanoparticle, increasing the local concentration of paramagnetic ions. In this work, we intend to associate AgInSe2 quantum dots (QDs) with gadolinium complexes (DOTA-Gd) to develop bimodal systems. The QDs were prepared in water and the synthesis parameters were optimized. The ligand DOTA was conjugated with cysteamine and complexed with Gd3+. The complex was then conjugated to QDs through the metal-thiol bond, obtaining the bimodal systems. Optical characterization indicated that the QDs remained stable and fluorescent, and an increase in emission intensity after conjugation was observed. The systems were characterized by relaxometry at 20MHz and 37 °C, obtaining longitudinal relaxivities by Gd3+ higher than the CAs used clinically. Thus, the prepared nanoprobes showed promising properties for MRI and optical imaging.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted an urgent need for development of new antiviral drugs. The main protease (Mpro) of SARS-CoV-2 plays an important role in viral replication and has become as an attractive drug target for virus inhibition. The active site of SARS-CoV-2 Mpro contains Cys145 and His41 which allows to use structural subunits (or “warheads”) for covalent binding to the thiol of a cysteine residue in the active site of cysteine proteases.

In our design of inhibitors considerably less chemically reactive and non-toxic lactams and their structural analogues as “warheads” for covalent inhibition of SARS-CoV-2 proteases Mpro were chosen. β- And ɣ-lactam subunit serves as the warhead for the covalent modification of cysteine proteases with the mechanism of action involving the cleavage of β-lactam ring by cysteine residue in the active site of the enzyme.

For chosen β- and ɣ-lactams IC₅₀ values for M^pro inhibition were determined using fluorescence resonance energy transfer (FRET) assay. For inhibitory activity improvement (1H-indole-2-carbonyl)-L-phenylalanine moiety was introduced.

Acknowledgements

This work was supported by the project 1.1.1.2/VIAA/4/20/754 “Development of lactam-based inhibitors of SARS-CoV-2 Mpro and other viral proteases”.

Photodynamic inactivation (PDI) is a therapeutic approach based on combined use of light, oxygen and a photosensitizing agent (PS). These three components interact to generate reactive oxygen species, which are cytotoxic and irreversibly damage vital components of microbial cells, leading to death. However, this methodology has not managed to be completely specific in its mode of action, since the photosensitizer can bind to both pathogenic and commensal microorganisms and even to host cells. Since subsequent irradiation of such cells could lead to their destruction, it is desirable to direct the photodynamic activity to the target cell. Therefore, the objective of this work was to direct the destruction of pathogenic microorganisms without affecting the normal flora. This could be achieved by binding the photosensitizing molecule to an antibody against the surface of the target organism. Therefore, a TCPP-IgG conjugate was synthesized using 4,4',4'',4'''-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) (TCPP) and the antibody anti-protein A of Staphylococcus aureus. The UV-visible spectra of TCPP-IgG showed the typical Soret and Q bands characteristic of porphyrin derivatives and, additionally, a new band was observed, corresponding to the absorbance of the protein. However, the results indicated that the conjugation reaction affects the photochemical properties of fluorescent emission and the production of reactive oxygen species compared to TCPP free base. As a consequence, a lower cytotoxicity was observed in planktonic cells of S. aureus. PDI can become a promising therapeutic alternative, having as a strategy the specific control of bacterial death, for an efficient eradication.