Fluorescent Light-up Probe for the Detection of Protein Aggregates

The detection methods currently available for protein aggregation in neurological diseases

Protein aggregation is a pathological feature in various neurodegenerative diseases and is thought to play a crucial role in the onset and progression of neurological disorders. This pathological phenomenon has attracted increasing attention from researchers, but the underlying mechanism has not been fully elucidated yet. Researchers are increasingly interested in identifying chemicals or methods that can effectively detect protein aggregation or maintain protein stability to prevent aggregation formation. To date, several methods are available for detecting protein aggregates, including fluorescence correlation spectroscopy, electron microscopy, and molecular detection methods. Unfortunately, there is still a lack of methods to observe protein aggregation in situ under a microscope. This article reviews the two main aspects of protein aggregation: the mechanisms and detection methods of protein aggregation. The aim is to provide clues for the development of new methods to study this pathological phenomenon.

Recent Advances in Fluorescent Theranostics for Alzheimer's Disease: A Comprehensive Survey on Design, Synthesis, and Properties

Alzheimer's disease (AD) is the most common form of neurodegenerative dementia that is rapidly becoming a major health problem, especially in developed countries because of their increasing life expectancy. Two main problems are often associated with the disease: (i) the absence of a widely accessible "gold-standard" for early diagnosis and (ii) lack of effective therapies with disease-modifying effects. The recent success of the monoclonal antibody lecanemab played an important role not only in clarifying a possible druggable pathway but also in spelling the revival of small molecule drug discovery. Unlike bulky biologics, small molecules are structurally less complex, generally cheaper, and compatible with at-home oral consumption, making it feasible for people to start their drug regimen early and stay on it longer. In this sense, small-molecule near-infrared fluorescent theranostics have been gaining more and more attention from the scientific community, as they have the potential to simultaneously provide diagnostic outputs and deliver therapeutic action, paving the way toward personalized medicine in AD patients. They also have the potential to shift the diagnostic "status-quo" from expensive and limited-access PET radiotracers toward inexpensive and handy imaging tools widely available for primary patient screening and preclinical animal studies. Herein, we review the most recent advances in the field of fluorescent theranostics for Alzheimer's disease, detailing their design strategies, synthetic approaches and imaging and therapeutic properties in vitro and in vivo. With this Review, we intend to provide a milestone in the acquired knowledge in the field of AD theranostics, encouraging the future development of properly designed theranostic compounds with improved chances to reach clinical applications.

Drug Discovery Based on Oxygen and Nitrogen (Non-)Heterocyclic Compounds Developed @LAQV-REQUIMTE/Aveiro

Artur Silva's research group has a long history in the field of medicinal chemistry. The development of new synthetic methods for oxygen (mostly polyphenols, e.g., 2- and 3-styrylchromones, xanthones, flavones) and nitrogen (e.g., pyrazoles, triazoles, acridones, 4-quinolones) heterocyclic compounds in order to be assessed as antioxidant, anti-inflammatory, antidiabetic, and anticancer agents has been the main core work of our research interests. Additionally, the synthesis of steroid-type compounds as anti-Alzheimer drugs as well as of several chromophores as important dyes for cellular imaging broadened our research scope. In this review article, we intend to provide an enlightened appraisal of all the bioactive compounds and their biological properties that were synthesized and studied by our research group in the last two decades.

Regioselective alkylation of 2,4-dihydroxybenzyaldehydes and 2,4-dihydroxyacetophenones

We report a cesium bicarbonate-mediated alkylation of 2,4-dihydroxybenzyaldehyde and 2,4-dihydroxyacetophenone to generate 4-alkylated products in acetonitrile at 80 °C with excellent regioselectivity, up to 95% isolated yields, and broad substrate scope.

Inclusion Compound of Efavirenz and γ-Cyclodextrin: Solid State Studies and Effect on Solubility

Efavirenz is an antiretroviral drug of widespread use in the management of infections with human immunodeficiency virus type 1 (HIV-1). Efavirenz is also used in paediatrics, but due to its very poor aqueous solubility the liquid formulations available resort to oil-based excipients. In this report we describe the interaction of γ-cyclodextrin with efavirenz in solution and in the solid state. In aqueous solution, the preferential host–guest stoichiometry was determined by the continuous variation method using ¹H NMR, which indicated a 3:2 host-to-guest proportion. Following, the solid inclusion compound was prepared at different stoichiometries by co-dissolution and freeze-drying. Solid-state characterisation of the products using FT-IR, ¹³C{¹H} CP-MAS NMR, thermogravimetry, and X-ray powder diffraction has confirmed that the 3:2 stoichiometry is the adequate starting condition to isolate a solid inclusion compound in the pure form. The effect of γ-cyclodextrin on the solubility of efavirenz is studied by the isotherm method.

Detection of Protein Aggregation in Live Plasmodium Parasites

The rapid evolution of resistance in the malaria parasite to every single drug developed against it calls for the urgent identification of new molecular targets. Using a stain specific for the detection of intracellular amyloid deposits in live cells, we have detected the presence of abundant protein aggregates in Plasmodium falciparum blood stages and female gametes cultured in vitro, in the blood stages of mice infected by Plasmodium yoelii, and in the mosquito stages of the murine malaria species Plasmodium berghei Aggregated proteins could not be detected in early rings, the parasite form that starts the intraerythrocytic cycle. A proteomics approach was used to pinpoint actual aggregating polypeptides in functional P. falciparum blood stages, which resulted in the identification of 369 proteins, with roles particularly enriched in nuclear import-related processes. Five aggregation-prone short peptides selected from this protein pool exhibited different aggregation propensity according to Thioflavin-T fluorescence measurements, and were observed to form amorphous aggregates and amyloid fibrils in transmission electron microscope images. The results presented suggest that generalized protein aggregation might have a functional role in malaria parasites. Future antimalarial strategies based on the upsetting of the pathogen's proteostasis and therefore affecting multiple gene products could represent the entry to new therapeutic approaches.