New trends for metal complexes with anticancer activity

Medicinal inorganic chemistry can exploit the unique properties of metal ions for the design of new drugs. This has, for instance, led to the clinical application of chemotherapeutic agents for cancer treatment, such as cisplatin. The use of cisplatin is, however, severely limited by its toxic side-effects. This has spurred chemists to employ different strategies in the development of new metal-based anticancer agents with different mechanisms of action. Recent trends in the field are discussed in this review. These include the more selective delivery and/or activation of cisplatin-related prodrugs and the discovery of new non-covalent interactions with the classical target, DNA. The use of the metal as scaffold rather than reactive centre and the departure from the cisplatin paradigm of activity towards a more targeted, cancer cell-specific approach, a major trend, are discussed as well. All this, together with the observation that some of the new drugs are organometallic complexes, illustrates that exciting times lie ahead for those interested in ‘metals in medicine

Dehydropeptide supramolecular hydrogels and nanostructures as potential peptidomimetic biomedical materials

Supramolecular peptide hydrogels are gaining increased attention, owing to their potential in a variety of biomedical applications. Their physical properties are similar to those of the extracellular matrix (ECM), which is key to their applications in the cell culture of specialized cells, tissue engineering, skin regeneration, and wound healing. The structure of these hydrogels usually consists of a di- or tripeptide capped on the N-terminus with a hydrophobic aromatic group, such as Fmoc or naphthalene. Although these peptide conjugates can offer advantages over other types of gelators such as cross-linked polymers, they usually possess the limitation of being particularly sensitive to proteolysis by endogenous proteases. One of the strategies reported that can overcome this barrier is to use a peptidomimetic strategy, in which natural amino acids are switched for non-proteinogenic analogues, such as D-amino acids, β-amino acids, or dehydroamino acids. Such peptides usually possess much greater resistance to enzymatic hydrolysis. Peptides containing dehydroamino acids, i.e., dehydropeptides, are particularly interesting, as the presence of the double bond also introduces a conformational restraint to the peptide backbone, resulting in (often predictable) changes to the secondary structure of the peptide. This review focuses on peptide hydrogels and related nanostructures, where α,β-didehydro-α-amino acids have been successfully incorporated into the structure of peptide hydrogelators, and the resulting properties are discussed in terms of their potential biomedical applications. Where appropriate, their properties are compared with those of the corresponding peptide hydrogelator composed of canonical amino acids. In a wider context, we consider the presence of dehydroamino acids in natural compounds and medicinally important compounds as well as their limitations, and we consider some of the synthetic strategies for obtaining dehydropeptides. Finally, we consider the future direction for this research area.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding of CQUM (UID/QUI/00686/2019). FCT, FEDER, PORTUGAL2020 and COMPETE2020 are also acknowledged for funding under research project PTDC/QUI-QOR/29015/2017 (POCI-01-0145-FEDER-029015)

Bromodomains as therapeutic targets

Acetylation of lysine residues is a post-translational modification with broad relevance to cellular signalling and disease biology. Enzymes that ‘write’ (histone acetyltransferases, HATs) and ‘erase’ (histone deacetylases, HDACs) acetylation sites are an area of extensive research in current drug development, but very few potent inhibitors that modulate the ‘reading process’ mediated by acetyl lysines have been described. The principal readers of ɛ-N-acetyl lysine (Kac) marks are bromodomains (BRDs), which are a diverse family of evolutionary conserved protein-interaction modules. The conserved BRD fold contains a deep, largely hydrophobic acetyl lysine binding site, which represents an attractive pocket for the development of small, pharmaceutically active molecules. Proteins that contain BRDs have been implicated in the development of a large variety of diseases. Recently, two highly potent and selective inhibitors that target BRDs of the BET (bromodomains and extra-terminal) family provided compelling data supporting targeting of these BRDs in inflammation and in an aggressive type of squamous cell carcinoma. It is likely that BRDs will emerge alongside HATs and HDACs as interesting targets for drug development for the large number of diseases that are caused by aberrant acetylation of lysine residues

Angiogenesis: An update and potential drug approaches

The therapeutic potential of targeting tumor endothelium and vascular supply is now widely recognized to treat different diseases. One such disease is cancer; where endothelial cells are actively proliferating to support the tumor growth. Solid tumors cannot grow beyond the size of a few millimeters without inducing the proliferation of endothelium and formation of new blood vessels. Hence it is crucial to search for new agents that selectively block tumor blood supply. These include anti-angiogenic molecules, vascular disrupting agents or endothelial disrupting agents. The anti-angiogenic molecules such as monoclonal antibodies and tyrosine kinase inhibitors disrupt endothelial cell survival mechanisms and new blood vessel formation, and vascular disrupting agents for instance ligand-directed and small molecules can be used to disrupt the already existing abnormal vasculature that support tumors by targeting their dysmorphic endothelial cells. The recent advances in this area of research have identified a variety of investigational agents which are currently in clinical development at various stages and some of these candidates are already approved in cancer treatment. This report will review some of the recent developments and most significant advances in this field and outline future challenges and directions

Advances in De Novo Drug Design : From Conventional to Machine Learning Methods

De novo drug design is a computational approach that generates novel molecular structures from atomic building blocks with no a priori relationships. Conventional methods include structure-based and ligand-based design, which depend on the properties of the active site of a biological target or its known active binders, respectively. Artificial intelligence, including ma-chine learning, is an emerging field that has positively impacted the drug discovery process. Deep reinforcement learning is a subdivision of machine learning that combines artificial neural networks with reinforcement-learning architectures. This method has successfully been em-ployed to develop novel de novo drug design approaches using a variety of artificial networks including recurrent neural networks, convolutional neural networks, generative adversarial networks, and autoencoders. This review article summarizes advances in de novo drug design, from conventional growth algorithms to advanced machine-learning methodologies and high-lights hot topics for further development.Peer reviewe

A multidisciplinary approach to the development of innovative tools for pharmaceutical and technological applications

The research activity carried out during the Ph.D. in Chemical and Pharmaceutical Sciences has regarded the design, synthesis, and characterization of innovative tools relevant to both pharmaceutical and technological fields. Great interest has been dedicated to the investigation of the “affinity polymerization” mechanism of novel polymeric materials founded on repetitive monomeric units based on the 3-phenylbenzofulvene scaffold that spontaneously polymerize by simple removal of the solvent. In this context, the attention has been focused on the synthesis of novel benzofulvene-based derivatives bearing complexed and non-complexed pyridine rings in different positions of the benzofulvene scaffold, to evaluate the effects generated by the insertion of a bulky substituent in the aggregation/polymerization behavior. The experience acquired with this study has been then capitalized on the design, synthesis, and characterization of a novel visible-light-sensitive biomimetic molecular switch inspired by the benzofulvene scaffold and the Green Fluorescent Protein (GFP) chromophore. The chemical-structural manipulation of the benzofulvene structure has made possible the development of a novel set of biomimetic photoswitches inspired by the supramolecular properties of the 3-phenylbenzofulvene scaffold and the molecular features of the GFP chromophore. In the framework of material chemistry, the well-known click-chemistry reaction of hyaluronic acid (HA) derivatives bearing propargylated ferulic groups has been exploited to obtain biomimetic and biocompatible materials useful in different biopharmaceutical fields. In particular, low molecular weight HA has been anchored on the hydrophobic surface of low-generation poly(propylene imine) (PPI) dendrimers by the click-chemistry reaction between their azido-functionalized surfaces and low molecular weight HA derivatives bearing propargylated ferulic groups. The resulting materials have been proposed as biocompatible drug delivery systems (DDSs) of Doxorubicin. Another application of HA has concerned the hyaluronan-based graft copolymers showing low and medium molecular weight values that have been exploited in cross-linking by the click-chemistry reaction. Interestingly, the interaction of resulting HA materials with water led to the formation of hydrogels, and the tunable rheological behavior of these materials led to their applicability in different biomedical fields. Lastly, the knowledge in medicinal chemistry has guided the design and synthesis of innovative bioactive compounds such as novel Cyclooxygenase‑2 (COX-2) inhibitors containing Nitric Oxide (NO) donor moiety (CINODs) endowed with vasorelaxant properties. The outcomes of these studies would provide fertile ground for future projects that will hopefully contribute to accelerate the research in several fields. Indeed, the increased knowledge on the behavior of these innovative tools, by means of a multidisciplinary approach, is the key for boosting the development of novel materials for pharmaceutical and technological applications

Mode of action and target identification of anti-inflammatory natural products

In the present thesis, the mode of action of three different natural secondary metabolites was clarified in human cancer cells and primary immune cells. The investigated compounds of this work were (I) the mycotoxin gliotoxin from Aspergillus fumigatus targeting leukotriene A4 hydrolase (LTA4H) resulting in a reduction of the biosynthesis of the neutrophil chemoattractant leukotriene B4 (LTB4) in vivo and in vitro. Furthermore, gliotoxin caused a reduced neutrophil infiltration into the peritoneal cavity. Interestingly, gliotoxin suppressed solely LTB4 formation without compromising other eicosanoids identifying thereby the cause of neutropenia during invasive aspergillosis (IA). However, gliotoxin failed to impede LTA4H activity in non-cellular systems but pre-incubation with GSH enables inhibition of LTA4H activity by gliotoxin indicating that reducing conditions were crucial to cleave the intramolecular disulfide bond. The formed free thiol groups chelated the zinc ion in the active epoxide hydrolase center of LTA4H. Second (II), the melleolide dehydroarmillylorsellinate (DAO) exhibiting, on the one hand, anti-inflammatory features by abrogating 5-lipoxygenase (5-LOX) product formation due to an interaction with surface cysteines especially C159 located at the entrance to the active center of 5-LOX hampering the interaction between 5-LOX and the 5-LOX activating protein (FLAP), and on the other hand, manipulate monocyte functions by covalent binding of the cellular membrane constituent phosphatidylethanolamine (PE). And finally (III), myxochelin A biosynthesized by Pyxidicoccus fallax hampering 5-LOX activity due to iron chelation by the catechol basic structure. Over the last decades, the link between inflammation and cancer gains relevance. Hence, it is important to investigate new anti-inflammatory drugs to prevent chronic diseases, and to elucidate the mechanism of action of cytotoxic compounds to develop new strategies of action for anti-cancer drugs