Design, Synthesis, and Biological Evaluation of Tetrahydro-β-carboline Derivatives as Selective Sub-Nanomolar Gelatinase Inhibitors

An overview of matrix metalloproteinase-12 in multiple disease conditions, potential selective inhibitors, and drug designing strategies

Matrix metalloproteases (MMPs) are the proteolytic enzymes accountable for extracellular matrix (ECM) modification through their Zn2+-dependent catalytic activity. Among these, MMP-12 is one of the crucial MMPs that contributes to various disease states including different types of cancers and other major pathophysiological conditions including COPD, asthma, emphysema, skin diseases, arthritis, vascular diseases, and neurological disorders. The majority of the MMP-12 inhibitors should have three constitutional pharmacophoric features (i.e., a hydrophobic group to occupy the S1' pocket, a zinc-binding motif for chelating to the catalytic Zn2+ ion present at the catalytic site, and a flexible and hydrogen bond forming linker region between the S1' pocket substituent and the zinc chelating group for interacting with the catalytic and Ω-loop amino acid residues). This review mainly focuses on the various roles of MMP-12 in different diseases along with the structural comparison with other MMPs as well as promising and MMP-12-selective inhibitors and molecular modeling studies performed on MMP-12 inhibitors. Therefore, this review will provide comprehensive information to the researchers for designing effective and MMP-12-selective inhibitors for therapeutic advancement in the future.

Ligand-based pharmacophore modeling and molecular dynamic simulation approaches to identify putative MMP-9 inhibitors

MMP-9 is a calcium-dependent zinc endopeptidase that plays a crucial role in various diseases and is a ubiquitous target for many classes of drugs. The availability of MMP-9 crystal structure in combination with aryl sulfonamide anthranilate hydroxamate inhibitor facilitates to accentuate the computer-aided screening of MMP-9 inhibitors with the presumed binding mode. In the current study, ligand-based pharmacophore modeling and 3D-QSAR analysis were performed using 67 reported MMP-9 inhibitors possessing pIC50 in the range of 5.221 to 9.000. The established five-point hypothesis model DDHRR_1 was statistically validated using various parameters R 2 (0.9076), Q 2 (0.8170), and F value (83.5) at a partial least square of four. Hypothesis validation and enrichment analysis were performed for the generated hypothesis. Further, Y-scrambling and Xternal validation using mean-absolute error-based criteria were performed to evaluate the reliability of the model. Docking in the XP mode and binding free energy was calculated for 67 selected ligands to explore the key binding interactions and binding affinity against the MMP-9 enzyme. Additionally, high-throughput virtual screening was carried out for 2.3 million chemical molecules to explore the potential virtual hits, and their predicted activity was calculated. Thus, the results obtained aid in developing novel MMP-9 inhibitors with significant activity and binding affinity.

Mechanisms of Proteolytic Enzymes and Their Inhibition in QM/MM Studies

Experimental evidence for enzymatic mechanisms is often scarce, and in many cases inadvertently biased by the employed methods. Thus, apparently contradictory model mechanisms can result in decade long discussions about the correct interpretation of data and the true theory behind it. However, often such opposing views turn out to be special cases of a more comprehensive and superior concept. Molecular dynamics (MD) and the more advanced molecular mechanical and quantum mechanical approach (QM/MM) provide a relatively consistent framework to treat enzymatic mechanisms, in particular, the activity of proteolytic enzymes. In line with this, computational chemistry based on experimental structures came up with studies on all major protease classes in recent years; examples of aspartic, metallo-, cysteine, serine, and threonine protease mechanisms are well founded on corresponding standards. In addition, experimental evidence from enzyme kinetics, structural research, and various other methods supports the described calculated mechanisms. One step beyond is the application of this information to the design of new and powerful inhibitors of disease-related enzymes, such as the HIV protease. In this overview, a few examples demonstrate the high potential of the QM/MM approach for sophisticated pharmaceutical compound design and supporting functions in the analysis of biomolecular structures.

Novel matrix metalloproteinase inhibitors: an updated patent review (2014 - 2020)

Introduction: Matrix MetalloProteinases (MMPs) are key enzymes in several pathophysiological processes connected to the extracellular matrix (ECM) degradation. Earlier clinical trials evaluating broad spectrum MMP inhibitors as cancer therapeutics failed to succeed, resulting in toxic side effects, such as musculoskeletal pain and inflammation, due to poor selectivity. As it is now recognized that some MMPs are essential for tumor progression and metastasis, but others play host-protective functions, selective MMP inhibitors are needed, and their interest has grown also for therapeutic applications beyond cancer, such as infectious, inflammatory and neurological diseases. Areas covered: This updated review describes patents concerning MMP inhibitors published within January 2014 and June 2020, with therapeutic applications spanning from cancer to inflammatory and neurological disorders. Expert opinion: Although the number of patents has decreased with respect to the previous decade, new applications provide selective matrix metalloproteinase inhibitors for therapeutic treatments beyond cancer. For several applications, the need of selective inhibitors resulted in the development of new non-hydroxamate compounds, paving the way towards a renewed interest towards MMPs as therapeutic targets. In particular, inhibitors able to cross the blood-brain barrier have been disclosed and proposed for the treatment of neurological conditions, infections, wound healing and cancer.