Mitochondrial dysfunction and Alzheimer's disease: prospects for therapeutic intervention.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease and has become a major socioeconomic issue in many developed countries. Currently available therapeutic agents for AD provide only symptomatic treatments, mainly because the complete mechanism of the AD pathogenesis is still unclear. Although several different hypotheses have been proposed, mitochondrial dysfunction has gathered interest because of its profound effect on brain bioenergetics and neuronal survival in the pathophysiology of AD. Various therapeutic agents targeting the mitochondrial pathways associated with AD have been developed over the past decade. Although most of these agents are still early in the clinical development process, they are used to restore mitochondrial function, which provides an alternative therapeutic strategy that is likely to slow the progression of the disease. In this mini review, we will survey the AD-related mitochondrial pathways and their small-molecule modulators that have therapeutic potential. We will focus on recently reported examples, and also overview the current challenges and future perspectives of ongoing research. [BMB Reports 2020; 53(1): 47-55].

Identification of crizotinib derivatives as potent SHIP2 inhibitors for the treatment of Alzheimer's disease.

SH2 domain-containing inositol 5'-phosphatase 2 (SHIP2) is a lipid phosphatase that produce phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2) from phosphatidylinositol 3,4,5-triphosphate (PI(3,4,5)P3), and is involved in many diseases such as neurodegenerative diseases. A recent report demonstrating that SHIP2 inhibition decreased tau hyperphosphorylation induced by amyloid ß and rescued memory impairment in a transgenic Alzheimer's disease mouse model indicates SHIP2 can be a promising therapeutic target for Alzheimer's disease. In the present study, we have developed novel, potent SHIP2 inhibitors by extensive structural elaboration of crizotinib discovered from a high-throughput screening. Our representative compound 43 potently inhibited SHIP2 activity as well as GSK3ß activation in HT22 neuronal cells. It was also shown that 43 has favorable physicochemical properties, especially high brain penetration. Considering SHIP2 is one of key signal mediators for tau hyperphosphorylation, our potent SHIP2 inhibitor 43 may function as a promising lead compound for the treatment of Alzheimer's disease.

GRP78-targeted in-silico virtual screening of novel anticancer agents.

Overexpression of GRP78 in a variety of cancers such as glioblastoma, leukemia, lung, prostate, breast, gastric, and colon makes it a prime target for anticancer drug development. Present study reports GRP78-based design of novel anticancer agents using in-silico methods. As a first step toward the work, the interactions between GRP78 and 15 known ligands were modeled by docking simulation. The docked complex, GRP78-13, superior to other compounds with respect to its experimental activity and energy descriptors, was deduced into a structure-based pharmacophore. This hypothesis was applied as a screening filter to Asinex and Chemdiv databases. Finally, 23 hits were tested in vitro. Among these, VH1019 and VH1011 induced a concentration-dependent strong broad antiproliferative effect in glioma (U87-MG), breast cancer (MCF-7), and prostate cancer (DU-145) cell lines as compared to nontumorigenic control, neonatal foreskin fibroblast (HFF-1). These compounds showed preferential growth inhibition of cancer cells over normal cells. The acetohydrazide derivative VH1019 was identified as a potential new chemotype for GRP78 inhibitors with an IC50 of 12.7 µM in MCF-7.

Discovery of non-peptidic small molecule inhibitors of cyclophilin D as neuroprotective agents in Aß-induced mitochondrial dysfunction.

Cyclophilin D (CypD) is a mitochondria-specific cyclophilin that is known to play a pivotal role in the formation of the mitochondrial permeability transition pore (mPTP).The formation and opening of the mPTP disrupt mitochondrial homeostasis, cause mitochondrial dysfunction and eventually lead to cell death. Several recent studies have found that CypD promotes the formation of the mPTP upon binding to ß amyloid (Aß) peptides inside brain mitochondria, suggesting that neuronal CypD has a potential to be a promising therapeutic target for Alzheimer's disease (AD). In this study, we generated an energy-based pharmacophore model by using the crystal structure of CypD-cyclosporine A (CsA) complex and performed virtual screening of ChemDiv database, which yielded forty-five potential hit compounds with novel scaffolds. We further tested those compounds using mitochondrial functional assays in neuronal cells and identified fifteen compounds with excellent protective effects against Aß-induced mitochondrial dysfunction. To validate whether these effects derived from binding to CypD, we performed surface plasmon resonance (SPR)-based direct binding assays with selected compounds and discovered compound 29 was found to have the equilibrium dissociation constants (KD) value of 88.2 nM. This binding affinity value and biological activity correspond well with our predicted binding mode. We believe that this study offers new insights into the rational design of small molecule CypD inhibitors, and provides a promising lead for future therapeutic development.

Synthesis, structure determination, and biological evaluation of phenylsulfonyl hydrazide derivatives as potential anti-inflammatory agents.

In our previous research, a novel series of phenylsulfonyl hydrazide derivatives were found to reduce LPS-induced PGE2 levels in RAW 264.7 macrophage cells via an inhibition of mPGES-1 enzyme. Recently, it was found that a regioisomeric mixture of phenylsulfonyl hydrazide was formed depending on the reaction conditions, which favor either of two regioisomers. One regioisomer corresponds to a kinetic product (7a-7c) and the other regioisomer corresponds to a thermodynamic product (8a-8c). Among them, the structure of kinetic product 7b was confirmed by measuring single X-ray crystallography. In vitro PGE2 assay studies showed that the kinetic product (7a and 7b; IC50=0.69 and 0.55µM against PGE2) is generally more potent than the thermodynamic product (8a and 8b; IC50=>10 and 0.79µM against PGE2). A molecular docking study also exhibited that the kinetic product (7a) has a higher MolDock Score (-147.4) than that of 8a (-142.4), which is consistent with the PGE2 assay results. A new potent phenylsulfonyl hydrazide (7d; IC50=0.06µM against PGE2) without affecting COX-1 and COX-2 enzyme activities was identified based on these overall results.