Sirtuin 1-activating derivatives belonging to the anilinopyridine class displaying in vivo cardioprotective activities

Sirtuin 1 (SIRT1) is an enzyme that relies on NAD+ cofactor and functions as a deacetylase. It has been associated with various biological and pathological processes, including cancer, diabetes, and cardiovascular diseases. Recent studies have shown that compounds that activate SIRT1 exhibit protective effects on the heart. Consequently, targeting SIRT1 has emerged as a viable approach to treat cardiovascular diseases, leading to the identification of several SIRT1 activators derived from natural or synthetic sources. In this study, we developed anilinopyridine-based SIRT1 activators that displayed significantly greater potency in activating SIRT1 compared to the reference compound resveratrol, as demonstrated in enzymatic assays. In particular, compounds 8 and 10, representative 6-aryl-2-anilinopyridine derivatives from this series, were further investigated pharmacologically and found to reduce myocardial damage caused by occlusion and subsequent reperfusion in vivo, confirming their cardioprotective properties. Notably, the cardioprotective effects of 8 and 10 were significantly superior to that of resveratrol. Significantly, compound 10 emerged as the most potent among the tested compounds, demonstrating the ability to substantially decrease the size of the ischemic area at a dosage one hundred times lower (0.1 mg kg-1) than that of resveratrol/compound 1. These promising findings open avenues for expanding and optimizing this chemical class of potent SIRT1 activators as potential agents for cardioprotection.

Design, synthesis, ADME and biological evaluation of benzylpiperidine and benzylpiperazine derivatives as novel reversible monoacylglycerol lipase (MAGL) inhibitors

The degradation of the endocannabinoid 2-arachidonoylglycerol is mediated by the enzyme monoacylglycerol lipase (MAGL), thus generating arachidonic acid, the precursor of prostaglandins and other pro-inflammatory mediators. MAGL also contributes to the hydrolysis of monoacylglycerols into glycerol and fatty acids in peripheral body districts, which may act as pro-tumorigenic signals. For this reason, MAGL inhibitors have been considered as interesting therapeutic agents for their anti-nociceptive, anti-inflammatory, antioxidant and anti-cancer properties. So far, only a limited series of reversible MAGL inhibitors, which are devoid of side effects shown by irreversible inhibitors in animal models, have been reported. Here we optimized a class of benzylpiperidine and benzylpiperazine-based compounds for a reversible MAGL inhibition. The best MAGL inhibitors of this class, compounds 28 and 29, showed a very good inhibition potency, both on the isolated enzyme and in U937 cells, as confirmed by molecular modeling studies that predicted their binding mode into the MAGL active site. Both compounds are characterized by a high selectivity for MAGL versus other serine hydrolases including enzymes of the endocannabinoid system, as confirmed by ABPP experiments in mouse brain membranes. Moreover, very good properties concerning ADME parameters and low in vivo toxicity have been observed for both compounds.

Sirtuin 1-Activating Compounds: Discovery of a Class of Thiazole-Based Derivatives

Sirtuin 1 (SIRT1) is a NAD⁺-dependent deacetylase implicated in various biological and pathological processes, including cancer, diabetes, and cardiovascular diseases. In recent years, SIRT1-activating compounds have been demonstrated to exert cardioprotective effects. Therefore, this enzyme has become a feasible target to treat cardiovascular diseases, and many SIRT1 activators, of a natural or synthetic origin, have been identified. In the present work, we developed thiazole-based SIRT1 activators, which showed remarkably higher SIRT1 activation potencies compared with those of the reference compound resveratrol when tested in enzymatic assays. Thiazole 8, a representative compound of this series, was also subjected to further pharmacological investigations, where it was proven to reduce myocardial damage induced by an in vivo occlusion/reperfusion event, thus confirming its cardioprotective properties. In addition, the cardioprotective effect of compound 8 was significantly higher than that of resveratrol. Molecular modeling studies suggest the binding mode of these derivatives within SIRT1 in the presence of the p53-AMC peptide. These promising results could pave the way to further expand and optimize this chemical class of new and potent SIRT1 activators as potential cardioprotective agents.

Reversible Monoacylglycerol Lipase Inhibitors: Discovery of a New Class of Benzylpiperidine Derivatives

Monoacylglycerol lipase (MAGL) is the enzyme responsible for the metabolism of 2-arachidonoylglycerol in the brain and the hydrolysis of peripheral monoacylglycerols. Many studies demonstrated beneficial effects deriving from MAGL inhibition for neurodegenerative diseases, inflammatory pathologies, and cancer. MAGL expression is increased in invasive tumors, furnishing free fatty acids as pro-tumorigenic signals and for tumor cell growth. Here, a new class of benzylpiperidine-based MAGL inhibitors was synthesized, leading to the identification of 13, which showed potent reversible and selective MAGL inhibition. Associated with MAGL overexpression and the prognostic role in pancreatic cancer, derivative 13 showed antiproliferative activity and apoptosis induction, as well as the ability to reduce cell migration in primary pancreatic cancer cultures, and displayed a synergistic interaction with the chemotherapeutic drug gemcitabine. These results suggest that the class of benzylpiperidine-based MAGL inhibitors have potential as a new class of therapeutic agents and MAGL could play a role in pancreatic cancer.

New Synthetic Analogues of Natural Polyphenols as Sirtuin 1-Activating Compounds

NAD⁺-dependent deacetylase SIRT1 regulates many different biological processes, thus being involved in pathogenic conditions such as metabolic diseases, neurogenerative disorders and cancer. Notably, experimental evidence underlined that the activation of SIRT1 had promising cardioprotective effects. Consequently, many efforts have been so far devoted to finding new SIRT1 activators, both derived from natural sources or prepared by synthetic procedures. Herein, we discovered new SIRT1-activating derivatives, characterized by phenolic rings spaced by sulfur, nitrogen or oxygen-based central linkers. The newly synthesized derivatives were analyzed in enzymatic assays to determine their ability to activate SIRT1, as compared with that of resveratrol. Among the tested molecules, bisarylaniline compound 10 proved to be the most efficient SIRT1 activator. An evaluation of the effects caused by focused structural variations revealed that its para-hydroxy-substituted diphenyl moiety of 10 was the fundamental structural requirement for achieving good SIRT1 activation. Compound 10 was further investigated in ex vivo studies in isolated and perfused rat hearts submitted to ischemia/reperfusion (I/R), where it showed significant protection of the myocardium against I/R injury. Molecular modeling studies suggest the binding mode of 10 within SIRT1 in the presence of the p53-AMC peptide. Our findings reveal that this chemical scaffold may be used as the starting point to develop a new class of more potent SIRT1 activators as cardioprotective agents.

α/β-Hydrolase Domain (ABHD) Inhibitors as New Potential Therapeutic Options against Lipid-Related Diseases

Much of the experimental evidence in the literature has linked altered lipid metabolism to severe diseases such as cancer, obesity, cardiovascular pathologies, diabetes, and neurodegenerative diseases. Therefore, targeting key effectors of the dysregulated lipid metabolism may represent an effective strategy to counteract these pathological conditions. In this context, α/β-hydrolase domain (ABHD) enzymes represent an important and diversified family of proteins, which are involved in the complex environment of lipid signaling, metabolism, and regulation. Moreover, some members of the ABHD family play an important role in the endocannabinoid system, being designated to terminate the signaling of the key endocannabinoid regulator 2-arachidonoylglycerol. This Perspective summarizes the research progress in the development of ABHD inhibitors and modulators: design strategies, structure-activity relationships, action mechanisms, and biological studies of the main ABHD ligands will be highlighted.

Monoacylglycerol lipase (MAGL) inhibitors based on a diphenylsulfide-benzoylpiperidine scaffold

Monoacylglycerol lipase (MAGL) is an enzyme belonging to the endocannabinoid system that mainly metabolizes the endocannabinoid 2-arachidonoylglycerol (2-AG). Numerous studies have shown the involvement of this enzyme in various pathological conditions such as pain, cancer progression, Parkinson's and Alzheimer's disease, thus encouraging the development of new MAGL modulators. In this context, we developed new diphenylsulfide-benzoylpiperidine derivatives characterized by a high enzymatic MAGL inhibition activity in the low nanomolar range, a reversible mechanism of action and selectivity. The three most active compounds (15-17) induced an appreciable inhibition of cell viability in a panel of nine cancer cell lines, with IC₅₀ values ranging between 0.32 and 10 μM, thus highlighting their potential as novel anticancer agents.

An updated patent review of monoacylglycerol lipase (MAGL) inhibitors (2018-present)

INTRODUCTION

Monoacylglycerol lipase (MAGL) belongs to the endocannabinoid system and is responsible for the inactivation of endocannabinoid 2-arachidonoylglycerol. Importantly, it was found that MAGL degradation of lipids in cancer cells enhances the availability of free fatty acids for new cellular membrane formation and pro-oncogenic lipid modulators. The multifaceted role of MAGL has greatly stimulated the search for MAGL inhibitors, which could be effective to treat diseases, such as inflammation, neurodegeneration and cancer.

AREAS COVERED

This review covers patents published since 2018 up to now, concerning new MAGL inhibitors and their potential therapeutic applications.

EXPERT OPINION

In the years 2018-2020, several well-known chemical scaffolds of MAGL inhibitors have been further optimized and developed and some new chemical classes have also been identified as MAGL inhibitors. Moreover, an increasing number of scientific publications covering MAGL inhibitors is focused on MAGL-specific positron emission tomography (PET) ligands. The numerous efforts of pharmaceutical companies and academic research groups finalized to find new potent MAGL inhibitors confirm that this research area is rapidly growing. Nevertheless, most of the patented compounds still belong to the large group of irreversible MAGL inhibitors, highlighting that the development of reversible MAGL inhibitors is still an unmet pharmaceutical need.

Design, synthesis and biological evaluation of second-generation benzoylpiperidine derivatives as reversible monoacylglycerol lipase (MAGL) inhibitors

An interesting enzyme of the endocannabinoid system is monoacylglycerol lipase (MAGL). This enzyme, which metabolizes the endocannabinoid 2-arachidonoylglycerol (2-AG), has attracted great interest due to its involvement in several physiological and pathological processes, such as cancer progression. Experimental evidences highlighted some drawbacks associated with the use of irreversible MAGL inhibitors in vivo, therefore the research field concerning reversible inhibitors is rapidly growing. In the present manuscript, the class of benzoylpiperidine-based MAGL inhibitors was further expanded and optimized. Enzymatic assays identified some compounds in the low nanomolar range and steered molecular dynamics simulations predicted the dissociation itinerary of one of the best compounds from the enzyme, confirming the observed structure-activity relationship. Biological evaluation, including assays in intact U937 cells and competitive activity-based protein profiling experiments in mouse brain membranes, confirmed the selectivity of the selected compounds for MAGL versus other components of the endocannabinoid system. An antiproliferative ability in a panel of cancer cell lines highlighted their potential as potential anticancer agents. Future studies on the potential use of these compounds in the clinical setting are also supported by the inhibition of cell growth observed both in cancer organoids derived from high grade serous ovarian cancer patients and in pancreatic ductal adenocarcinoma primary cells, which showed genetic and histological features very similar to the primary tumors.

Glycoconjugated Metal Complexes as Cancer Diagnostic and Therapeutic Agents

The possibility of selectively delivering metal complexes to a defined cohort of cells on the basis of their metabolic features is a highly challenging goal, which may be extremely useful for a series of purposes, including diagnosis and therapy of pathological states, such as cancer. Tumor cells display augmented requests for carbohydrates and, in particular, for glucose in order to sustain their high proliferation rate, which causes an increased glycolytic process (Warburg effect). Since several metal complexes display diagnostic and/or therapeutic properties, their conjugation to carbohydrate portions often induce their preferential accumulation in cancer cells, similarly to what is observed with fluorodeoxyglucose (FDG). In this review we have considered the latest developments of glycoconjugates containing metal complexes in their structures. These compounds are classified as diagnostic or therapeutic agents and are further systematically discussed on the basis of the metal atom they contain. Several diagnostic techniques are possible with these probes, since, depending on the metal species included in their structures, they may be employed in nuclear medicine (PET, SPECT), magnetic resonance imaging, luminescence and phosphorescence. At the same time, the lack of selective cytotoxicity displayed by several metal-based chemotherapeutic agents, may also be solved by the conjugation of these agents to carbohydrate portions. Overall, data so far available reveal the great potential of this chemical class in the early detection and in the cure of severe neoplastic diseases, which still needs to be fully explored in the clinic.

New Phenylethanoid Glycosides from Cistanche phelypaea and Their Activity as Inhibitors of Monoacylglycerol Lipase (MAGL)

Four new phenylethanoid glycosides (1: -4: ), 1-β-p-hydroxyphenyl-ethyl-2-O-acetyl-3,6-di-α-l-rhamnopyranosyl-β-d-glucopyranoside (1: ), 1-β-p-hydroxyphenyl-ethyl-3,6-O-di-α-l-rhamnopyranosyl-β-d-glucopyranoside (2: ), 1-β-p-hydroxyphenyl-ethyl-2-O-acetyl-3,6-di-α-l-rhamnopyranosyl-4-p-coumaroyl-β-d-glucopyranoside (3: ), and 1-β-p-hydroxyphenyl-ethyl-3,6-di-α-l-rhamnopyranosyl-4-p-coumaroyl-β-d-glucopyranoside (4: ), together with three known compounds, were isolated from the n-butanol extract of Cistanche phelypaea aerial parts. The structural characterization of all compounds was performed by spectroscopic analyses, including 1D and 2D NMR, and HRESIMS experiments. The isolated compounds were assayed for their inhibitory activity on two enzymes involved in the peculiar glycolytic or lipidic metabolism of cancer cells, human lactate dehydrogenase (LDH), and monoacylglycerol lipase (MAGL), respectively. All the compounds showed negligible activity on LDH, whereas some of them displayed a certain inhibition activity on MAGL. In particular, compound 1: was the most active on MAGL, showing an IC₅₀ value of 88.0 µM, and modeling studies rationalized the supposed binding mode of 1: in the MAGL active site.