Identification of a novel hormone sensitive lipase inhibitor with a reduced potential of reactive metabolites formation

Targeting autophagy drug discovery: Targets, indications and development trends

Autophagy plays a vital role in sustaining cellular homeostasis and its alterations have been implicated in the etiology of many diseases. Drugs development targeting autophagy began decades ago and hundreds of agents were developed, some of which are licensed for the clinical usage. However, no existing intervention specifically aimed at modulating autophagy is available. The obstacles that prevent drug developments come from the complexity of the actual impact of autophagy regulators in disease scenarios. With the development and application of new technologies, several promising categories of compounds for autophagy-based therapy have emerged in recent years. In this paper, the autophagy-targeted drugs based on their targets at various hierarchical sites of the autophagic signaling network, e.g., the upstream and downstream of the autophagosome and the autophagic components with enzyme activities are reviewed and analyzed respectively, with special attention paid to those at preclinical or clinical trials. The drugs tailored to specific autophagy alone and combination with drugs/adjuvant therapies widely used in clinical for various diseases treatments are also emphasized. The emerging drug design and development targeting selective autophagy receptors (SARs) and their related proteins, which would be expected to arrest or reverse the progression of disease in various cancers, inflammation, neurodegeneration, and metabolic disorders, are critically reviewed. And the challenges and perspective in clinically developing autophagy-targeted drugs and possible combinations with other medicine are considered in the review.

Regioselective O-alkylation of 2-pyridones by TfOH-catalyzed carbenoid insertion

Selective alkylation of 2-pyridone could solve a challenge in chemistry and streamline the synthesis of important molecules. Here we report the regioselective O-alkylation of 2-pyridones by TfOH-catalyzed carbenoid insertion. In the catalytic system, alkylation of 2-pyridone was achieved with unprecedented regioselectiviy (>99 : 1). This protocol is characterized by mild reaction conditions, metal-free, and simplicity. Moreover, this method provides the desired products in good yield and demonstrates a broad substrate scope in this transformation.

An Overview of Hormone-Sensitive Lipase (HSL)

Hormone-sensitive lipase (HSL) is a pivotal enzyme that mediates triglyceride hydrolysis to provide free fatty acids and glycerol in adipocytes in a hormonally controlled lipolysis process. Elevated plasma-free fatty acids were accompanied by insulin resistance, type-2 diabetes, and obesity. Inhibition of lipolysis through HSL inhibition may provide a mechanism to prevent the accumulation of free fatty acids and to improve the affectability of insulin and blood glucose handling in type II diabetes. The published studies that examine the structure, regulation, and function of HSL and major inhibitors were reviewed in this paper.

Omega-6 highly unsaturated fatty acids in Leydig cells facilitate male sex hormone production

Highly unsaturated fatty acids (HUFAs) are fatty acids with more than three double bonds in the molecule. Mammalian testes contain very high levels of omega-6 HUFAs compared with other tissues. However, the metabolic and biological significance of these HUFAs in the mammalian testis is poorly understood. Here we show that Leydig cells vigorously synthesize omega-6 HUFAs to facilitate male sex hormone production. In the testis, FADS2 (Fatty acid desaturase 2), the rate-limiting enzyme for HUFA biosynthesis, is highly expressed in Leydig cells. In this study, pharmacological and genetic inhibition of FADS2 drastically reduces the production of omega-6 HUFAs and male steroid hormones in Leydig cells; this reduction is significantly rescued by supplementation with omega-6 HUFAs. Mechanistically, hormone-sensitive lipase (HSL; also called LIPE), a lipase that supplies free cholesterol for steroid hormone production, preferentially hydrolyzes HUFA-containing cholesteryl esters as substrates. Taken together, our results demonstrate that Leydig cells highly express FADS2 to facilitate male steroid hormone production by accumulating omega-6 HUFA-containing cholesteryl esters, which serve as preferred substrates for HSL. These findings unveil a previously unrecognized importance of omega-6 HUFAs in the mammalian male reproductive system.

Leydig cells highly express FADS2 to facilitate male steroid hormone production by accumulating omega-6 HUFA-containing cholesteryl esters, which serve as preferred substrates for hormone-sensitive lipase

Visible-light-promoted selective O-alkylation of 2-pyridones with α-aryldiazoacetates

A visible-light-promoted O-H insertion reaction between 2-pyridones and α-aryldiazoacetates has been developed. Upon visible light irradiation, the reaction proceeds smoothly under mild and catalyst-free conditions. A wide scope of 2-pyridones and α-aryldiazoacetates are well tolerated, and various O-alkylated 2-pyridones are obtained with perfect selectivity and good functional group tolerance. A photoinduced radical process is probably responsible for the excellent selectivity.

Discovery of a series of benzopyrimidodiazepinone TNK2 inhibitors via scaffold morphing

The protein kinase TNK2 (ACK1) is an emerging drug target for a variety of indications, in particular for cancer where it plays a key role transmitting cell survival, growth and proliferative signals via modification of multiple downstream effectors by unique tyrosine phosphorylation events. Scaffold morphing based on our previous TNK2 inhibitor XMD8-87 identified urea 17 from which we developed the potent and selective compound 32. A co-crystal structure was obtained showing 32 interacting primarily with the main chain atoms of an alanine residue of the hinge region. Additional H-bonds exist between the urea NHs and the Thr205 and Asp270 residues.

N- and O-arylation of pyridin-2-ones with diaryliodonium salts: base-dependent orthogonal selectivity under metal-free conditions

Metal-free N- and O-arylation reactions of pyridin-2-ones as ambident nucleophiles have been achieved with diaryliodonium salts on the basis of base-dependent chemoselectivity. In the presence of N,N-diethylaniline in fluorobenzene, pyridin-2-ones were very selectively converted to N-arylated products in high yields. On the other hand, the O-arylation reactions smoothly proceeded with the use of quinoline in chlorobenzene, leading to high yields and selectivities. In these methods, a variety of pyridin-2-ones in addition to pyridin-4-one and a set of diaryliodonium salts were accepted as suitable reaction partners.

The herbicide quinclorac as potent lipase inhibitor: Discovery via virtual screening and in vitro/in vivo validation

Lipolysis is primarily controlled by the stepwise action of hormone-sensitive lipase (HSL) and monoglyceride lipase (MGL) to release free fatty acids and glycerol. A high level of circulating free fatty acids is well-known to mediate insulin resistance. Thus, the need to discover lipase inhibitors against both enzyme systems remains urgent. Agrochemicals are tightly regulated chemicals and therefore are potential source of new medicinal agents. Accordingly, we implemented a computational workflow to search for new lipase inhibitory leads by virtually screening commercial agrochemicals against HSL and MGL employing binding pharmacophores and docking experiments. Ten agrochemicals were identified as potential lipase inhibitors, out of which quinclorac, a safe herbicide, achieved high-ranking score. Subsequent in vitro evaluation against rat epididymal lipase activity showed quinclorac to exhibit nanomolar anti-lipase IC₅₀ . Subsequent in vivo testing showed quinclorac to significantly decrease blood glycerol levels after acute exposure (150 mg/kg) and multiple dosing (50 or 25 mg/kg) (p < 0.05).

Pharmacological intervention of liver triacylglycerol lipolysis: The good, the bad and the ugly

Excessive triacylglycerol (TG) accumulation is the distinctive feature of obesity. In the liver, sustained TG accretion leads to nonalcoholic fatty liver disease (NAFLD), eventually progressing to non-alcoholic steatohepatitis (NASH) and cirrhosis, which is associated with complications including hepatic failure, hepatocellular carcinoma and death. Pharmacological interventions are actively pursued to prevent lipid accumulation in hepatocytes and, therefore, to ameliorate the associated pathophysiological conditions. Here, we sought to provide an overview of the pharmacological approaches to up- or downregulate the expression and activities of the enzymes involved in hepatic TG hydrolysis. Fatty acids (FA) released by hydrolysis of hepatic TG can be used for β-oxidation, signaling, and for very low-density lipoprotein (VLDL)-TG synthesis. Originally, lipolysis was believed to be centered in the adipose and to be catalyzed by only two lipases, hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MAGL). However, genetic ablation of HSL expression in mice failed to erase TG hydrolysis in adipocytes leading to the identification of a third lipase termed adipose triglyceride lipase (ATGL). Although these three enzymes are considered to be the main players governing lipolysis in the adipocyte, other lipolytic enzymes have been described to contribute to hepatic TG metabolism. These include adiponutrin/patatin-like phospholipase domain containing 3 (PNPLA3), some members of the carboxylesterase family (CES/Ces), arylacetamide deacetylase (AADAC), lysosomal acid lipase (LAL) and hepatic lipase (HL). This review highlights the consequences of pharmacological interventions of liver lipases that degrade TG in cytosolic lipid droplets, in the endoplasmic reticulum, in the late endosomes/lysosomes and along the secretory route.