The lipase inhibitor tetrahydrolipstatin binds covalently to the putative active site serine of pancreatic lipase

Design, synthesis and biological evaluation of naphthyl amide derivatives as reversible monoacylglycerol lipase (MAGL) inhibitors

Monoacylglycerol lipase (MAGL) is a key enzyme responsible for the metabolism of the endocannabinoid 2-arachidonoylglycerol (2-AG), and has attracted great interest due to its involvement in various physiological and pathological processes, such as cancer progression. In the past, a number of covalent irreversible inhibitors have been reported for MAGL, however, experimental evidence highlighted some drawbacks associated with the use of these irreversible agents. Therefore, efforts were mainly focused on the development of reversible MAGL inhibitor in recent years. Here, we designed and synthesized a series of naphthyl amide derivatives (12-39) as another type of reversible MAGL inhibitors, exemplified by ± 34, which displayed good MAGL inhibition with a pIC50 of 7.1, and the potency and selectivity against endogenous MAGL were further demonstrated by competitive ABPP. Moreover, the compound showed appreciable antiproliferative activities against several cancer cells, including H460, HT29, CT-26, Huh7 and HCCLM-3. The investigations culminated in the discovery of the naphthyl amide derivative ± 34, and it may represent as a new scaffold for MAGL inhibitor development, particularly for the reversible ones.

Suppressive Effect of Coffee Leaves on Lipid Digestion and Absorption In Vitro

BACKGROUND

Coffee leaves are a major source of bioactive components and are used as ethnomedicine. However, despite their traditional medicinal use, information about their effects on antihyperlipidemia remains limited.

METHODS

The aims of this study were to evaluate the main components of leaf extracts from Arabica and Robusta coffees and to examine the potential of these coffee leaves in reducing lipid digestion and absorption in vitro.

RESULTS

Coffee leaf extracts from Arabica coffee contain a high amount of caffeine, whereas extracts from Robusta coffee contain high amounts of chlorogenic acid (CGA) and caffeine. Additionally, leaf extracts from Arabica and Robusta coffee demonstrated the inhibition of pancreatic lipase, decreased micellar cholesterol solubility, and reduced bile acid binding. Furthermore, these extracts resulted in a reduction in cholesterol uptake in Caco-2 cells. Molecular docking experiments supported this discovery, showing CGA and caffeine binding to Niemann-Pick C1-like 1 (NPC1L1), a key protein in cholesterol absorption. The results indicated that CGA and caffeine can competitively bind to NPC1L1 at the cholesterol binding pocket, reducing its cholesterol binding rate. These findings suggest that coffee leaves might help suppress lipid absorption and digestion, highlighting their potential use in preventing and treating hyperlipidemia.

Discovery of thiazolidinedione-based pancreatic lipase inhibitors as anti-obesity agents: synthesis, in silico studies and pharmacological investigations

A series of new 2,5-disubstituted arylidene derivatives of thiazolidinedione (16a-e, 17a-d, 18a-c) designed using molecular hybridization approach were synthesized, structurally characterized, and explored for their anti-obesity potential via inhibition of Pancreatic Lipase (PL). Compound 18a presented the most potent PL inhibitory activity with IC50 = 2.71 ± 0.31 µM, as compared to the standard drug, Orlistat (IC50 = 0.99 µM). Kinetic study revealed reversible competitive mode of enzyme inhibition by compound 18a with an inhibitory constant value of 1.19 µM. The most promising compound 18a revealed satisfactory binding mode within the active site of the target protein (human PL, PDB ID: 1LPB). Also, MM/PBSA binding free energy and molecular dynamics (MD) simulation analysis were performed for the most promising compound 18a, which showed potent inhibition according to the results of in vitro studies. Furthermore, a stable conformation of the 1LPB-ligand suggested the stability of this compound in the dynamic environment. The ADME and toxicity analysis of the compounds were examined using web-based online platforms. Results of in vivo studies confirmed the anti-obesity efficacy of compound 18a, wherein oral treatment with compound 18a (30 mg/kg) resulted in a significant reduction in the body weight, BMI, Lee index, feed intake (in Kcal), body fat depots and serum triglycerides. Compound 18a significantly decreased the levels of serum total cholesterol (TC) to 128.6 ± 0.59 mg/dl and serum total triglycerides (TG) to 95.73 ± 0.67 mg/dl as compared to the HFD control group. The present study identified disubstituted TZD derivatives as a new promising class of anti-obesity agents.Communicated by Ramaswamy H. Sarma.

Inhibition of Pancreatic Lipase by Flavonoid Derivatives: In Vitro and In Silico Investigations

Obesity, characterized by excessive adipose tissue accumulation, has emerged as a crucial determinant for a wide range of chronic medical conditions. The identification of effective interventions for obesity is of utmost importance. Widely researched antiobesity agents focus on pancreatic lipase, a significant therapeutic target. This study presented the evaluation of ten flavonoid compounds in terms of their inhibitory activities against pancreatic lipase, utilizing both in vitro and in silico approaches. The results indicated that all tested compounds demonstrated modest and weaker inhibitory activities compared to the reference compound, orlistat. Among the compounds investigated, F01 exhibited the highest potency, with an IC50 value of 17.68 ± 1.43 µM. The enzymatic inhibition kinetic analysis revealed that F01 operated through a competitive inhibition mechanism with a determined Ki of 7.16 μM. This value suggested a moderate binding affinity for the pancreatic lipase enzyme. Furthermore, the associated Vmax value was quantified at 0.03272 ΔA·min-1. In silico studies revealed that F01 displayed a binding mode similar to that of orlistat, despite lacking an active functional group capable of forming a covalent bond with Ser152 of the catalytic triad. However, F01 formed a hydrogen bond with this crucial amino acid. Furthermore, F01 interacted with other significant residues at the enzyme's active site, particularly those within the lid domain. Based on these findings, F01 demonstrates substantial potential as a candidate for further investigations.

Pancreatic lipase and its related proteins: where are we now?

Obesity is a disease of epidemic proportions, with a worrisome upward trend. The high consumption of lipids, a major energy source, leads to obesity because of their high calorific value. Pancreatic lipase (PTL), produced by pancreatic acinar cells, hydrolyzes 50-70% of triacylglycerol (TAG) from food. PTL-related protein 1 (PLRP1) and 2 (PLRP2) are also produced by these cells. In vertebrates, PLRP1 has relatively less lipolytic activity, whereas PLRP2 has an essential role in lipid digestion, especially in infants. In this review, we summarize the structure and function of PTL, PLRP1, and PLRP2, and the metabolic fate of PTL inhibitors. We also discuss the current status of clinical trials on orlistat and its combinations for obesity treatment.

The colloid and interface strategies to inhibit lipid digestion for designing low-calorie food

Although fat is one of the indispensable components of food flavor, excessive fat consumption could cause obesity, metabolism syndromes and an imbalance in the intestinal flora. In the pursuit of a healthy diet, designing fat reducing foods by inhibiting lipid digestion and calorie intake is a promising strategy. Altering the gastric emptying rates of lipids as well as acting on the lipase by suppressing the enzymatic activity or limiting lipase diffusion via interfacial modulation can effectively decrease lipolysis rates. In this review, we provide a comprehensive overview of colloid-based strategies that can be employed to retard lipid hydrolysis, including pancreatic lipase inhibitors, emulsion-based interfacial modulation and fat substitutes. Plants-/microorganisms-derived lipase inhibitors bind to catalytic active sites and change the enzymatic conformation to inhibit lipase activity. Introducing oil-in-water Pickering emulsions into the food can effectively delay lipolysis via steric hindrance of interfacial particulates. Regulating stability and physical states of emulsions can also affect the rate of hydrolysis by altering the active hydrolysis surface. 3D network structure assembled by fat substitutes with high viscosity can not only slow down the peristole and obstruct the diffusion of lipase to the oil droplets but also impede the transportation of lipolysis products to epithelial cells for adsorption. Their applications in low-calorie bakery, dairy and meat products were also discussed, emphasizing fat intake reduction, structure and flavor retention and potential health benefits. However, further application of these strategies in large-scale food production still requires more optimization on cost and lipid reducing effects. This review provides a comprehensive review on colloidal approaches, design, principles and applications of fat reducing strategies to meet the growing demand for healthier diet and offer practical insights for the low-calorie food industry.

Molecular modelling, synthesis and in vitro evaluation of quinazolinone hybrid analogues as potential pancreatic lipase inhibitors

Obesity is a multifactorial metabolic disorder, growing in an alarming rate across the world. Amongst the numerous targets explored for obesity management, inhibition of pancreatic lipase (PL) is considered as one of the promising approaches. Orlistat is the only PL inhibitory drug approved for long term treatment of obesity. However, it is reported to possess hepatotoxicity and nephrotoxicity. Thus, novel drug candidates that act through PL inhibition are considered the hour's need. Based on this aim, a series of quinazolinone hybrid analogues have been synthesized, characterized and evaluated for their PL inhibitory potential. The physicochemical properties and toxicity parameters suggested that these parameters are in an acceptable range for the screened analogues. Amongst the synthesised analogues, QH-25 exerted potential PL inhibition (IC50 = 16.99 ± 0.54 µM). Further, enzyme inhibition studies suggested a reversible competitive inhibition. Molecular docking of these analogues was in line with in vitro results, wherein the obtained MolDock scores exhibited a significant correlation with their inhibitory activity (Pearson's r = 0.6629). To further confirm the stability of the QH-25-PL complex in a dynamic environment, a molecular dynamics study (100 ns) was carried out and the results suggested that this complex is stable at dynamic conditions. Overall, these results shed light on the quinazolinone hybrids as potential PL inhibitors. Further structural modification may result in the development of potent anti-obesity agents which acts through PL inhibition.Communicated by Ramaswamy H. Sarma.

Analysis of metabolites in human gut: illuminating the design of gut-targeted drugs

Gut-targeted drugs provide a new drug modality besides that of oral, systemic molecules, that could tap into the growing knowledge of gut metabolites of bacterial or host origin and their involvement in biological processes and health through their interaction with gut targets (bacterial or host, too). Understanding the properties of gut metabolites can provide guidance for the design of gut-targeted drugs. In the present work we analyze a large set of gut metabolites, both shared with serum or present only in gut, and compare them with oral systemic drugs. We find patterns specific for these two subsets of metabolites that could be used to design drugs targeting the gut. In addition, we develop and openly share a Super Learner model to predict gut permanence, in order to aid in the design of molecules with appropriate profiles to remain in the gut, resulting in molecules with putatively reduced secondary effects and better pharmacokinetics.

Bioassay-guided isolation and in silico study of antihyperlipidemic compounds from Onosma hispidum Wall

Isolation of bioactive compounds from plants and their therapeutic evaluation is crucial in the pursuit of novel phytochemicals and contributes an indispensable role in drug discovery and design. The literature has documented the hypolipidemic effect of numerous Onosma species. Taking that into consideration, the current study was designed to isolate, purify and evaluate the antihyperlipidemic potential of leaves of Onosma hispidum Wall. For the first time, the bioassay-guided isolation led to the separation of 3 compounds that were identified by spectroscopic techniques as o-phthalic acid bis-(2-ethyl decyl)-ester (1), bis (2-ethyloctyl) phthalate (2), and 1,2 benzenedicarboxylic acid bis(2-methyl heptyl) ester (3). Lipase inhibition assay was utilized to scrutinize the antihyperlipidemic potential of methanolic extract fractions and subsequently isolated compounds. Further, the isolated compounds were employed for in silico studies via molecular docking, molecular mechanics with generalized born and surface area solvation (MM-GBSA), and MD simulations with Pancreatic Lipase Colipase (PDB ID: 1LPB). Molecular docking and MM-GBSA of isolated compounds were employed to explain the mode of binding between the protein-ligand complex and binding free energy calculation, respectively. Since compound (3) displayed the best docking score of -6.689 kcal/mol as compared to orlistat -5.529 kcal/mol with PDB: 1LPB. So, it was chosen for MD simulations to evaluate ligand stability and flexibility of the complex which was validated by the fluctuation of α-carbon chain, root mean square deviation (RMSD), root mean square fluctuation (RMSF), and type of interactions involved which authenticated the in vitro lipase inhibitory potential. Overall, in silico and in vitro results validated that compound (3) could be exploited as a promising pancreatic lipase inhibitor.Communicated by Ramaswamy H. Sarma.

Signaling pathways in obesity: mechanisms and therapeutic interventions

Obesity is a complex, chronic disease and global public health challenge. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine.

Proanthocyanidins as the main pancreatic lipase inhibitors in chokeberry fruits

Pancreatic lipase inhibitors are recognized as important in strategies for the management of overweight and obesity. The phytocompounds in chokeberry fruit show multidirectional pro-health effects, including anti-obesity activity. The aims of this study were to fractionate and identify the phenolic compounds of chokeberry fruit phenolic-rich extract that are active as pancreatic lipase inhibitors. Phenolic compounds were fractionated using Sephadex LH-20 resin, followed by polyphenol profile analysis using chromatographic and spectrophotometric methods, while pancreatic inhibitory activity was determined using 4-methylumbelliferyl oleate and emulsified triolein as enzyme substrates. Among the six fractions isolated from extract, two fractions rich in highly polymerized proanthocyanidins showed the greatest ability to inhibit pancreatic lipase activity. In comparison, fractions containing mainly low-molecular-weight phenolic compounds, such as phenolic acids, flavonols and anthocyanins, were 11-64 times less active. The most active fraction showed a mixed mode of pancreatic lipase inhibition, as determined by Lineweaver-Burk plot analysis, and exhibited a cumulative effect with orlistat. This study shows that black chokeberry polyphenols, particularly highly polymerized procyanidins, can effectively inhibit pancreatic lipase activity determined by in vitro methods.

Thietanes and derivatives thereof in medicinal chemistry

Unlike the oxetane ring, which, as evidenced by numerous studies, is known to play an increasingly important role in medicinal chemistry, the thietane ring has thus far received comparatively limited attention. Nonetheless, a growing number of reports now indicate that this 4-membered ring heterocycle may provide opportunities in analog design. In the present review article, we discuss the possible use and utility of the thietane fragment in medicinal chemistry and provide an overview of its properties and recent applications with a focus on isosteric replacements.

Whey Proteins Isolate-Based Biopolymeric Combinations to Microencapsulate Supercritical Fluid Extracted Oleoresins from Sea Buckthorn Pomace

In this study, high-value, carotenoid-rich oleoresin obtained by supercritical carbon dioxide (SFE-CO₂) extraction was used to develop five variants of microencapsulated delivery system, based on whey proteins isolate (WPI), in combination with inulin (I), pectin (P) or lactose (L). The WPI:I and WPI:L variants were also obtained by conjugation via Maillard reaction. The microencapsulation of the SFE-CO₂ sea buckthorn pomace oleoresin was performed by emulsion, complex coacervation and freeze-drying, which allowed for the obtaining of five powders, with different phytochemicals profile. The WPI:I conjugate showed the highest level of total carotenoids, whereas the counterpart WPI:L showed the highest content in linoleic acid (46 ± 1 mg/g) and palmitoleic acid (20.0 ± 0.5 mg/g). The β-tocopherol and β-sitosterol were identified in all variants, with the highest content in the conjugated WPI:L variant. Both WPI:L and WPI:I conjugate samples presented similar IC50 value for inhibitory activity against pancreatic lipase and α-amylase; the highest activity was observed for the conjugated WPI:I. The WPI:P combination allowed the highest release of carotenoids in the gastro-intestinal environment. All the powders exhibited poor flowing properties, whereas water activity (a_w) ranged from 0.084 ± 0.03 to 0.241 ± 0.003, suggesting that all variants are stable during storage. In case of solubility, significant differences were noticed between non-heated and glycated samples, with the highest value for the WPI:I and the lowest for glycated WPI:I. The structural analysis revealed the presence of finer spherosomes in WPI:I and WPI:L, with a reduced clustering capacity, whereas the particles in the conjugated samples were more uniform and aggregated into a three-dimensional network.

Bioactive's Characterization, Biological Activities, and In Silico Studies of Red Onion (Allium cepa L.) Skin Extracts

This study aimed to investigate the thermal stability and biological activities of the phytochemicals from the red onion skins extract, which are a rich source of anthocyanins. Eight anthocyanins were identified in the extract by high-performance liquid chromatography, the most abundant ones being cyanidin 3-O-laminaribioside and cyanidin 3-O-(6″-malonoyl-laminaribioside). The study also involved the assessment of the thermal degradation kinetics of anthocyanins and antioxidant activity in the 75-155 °C temperature range. The thermal degradation kinetics was described using the first-order kinetics model. In terms of thermal stability, increasing the temperature resulted in lower half-life values (t_1/2) and higher degradation rate constant values (k) for both anthocyanins and antioxidant activity. The thermodynamic parameters revealed that the phytochemicals' degradation is a non-spontaneous and endothermic reaction. Furthermore, the inhibitory effect of the extract was investigated against the enzymes affiliated with metabolic syndrome, oxidative stress, and inflammatory process diseases. Thus, we also demonstrated that the red onion skins extract exerted inhibitory activity on α-glucosidase, α-amylase, lipase, and lipoxygenase. Considering the high content of bioactives and various biological properties, the red onion skins extract is suitable for multiple applications.

Total Synthesis of Tetrahydrolipstatin, Its Derivatives, and Evaluation of Their Ability to Potentiate Multiple Antibiotic Classes against Mycobacterium Species

Tetrahydrolipstatin (THL, 1a) has been shown to inhibit both mammalian and bacterial α/β hydrolases. In the case of bacterial systems, THL is a known inhibitor of several Mycobacterium tuberculosis hydrolases involved in mycomembrane biosynthesis. Herein we report a highly efficient eight-step asymmetric synthesis of THL using a route that allows modification of the THL α-chain substituent to afford compounds 1a through 1e. The key transformation in the synthesis was use of a (TPP)CrCl/Co2(CO)8-catalyzed regioselective and stereospecific carbonylation on an advanced epoxide intermediate to yield a trans-β-lactone. These compounds are modest inhibitors of Ag85A and Ag85C, two α/β hydrolases of M. tuberculosis involved in the biosynthesis of the mycomembrane. Among these compounds, 10d showed the highest inhibitory effect on Ag85A (34 ± 22 μM) and Ag85C (66 ± 8 μM), and its X-ray structure was solved in complex with Ag85C to 2.5 Å resolution. In contrast, compound 1e exhibited the best-in-class MICs of 50 μM (25 μg/mL) and 16 μM (8.4 μg/mL) against M. smegmatis and M. tuberculosis H37Ra, respectively, using a microtiter assay plate. Combination of 1e with 13 well-established antibiotics synergistically enhanced the potency of few of these antibiotics in M. smegmatis and M. tuberculosis H37Ra. Compound 1e applied at concentrations 4-fold lower than its MIC enhanced the MIC of the synergistic antibiotic by 2-256-fold. In addition to observing synergy with first-line drugs, rifamycin and isoniazid, the MIC of vancomycin against M. tuberculosis H37Ra was 65 μg/mL; however, the MIC was lowered to 0.25 μg/mL in the presence of 2.1 μg/mL 1e demonstrating the potential of targeting mycobacterial hydrolases involved in mycomembrane and peptidoglycan biosynthesis.

Balanced lipase interactions for degradation-controlled paclitaxel release from lipid cubic phase formulations

Lipid cubic phase (LCP) formulations enhance the intestinal solubility and bioavailability of hydrophobic drugs by reducing precipitation and facilitating their mass transport to the intestinal surface for absorption. LCPs with an ester linkage connecting the acyl chain to the glycerol backbone (monoacylglycerols), are susceptible to chemical digestion by several lipolytic enzymes including lipases, accelerating the release of hydrophobic agents from the lipid bilayers of the matrix. Unlike regular enzymes that transform soluble substrates, lipolytic enzymes act at the interface of water and insoluble lipid. Therefore, compounds that bind to this interface can enhance or inhibit the activity of enzymes to varying extent. Here, we explore how the lipolysis rate can be tuned by the interfacial interaction of porcine pancreatic lipase with monoolein LCPs containing a known lipase inhibitor, tetrahydrolipstatin. Release of the Biopharmaceutical Classification System (BCS) class IV drug, paclitaxel, from the inhibitor-modified LCP was examined in the presence of lipase and its effectors colipase and calcium. By combining experimental dynamic digestion studies, thermodynamic measurements and molecular dynamics simulations of the competitive inhibition of lipase by tetrahydrolipstatin, we reveal the role and mode of action of lipase effectors in creating a precisely-balanced degradation-controlled LCP release system for the poorly soluble paclitaxel drug.

Synthesis, molecular modelling, in vitro and in vivo evaluation of conophylline inspired novel benzyloxy substituted indole glyoxylamides as potent pancreatic lipase inhibitors

Pancreatic lipase is a digestive enzyme involved in the hydrolysis of dietary fats. Orlistat, a potent pancreatic lipase inhibitor, is widely prescribed for long-term obesity treatment. Nevertheless, orlistat is reported for severe adverse effects including hepatotoxicity and pancreatitis. In the present study, a novel series of 11 benzyloxy substituted indole glyoxylamides were designed, synthesized and evaluated for in vitro pancreatic lipase inhibitory activity. Three analogues, 10b, 11b and 11c, exhibited potent activity (IC₅₀ ≤ 2.5 µM), with 11b exhibiting a potent IC₅₀ of 1.68 µM comparable to orlistat (IC₅₀ = 0.99 µM). Further, 11b exhibited reversible competitive inhibition with an inhibitory constant value of 0.98 μM. Molecular docking of these analogues was in agreement with in vitro results, wherein the MolDock scores exhibited significant correlation with their inhibitory activity (Pearson's r = 0.7122). A 50 ns molecular dynamics simulation of 11b-pancreatic lipase complex confirmed the role of extended alkyl interactions along with π-π stacking and π-cation interactions, in stabilizing the ligand (Maximum RMSD ≈ 3 Å) in the active site. Gastro-intestinal absorption and toxicity prediction of the three potent analogues highlighted the suitability of 11b for in vivo experiments. 11b at a dose of 20 mg/kg exhibited anti-obesity efficacy comparable to orlistat (10 mg/kg), wherein the serum triglycerides were found to be 94.95 and 83.85 mg/dL, respectively. Further, faecal triglyceride quantification indicated 11b to act through pancreatic lipase inhibition similar to orlistat. The present study identified a novel pancreatic lipase inhibitory benzyloxy substituted bis(indolyl) glyoxylamide 11b, with promising anti-obesity activity.Communicated by Ramaswamy H. Sarma.

Protein Lipidation by Palmitoylation and Myristoylation in Cancer

Posttranslational modification of proteins with lipid moieties is known as protein lipidation. The attachment of a lipid molecule to proteins endows distinct properties, which affect their hydrophobicity, structural stability, localization, trafficking between membrane compartments, and influences its interaction with effectors. Lipids or lipid metabolites can serve as substrates for lipidation, and the availability of these lipid substrates are tightly regulated by cellular metabolism. Palmitoylation and myristoylation represent the two most common protein lipid modifications, and dysregulation of protein lipidation is strongly linked to various diseases such as metabolic syndromes and cancers. In this review, we present recent developments in our understanding on the roles of palmitoylation and myristoylation, and their significance in modulating cancer metabolism toward cancer initiation and progression.

Plasmodium falciparum Atg18 localizes to the food vacuole via interaction with the multi-drug resistance protein 1 and phosphatidylinositol 3-phosphate

Autophagy, a lysosome-dependent degradative process, does not appear to be a major degradative process in malaria parasites and has a limited repertoire of genes. To better understand the autophagy process, we investigated Plasmodium falciparum Atg18 (PfAtg18), a PROPPIN family protein, whose members like S. cerevisiae Atg18 (ScAtg18) and human WIPI2 bind PI3P and play an essential role in autophagosome formation. Wild type and mutant PfAtg18 were expressed in P. falciparum and assessed for localization, the effect of various inhibitors and antimalarials on PfAtg18 localization, and identification of PfAtg18-interacting proteins. PfAtg18 is expressed in asexual erythrocytic stages and localized to the food vacuole, which was also observed with other Plasmodium Atg18 proteins, indicating that food vacuole localization is likely a shared feature. Interaction of PfAtg18 with the food vacuole-associated PI3P is essential for localization, as PfAtg18 mutants of PI3P-binding motifs neither bound PI3P nor localized to the food vacuole. Interestingly, wild type ScAtg18 interacted with PI3P, but its expression in P. falciparum showed complete cytoplasmic localization, indicating additional requirement for food vacuole localization. The food vacuole multi-drug resistance protein 1 (MDR1) was consistently identified in the immunoprecipitates of PfAtg18 and P. berghei Atg18, and also interacted with PfAtg18. In contrast with PfAtg18, ScAtg18 did not interact with MDR1, which, in addition to PI3P, could play a critical role in localization of PfAtg18. Chloroquine and amodiaquine caused cytoplasmic localization of PfAtg18, suggesting that these target PfAtg18 transport pathway. Thus, PI3P and MDR1 are critical mediators of PfAtg18 localization.

Design, synthesis and biological evaluation of N-substituted indole-thiazolidinedione analogues as potential pancreatic lipase inhibitors

Pancreatic Lipase (PL) is a key enzyme responsible for the digestion of 50%-70% of dietary triglycerides, hence its inhibition is considered as a viable approach for the management of obesity. A series of indole-TZD hybrid analogues were synthesized, characterized and evaluated for their PL inhibitory activity. Knoevenagel condensation of various substituted indole-3-carboxaldehyde with substituted thiazolidinediones resulted in the formation of titled analogues. Analogues 6d and 6e exerted potent PL inhibitory activity (IC₅₀ -6.19 and 8.96 µM, respectively). Further, these analogues exerted a competitive mode of PL inhibition. Moreover, molecular modelling studies were in agreement with the in vitro results (Pearson's r = .8682, p < .05). The fluorescence spectroscopic analysis further supported the strong binding affinity of these analogues with PL. A molecular dynamics study (20 ns) indicated that these analogues were stable in a dynamic environment. Thus, the present study highlighted the potential role of indole-thiazolidinedione hybrid analogues as potential PL inhibitors and further optimization might result in the development of new PL inhibitory lead candidates.

High-Throughput, Fluorescence-Based Esterase Activity Assay for Assessing Polysorbate Degradation Risk during Biopharmaceutical Development

PURPOSE

Hydrolytic degradation of polysorbate during 2-8°C storage of monoclonal antibody drug products has been attributed to residual enzymes (e.g., esterases) from bioprocessing steps. Robust detection of esterase activity using sensitive, non-polysorbate surrogate substrates can provide an alternate method to assess polysorbate degradation risk, if the correlation between the esterase activity and polysorbate degradation is established.

METHODS

A general esterase activity assay was developed as a monitoring and characterization tool during bioprocess development of monoclonal antibodies.

RESULTS

We report a fluorescence plate-based assay for quantifying esterase activity, utilizing 4-methylumbelliferyl caprylate (MU-C8) as the esterase substrate. The assay was first assessed for substrate, inhibitor and pH specificity using both model enzymes and purified protein samples. The assay was then extensively tested to understand sample matrix effects on activity rates.

CONCLUSIONS

The use of this high-throughput method will allow for rapid characterization of protein samples in under three hours. The esterase activity correlated directly with polysorbate degradation and can provide valuable information on polysorbate degradation risk throughout drug development.

Exploring Aurone Derivatives as Potential Human Pancreatic Lipase Inhibitors through Molecular Docking and Molecular Dynamics Simulations

Inhibition of human pancreatic lipase, a crucial enzyme in dietary fat digestion and absorption, is a potent therapeutic approach for obesity treatment. In this study, human pancreatic lipase inhibitory activity of aurone derivatives was explored by molecular modeling approaches. The target protein was human pancreatic lipase (PDB ID: 1LPB). The 3D structures of 82 published bioactive aurone derivatives were docked successfully into the protein catalytic active site, using AutoDock Vina 1.5.7.rc1. Of them, 62 compounds interacted with the key residues of catalytic trial Ser152-Asp176-His263. The top hit compound (A14), with a docking score of −10.6 kcal⋅mol⁻¹, was subsequently submitted to molecular dynamics simulations, using GROMACS 2018.01. Molecular dynamics simulation results showed that A14 formed a stable complex with 1LPB protein via hydrogen bonds with important residues in regulating enzyme activity (Ser152 and Phe77). Compound A14 showed high potency for further studies, such as the synthesis, in vitro and in vivo tests for pancreatic lipase inhibitory activity.

Lipolytic enzymes inhibitors: A new way for antibacterial drugs discovery

Tuberculosis (TB) caused by Mycobacterium tuberculosis (M. tb) still remains the deadliest infectious disease worldwide with 1.5 million deaths in 2018, of which about 15% are attributed to resistant strains. Another significant example is Mycobacterium abscessus (M. abscessus), a nontuberculous mycobacteria (NTM) responsible for cutaneous and pulmonary infections, representing up to 95% of NTM infections in cystic fibrosis (CF) patients. M. abscessus is a new clinically relevant pathogen and is considered one of the most drug-resistant mycobacteria for which standardized chemotherapeutic regimens are still lacking. Together the emergence of M. tb and M. abscessus multi-drug resistant strains with ineffective and expensive therapeutics, have paved the way to the development of new classes of anti-mycobacterial agents offering additional therapeutic options. In this context, specific inhibitors of mycobacterial lipolytic enzymes represent novel and promising antibacterial molecules to address this challenging issue. The results highlighted here include a complete overview of the antibacterial activities, either in broth medium or inside infected macrophages, of two families of promising and potent anti-mycobacterial multi-target agents, i.e. oxadiazolone-core compounds (OX) and Cyclophostin & Cyclipostins analogs (CyC); the identification and biochemical validation of their effective targets (e.g., the antigen 85 complex and TesA playing key roles in mycolic acid metabolism) together with their respective crystal structures. To our knowledge, these are the first families of compounds able to target and impair replicating as well as intracellular bacteria. We are still impelled in deciphering their mode of action and finding new potential therapeutic targets against mycobacterial-related diseases.

Modulating the release of pharmaceuticals from lipid cubic phases using a lipase inhibitor

Lipid cubic phase formulations have gained recognition as potential controlled delivery systems for a range of active pharmaceutical and biological agents on account of their desirable physiochemical properties and ability to encapsulate both hydrophobic and hydrophilic molecules. The most widely studied lipid cubic systems are those of the monoacylglycerol lipid family. These formulations are susceptible to lipolysis by a variety of enzymes, including lipases and esterases, which attack the ester bond present on the lipid chain bridging the oleic acid component to the glycerol backbone. The release of poorly soluble molecules residing in the lipid membrane portions of the phase is limited by the breakdown of the matrix; thus, presenting a potential means for further controlling and sustaining the release of therapeutic agents by targeting the matrix stability and its rate of degradation. The aims of the present study were twofold: to evaluate an approach to regulate the rate of degradation of lipid cubic phase drug delivery systems by targeting the enzyme interactions responsible for their demise; and to study the subsequent drug release profiles from bulk lipid cubic gels using model drugs of contrasting hydrophobicity. Here, hybrid materials consisting of cubic phases with monoacylglycerol lipids of different chain lengths formulated with a potent lipase inhibitor tetrahydrolipstatin were designed. Modulation of the release of a hydrophobic model pharmaceutical, a clofazimine salt, was obtained by exploiting the matrices' enzyme-driven digestion. A stable cubic phase is described, displaying controlled degradation with at least a 4-fold improvement compared to the blank systems shown in inhibitor-containing cubic systems. Sustained release of the model hydrophobic pharmaceutical was studied over 30 days to highlight the advantage of incorporating an inhibitor into the cubic network to achieve tunable lipid release systems. This is done without negatively affecting the structure of the matrix itself, as shown by comprehensive small-angle x-ray scattering experiments.

Interaction between Myricetin Aggregates and Lipase under Simplified Intestinal Conditions

Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible for fat digestion. In this study, we investigate the interaction between myricetin and lipase under simplified intestinal conditions from a colloidal point of view. The results show that myricetin form aggregates in aqueous medium and under simplified intestinal condition, where it was found that lipase is in its monomeric form. Although lipase inhibition by myricetin at a molecular level has been reported previously, the results of this study suggest that myricetin aggregates inhibit lipase by a sequestering mechanism as well. The size of these aggregates was determined to be in the range of a few nm to >200 nm.

Measuring Lipolytic Activity to Support Process Improvements to Manage Lipase-Mediated Polysorbate Degradation

PURPOSE

Polysorbates are critical stabilizers in biopharmaceutical protein formulations. However, they may degrade in drug substance (DS) or drug product (DP) during storage. Degradation catalyzed by lipases present in host cell proteins (HCPs) is one suspected root cause. The purpose of this study was to develop an assay to detect lipolytic activity in biopharmaceutical DS and DP formulations.

METHODS

The assay is based on the hydrolysis of the lipase substrate 4-methylumbelliferyl oleate to yield the fluorescent product 4-methylumbelliferone.

RESULTS

First, the assay components and their concentrations (buffer salts and pH, solvent and inhibitor Orlistat) were established and optimized using a model lipase (Porcine pancreatic lipase) and cell culture harvest fluid that exhibited lipolytic activity. The assay was then successfully applied and thereby qualified in protein formulations and at lipase concentrations possibly encountered in actual biopharmaceutical DS and DP formulations.

CONCLUSION

The lipase assay can be used to detect lipolytic activity in intermediate and final DS, for example during process optimization in downstream purification, to better and specifically reduce the level, or deplete, lipases from HCPs. The assay is also suitable to be applied during root cause investigations related to polysorbate degradation in biopharmaceutical DP.

Design, synthesis, evaluation, and molecular modeling studies of indolyl oxoacetamides as potential pancreatic lipase inhibitors

A series of indolyl oxoacetamide analogs was synthesized, characterized, and evaluated for their pancreatic lipase inhibitory activity using porcine pancreatic lipase (type II) and 4-nitrophenyl butyrate. Compound 8d exhibited a potent inhibition, with an IC₅₀ value of 4.53 µM, followed by 8c (IC₅₀  = 5.12 µM), compared with the standard drug, orlistat (IC₅₀  = 0.99 µM). Furthermore, analogs 8c and 8d exhibited a reversible competitive inhibition, similar to orlistat. Molecular docking studies of the compounds 7a-f and 8a-f were in agreement with the in vitro results, wherein 8d exhibited a potential MolDock score of -163.052 kcal/mol. A 10-ns molecular dynamics simulation of 8d complexed with pancreatic lipase confirmed the role of π-π stacking and π-cation interactions with the lid domain and Arg 256, respectively, in stabilizing the ligand at the active site (maximum observed root mean square deviation ≈ 2 Å). The present study led to the identification of novel indolyl oxoacetamides (8a-d) as potential pancreatic lipase inhibitory leads that might further result in enhanced potency through lead optimization.

Monoacylglycerol lipase inhibitors: modulators for lipid metabolism in cancer malignancy, neurological and metabolic disorders

Monoacylglycerol lipase (MAGL) is a serine hydrolase that plays a crucial role catalysing the hydrolysis of monoglycerides into glycerol and fatty acids. It links the endocannabinoid and eicosanoid systems together by degradation of the abundant endocannabinoid 2-arachidaoylglycerol into arachidonic acid, the precursor of prostaglandins and other inflammatory mediators. MAGL inhibitors have been considered as important agents in many therapeutic fields, including anti-nociceptive, anxiolytic, anti-inflammatory, and even anti-cancer. Currently, ABX-1431, a first-in-class inhibitor of MAGL, is entering clinical phase 2 studies for neurological disorders and other diseases. This review summarizes the diverse (patho)physiological roles of MAGL and will provide an overview on the development of MAGL inhibitors. Although a large number of MAGL inhibitors have been reported, novel inhibitors are still required, particularly reversible ones.

Calorimetric approach for comparison of Angiopoietin-like protein 4 with other pancreatic lipase inhibitors

Pancreatic lipase (PNLIP) is a digestive enzyme that is a potential drug target for the treatment of obesity. A better understanding of its regulation mechanisms would facilitate the development of new therapeutics. Recent studies indicate that intestinal lipolysis by PNLIP is reduced by Angiopoietin-like protein 4 (ANGPTL4), whose N-terminal domain (nANGPTL4) is a known inactivator of lipoprotein lipase (LPL) in blood circulation and adipocytes. To elucidate the mechanism of PNLIP inhibition by ANGPTL4, we developed a novel approach, using isothermal titration calorimetry (ITC). The obtained results were compared with those of well-described inhibitors of PNLIP - ε-polylysine (EPL), (-)-epigallocatechin-3-gallate (EGCG) and tetrahydrolipstatin. We demonstrate that ITC allows to investigate PNLIP inhibition mechanisms in complex substrate emulsions and that the ITC-based assay is highly sensitive - the lowest concentration for quantification of PNLIP is 1.5 pM. Combining ITC with surface plasmon resonance and fluorescence measurements, we present evidence that ANGPTL4 is a lipid-binding protein that influences PNLIP activity through interactions with components of substrate emulsions (bile salts, phospholipids and triglycerides), and this promotes the aggregation of triglyceride emulsions similarly to the PNLIP inhibitors EPL and EGCG. In the absence of substrate emulsion, unlike in the case of LPL, ANGPTL4 did not induce the inactivation of PNLIP. Our data also prove that due to various interactions with components of substrate systems, the effect of a PNLIP inhibitor depends on whether its effect is measured in a complex substrate emulsion or in a simple substrate system.

Inhibition of CpLIP2 Lipase Hydrolytic Activity by Four Flavonols (Galangin, Kaempferol, Quercetin, Myricetin) Compared to Orlistat and Their Binding Mechanisms Studied by Quenching of Fluorescence

The inhibition of recombinant CpLIP2 lipase/acyltransferase from Candida parapsiolosis was considered a key model for novel antifungal drug discovery and a potential therapeutic target for candidiasis. Lipases have identified recently as potent virulence factors in C. parapsilosis and some other yeasts. The inhibition effects of orlistat and four flavonols (galangin, kaempferol, quercetin and myricetin) characterized by an increasing degree of hydroxylation in B-ring, were investigated using ethyl oleate hydrolysis as the model reaction. Orlistat and kaempferol (14 µM) strongly inhibited CpLIP2 catalytic activity within 1 min of pre-incubation, by 90% and 80%, respectively. The relative potency of flavonols as inhibitors was: kaempferol > quercetin > myricetin > galangin. The results suggested that orlistat bound to the catalytic site while kaempferol interacted with W294 on the protein lid. A static mechanism of interactions between flavonols and CpLIP2 lipase was confirmed by fluorescence quenching analyses, indicating that the interactions were mainly driven by hydrophobic bonds and electrostatic forces. From the Lehrer equation, fractions of tryptophan accessibility to the quencher were evaluated, and a relationship with the calculated number of binding sites was suggested.

Methyl arachidonyl fluorophosphonate inhibits Mycobacterium tuberculosis thioesterase TesA and globally affects vancomycin susceptibility

Phthiocerol dimycocerosates and phenolic glycolipids (PGL) are considered as major virulence elements of Mycobacterium tuberculosis, in particular because of their involvement in cell wall impermeability and drug resistance. The biosynthesis of these waxy lipids involves multiple enzymes, including thioesterase A (TesA). We observed that purified recombinant M. tuberculosis TesA is able to dimerize in the presence of palmitoyl-CoA and our 3D structure model of TesA with this acyl-CoA suggests hydrophobic interaction requirement for dimerization. Furthermore, we identified that methyl arachidonyl fluorophosphonate, which inhibits TesA by covalently modifying the catalytic serine, also displays a synergistic antimicrobial activity with vancomycin further warranting the development of TesA inhibitors as valuable antituberculous drug candidates.

Acceptability of alginate enriched bread and its effect on fat digestion in humans

Lifestyle interventions and physical activity remain the cornerstone of obesity management, as pharmacological therapies (orlistat) are associated with gastrointestinal (GI) side effects. Combining orlistat with fibers can reduce side effects, improving compliance. Therefore, a fiber that inhibits lipase without side effects could help treat obesity.

The aims of the present work were to assess whether alginate enriched bread could inhibit fat digestion, and assess the acceptability of alginate bread and its effect on GI wellbeing.

A double-blind, randomised, controlled cross-over pilot study (NCT03350958) assessed the impact of an alginate bread meal on; lipid content in ileal effluent and circulating triacylglycerol levels. This was compared against the same meal with non-enriched (control) bread.

GI wellbeing and acceptability of alginate bread was compared to control bread through daily wellbeing questionnaires and food diaries (NCT03477981). Control bread followed by alginate bread were consumed for two weeks respectively.

Consumption of alginate bread reduced circulating triacylglycerol compared to control (2% reduction in AUC) and significantly increased lipid content in ileal effluent (3.8 g ± 1.6 after 210 min).

There were no significant changes to GI wellbeing when comparing alginate bread to control bread. A significant increase in the feeling of fullness occurred with alginate bread compared to baseline and the first week of control bread consumption.

This study showed that sustained consumption of alginate enriched bread does not alter GI wellbeing and can decrease lipolysis, increasing lipid leaving the small intestine.

Further studies are required to demonstrate that reduced fat digestion through the action of alginate can reduce fat mass or body weight.

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Alginate can be incorporated into a highly acceptable loaf at 4%.

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Sustained (two weeks) consumption of alginate bread did not affect GI wellbeing.

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Consumption of alginate bread decreases circulating triglyceride after the meal.

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Consumption of alginate bread increases lipid leaving the ileum after the meal.

New Electrophiles and Strategies for Mechanism-Based and Targeted Covalent Inhibitor Design

Covalent inhibitors are experiencing a growing resurgence in drug design and are an increasingly useful tool in molecular biology. The ability to attach inhibitors to their targets by a covalent linkage offers pharmacodynamic and pharmacokinetic advantages, but this can also be a liability if undesired off-target reactions are not mitigated. The discovery of new electrophilic groups that react selectively with specific amino acid residues is therefore highly desirable in the design of targeted covalent inhibitors (TCIs). Additionally, the ability to control the reactivity through exploitation of the target enzyme's machinery, as in mechanism-based inhibitors (MBIs), greatly benefits from the discovery of new strategies. This Perspective showcases recent advances in electrophile development and their application in TCIs and MBIs, exhibiting high selectivity for their targets.

Covalent binders in drug discovery

Covalent modulation of protein function can have multiple utilities including therapeutics, and probes to interrogate biology. While this field is still viewed with scepticism due to the potential for (idiosyncratic) toxicities, significant strides have been made in terms of understanding how to tune electrophilicity to selectively target specific residues. Progress has also been made in harnessing the potential of covalent binders to uncover novel biology and to provide an enhanced utility as payloads for Antibody Drug Conjugates. This perspective covers the tenets and applications of covalent binders.

Pancreatic lipase inhibitory activity of selected pharmaceutical agents

Twenty-five structurally diverse compounds have been tested in vitro for their pancreatic lipase (PL) inhibitory activity. Despite the diversity of tested compounds, the relationship comprising structural attributes of the compounds could be established to correlate with the observed inhibitory activity. Compounds that exerted inhibitory action through surface activity were of different profile from the rest of compounds. When co-incubated with orlistat (OsT), important synergistic effects for some compounds (orphenadrine, gliclazide, cefuroxime and sulfacetamide) were revealed, while antagonistic effects were demonstrated for others (camphor sulfonic acid and dinitro salicylic acid). Docking studies for the most active molecules were performed and molecular interaction forces with the PL active site were identified. The results suggested co-binding of OsT along with the other inhibitor in the binding site in cases of synergistic effect but not in the case of antagonistic effect. These results were additionally supported by affinity capillary electrophoresis. In conclusion, synergistic lipase inhibitory activity between OsT and some other pharmaceutical compounds was demonstrated for the first time, which might help improve the pharmacological effect of OsT.

Design, synthesis, biological evaluation and molecular modelling studies of indole glyoxylamides as a new class of potential pancreatic lipase inhibitors

A series of eighteen indole glyoxylamide analogues were synthesized, characterized and evaluated for their pancreatic lipase inhibitory activity. Porcine pancreatic lipase (Type II) was used with 4-nitrophenyl butyrate (as substrate) for the in vitro assay. Compound 8f exhibited competitive inhibition against pancreatic lipase with IC₅₀ value of 4.92 µM, comparable to that of the standard drug, orlistat (IC₅₀ = 0.99 µM). Compounds 7a-i and 8a-i were subjected to molecular docking into the active site of human PL (PDB ID: 1LPB) wherein compound 8f possessed a potential MolDock score of -153.037 kcal/mol. Molecular dynamics simulation of 8f complexed with pancreatic lipase, confirmed the role of aromatic substitution in stabilizing the ligand through hydrophobic interactions (maximum observed RMSD = 3.5 Å).

Sanguinarine in Chelidonium majus induced antifeeding and larval lethality by suppressing food intake and digestive enzymes in Lymantria dispar

Our previous studies had identified that both crude extracts and total alkaloid from Chelidonium majus exerted a significant antifeeding and larval lethality on Lymantria dispar. Moreover, sanguinarine, chelidonine, berberine hydrochloride and coptisine were the main alkaloid in C. majus exerting toxicity to L. dispar. In this paper, we evaluated the insecticidal and antifeeding activities of each alkaloid on the 3rd instar L. dispar larvae by bioassay. Meanwhile, the effects of alkaloids from C. majus on the activities and mRNA levels of three main digestive enzymes in L. dispar larvae were investigated. The results indicated that sanguinarine possessed the strongest insecticidal activity with a LD₅₀ value of 4.963 μg/larva, and the coptisine showed little lethality to 3 rd instar L. dispar larvae among four alkaloids from C. majus. The insecticidal capacity of four alkaloids on 3rd instar L. dispar larvae was in the following decreasing order of sanguinarine > chelidonine > berberine hydrochloride > coptisine. Similarly, except coptisine, the other three alkaloids significantly reduced food intakes of third instar L. dispar larvae and suppressed activities of three digestive enzymes (α-amylase, lipase and total protease) simultaneously. Finally, qRT-PCR analysis revealed that the transcriptions of α-amylase, lipase and serine protease were affected by sanguinarine. Especially, at 48 h after treatment, the mRNA expressions of those digestive enzymes were significantly suppressed by sanguinarine. In conclusion, we suggested that alkaloids from C. majus induced antifeeding and larval lethality on L. dispar larvae by suppressing food intake and digestive enzymes in L. dispar. Our findings provide a novel insight into evaluating the antifeeding and insecticidal properties of C. majus, which afford a new strategy for integrated pest management programs as well.

A novel protocol for the preparation of active recombinant human pancreatic lipase from Escherichia coli

An active recombinant human pancreatic lipase (recHPL) was successfully prepared for the first time from the Escherichia coli expression system using short Strep-tag II (ST II). The recHPL-ST II was solubilized using 8 M urea from E.coli lysate and purified on a Strep-Tactin-Sepharose column. After refolding by stepwise dialyses in the presence of glycerol and Ca2+ for 2 days followed by gel filtration, 1.8-6 mg of active recHPL-ST II was obtained from 1 L of culture. The recHPL was non-glycosylated, but showed almost equal specific activity, pH-dependency and time-dependent stability compared to those of native porcine pancreatic lipase (PPL) at 37°C. However, the recHPL lost its lipolytic activity above 50°C, showing a lower heat-stability than that of native PPL, which retained half its activity at this temperature.

Median nerve stimulation induces analgesia via orexin-initiated endocannabinoid disinhibition in the periaqueductal gray

Adequate pain management remains an unmet medical need. We previously revealed an opioid-independent analgesic mechanism mediated by orexin 1 receptor (OX1R)-initiated 2-arachidonoylglycerol (2-AG) signaling in the ventrolateral periaqueductal gray (vlPAG). Here, we found that low-frequency median nerve stimulation (MNS) through acupuncture needles at the PC6 (Neiguan) acupoint (MNS-PC6) induced an antinociceptive effect that engaged this mechanism. In mice, MNS-PC6 reduced acute thermal nociceptive responses and neuropathy-induced mechanical allodynia, increased the number of c-Fos-immunoreactive hypothalamic orexin neurons, and led to higher orexin A and lower GABA levels in the vlPAG. Such responses were not seen in mice with PC6 needle insertion only or electrical stimulation of the lateral deltoid, a nonmedian nerve-innervated location. Directly stimulating the surgically exposed median nerve also increased vlPAG orexin A levels. MNS-PC6-induced antinociception (MNS-PC6-IA) was prevented by proximal block of the median nerve with lidocaine as well as by systemic or intravlPAG injection of an antagonist of OX1Rs or cannabinoid 1 receptors (CB1Rs) but not by opioid receptor antagonists. Systemic blockade of OX1Rs or CB1Rs also restored vlPAG GABA levels after MNS-PC6. A cannabinoid (2-AG)-dependent mechanism was also implicated by the observations that MNS-PC6-IA was prevented by intravlPAG inhibition of 2-AG synthesis and was attenuated in Cnr1 ^-/- mice. These findings suggest that PC6-targeting low-frequency MNS activates hypothalamic orexin neurons, releasing orexins to induce analgesia through a CB1R-dependent cascade mediated by OX1R-initiated 2-AG retrograde disinhibition in the vlPAG. The opioid-independent characteristic of MNS-PC6-induced analgesia may provide a strategy for pain management in opioid-tolerant patients.

Oxadiazolone derivatives, new promising multi-target inhibitors against M. tuberculosis

A set of 19 oxadiazolone (OX) derivatives have been investigated for their antimycobacterial activity against two pathogenic slow-growing mycobacteria, Mycobacterium marinum and Mycobacterium bovis BCG, and the avirulent Mycobacterium tuberculosis (M. tb) mc²6230. The encouraging minimal inhibitory concentrations (MIC) values obtained prompted us to test them against virulent M. tb H37Rv growth either in broth medium or inside macrophages. The OX compounds displayed a diversity of action and were found to act either on extracellular M. tb growth only with moderated MIC₅₀, or both intracellularly on infected macrophages as well as extracellularly on bacterial growth. Of interest, all OX derivatives exhibited very low toxicity towards host macrophages. Among the six potential OXs identified, HPOX, a selective inhibitor of extracellular M. tb growth, was selected and further used in a competitive labelling/enrichment assay against the activity-based probe Desthiobiotin-FP, in order to identify its putative target(s). This approach, combined with mass spectrometry, identified 18 potential candidates, all being serine or cysteine enzymes involved in M. tb lipid metabolism and/or in cell wall biosynthesis. Among them, Ag85A, CaeA, TesA, KasA and MetA have been reported as essential for in vitro growth of M. tb and/or its survival and persistence inside macrophages. Overall, our findings support the assumption that OX derivatives may represent a novel class of multi-target inhibitors leading to the arrest of M. tb growth through a cumulative inhibition of a large number of Ser- and Cys-containing enzymes involved in various important physiological processes.

Delineating the Physiological Roles of the PE and Catalytic Domains of LipY in Lipid Consumption in Mycobacterium-Infected Foamy Macrophages

Within tuberculous granulomas, a subpopulation of Mycobacterium tuberculosis resides inside foamy macrophages (FM) that contain abundant cytoplasmic lipid bodies (LB) filled with triacylglycerol (TAG). Upon fusion of LB with M. tuberculosis-containing phagosomes, TAG is hydrolyzed and reprocessed by the bacteria into their own lipids, which accumulate as intracytosolic lipid inclusions (ILI). This phenomenon is driven by many mycobacterial lipases, among which LipY participates in the hydrolysis of host and bacterial TAG. However, the functional contribution of LipY's PE domain to TAG hydrolysis remains unclear. Here, enzymatic studies were performed to compare the lipolytic activities of recombinant LipY and its truncated variant lacking the N-terminal PE domain, LipY(ΔPE). Complementarily, an FM model was used where bone marrow-derived mouse macrophages were infected with M. bovis BCG strains either overexpressing LipY or LipY(ΔPE) or carrying a lipY deletion mutation prior to being exposed to TAG-rich very-low-density lipoprotein (VLDL). Results indicate that truncation of the PE domain correlates with increased TAG hydrolase activity. Quantitative electron microscopy analyses showed that (i) in the presence of lipase inhibitors, large ILI (ILI⁺³) were not formed because of an absence of LB due to inhibition of VLDL-TAG hydrolysis or inhibition of LB-neutral lipid hydrolysis by mycobacterial lipases, (ii) ILI⁺³ profiles in the strain overexpressing LipY(ΔPE) were reduced, and (iii) the number of ILI⁺³ profiles in the ΔlipY mutant was reduced by 50%. Overall, these results delineate the role of LipY and its PE domain in host and mycobacterial lipid consumption and show that additional mycobacterial lipases take part in these processes.

From Oxiranes to Oligomers: Architectures of U.S. FDA Approved Pharmaceuticals Containing Oxygen Heterocycles

Oxygen heterocycles are the second most common type of heterocycles that appear as structural components of U.S. Food and Drug Administration (FDA) approved pharmaceuticals. Analysis of our database of drugs approved through 2017 reveals 311 distinct pharmaceuticals containing at least one oxygen heterocycle. Most prevalent among these are pyranoses, with furanoses, macrolactones, morpholines, and dioxolanes rounding off the top five. The main body of this Perspective is organized according to ring size, commencing with three- and four-membered rings and ending with macrocycles, polymers, and unusual oxygen-containing heterocycles. For each section, all oxygen heterocycle-containing drugs are presented along with a brief discussion about structural and drug application patterns.

Stereochemical Structure Activity Relationship Studies (S-SAR) of Tetrahydrolipstatin

Tetrahydrolipstatin (THL), its enantiomer, and an additional six diastereomers were evaluated as inhibitors of the hydrolysis of p-nitrophenyl butyrate by porcine pancreatic lipase. IC₅₀s were found for all eight stereoisomers ranging from a low of 4.0 nM for THL to a high of 930 nM for the diastereomer with the inverted stereocenters at the 2,3,2'-positions. While the enantiomer of THL was also significantly less active (77 nM) the remaining five stereoisomers retained significant inhibitory activities (IC₅₀s = 8.0 to 20 nM). All eight compounds were also evaluated against three human cancer cell lines (human breast cancers MCF-7 and MDA-MB-231, human large-cell lung carcinoma H460). No appreciable cytotoxicity was observed for THL and its seven diastereomers, as their IC₅₀s in a MTT cytotoxicity assay were all greater than 3 orders of magnitude of camptothecin.

Lipase inhibitor orlistat prevents hepatitis B virus infection by targeting an early step in the virus life cycle

Hepatitis B Virus (HBV) is a strictly hepatotropic pathogen which is very efficiently targeted to the liver and into its host cell, the hepatocyte. The sodium taurocholate co-transporting polypeptide (NTCP) has been identified as a key virus entry receptor, but the early steps in the virus life cycle are still only barely understood. Here, we investigated the effect of lipase inhibition and lipoprotein uptake on HBV infection using differentiated HepaRG cells and primary human hepatocytes. We found that an excess of triglyceride rich lipoprotein particles in vitro diminished HBV infection and a reduced hepatic virus uptake in vivo if apolipoprotein E is lacking indicating virus transport along with lipoproteins to target hepatocytes. Moreover, we showed that HBV infection of hepatocytes was inhibited by the broadly active lipase inhibitor orlistat, approved as a therapeutic agent which blocks neutral lipid hydrolysis activity. Orlistat treatment targets HBV infection at a post-entry step and inhibited HBV infection during virus inoculation strongly in a dose-dependent manner. In contrast, orlistat had no effect on HBV gene expression or replication or when added after HBV infection. Taken together, our data indicate that HBV connects to the hepatotropic lipoprotein metabolism and that inhibition of cellular hepatic lipase(s) may allow to target early steps of HBV infection.

Autophagy-Dependent Generation of Free Fatty Acids Is Critical for Normal Neutrophil Differentiation

Neutrophils are critical and short-lived mediators of innate immunity that require constant replenishment. Their differentiation in the bone marrow requires extensive cytoplasmic and nuclear remodeling, but the processes governing these energy-consuming changes are unknown. While previous studies show that autophagy is required for differentiation of other blood cell lineages, its function during granulopoiesis has remained elusive. Here, we have shown that metabolism and autophagy are developmentally programmed and essential for neutrophil differentiation in vivo. Atg7-deficient neutrophil precursors had increased glycolytic activity but impaired mitochondrial respiration, decreased ATP production, and accumulated lipid droplets. Inhibiting autophagy-mediated lipid degradation or fatty acid oxidation alone was sufficient to cause defective differentiation, while administration of fatty acids or pyruvate for mitochondrial respiration rescued differentiation in autophagy-deficient neutrophil precursors. Together, we show that autophagy-mediated lipolysis provides free fatty acids to support a mitochondrial respiration pathway essential to neutrophil differentiation.

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Autophagy is critical for neutrophil differentiation in vivo

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Differentiating neutrophils shift from glycolysis to fatty acid oxidation

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By degrading lipid droplets, autophagy provides fatty acids, enabling this shift

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Fatty acids restore energy metabolism and differentiation in Atg7^–/– granulopoiesis