Design, synthesis, biological evaluation, and molecular modeling studies of rhodanine derivatives as pancreatic lipase inhibitors

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.

Recent Studies of Nitrogen and Sulfur Containing Heterocyclic Analogues as Novel Antidiabetic Agents: A Review

The prevalence of diabetes mellitus is on the rise, which demands the identification of novel antidiabetic drugs. There is a need for safer and more effective alternatives because the therapy methods now available to manage diabetes have limits. Due to their diverse pharmacological characteristics, heterocyclic molecules with nitrogen and Sulfur atoms have become intriguing candidates in medicinal chemistry. These substances have a wide variety of structures that can be customized to target different pathways associated with diabetes and can affect important biological targets involved in glucose homeostasis. This review provides a thorough summary of the most recent studies on heterocyclic analogues of nitrogen and Sulfur as prospective antidiabetic agents. This review examines the variety of their structural forms, their methods of action, and assesses the results of preclinical and clinical investigations on their effectiveness and safety. Additionally, further optimization and development of innovative antidiabetic medications are highlighted, as well as the difficulties and prospects for the future in utilizing the therapeutic potential of these analogues. This study seeks to stimulate additional investigation and cooperation between researchers and medicinal chemists, promoting improvements in the creation of efficient and secure antidiabetic medicines to fulfill the needs in the management of diabetes.

Rhodanine derivatives: An insight into the synthetic and medicinal perspectives as antimicrobial and antiviral agents

Rhodanine or 2-Thioxothiazolidin-4-one is a privileged heterocyclic compound offering a wide opportunity for structural modification, lead development, and modification. It is one of the highly decorated scaffolds in the drug discovery process. Rhodanine derivatives possess a plethora of biological activities due to their ability to interact with a diverse range of protein targets, which provide tremendous opportunities to discover new drugs with different modes of action. The most common strategy for developing novel rhodanine derivatives is the introduction of structurally diverse substituents at the C-5 or N-3, or both positions. Since the inception of Epralestat into the market in 1992, the exploration of rhodanine-3-acetic acids has led to the development of novel leads against different biological targets such as MRSA, HHV-6, Mycobacterial tuberculosis, dengue, etc. In the current pandemic era, some rhodanine compounds have been explored against SARS-CoV-2. In recent years, rhodanine and its derivatives have witnessed significant progress in developing new drug leads as potential antimicrobial and antiviral agents. Different synthetic methodologies and recent developments in the medicinal chemistry of rhodanine derivatives, including biological activities, their mechanistic aspects, structure-activity relationships, and in silico findings, have been compiled in the present review. This article will benefit the scientific community and offer perspectives on how these scaffolds as privileged structures might be exploited in the future for rational design and discovery of rhodanine-based bio-active molecules.

Synthesis, Crystal Structures, Lipophilic Properties and Antimicrobial Activity of 5-Pyridylmethylidene-3-rhodanine-carboxyalkyl Acids Derivatives

The constant increase in the resistance of pathogenic bacteria to the commonly used drugs so far makes it necessary to search for new substances with antibacterial activity. Taking up this challenge, we obtained a series of rhodanine-3-carboxyalkyl acid derivatives containing 2- or 3- or 4-pyridinyl moiety at the C-5 position. These compounds were tested for their antibacterial and antifungal activities. They showed activity against Gram-positive bacteria while they were inactive against Gram-negative bacteria and yeast. In order to explain the relationship between the activity of the compounds and their structure, for selected derivatives crystal structures were determined using the X-ray diffraction method. Modeling of the isosurface of electron density was also performed. For all tested compounds their lipophilicity was determined by the RP-TLC method and by calculation methods. On the basis of the carried-out research, it was found that the derivatives with 1.5 N···S electrostatics interactions between the nitrogen atom in the pyridine moiety and the sulfur atom in the rhodanine system showed the highest biological activity.

Novel Pyridinium Based Ionic Liquid Promoter for Aqueous Knoevenagel Condensation: Green and Efficient Synthesis of New Derivatives with Their Anticancer Evaluation

Herein, a distinctive dihydroxy ionic liquid ([Py-2OH]OAc) was straightforwardly assembled from the sonication of pyridine with 2-chloropropane-1,3-diol by employing sodium acetate as an ion exchanger. The efficiency of the ([Py-2OH]OAc as a promoter for the sono-synthesis of a novel library of condensed products through DABCO-catalyzed Knoevenagel condensation process of adequate active cyclic methylenes and ninhydrin was next investigated using ultimate greener conditions. All of the reactions studied went cleanly and smoothly, and the resulting Knoevenagel condensation compounds were recovered in high yields without detecting the aldol intermediates in the end products. Compared to traditional strategies, the suggested approach has numerous advantages including mild reaction conditions with no by-products, eco-friendly solvent, outstanding performance in many green metrics, and usability in gram-scale synthesis. The reusability of the ionic liquid was also studied, with an overall retrieved yield of around 97% for seven consecutive runs without any substantial reduction in the performance. The novel obtained compounds were further assessed for their in vitro antitumor potential toward three human tumor cell lines: Colo-205 (colon cancer), MCF-7 (breast cancer), and A549 (lung cancer) by employing the MTT assay, and the findings were evaluated with the reference Doxorubicin. The results demonstrated that the majority of the developed products had potent activities at very low doses. Compounds comprising rhodanine (5) or chromane (12) moieties exhibited the most promising cytotoxic effects toward three cell lines, particularly rhodanine carboxylic acid derivative (5c), showing superior cytotoxic effects against the investigated cell lines compared to the reference drug. Furthermore, automated docking simulation studies were also performed to support the results obtained.

Discovery of triterpenoids as potent dual inhibitors of pancreatic lipase and human carboxylesterase 1

Pancreatic lipase (PL) is a well-known key target for the prevention and treatment of obesity. Human carboxylesterase 1A (hCES1A) has become an important target for the treatment of hyperlipidaemia. Thus, the discovery of potent dual-target inhibitors based on PL and hCES1A hold great potential for the development of remedies for treating related metabolic diseases. In this study, a series of natural triterpenoids were collected and the inhibitory effects of these triterpenoids on PL and hCES1A were determined using fluorescence-based biochemical assays. It was found that oleanolic acid (OA) and ursolic acid (UA) have the excellent inhibitory effects against PL and hCES1A, and highly selectivity over hCES2A. Subsequently, a number of compounds based on the OA and UA skeletons were synthesised and evaluated. Structure–activity relationship (SAR) analysis of these compounds revealed that the acetyl group at the C-3 site of UA (compound 41) was very essential for both PL and hCES1A inhibition, with IC₅₀ of 0.75 µM and 0.014 µM, respectively. In addition, compound 39 with 2-enol and 3-ketal moiety of OA also has strong inhibitory effects against both PL and hCES1A, with IC₅₀ of 2.13 µM and 0.055 µM, respectively. Furthermore, compound 39 and 41 exhibited good selectivity over other human serine hydrolases including hCES2A, butyrylcholinesterase (BChE) and dipeptidyl peptidase IV (DPP-IV). Inhibitory kinetics and molecular docking studies demonstrated that both compounds 39 and 41 were effective mixed inhibitors of PL, while competitive inhibitors of hCES1A. Further investigations demonstrated that both compounds 39 and 41 could inhibit adipocyte adipogenesis induced by mouse preadipocytes. Collectively, we found two triterpenoid derivatives with strong inhibitory ability on both PL and hCES1A, which can be served as promising lead compounds for the development of more potent dual-target inhibitors targeting on PL and hCES1A.

Review of anticancer potentials and structure-activity relationships (SAR) of rhodanine derivatives

Rhodanine has been recognized as a privileged scaffold in medicinal chemistry due to its well-known ability to demonstrate a broad range of biological activities. The possibility of structural diversification has contributed to the significance of rhodanine structure in effective drug discovery and design. Many studies have confirmed the potential of rhodanine-derived compounds in the treatment of different types of cancer through the apoptosis induction mechanism. Furthermore, most of the rhodanine derivatives exhibited remarkable anticancer activity in the micromolar range while causing negligible cytotoxicity to normal cells. This review critically describes the anticancer activity profile of reported rhodanine compounds and the structure-activity relationships (SAR) to highlight the value of rhodanine as the core structure for future cancer drug development as well as to assist the researchers in rational drug design.

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.

Screening for pancreatic lipase natural modulators by capillary electrophoresis hyphenated to spectrophotometric and conductometric dual detection

The search for novel pancreatic lipase (PL) inhibitors has gained increasing attention in recent years. For the first time, a dual detection capillary electrophoresis (CE)-based homogeneous lipase assay was developed employing both the offline and online reaction modes. The hydrolysis of 4-nitrophenyl butyrate (4-NPB) catalyzed by PL into 4-nitrophenol and butyrate was monitored by spectrophotometric and conductimetric detection, respectively. The assays presented several advantages such as economy in consumption (few tens of nanoliters for online assays to few tens of microliters for offline assays), no modification of lipase, rapidity (<10 min) and versatility. Tris/MOPS (10 mM, pH 6.6) was used as the background electrolyte and the incubation buffer for enzymatic reactions. We confirmed that in the conditions of the study (small substrate 4-NPB, 37 °C, pH 6.6), the PL was active even in the absence of dipalmitoylphosphatidylcholine (DPPC) vesicles, generally used to mimic the lipid-water interface. This was confirmed by the maximum velocity (Vmax) and the Michaelis-Menten constant (Km) values that were the same order of magnitude in the absence and presence of DPPC. The developed method was used to screen crude aqueous plant extracts and purified compounds. We were able to identify the promising PL inhibition of hawthorn leaf herbal infusions at 1 mg mL-1 (37%) and PL activation by fresh and dry hawthorn flowers (∼24%). Additionally, two triterpenoids purified from extracts of oakwood were identified for the first time as potent PL inhibitors demonstrating 51 and 58% inhibition at 1 mg mL-1, respectively.

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.

Design, Synthesis, and Structure-Activity Relationship Study of Pyrazolones as Potent Inhibitors of Pancreatic Lipase

Pancreatic lipase (PL), a key target for the prevention and treatment of obesity, plays crucial roles in the hydrolysis and absorption of in dietary fat. In this study, a series of pyrazolones was synthesized, and their inhibitory effects against PL were assayed by using 4-methylumbelliferyl oleate (4-MUO) as optical substrate for PL. Comprehensive structure-activity relationship analysis of these pyrazolones led us to design and synthesize a novel compound P32 (5-(naphthalen-2-yl)-2-phenyl-4-(thiophen-2-ylmethyl)-2,4-dihydro-3H-pyrazol-3-one) as a potent mixed-competitive inhibitor of PL (IC₅₀ =0.30 μM). In addition, P32 displayed some selectivity over other known serine hydrolases. A molecular docking study for P32 demonstrated that the inhibitory activity of P32 towards PL could be attributed to the π-π interactions of 2-naphthyl unit (R¹ ) and hydrophobic interactions of phenyl moiety (R³ ) with the active site of PL. Thus, P32 could serve as promising lead compound for the development of more efficacious and selective pyrazolones-type PL inhibitors for biomedical applications.

Pancreatic lipase inhibitors: The road voyaged and successes

Human pancreatic lipase (triacylglycerol acyl hydrolase EC3.1.1.3) is the most widely studied member of the human lipase superfamily related to carboxyl esterase. It is secreted from the acinar cell of pancreas and has strong preference for triacylglycerides over cholesterol esters, phospholipids, and galactolipids. Apart from the hydrolysis of triacylglycerides, pancreatic lipase may cause the hydrolysis of retinyl esters in vivo. So, it is very much evidenced that pancreatic lipase with its cofactor colipase has prominent role in efficient digestion of dietary fat. Hence, the modulation of human pancreatic lipase may represent a new insight in the discovery of a number of therapeutics that can inhibit the absorption of fat in body and can be used in obesity and other related metabolic disorders. Even, the only Food and drug administration (FDA) approved antiobesity drug, orlistat, is also an inhibitor of pancreatic lipase. This review summarizes studies about structure, mechanistic approach of pancreatic lipase enzyme while emphasizing on the various synthetic pancreatic lipase inhibitors with their structure activity relationship (SAR).

Design, synthesis, in silico molecular modelling studies and biological evaluation of novel indole-thiazolidinedione hybrid analogues as potential pancreatic lipase inhibitors

A series of thiazolidinedione-indole hybrids are designed and synthesized as a potential inhibitor for pancreatic lipase (PL).

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.

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.

Design, synthesis, biological evaluation and molecular modelling studies of conophylline inspired novel indolyl oxoacetamides as potent pancreatic lipase inhibitors

Twenty-one indolyl oxoacetamides were designed and synthesized inspired by conophylline. Analogues 12c and 12b with N-geranyl substitution on indole exhibited potent pancreatic lipase inhibition.