Synthesis and biological evaluation of lisofylline (LSF) analogs as a potential treatment for Type 1 diabetes

Regio- and enantioselective remote dioxygenation of internal alkenes

Methods for the enantioselective direct oxygenation of internal alkenes have provided chemists with versatile and powerful toolboxes for the synthesis of optically pure alcohols, one of the most privileged structural motifs. Regioselectivity, however, remains a formidable challenge in the functionalization of internal alkenes. Here we report a palladium-catalysed highly regio- and enantioselective remote 1,n-dioxygenation (n ≥ 4) of internal alkenes with engineered pyridine-oxazoline (Pyox) ligands. The reactions proceed efficiently and exhibit a broad substrate scope with excellent regio- and enantioselectivity, affording optically pure 1,n-diol acetates as the key synthons for important bioactive molecules. Experimental studies and density functional theory calculations provide evidence that the regioselectivity is governed by the reactivity disparity of two allylic C-H bonds, where the oxypalladation is reversible and the first palladium migration step proves to be the regioselectivity-determining step, enabled by the modified phenyl-substituted Pyox ligands.

Role of Chain Length and Degree of Unsaturation of Fatty Acids in the Physicochemical and Pharmacological Behavior of Drug-Fatty Acid Conjugates in Diabetes

Several drug-fatty acid (FA) prodrugs have been reported to exhibit desirable physicochemical and pharmacological profile; however, comparative beneficial effects rendered by different FAs have not been explored. In the present study, four different FAs (linoleic acid, oleic acid, palmitic acid, and α-lipoic acid) were selected based on their chain length and degree of unsaturation and conjugated to Lisofylline (LSF), an antidiabetic molecule to obtain different drug-FA prodrugs and characterized for molecular weight, hydrophobicity, purity, self-assembly, and efficacy in vitro and in vivo in type 1 diabetes model. Prodrugs demonstrated a 2- to 6-fold increase in the plasma half-life of LSF. Diabetic animals treated with prodrugs, once daily for 5 weeks, maintained a steady fasting blood glucose level with a significant increase in insulin level, considerable restoration of biochemical parameters, and preserved β-cells integrity. Among the different LSF-FA prodrugs, LSF-OA and LSF-PA demonstrated the most favorable physicochemical, systemic pharmacokinetic, and pharmacodynamic profiles.

Nanoparticulate tablet dosage form of lisofylline-linoleic acid conjugate for type 1 diabetes: in situ single-pass intestinal perfusion (SPIP) studies and pharmacokinetics in rat

Lisofylline (LSF) is an anti-inflammatory molecule with high aqueous solubility and rapid metabolic interconversion to its parent drug, pentoxifylline (PTX) resulting in very poor pharmacokinetic (PK) parameters, necessitating high dose and dosing frequency. In the present study, we resolved the physicochemical and pharmacokinetic limitations associated with LSF and designed its oral dosage form as a tablet for effective treatment in type 1 diabetes (T1D). Self-assembling polymeric micelles of LSF (lisofylline-linoleic acid polymeric micelles (LSF-LA PLM)) were optimized for scale-up (6 g batch size) and lyophilized followed by compression into tablets. Powder blend and tablets were evaluated as per USP. LSF-LA PLM tablet so formed was evaluated for in vitro release in simulated biological fluids (with enzymes) and for cell viability in MIN-6 cells. LSF-LA PLM in tablet formulation was further evaluated for intestinal permeability (in situ) along with LSF and LSF-LA self-assembled micelles (SM) as controls in a rat model using single-pass intestinal perfusion (SPIP) study. SPIP studies revealed 1.8-fold higher oral absorption of LSF-LA from LSF-LA PLM as compared to LSF-LA SM and ~5.9-fold higher than LSF (alone) solution. Pharmacokinetic studies of LSF-LA PLM tablet showed greater C_max than LSF, LSF-LA, and LSF-LA PLM. Designed facile LSF-LA PLM tablet dosage form has potential for an immediate decrease in the postprandial glucose levels in patients of T1D.

Lisofylline mitigates cardiac inflammation in a mouse model of obesity through improving insulin secretion and activating cardiac AMPK signaling pathway

Obesity has emerged as a leading cause of death in the last few decades, mainly due to associated cardiovascular diseases. Obesity, inflammation, and insulin resistance are strongly interlinked. Lisofylline (LSF), an anti-inflammatory agent, demonstrated protection against type 1 diabetes, as well as reduced obesity-induced insulin resistance and adipose tissue inflammation. However, its role in mitigating cardiac inflammation associated with obesity is not well studied. Mice were divided into 4 groups; the first group was fed regular chow diet, the second was fed regular chow diet and treated with LSF, the third was fed high fat diet (HFD), and the fourth was fed HFD and treated with LSF. Cardiac inflammation was interrogated via expression levels of TNF α, interleukins 6 and 10, phosphorylated STAT4 and lipoxygenases 12 and 12/15. Apoptosis and expression of the survival gene, AMPK, were also evaluated. We observed that LSF alleviated obesity-induced cardiac injury indirectly by improving both pancreatic β-cell function and insulin sensitivity, as well as, directly via upregulation of cardiac AMPK expression and downregulation of cardiac inflammation and apoptosis. LSF may represent an effective therapy targeting obesity-induced metabolic and cardiovascular complications.

Influence of inflammatory disorders on pharmacokinetics of lisofylline in rats: implications for studies in humans

1. Despite the number of favourable properties of lisofylline (LSF), clinical trials on this compound have not yielded the expected results yet. 2. The aims of this study were to evaluate the pharmacokinetics of LSF enantiomers in rats following intravenous, oral and subcutaneous administration of (±)-LSF and to assess the influence of experimental inflammatory disorders, such as multiple organ dysfunction syndrome and severe sepsis on LSF pharmacokinetics. 3. In addition, based on the results obtained an attempt was made to elucidate the possible reasons for the failure of LSF therapy in clinical trials carried out in patients with severe inflammatory disorders. 4. A subcutaneous route of (±)-LSF administration to rats is more favourable than an oral one due to a high bioavailability and a fast absorption of both LSF enantiomers. Pharmacokinetics of LSF in rats is significantly influenced by inflammatory diseases. Too low LSF serum levels might have been one of the reasons for clinical trial failures. A long-term i.v. infusion of LSF seems to be more effective compared to short-term multiple infusions that were used in clinical trials, as it may provide concentrations above IC₅₀ for inhibition of both TNF-alpha release and cAMP degradation in serum for a longer period of time.

A one-pot, multicomponent reaction for the synthesis of novel 2-alkyl substituted 4-aminoimidazo[1,2-a][1,3,5]triazines

A highly selective, one-pot, three-component synthesis of novel 2-alkyl-substituted 4-aminoimidazo[1,2-a][1,3,5]triazines has been developed. The scope of the method was explored in two dimensions, varying the structures of trialkyl orthoesters and 2-aminoimidazoles in their reactions with cyanamide. Conveniently performed under microwave irradiation, this method was also proved to be efficient under conventional heating. A library of 24 novel compounds was prepared in high purity using this multicomponent approach. Molecular and crystal structures of representative molecules were studied using X-ray crystallography.

Simultaneous estimation of lisofylline and pentoxifylline in rat plasma by high performance liquid chromatography-photodiode array detector and its application to pharmacokinetics in rat

Lisofylline (LSF) is an anti-inflammatory and immunomodulatory agent with proven activity in serious infections associated with cancer chemotherapy, hyperoxia-induced acute lung injury, autoimmune disorders including type-1 diabetes (T1DM) and islet rejection after islet transplantation. It is also an active metabolite of another anti-inflammatory agent, Pentoxifylline (PTX). LSF bears immense therapeutic potential in multiple pharmacological activities and hence appropriate and accurate quantification of LSF is very important. Although a number of analytical methods for quantification of LSF and PTX have been reported for pharmacokinetics and metabolic studies, each of these have certain limitations in terms of large sample volume required, complex extraction procedure and/or use of highly sophisticated instruments like LC-MS/MS. The aim of current study is to develop a simple reversed-phase HPLC method in rat plasma for simultaneous determination of LSF and PTX with the major objective of ensuring minimum sample volume, ease of extraction, economy of analysis, selectivity and avoiding use of instruments like LC-MS/MS to ensure a widespread application of the method. A simple liquid-liquid extraction method using methylene chloride as extracting solvent was used for extracting LSF and PTX from rat plasma (200μL). Samples were then evaporated, reconstituted with mobile phase and injected into HPLC coupled with photo-diode detector (PDA). LSF, PTX and 3-isobutyl 1-methyl xanthine (IBMX, internal standard) were separated on Inertsil® ODS (C18) column (250×4.6mm, 5μm) with mobile phase consisting of A-methanol B-water (50:50v/v) run in isocratic mode at flow rate of 1mL/min for 15min and detection at 273nm. The method showed linearity in the concentration range of 50-5000ng/mL with LOD of 10ng/mL and LLOQ of 50ng/mL for both LSF and PTX. Weighted linear regression analysis was also performed on the calibration data. The mean absolute recoveries were found to be 80.47±3.44 and 80.89±3.73% for LSF and PTX respectively. The method was successfully applied for studying the pharmacokinetics of LSF and PTX after IV bolus administration at dose of 25mg/kg in Wistar rat. In conclusion, a simple, sensitive, accurate and precise reversed-phase HPLC-UV method was established for simultaneous determination of LSF and PTX in rat plasma.

A multicomponent reaction of 2-aminoimidazoles: microwave-assisted synthesis of novel 5-aza-7-deaza-adenines

An efficient and highly selective multicomponent synthesis of 4-aminoimidazo[1,2-a]triazines, which are 5-aza-7-deaza-isosteres of adenine, was developed.

Theophylline as the catalyst for the diastereoselective synthesis of trans-1,2-dihydrobenzo[a]furo[2,3-c]phenazines in water

Theophylline-catalyzed efficient and environmentally benign procedure for the diastereoselective synthesis of trans-1,2-dihydrobenzo[a]furo[2,3-c]phenazines with pyridinium ylide assisted domino reaction in water.

An Efficient Synthesis of Bis-Purine Derivatives by a PPh3-catalysed Double Addition of Dialkylated Xanthine Derivatives to Alkyl Propiolates

Reaction between 5,7-dialkylated xanthine derivatives (2 equiv.) and an alkyl propiolate in the presence of catalytic amounts of triphenyl phosphine yields alkyl 2,3-bis(1,3-dialkyl-2,6-dioxo/oxothio-2,3-dihydro-1H-purin-7(6H)-yl)propanoates in excellent yield.

Reaction of pregnenolone with cyanoacetylhydrazine: novel synthesis of hydrazide-hydrazone, pyrazole, pyridine, thiazole, thiophene derivatives and their cytotoxicity evaluations

Pregnenolone (1) was used as a template to develop new anticancer compounds. Ring D modification of 1 through its reaction with cyanoacetylhydrazine (2) gave the hydrazide-hydrazone derivative 3. The latter compound underwent heterocyclization reactions to give the pyrazole, pyridine, thiazole and thiophene derivatives of pregnenolone. The cytotoxicity of the newly synthesized heterocyclic steroids against three human tumor cell lines namely breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were studied. Some of tested compounds were found to exhibit much higher inhibitory effects towards the three tumor cell lines than the reference drug, doxorubicin.

Evidence for activation of inflammatory lipoxygenase pathways in visceral adipose tissue of obese Zucker rats

Central obesity is associated with low-grade inflammation that promotes type 2 diabetes and cardiovascular disease in obese individuals. The 12- and 5-lipoxygenase (12-LO and 5-LO) enzymes have been linked to inflammatory changes, leading to the development of atherosclerosis. 12-LO has also been linked recently to inflammation and insulin resistance in adipocytes. We analyzed the expression of LO and proinflammatory cytokines in adipose tissue and adipocytes in obese Zucker rats, a widely studied genetic model of obesity, insulin resistance, and the metabolic syndrome. mRNA expression of 12-LO, 5-LO, and 5-LO-activating protein (FLAP) was upregulated in adipocytes and adipose tissue from obese Zucker rats compared with those from lean rats. Concomitant with increased LO gene expression, the 12-LO product 12-HETE and the 5-LO products 5-HETE and leukotriene B4 (LTB4) were also increased in adipocytes. Furthermore, upregulation of key proinflammatory markers interleukin (IL)-6, TNFα, and monocyte chemoattractant protein-1 were observed in adipocytes isolated from obese Zucker rats. Immunohistochemistry indicated that the positive 12-LO staining in adipose tissue represents cells in addition to adipocytes. This was confirmed by Western blotting in stromal vascular fractions. These changes were in part reversed by the novel anti-inflammatory drug lisofylline (LSF). LSF also reduced p-STAT4 in visceral adipose tissue from obese Zucker rats and improved the metabolic profile, reducing fasting plasma glucose and increasing insulin sensitivity in obese Zucker rats. In 3T3-L1 adipocytes, LSF abrogated the inflammatory response induced by LO products. Thus, therapeutic agents reducing LO or STAT4 activation may provide novel tools to reduce obesity-induced inflammation.

Synthesis of 7-aza-5-deazapurine analogues via copper(I)-catalyzed hydroamination of alkynes and 1-iodoalkynes

A new method for the synthesis of dihydroimidazo[1,2-a][1,3,5]triazin-4(6H)-ones via copper(I)-catalyzed hydroamination was developed. In addition, for the first time, iodoalkynes were shown to participate in the copper(I)-catalyzed intramolecular hydroamination reaction with exclusive formation of E-isomers.

Epithelial restitution and wound healing in inflammatory bowel disease

Inflammatory bowel disease is characterized by a chronic inflammation of the intestinal mucosa. The mucosal epithelium of the alimentary tract constitutes a key element of the mucosal barrier to a broad spectrum of deleterious substances present within the intestinal lumen including bacterial microorganisms, various dietary factors, gastrointestinal secretory products and drugs. In addition, this mucosal barrier can be disturbed in the course of various intestinal disorders including inflammatory bowel diseases. Fortunately, the integrity of the gastrointestinal surface epithelium is rapidly reestablished even after extensive destruction. Rapid resealing of the epithelial barrier following injuries is accomplished by a process termed epithelial restitution, followed by more delayed mechanisms of epithelial wound healing including increased epithelial cell proliferation and epithelial cell differentiation. Restitution of the intestinal surface epithelium is modulated by a range of highly divergent factors among them a broad spectrum of structurally distinct regulatory peptides, variously described as growth factors or cytokines. Several regulatory peptide factors act from the basolateral site of the epithelial surface and enhance epithelial cell restitution through TGF-β-dependent pathways. In contrast, members of the trefoil factor family (TFF peptides) appear to stimulate epithelial restitution in conjunction with mucin glycoproteins through a TGF-β-independent mechanism from the apical site of the intestinal epithelium. In addition, a number of other peptide molecules like extracellular matrix factors and blood clotting factors and also non-peptide molecules including phospholipids, short-chain fatty acids (SCFA), adenine nucleotides, trace elements and pharmacological agents modulate intestinal epithelial repair mechanisms. Repeated damage and injury of the intestinal surface are key features of various intestinal disorders including inflammatory bowel diseases and require constant repair of the epithelium. Enhancement of intestinal repair mechanisms by regulatory peptides or other modulatory factors may provide future approaches for the treatment of diseases that are characterized by injuries of the epithelial surface.