Novel fatty acid binding protein 4 (FABP4) inhibitors: virtual screening, synthesis and crystal structure determination

Recent Advances on Small-Molecule Inhibitors of Lipocalin-like Proteins

Lipid transfer proteins (LTPs) are crucial players in nonvesicular lipid trafficking. LTPs sharing a lipocalin lipid transfer domain (lipocalin-like proteins) have a wide range of biological functions, such as regulating immune responses and cell proliferation, differentiation, and death as well as participating in the pathogenesis of inflammatory, metabolic, and neurological disorders and cancer. Therefore, the development of small-molecule inhibitors targeting these LTPs is important and has potential clinical applications. Herein, we summarize the structure and function of lipocalin-like proteins, mainly including retinol-binding proteins, lipocalins, and fatty acid-binding proteins and discuss the recent advances on small-molecule inhibitors for these protein families and their applications in disease treatment. The findings of our Perspective can provide guidance for the development of inhibitors of these LTPs and highlight the challenges that might be faced during the procedures.

Structure-based design of potent FABP4 inhibitors with high selectivity against FABP3

Fatty-acid binding protein 4 (FABP4) presents an attractive target for therapeutic intervention in metabolic and inflammatory diseases in recent years. However, highly similar three-dimensional structures and fatty acid binding ability of multiple FABP family members pose a significant challenge in design of FABP4-selective inhibitors. Particularly, inhibition of FABP3 raises safety concerns such as cardiac dysfunction and exercise intolerance. Here, we reported the discovery of new FABP4 inhibitors with high selectivity over FABP3 by exploiting the little structural difference in the ligand binding pockets of FABP4 and FABP3. On the basis of our previously reported FABP4 inhibitors with nanomolar potency, different substituents were further introduced to perfectly occupy two sub-pockets of FABP4 that are distinct from those of FABP3. Remarkably, a single methyl group introduction leads to the discovery of compound C3 that impressively exhibits a 601-fold selectivity over FABP3 when maintained nanomolar binding affinity for FABP4. Moreover, C3 also shows good metabolic stability and potent cellular anti-inflammatory activity, making it a promising inhibitor for further development. Therefore, the present study highlights the utility of the structure-based rational design strategy for seeking highly selective and potent inhibitors of FABP4 and the importance of identifying the appropriate subsite as well as substituent for gaining the desired selectivity.

Pharmaceutical targeting of OTUB2 sensitizes tumors to cytotoxic T cells via degradation of PD-L1

PD-1 is a co-inhibitory receptor expressed by CD8+ T cells which limits their cytotoxicity. PD-L1 expression on cancer cells contributes to immune evasion by cancers, thus, understanding the mechanisms that regulate PD-L1 protein levels in cancers is important. Here we identify tumor-cell-expressed otubain-2 (OTUB2) as a negative regulator of antitumor immunity, acting through the PD-1/PD-L1 axis in various human cancers. Mechanistically, OTUB2 directly interacts with PD-L1 to disrupt the ubiquitination and degradation of PD-L1 in the endoplasmic reticulum. Genetic deletion of OTUB2 markedly decreases the expression of PD-L1 proteins on the tumor cell surface, resulting in increased tumor cell sensitivity to CD8+ T-cell-mediated cytotoxicity. To underscore relevance in human patients, we observe a significant correlation between OTUB2 expression and PD-L1 abundance in human non-small cell lung cancer. An inhibitor of OTUB2, interfering with its deubiquitinase activity without disrupting the OTUB2-PD-L1 interaction, successfully reduces PD-L1 expression in tumor cells and suppressed tumor growth. Together, these results reveal the roles of OTUB2 in PD-L1 regulation and tumor evasion and lays down the proof of principle for OTUB2 targeting as therapeutic strategy for cancer treatment.

Fatty acid-binding protein 4 in kidney diseases: From mechanisms to clinics

Considerable evidence indicated the relationship between fatty acid-binding protein 4 (FABP4) and kidney diseases. FABP4, a small molecular lipid chaperone, is identified to regulate fatty acid oxidation, inflammation, apoptosis, endoplasmic reticulum stress and macrophage-to-myofibroblast transition in kidney diseases. Many studies have shown that circulating FABP4 level is related to proteinuria, renal function decline, cardiovascular complications of end-stage renal disease and even the prognosis of kidney transplanted patients. Notably, pharmacological or genetic inhibition of FABP4 attenuated renal injury in the various experimental models of kidney diseases, making it promising to develop potential therapeutic strategies targeting FABP4 in kidney diseases. In this study, we updated and reviewed the mechanisms and clinical significance of FABP4 in kidney diseases.

Discovery of Cobimetinib as a novel A-FABP inhibitor using machine learning and molecular docking-based virtual screening

Adipocyte fatty acid-binding protein (A-FABP, also called FABP4, aP2) is an adipokine identified as a critical regulator of metabolic function due to its dual functions of fatty acid transport and pro-inflammation. Because of the high therapeutic potential of A-FABP inhibition for the treatment of metabolic diseases and related vascular complications, numerous inhibitors have been developed against A-FABP. However, none of these inhibitors have been approved for use in patients due to severe side effects. Here, we used a virtual screening (VS) strategy to identify potential inhibitors of A-FABP in the latest FDA-approved drug library (∼2600 compounds), aiming to explore the existing drugs with proven safety profiles. We firstly combined ligand-based machine learning and structure-based molecular docking to develop a screening pipeline for identifying A-FABP inhibitors. The screening of FDA-approved drugs identified four compounds (Cobimetinib, Larotrectinib, Pantoprazole, and Vildagliptin) with the highest scores, whose inhibitory effects on A-FABP were further assessed in cellular assays. Among the selected compounds, Cobimetinib significantly inhibited the activation of the JNK/c-Jun signaling pathway by A-FABP in mouse macrophages without causing obvious cytotoxicity. In summary, we present an integrated VS pipeline for A-FABP inhibitor screening, and identified Cobimetinib as a novel A-FABP inhibitor that may be repurposed for the treatment of metabolic diseases and associated vascular complications.

Adipogenesis and therapeutic potentials of antiobesogenic phytochemicals: Insights from preclinical studies

Obesity is one of the most serious public health problems in both developed and developing countries in recent years. While lifestyle and diet modifications are the most important management strategies of obesity, these may be insufficient to ensure long-term weight reduction in certain individuals and alternative strategies including pharmacotherapy need to be considered. However, drugs option remains limited due to low efficacy and adverse effects associated with their use. Hence, identification of safe and effective alternative therapeutic agents remains warranted to combat obesity. In recent years, bioactive phytochemicals are considered as valuable sources for the discovery of new pharmacological agents for the treatment of obesity. Adipocyte hypertrophy and hyperplasia increases with obesity and undergo molecular and cellular alterations that can affect systemic metabolism giving rise to metabolic syndrome and comorbidities such as type 2 diabetes and cardiovascular diseases. Many phytochemicals have been reported to target adipocytes by inhibiting adipogenesis, inducing lipolysis, suppressing the differentiation of preadipocytes to mature adipocytes, reducing energy intake, and boosting energy expenditure mainly in vitro and in animal studies. Nevertheless, further high-quality studies are needed to firmly establish the clinical efficacy of these phytochemicals. This review outlines common pathways involved in adipogenesis and phytochemicals targeting effector molecules of these pathways, the challenges faced and the way forward for the development of phytochemicals as antiobesity agents.

A proteome signature for acute incisional pain in dorsal root ganglia of mice

ABSTRACT

After surgery, acute pain is still managed insufficiently and may lead to short-term and long-term complications including chronic postsurgical pain and an increased prescription of opioids. Thus, identifying new targets specifically implicated in postoperative pain is of utmost importance to develop effective and nonaddictive analgesics. Here, we used an integrated and multimethod workflow to reveal unprecedented insights into proteome dynamics in dorsal root ganglia (DRG) of mice after plantar incision (INC). Based on a detailed characterization of INC-associated pain-related behavior profiles, including a novel paradigm for nonevoked pain, we performed quantitative mass-spectrometry-based proteomics in DRG 1 day after INC. Our data revealed a hitherto unknown INC-regulated protein signature in DRG with changes in distinct proteins and cellular signaling pathways. In particular, we show the differential regulation of 44 protein candidates, many of which are annotated with pathways related to immune and inflammatory responses such as MAPK/extracellular signal-regulated kinases signaling. Subsequent orthogonal assays comprised multiplex Western blotting, bioinformatic protein network analysis, and immunolabeling in independent mouse cohorts to validate (1) the INC-induced regulation of immune/inflammatory pathways and (2) the high priority candidate Annexin A1. Taken together, our results propose novel potential targets in the context of incision and, therefore, represent a highly valuable resource for further mechanistic and translational studies of postoperative pain.

Combined treatment with FABP4 inhibitor ameliorates rosiglitazone-induced liver steatosis in obese diabetic db/db mice

Rosiglitazone has been reported to exert dual effects on liver steatosis, and it could exacerbate liver steatosis in obese animal models, which was suggested to be closely related to the elevated hepatic expression of FABP4. This study aimed to investigate whether combined treatment with FABP4 inhibitor I-9 could alleviate rosiglitazone-induced liver steatosis in obese diabetic db/db mice. Male C57BL/KsJ-db/db mice were orally treated with rosiglitazone, rosiglitazone combined with I-9 daily for 8 weeks. The liver steatosis was evaluated by triglyceride content and H&E staining. The expression of hepatic lipogenic genes or proteins in liver tissue or in FFA-treated hepatocytes and PMA-stimulated macrophages were determined by real-time quantitative polymerase chain reaction (RT-qPCR) or western blotting. Results showed that combined treatment with I-9 decreased rosiglitazone-induced increase in serum FABP4 level and expression of lipogenic genes in liver, especially FABP4, and ameliorated liver steatosis in db/db mice. Rosiglitazone-induced intracellular TG accumulation and increased expression of FABP4 in the cultured hepatocytes and macrophages were also suppressed by combined treatment. We concluded that combined treatment with FABP4 inhibitor I-9 could ameliorate rosiglitazone-exacerbated elevated serum FABP4 level and ectopic liver fat accumulation in obese diabetic db/db mice without affecting its anti-diabetic efficacy.

The effect of lipid metabolism regulator anthocyanins from Aronia melanocarpa on 3T3-L1 preadipocytes and C57BL/6 mice via activating AMPK signaling and gut microbiota

This study investigated lipid metabolism regulation by anthocyanins from Aronia melanocarpa (AAM) in 3T3-L1 preadipocytes and high fat diet (HFD) mice. Ultra-performance liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry analysis identified the constituents of AAM, which decreased lipid content and inflammation in 3T3-L1 cells without cytotoxicity. Meanwhile, taking normal diet and orlistat mice as references, AAM supplementation improved blood lipid levels and adipocyte degeneration, promoted beneficial gut microbial growth, and maintained lipid metabolism in HFD mice. Furthermore, AAM activated the AMP-activated protein kinase (AMPK) signaling pathway, accompanied by the regulation of adipogenic transcription factors and their target genes in vitro and in vivo. Collectively, our data demonstrated that AAM exhibits anti-adipogenic activities that were partially mediated by the AMPK pathway and gut microbiota regulation. This study provides new insight into the regulation of lipid metabolism by AAM and suggests that AAM has potential therapeutic effects on hyperlipidemia.

Application of target repositioning and in silico screening to exploit fatty acid binding proteins (FABPs) from Echinococcus multilocularis as possible drug targets

Fatty acid binding proteins (FABPs) are small intracellular proteins that reversibly bind fatty acids and other hydrophobic ligands. In cestodes, due to their inability to synthesise fatty acids and cholesterol de novo, FABPs, together with other lipid binding proteins, have been proposed as essential, involved in the trafficking and delivery of such lipophilic metabolites. Pharmacological agents that modify specific parasite FABP function may provide control of lipid signalling pathways, inflammatory responses and metabolic regulation that could be of crucial importance for the parasite development and survival. Echinococcus multilocularis and Echinococcus granulosus are, respectively, the causative agents of alveolar and cystic echinococcosis (or hydatidosis). These diseases are included in the World Health Organization's list of priority neglected tropical diseases. Here, we explore the potential of FABPs from cestodes as drug targets. To this end, we have applied a target repurposing approach to identify novel inhibitors of Echinococcus spp. FABPs. An ensemble of computational models was developed and applied in a virtual screening campaign of DrugBank library. 21 hits belonging to the applicability domain of the ensemble models were identified, and 3 of the hits were assayed against purified E. multilocularis FABP, experimentally confirming the model's predictions. Noteworthy, this is to our best knowledge the first report on isolation and purification of such four FABP, for which initial structural and functional characterization is reported here.

Computational Drug Repurposing Approach to Identify Potential Fatty Acid-Binding Protein-4 Inhibitors to Develop Novel Antiobesity Therapy

Obesity is a chronic human disorder caused by multiple factors, causing excessive accumulation of fat because of the disparity in take of energy intake with respect to its expenditure. Genetic, environmental, and behavioral factors are having a crucial role in its pathogenesis. Fatty acid-binding protein (FABP) is a superfamily that was involved in the transportation, metabolism, and storage of lipids. The experimental studies have revealed that there is a significant rise in the fatty acid-binding protein-4 (FABP4) expression, and plasma concentration in obese and its downregulation or inhibition can be a potential drug target for obesity. Repurposing of drugs is a trending method for the identification of the newer pharmacological action of an established drug molecule having initially approved indication. It is a cost-effective and economical approach for the development of alternative therapies for existing dreadful diseases in quick succession. Thus, the in silico drug repurposing technique is a highly effective approach for identifying an existing drug molecule having an antiobesity therapeutic activity against the human FABP4, and Floxacillin was selected as safe and effective drug for candidates for developing an antiobesity therapy.

Exogenous FABP4 interferes with differentiation, promotes lipolysis and inflammation in adipocytes

PURPOSE

Fatty acid binding protein 4 (FABP4) has been demonstrated to be secreted from adipocytes in an unconventional pathway associated with lipolysis. Circulating FABP4 is elevated in metabolic disorders and has been shown to affect various peripheral cells such as pancreatic β-cells, hepatocytes and macrophages, but its effects on adipocytes remains unclear. The aim of this study was to investigate the effects of exogenous FABP4 (eFABP4) on adipocyte differentiation and function.

METHODS

3T3-L1 pre-adipocytes or mature adipocytes were treated with recombinant FABP4 in the absence or presence of FABP4 inhibitor I-9/p38 MAPK inhibitor SB203580; Meanwhile male C57BL/6J mice were subcutaneously injected twice a day with recombinant FABP4 (0.35 mg/kg) with or without I-9 (50 mg/kg) for 2 weeks. The effects of eFABP4 on differentiation, lipolysis and inflammation were determined by triglyceride measurement or lipolysis assay, western blotting, or RT-qPCR analysis.

RESULTS

eFABP4 treatment significantly reduced intracellular triglyceride content and decreased expression of adipogenic markers peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), intracellular FABP4, and adiponectin in 3T3-L1 cells. Besides, eFABP4 promoted lipolysis and inflammation in differentiated 3T3-L1 adipocytes as well as in adipose tissue of eFABP4-treated C57BL/6J mice, with elevated gene expression of monocyte chemoattractant protein (MCP)-1, tumor necrosis factor (TNF)-α, and elevated protein expression of adipose triglyceride lipase (ATGL), phosphorylation of hormone-sensitive lipase (HSL) (Ser-660), p38, and nuclear factor-kappa B (NF-κB). The pro-inflammatory and pro-lipolytic effects of eFABP4 could be reversed by SB203580/I-9.

CONCLUSIONS

These findings indicate that eFABP4 interferes with adipocyte differentiation, induces p38/HSL mediated lipolysis and p38/NF-κB mediated inflammation in adipocytes in vitro and in vivo.

Computational Tools in the Discovery of FABP4 Ligands: A Statistical and Molecular Modeling Approach

Small molecule inhibitors of adipocyte fatty-acid binding protein 4 (FABP4) have received interest following the recent publication of their pharmacologically beneficial effects. Recently, it was revealed that FABP4 is an attractive molecular target for the treatment of type 2 diabetes, other metabolic diseases, and some type of cancers. In past years, hundreds of effective FABP4 inhibitors have been synthesized and discovered, but, unfortunately, none have reached the clinical research phase. The field of computer-aided drug design seems to be promising and useful for the identification of FABP4 inhibitors; hence, different structure- and ligand-based computational approaches have been used for their identification. In this paper, we searched for new potentially active FABP4 ligands in the Marine Natural Products (MNP) database. We retrieved 14,492 compounds from this database and filtered through them with a statistical and computational filter. Seven compounds were suggested by our methodology to possess a potential inhibitory activity upon FABP4 in the range of 97–331 nM. ADMET property prediction was performed to validate the hypothesis of the interaction with the intended target and to assess the drug-likeness of these derivatives. From these analyses, three molecules that are excellent candidates for becoming new drugs were found.

The compromise of virtual screening and its impact on drug discovery

Introduction: Docking and structure-based virtual screening (VS) have been standard approaches in structure-based design for over two decades. However, our understanding of the limitations, potential, and strength of these techniques has enhanced, raising expectations. Areas covered: Based on a survey of reports in the past five years, we assess whether VS: (1) predicts binding poses in agreement with crystallographic data (when available); (2) is a superior screening tool, as often claimed; (3) is successful in identifying chemical scaffolds that can be starting points for subsequent lead optimization cycles. Data shows that knowledge of the target and its chemotypes in postprocessing lead to viable hits in early drug discovery endeavors. Expert opinion: VS is capable of accurate placements in the pocket for the most part, but does not consistently score screening collections accurately. What matters is capitalization on available resources to get closer to a viable lead or optimizable series. Integration of approaches, subjective hit selection guided by knowledge of the receptor or endogenous ligand, libraries driven by experimental guides, validation studies to identify the best docking/scoring that reproduces experimental findings, constraints regarding receptor-ligand interactions, thoroughly designed methodologies, and predefined cutoff scoring criteria strengthen VS's position in pharmaceutical research.

Inhibition of MPTP-induced α-synuclein oligomerization by fatty acid-binding protein 3 ligand in MPTP-treated mice

Accumulation and aggregation of α-synuclein (αSyn) triggers dopaminergic (DAergic) neuronal loss in Parkinson's disease (PD). This pathological event is partly facilitated by the presence of long-chain polyunsaturated fatty acids (LC-PUFAs), including arachidonic acid. The intracellular transport and metabolism of LC-PUFAs are mediated by fatty acid-binding proteins (FABPs). We previously reported that heart-type FABP (FABP3) interacts with αSyn, thereby promoting αSyn oligomerization in DAergic neurons in the substantia nigra pars compacta (SNpc) following 1-methyl-1,2,3,6-tetrahydropyridine (MPTP) treatment. This αSyn oligomerization is prevented in Fabp3 gene knock out mice. We document a novel FABP3 ligand, MF1 (4-(2-(1-(2-chlorophenyl)-5-phenyl-1H-pyrazol-3-yl)phenoxy)butanoic acid), that inhibits αSyn accumulation in DA neurons, thereby inhibiting the oligomerization of αSyn, loss of DAergic neurons, and PD-like motor deficits in MPTP-treated mice. Chronic oral administration of MF1 (0.3 or 1.0 mg/kg/day) significantly improved motor impairments and inhibited MPTP-induced accumulation and oligomerization of αSyn in the SNpc, and in turn prevented loss of tyrosine hydroxylase (TH)-positive cells in the SNpc. MF1 administration (0.1, 0.3, or 1.0 mg/kg/day) also restored MPTP-induced cognitive impairments. Although chronic administration of l-DOPA (3,4-dihydroxl-l-phenylalanine; 25 mg/kg/day, i.p.) also improved motor deficits, it failed to improve the cognitive impairments. In addition, l-DOPA failed to inhibit DAergic neuronal loss and αSyn pathologies in the SNpc. In summary, the novel FABP3 ligand MF1 rescues MPTP-induced behavioural and neuropathological features, suggesting that MF1 may be a disease-modifying drug candidate for synucleinopathies.

FABP4 inhibitors 3D-QSAR model and isosteric replacement of BMS309403 datasets

The data have been obtained from FABP4 inhibitor molecules previously published. The 120 compounds were used to build a 3D-QSAR model. The development of the QSAR model has been undertaken with the use of Forge software using the PM3 optimized structure and the experimental IC₅₀ of each compound. The QSAR model was also employed to predict the activity of 3000 new isosteric derivatives of BMS309403. The isosteric replacement was also validated by the synthesis and the biological screening of three new compounds reported in the related research article “3D-QSAR assisted identification of FABP4 inhibitors: An effective scaffold hopping analysis/QSAR evaluation” (Floresta et al., 2019).

3D-QSAR assisted identification of FABP4 inhibitors: An effective scaffold hopping analysis/QSAR evaluation

Following on the recent publication of pharmacologically relevant effects, small molecule inhibitors of adipocyte fatty-acid binding protein 4 (FABP4) have attracted high interest. FABP4 is mainly expressed in macrophages and adipose tissue, where it regulates fatty acid storage and lipolysis, being also an important mediator of inflammation. In this regard, FABP4 recently demonstrated an interesting molecular target for the treatment of type 2 diabetes, other metabolic diseases and some type of cancers. In the past years, hundreds of effective FABP4 inhibitors have been synthesized. In this paper, a quantitative structure-activity relationship (QSAR) model has been produced, in order to predict the bioactivity of FABP4 inhibitors. The methodology has been combined with a scaffold-hopping approach, allowing to identify three new molecules that act as effective inhibitors of this protein. These molecules, synthesized and tested for their FABP4 inhibitor activity, showed IC₅₀ values between 3.70 and 5.59 μM, with a high level of agreement with the predicted values.

Circulating adipocyte fatty acid-binding protein is a predictor of cardiovascular events in patients with stable angina undergoing percutaneous coronary intervention

Background

Adipocyte fatty acid-binding protein (A-FABP) is expressed in both adipocytes and macrophages. Recent studies have shown that A-FABP is secreted by adipocytes and that the A-FABP concentration is associated with obesity, insulin resistance, and atherosclerosis. We have reported that the coronary atherosclerotic burden is associated with the serum A-FABP concentration. In the present study, we investigated whether the serum A-FABP concentration is associated with prognosis in patients with stable angina pectoris who have undergone percutaneous coronary intervention (PCI).

Methods

This was a prospective single-center trial. In total, 130 patients with stable angina pectoris undergoing their first PCI were enrolled from August 2008 to July 2010 at Kagawa Prefectural Central Hospital. The primary endpoints were cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, revascularization, and hospitalization for heart failure.

Results

During the follow-up (median, 50 months; interquartile range, 23–66 months), 49 cardiovascular events occurred. Kaplan–Meier analysis showed that the cumulative incidence of the primary endpoints in the high A-FABP group (median A-FABP concentration of ≥ 18.6 ng/ml) was greater than that in the low A-FABP group. Cox analysis showed that the A-FABP concentration was an independent predictor of cardiovascular events adjusted for age and the presence of multi-vessel disease (hazard ratio, 1.03; 95% confidence interval, 1.01–1.04; p = 0.01).

Conclusion

The serum A-FABP concentration is associated with prognosis in patients with stable angina undergoing PCI, suggesting that the serum A-FABP concentration could be useful for risk assessment of secondary prevention.

Trial registration

UMIN Clinical Trials Registry UMIN000029283 (registration date: September 25, 2017), retrospectively registered.

Combined Virtual Screening and Substructure Search for Discovery of Novel FABP4 Inhibitors

Fatty acid-binding protein 4 (FABP4, AFABP) is a potential drug target for diabetes and atherosclerosis. In this study, a series of novel FABP4 inhibitors were discovered through combining virtual screening and substructure search. Seventeen compounds exhibited FABP4 inhibitory activities with IC₅₀ < 10 μM, among which 11 compounds showed high selectivity against FABP3. The best compound 36b displayed an IC₅₀ value of 1.5 μM. Molecular docking and point mutation studies revealed that Gln95, Arg126, and Tyr128 play key roles for these compounds binding with FABP4. Interestingly, Gln95 seems to be essential for conformation stability of FABP4. The new scaffolds of these compounds and their interaction mechanisms binding with FABP4 should provide an important clue for the further development of novel FABP4 inhibitors.

Adipocyte fatty acid binding protein 4 (FABP4) inhibitors. A comprehensive systematic review

Small molecule inhibitors of adipocyte fatty acid binding protein 4 (FABP4) have attracted interest following the recent publications of beneficial pharmacological effects of these compounds. FABP4 is predominantly expressed in macrophages and adipose tissue where it regulates fatty acids (FAs) storage and lipolysis and is an important mediator of inflammation. In the past years, hundreds FABP4 inhibitors have been synthesized for effective atherosclerosis and diabetes treatments, including derivatives of niacin, quinoxaline, aryl-quinoline, bicyclic pyridine, urea, aromatic compounds and other novel heterocyclic compounds. This review provides an overview of the synthesized and discovered molecules as adipocyte fatty acid binding protein 4 inhibitors (FABP4is) since the synthesis of the putative FABP4i, BMS309403, highlighting the interactions of the different classes of inhibitors with the targets.

Anti-obesity effects of zeaxanthin on 3T3-L1 preadipocyte and high fat induced obese mice

Zeaxanthin inhibited lipogenesis in adipocytes and attenuated progression of obesity in mice by inducing AMPK activation and suppressing adipocyte-specific factors.

The discovery of novel and selective fatty acid binding protein 4 inhibitors by virtual screening and biological evaluation

Adipocyte fatty acid binding protein (AFABP, FABP4) has been proven to be a potential therapeutic target for diabetes, atherosclerosis and inflammation-related diseases. In this study, a series of new scaffolds of small molecule inhibitors of FABP4 were identified by virtual screening and were validated by a bioassay. Fifty selected compounds were tested, which led to the discovery of seven hits. Structural similarity-based searches were then performed based on the hits and led to the identification of one high affinity compound 33b (Ki=0.29±0.07μM, ΔTm=8.5°C). This compound's effective blockade of inflammatory response was further validated by its ability to suppress pro-inflammatory cytokines induced by lipopolysaccharide (LPS) stimulation. Molecular dynamics simulation (MD) and mutagenesis studies validated key residues for its inhibitory potency and thus provide an important clue for the further development of drugs.