Squalene synthase inhibition: A novel target for the management of dyslipidemia

Identification of non-conventional small molecule degraders and stabilizers of squalene synthase

Squalene synthase (SQS) is an essential enzyme in the mevalonate pathway, which controls cholesterol biosynthesis and homeostasis. Although catalytic inhibitors of SQS have been developed, none have been approved for therapeutic use so far. Herein we sought to develop SQS degraders using targeted protein degradation (TPD) to lower overall cellular cholesterol content. We found that KY02111, a small molecule ligand of SQS, selectively causes SQS to degrade in a proteasome-dependent manner. Unexpectedly, compounds based on the same scaffold linked to E3 ligase recruiting ligands led to SQS stabilization. Proteomic analysis found KY02111 to reduce only the levels of SQS, while lipidomic analysis determined that KY02111-induced degradation lowered cellular cholesteryl ester content. Stabilizers shielded SQS from its natural turnover without recruiting their matching E3 ligase or affecting enzymatic target activity. Our work shows that degradation of SQS is possible despite a challenging biological setting and provides the first chemical tools to degrade and stabilize SQS.

Effect of a new squalene synthase inhibitor on an ApoE-/- mouse model of atherosclerosis

Ηypercholesterolemia/hyperlipidemia in conjunction with oxidative stress and inflammatory processes contribute synergistically to the pathogenesis of atherosclerosis. We hereby evaluated the antiatherosclerotic effect of the multi-target derivative 4-methyl-2-(10H-phenothiazin-3-yl)morpholin-2-ol hydrobromide 1 in apoE^-/- mice; compound 1 is a potent antihyperlipidemic agent acting through Squalene Synthase inhibition, while it has exhibited an outstanding antioxidant and anti-inflammatory activity in various experimental animal models. The new analogue was evaluated in terms of its antiatherosclerotic/antioxidant effect in the ApoE^-/- transgenic mouse model. Its toxicity profile was also assessed by measuring the levels of four sensitive indicators of liver toxicity. Prolonged administration of 1 in ApoE^-/- mice fed with a western-type (wt) diet efficiently reduced the aortic atheromatic lesions, an effect that took place through a cholesterol lowering independent manner. In addition, 1 displayed a significant reduction not only of glucose but also of oxidative stress levels, while it did not cause any toxicity. To the best of our knowledge this is the first time that the antiatherosclerotic effect of a Squalene Synthase inhibitor is studied in this specific atherosclerosis mouse model. As a result, compound 1 may serve as a promising starting point towards developing new bioactive analogues against the onset and subsequent development of atherosclerosis.

Bio-inspired formal total synthesis of (±)-bisabosqual A

A new approach was developed to construct a hexahydrobenzofurobenzopyran ring system by an oxa-[3+3], Diels–Alder reaction and oxidative aromatization. As a synthetic application, the bio-inspired formal synthesis of bisabosqual A was achieved.

Effect of statin treatment in obese selenium-supplemented mice lacking selenocysteine lyase

People with obesity are often dyslipidemic and prescribed statins to prevent cardiovascular events. A common side effect of statin use is myopathy. This could potentially be caused by the reduction of selenoproteins that curb oxidative stress, in turn, affecting creatine metabolism. We determined if statins regulate hepatic and muscular selenoprotein expression, oxidative stress and creatine metabolism. Mice lacking selenocysteine lyase (Scly KO), a selenium-provider enzyme for selenoprotein synthesis, were fed a high-fat, Se-supplemented diet and treated with simvastatin. Statin improved creatine metabolism in females and oxidative responses in both sexes. Male Scly KO mice were heavier than females after statin treatment. Hepatic selenoproteins were unaffected by statin and genotype in females. Statin upregulated muscular Gpx1 in females but not males, while Scly loss downregulated muscular Gpx1 in males and Selenon in females. Osgin1 was reduced in statin-treated Scly KO males after AmpliSeq analysis. These results refine our understanding of the sex-dependent role of selenium in statin responses.

Recent Molecular Mechanisms and Beneficial Effects of Phytochemicals and Plant-Based Whole Foods in Reducing LDL-C and Preventing Cardiovascular Disease

Abnormal lipid metabolism leads to the development of hyperlipidemia, a common cause of multiple chronic disorders, including cardiovascular disease (CVD), obesity, diabetes, and cerebrovascular disease. Low-density lipoprotein cholesterol (LDL-C) currently remains the primary target for treatment of hyperlipidemia. Despite the advancement of treatment and prevention of hyperlipidemia, medications used to manage hyperlipidemia are limited to allopathic drugs, which present certain limitations and adverse effects. Increasing evidence indicates that utilization of phytochemicals and plant-based whole foods is an alternative and promising strategy to prevent hyperlipidemia and CVD. The current review focuses on phytochemicals and their pharmacological mode of actions for the regulation of LDL-C and prevention of CVD. The important molecular mechanisms illustrated in detail in this review include elevation of reverse cholesterol transport, inhibition of intestinal cholesterol absorption, acceleration of cholesterol excretion in the liver, and reduction of cholesterol synthesis. Moreover, the beneficial effects of plant-based whole foods, such as fresh fruits, vegetables, dried nuts, flax seeds, whole grains, peas, beans, vegan diets, and dietary fibers in LDL-C reduction and cardiovascular health are summarized. This review concludes that phytochemicals and plant-based whole foods can reduce LDL-C levels and lower the risk for CVD.

Optimizing the Pharmacological Profile of New Bifunctional Antihyperlipidemic/Antioxidant Morpholine Derivatives

Among the causal risk factors directly promoting the development of coronary and peripheral atherosclerosis are reactive oxygen species and elevated low-density lipoprotein plasma levels. We hereby designed new potent squalene synthase (SQS) inhibitors that may simultaneously tackle the oxidative stress induced by lipid peroxidation. Using previously developed morpholine derivatives as a starting point, we conducted extensive structural changes by either substituting or modifying the morpholine ring, aiming at an optimal SQS-antioxidant pharmacological profile. Compounds 2, 3, and 7 emerged as the most potent bifunctional analogues, displaying IC₅₀ values for SQS inhibition of 0.014, 0.16, and 0.51 μΜ, respectively, and further significantly decreasing lipid peroxidation of hepatic microsomal membranes. The aforementioned activities were also confirmed in vivo since the most promising derivative 2 exhibited a remarkable antihyperlipidemic and antioxidant effect. In conclusion, rational drug design accompanied by structure-activity relationship studies led to compounds combining improved antioxidant and antihyperlipidemic activity that may serve as multifunctional agents against atherosclerosis.

A Component Formula of Chinese Medicine for Hypercholesterolemia Based on Virtual Screening and Biology Network

Hypercholesterolemia is a risk factor to atherosclerosis and coronary heart disease II. The abnormal rise of cholesterol in plasma is the main symptom. Cholesterol synthesis pathway is an important pathway of the origin of cholesterol, which is an essential pathway for the therapy of hypercholesterolemia. The 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase), squalene synthase (SQS), and sterol regulatory element binding protein-2 (SREBP-2) are closely connected with the synthesis of cholesterol. The inhibition of these targets can reduce the cholesterol in plasma. This study aimed to build a component formula including three Traditional Chinese Medicines (TCM) components with the inhibition activity of these targets by using virtual screening and biological network. Structure-based pharmacophore models of HMG-CoA reductase and SQS and ligand-based pharmacophore model of SREBP-2 were constructed to screen the Traditional Chinese Medicine Database (TCMD). Molecular docking was used for further screening of components of HMG-CoA reductase and SQS. Then, metabolic network was constructed to elucidate the comprehensive interaction of three targets for lipid metabolism. Finally, three potential active compounds were obtained, which are poncimarin, hexahydrocurcumin, and forsythoside C. The source plants of the compounds were also taken into account, which should have known action of lowering hyperlipidemia. The lipid-lowering effect of hexahydrocurcumin was verified by experiment in vitro. The components that originated from TCMs with lipid-lowering efficacy made up a formula with a synergistic effect through the computer aid drug design methods. The research provides a fast and efficient method to build TCM component formula and it may inspire the study of the explanation of TCM formula mechanism.

Discovery of Potential Inhibitors of Squalene Synthase from Traditional Chinese Medicine Based on Virtual Screening and In Vitro Evaluation of Lipid-Lowering Effect

Squalene synthase (SQS), a key downstream enzyme involved in the cholesterol biosynthetic pathway, plays an important role in treating hyperlipidemia. Compared to statins, SQS inhibitors have shown a very significant lipid-lowering effect and do not cause myotoxicity. Thus, the paper aims to discover potential SQS inhibitors from Traditional Chinese Medicine (TCM) by the combination of molecular modeling methods and biological assays. In this study, cynarin was selected as a potential SQS inhibitor candidate compound based on its pharmacophoric properties, molecular docking studies and molecular dynamics (MD) simulations. Cynarin could form hydrophobic interactions with PHE54, LEU211, LEU183 and PRO292, which are regarded as important interactions for the SQS inhibitors. In addition, the lipid-lowering effect of cynarin was tested in sodium oleate-induced HepG2 cells by decreasing the lipidemic parameter triglyceride (TG) level by 22.50%. Finally. cynarin was reversely screened against other anti-hyperlipidemia targets which existed in HepG2 cells and cynarin was unable to map with the pharmacophore of these targets, which indicated that the lipid-lowering effects of cynarin might be due to the inhibition of SQS. This study discovered cynarin is a potential SQS inhibitor from TCM, which could be further clinically explored for the treatment of hyperlipidemia.

Genome editing approaches: manipulating of lovastatin and taxol synthesis of filamentous fungi by CRISPR/Cas9 system

Filamentous fungi are prolific repertoire of structurally diverse secondary metabolites of remarkable biological activities such as lovastatin and paclitaxel that have been approved by FDA as drugs for hypercholesterolemia and cancer treatment. The clusters of genes encoding lovastatin and paclitaxel are cryptic at standard laboratory cultural conditions (Kennedy et al. Science 284:1368-1372, 1999; Bergmann et al. Nature Chem Biol 3:213-217, 2007). The expression of these genes might be triggered in response to nutritional and physical conditions; nevertheless, the overall yield of these metabolites does not match the global need. Consequently, overexpression of the downstream limiting enzymes and/or blocking the competing metabolic pathways of these metabolites could be the most successful technologies to enhance their yield. This is the first review summarizing the different strategies implemented for fungal genome editing, molecular regulatory mechanisms, and prospective of clustered regulatory interspaced short palindromic repeat/Cas9 system in metabolic engineering of fungi to improve their yield of lovastatin and taxol to industrial scale. Thus, elucidating the putative metabolic pathways in fungi for overproduction of lovastatin and taxol was the ultimate objective of this review.

A Genomic DNA Reporter Screen Identifies Squalene Synthase Inhibitors That Act Cooperatively with Statins to Upregulate the Low-Density Lipoprotein Receptor

Hypercholesterolemia remains one of the leading risk factors for the development of cardiovascular disease. Many large double-blind studies have demonstrated that lowering low-density lipoprotein (LDL) cholesterol using a statin can reduce the risk of having a cardiovascular event by approximately 30%. However, despite the success of statins, some patient populations are unable to lower their LDL cholesterol to meet the targeted lipid levels, due to compliance or potency issues. This is especially true for patients with heterozygous familial hypercholesterolemia who may require additional upregulation of the low-density lipoprotein receptor (LDLR) to reduce LDL cholesterol levels below those achievable with maximal dosing of statins. Here we identify a series of small molecules from a genomic DNA reporter screen that upregulate the LDLR in mouse and human liver cell lines at nanomolar potencies (EC₅₀ = 39 nM). Structure-activity relationship studies carried out on the lead compound, OX03771 [(E)-N,N-dimethyl-3-(4-styrylphenoxy)propan-1-amine], led to the identification of compound OX03050 [(E)-3-(4-styrylphenoxy)propan-1-ol], which had similar potency (EC₅₀ = 26 nM) but a much-improved pharmacokinetic profile and showed in vivo efficacy. Compounds OX03050 and OX03771 were found to inhibit squalene synthase, the first committed step in cholesterol biosynthesis. These squalene synthase inhibitors were shown to act cooperatively with statins to increase LDLR expression in vitro. Overall, we demonstrated here a novel series of small molecules with the potential to be further developed to treat patients either alone or in combination with statins.

Antihyperlipidemic morpholine derivatives with antioxidant activity: An investigation of the aromatic substitution

Drugs affecting more than one target could result in a more efficient treatment of multifactorial diseases as well as fewer safety concerns, compared to a one-drug one-target approach. Within our continued efforts towards the design of multifunctional molecules against atherosclerosis, we hereby report the synthesis of 17 new morpholine derivatives which structurally vary in terms of the aromatic substitution on the morpholine ring. These derivatives simultaneously suppress cholesterol biosynthesis through SQS inhibition (IC50 values of the most active compounds are between 0.7 and 5.5 μM) while exhibiting a significant protection of hepatic microsomal membranes against lipid peroxidation (with IC50 values for the most active compounds being between 73 and 200 μM). Further evaluation of these compounds was accomplished in vivo in an animal model of acute experimental hyperlipidemia, where it was observed that compounds reduced the examined lipidemic parameters (TC, TG and LDL) by 15-80%. In order to examine the mode of binding of these molecules in the active catalytic site of SQS, we also performed docking simulation studies. Our results indicate that some of the new compounds can be considered interesting structures in the search for new multifunctional agents of potential application in atherosclerosis.

Total synthesis of (±)-bisabosqual A

The synthesis of the novel squalene synthase inhibitor, bisabosqual A, was completed in 14 steps (longest linear sequence) from commercially available starting materials. The doubly convergent route employs a tandem 5-exo, 6-exo radical cyclization as the key step. This reaction assembles the fully functionalized tetracyclic core and introduces three stereogenic centers. Other effective transformations are the regioselective deoxygenation of an advanced enone intermediate and the chemo- and diastereoselective addition of trimethylaluminum to a ketone in the presence of esters.

Preventive aspects in peripheral artery disease

The prevalence of peripheral artery disease is steadily increasing and is associated with significant morbidity, including a significant percentage of amputations. Peripheral artery disease often goes undiagnosed, making its prevention increasingly important. Patients with peripheral arterial disease are at increased risk of adverse cardiovascular outcomes which makes prevention even more important. Several risk factors have been identified in the pathophysiology of peripheral artery disease which should be modified to decrease risk. Smoking, hyperlipidemia, hypertension, and diabetes are among proven risk factors for the development of peripheral artery disease, thus smoking cessation, lipid control, blood pressure control, and glucose control have been tried and shown to be effective in preventing the morbidity associated with this disease. Pharmacologic agents such as aspirin and clopidogrel alone or in combination have been shown to be effective, though risk of bleeding might be increased with the combination. Anticoagulation use is recommended only for acute embolic cases. Other treatment modalities that have been tried or are under investigation are estrogen replacement, naftidrofuryl, pentoxifylline, hyperbaric oxygen, therapeutic angiogenesis, and advanced glycation inhibitors. The treatment for concomitant vascular diseases does not change in the presence of peripheral artery disease, but aggressive management of risk factors should be undertaken in such cases.

A genome-wide RNAi screen identifies novel targets of neratinib resistance leading to identification of potential drug resistant genetic markers

Neratinib (HKI-272) is a small molecule tyrosine kinase inhibitor of the ErbB receptor family currently in Phase III clinical trials. Despite its efficacy, the mechanism of potential cellular resistance to neratinib and genes involved with it remains unknown. We have used a pool-based lentiviral genome-wide functional RNAi screen combined with a lethal dose of neratinib to discover chemoresistant interactions with neratinib. Our screen has identified a collection of genes whose inhibition by RNAi led to neratinib resistance including genes involved in oncogenesis (e.g. RAB33A, RAB6A and BCL2L14), transcription factors (e.g. FOXP4, TFEC, ZNF), cellular ion transport (e.g. CLIC3, TRAPPC2P1, P2RX2), protein ubiquitination (e.g. UBL5), cell cycle (e.g. CCNF), and genes known to interact with breast cancer-associated genes (e.g. CCNF, FOXP4, TFEC, several ZNF factors, GNA13, IGFBP1, PMEPA1, SOX5, RAB33A, RAB6A, FXR1, DDO, TFEC, OLFM2). The identification of novel mediators of cellular resistance to neratinib could lead to the identification of new or neoadjuvant drug targets. Their use as patient or treatment selection biomarkers could make the application of anti-ErbB therapeutics more clinically effective.

Emerging options in the treatment of dyslipidemias: a bright future?

INTRODUCTION

Hypercholesterolemia is a major risk factor for cardiovascular disease (CVD). Low-density lipoprotein cholesterol (LDL-C) reduction has been demonstrated to decrease CVD-related morbidity and mortality. However, several patients do not reach LDL-C target levels with the currently available lipid lowering agents, particularly statins. Lipid and non-lipid parameters other than LDL-C may account for the residual CVD risk after adequate LDL-C lowering with statins.

AREAS COVERED

This review focuses on the efficacy and safety of emerging drugs aiming at high-density lipoprotein cholesterol (HDL-C) elevation (i.e., recombinant or plasma-derived wild-type apolipoprotein (apo) A-I, apo A-I mimetic peptides, reconstituted mutant HDL, partially delipidated HDL and cholesterol ester transfer protein inhibitors), microsomal triglyceride transfer protein inhibitors and antisense oligonucleotides.

EXPERT OPINION

Several lipid modifying agents in development may potently reduce the residual CVD risk. Ongoing and future studies with clinical outcomes will clarify their efficacy in clinical practice.

Enantioselective inhibition of squalene synthase by aziridine analogues of presqualene diphosphate

Squalene synthase catalyzes the conversion of two molecules of (E,E)-farnesyl diphosphate to squalene via the cyclopropylcarbinyl intermediate, presqualene diphosphate (PSPP). Since this novel reaction constitutes the first committed step in sterol biosynthesis, there has been considerable interest and research on the stereochemistry and mechanism of the process and in the design of selective inhibitors of the enzyme. This paper reports the synthesis and characterization of five racemic and two enantiopure aziridine analogues of PSPP and the evaluation of their potencies as inhibitors of recombinant yeast squalene synthase. The key aziridine-2-methanol intermediates (6-OH, 7-OH, and 8-OH) were obtained by N-alkylations or by an N-acylation-reduction sequence of (+/-)-, (2R,3S)-, and (2S,3R)-2,3-aziridinofarnesol (9-OH) protected as tert-butyldimethylsilyl ethers. S(N)2 displacements of the corresponding methanesulfonates with pyrophosphate and methanediphosphonate anions afforded aziridine 2-methyl diphosphates and methanediphosphonates bearing N-undecyl, N-bishomogeranyl, and N-(alpha-methylene)bishomogeranyl substituents as mimics for the 2,6,10-trimethylundeca-2,5,9-trienyl side chain of PSPP. The 2R,3S diphosphate enantiomer bearing the N-bishomogeranyl substituent corresponding in absolute stereochemistry to PSPP proved to be the most potent inhibitor (IC(50) 1.17 +/- 0.08 muM in the presence of inorganic pyrophosphate), a value 4-fold less than that of its 2S,3R stereoisomer. The other aziridine analogues bearing the N-(alpha-methylene)bishomogeranyl and N-undecyl substituents, and the related methanediphosphonates, exhibited lower affinities for recombinant squalene synthase.

Novel nonstatin strategies to lower low-density lipoprotein cholesterol

There remains an unmet need to reduce elevated low-density lipoprotein cholesterol (LDL-C) in patients who are maximized on current therapy or intolerant to statins. Several novel agents have been developed to lower LDL-C, either as monotherapy or in combination with statins. These novel therapies include squalene synthase inhibitors, microsomal triglyceride transfer protein inhibitors, and antisense apolipoprotein B. Although each of these novel therapies effectively lowers LDL-C, challenges remain in the clinical development to assess long-term safety.

Current and future pharmacologic options for the management of patients unable to achieve low-density lipoprotein-cholesterol goals with statins

Low-density lipoprotein-cholesterol (LDL-C) lowering is the mainstay of the current treatment guidelines in the management of cardiovascular risk. HMG-CoA reductase inhibitors (statins) are currently the most effective LDL-C-lowering drugs. However, a substantial number of patients do not reach treatment targets with statins. Therefore, an unmet medical need exists for lipid-lowering drugs with novel mechanisms of action to reach the recommended cholesterol target levels, either by monotherapy or combination therapy. Upregulation of the LDL receptor with squalene synthase inhibitors has shown promising results in animal studies but the clinical development of the lead compound lapaquistat (TAK-475) has recently been discontinued. Ezetimibe combined with statins allowed significantly more patients to reach their LDL-C targets. Other inhibitors of intestinal cholesterol absorption such as disodium ascorbyl phytostanol phosphate (FM-VP4) and bile acid transport inhibitors have shown positive results in early development trials, whereas the prospect of acyl coenzyme A: cholesterol acyltransferase inhibition in cardiovascular prevention is dire. Selective inhibition of messenger RNA (mRNA) by antisense oligonucleotides is a new approach to modify cholesterol levels. The inhibition of apolipoprotein B mRNA is in advanced development and mipomersen sodium (ISIS 301012) has shown striking results in phase II studies both as monotherapy as well as in combination with statins.

K45R variant of squalene synthase increases total cholesterol levels in two study samples from a French Canadian population

Squalene synthase is an important component of the cholesterol biosynthetic pathway, and inhibitors of this enzyme have been shown to lower plasma cholesterol levels. Previously, we sequenced the squalene synthase gene, FDFT1 (farnesyl-diphosphate farnesyltransferase), and identified several SNPs, including a nonsynonymous variant, rs11549147:A>G (K45R). To examine the possible association of K45R with plasma lipid traits, we tested 887 individuals from 149 families from the founder population of Saguenay-Lac St. Jean (SLSJ), Quebec. K45R was associated with increased total cholesterol (TC) (P=0.035) and non-high-density lipoprotein cholesterol (non-HDL-C) (P=0.01). These results were replicated in an independent sample of unrelated individuals (P=0.0008 for TC, P=0.004 for non-HDL-C). This SNP also influenced low-density lipoprotein cholesterol (P=0.042) and HDL-C (P=0.025) in the family-based sample, and triglycerides (TG) (P=0.007) in the unrelated subjects. The lysine (K) in codon 45 is conserved across 11 mammals and lies in a potential exonic splicing enhancer (ESE) site. These results suggest that this coding variant in the squalene synthase gene influences plasma cholesterol levels, possibly by affecting the intracellular production of cholesterol.

Farnesyl Pyrophosphate Is a Novel Transcriptional Activator for a Subset of Nuclear Hormone Receptors

In silico docking of a chemical library with the ligand-binding domain of thyroid hormone nuclear receptor-beta (TRbeta) suggested that farnesyl pyrophosphate (FPP), a key intermediate in cholesterol synthesis and protein farnesylation, might function as an agonist. Surprisingly, addition of FPP to cells activated TR as well as the classical steroid hormone receptors but not peroxisome proliferative-activating receptors, farnesoid X receptor, liver X receptor, or several orphan nuclear receptors the ligands of which are unknown. FPP enhanced receptor-coactivator binding in vitro and in vivo, and elevation of FPP levels in cells by squalene synthetase or farnesyl transferase inhibitors leads to activation. The FPP effect was blocked by selective receptor antagonists, and in silico docking with 143 nuclear receptor ligand-binding domain structures revealed that FPP only docked with the agonist conformation of those receptors activated by FPP. Our results suggest that certain nuclear receptors maintain a common structural feature that may reflect an action of FPP on an ancient nuclear receptor or that FPP could function as a ligand for one of the many orphan nuclear receptors the ligands of which have not yet been identified. This finding also has potential interesting implications that may, in part, explain the pleotropic effects of statins as well as certain actions of farnesylation inhibitors in cells.

EP2306 [2-(4-Biphenyl)-4-methyl-octahydro-1,4-benzoxazin-2-ol, hydrobromide], A Novel Squalene Synthase Inhibitor, Reduces Atherosclerosis in the Cholesterol-Fed Rabbit

EP2306 [2-(4-biphenyl)-4-methyl-octahydro-1,4-benzoxazin-2-ol, hydrobromide] inhibits squalene synthase and lipid biosynthesis and possesses antioxidant properties. We hypothesized that EP2306 can effectively modify circulating lipids and reduce atherosclerosis in the cholesterol-fed rabbit. Animals were fed a high-cholesterol diet for 4 weeks followed by 4 (phase 1 and 2) or 12 weeks (phase 3) of drug treatment while on high-cholesterol diet. In phase 1, the dose-effect relationship of EP2306 on lipids and atherosclerosis was established, and its most effective dose was determined (2 mg/kg). This dose reduced significantly total cholesterol (512 +/- 96 mg/dl before versus 320 +/- 124 mg/dl after treatment, p < 0.05) and atherosclerotic lesions compared with control animals. In phase 2, the effects of 2 mg/kg EP2306, 2.5 mg/kg simvastatin, and their combination were assessed. Although no significant effect on lipid parameters was observed, there was a significant reduction (35 +/- 5%, p < 0.05) of atherosclerotic lesions in animals treated with EP2306, a similar reduction with simvastatin, and a further reduction (48 +/- 7%, p < 0.05) when the two agents were combined. In animals treated for 12 weeks with the drugs (phase 3), only EP2306 significantly reduced atherosclerotic lesions by more than 50%, whereas simvastatin alone or in combination with EP2306 had no effect. Treatment with EP2306 did not adversely affect liver transaminases or cause any histopathological changes on various organs of the animals. In conclusion, we have shown that EP2306 inhibits atherosclerosis in vivo, indicating potential as a novel therapeutic agent for coronary artery disease and other atherosclerosis-related disorders.