Invention of MK-8262, a Cholesteryl Ester Transfer Protein (CETP) Inhibitor Backup to Anacetrapib with Best-in-Class Properties

Cholesteryl ester transfer protein (CETP) represents one of the key regulators of the homeostasis of lipid particles, including high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles. Epidemiological evidence correlates increased HDL and decreased LDL to coronary heart disease (CHD) risk reduction. This relationship is consistent with a clinical outcomes trial of a CETP inhibitor (anacetrapib) combined with standard of care (statin), which led to a 9% additional risk reduction compared to standard of care alone. We discuss here the discovery of MK-8262, a CETP inhibitor with the potential for being the best-in-class molecule. Novel in vitro and in vivo paradigms were integrated to drug discovery to guide optimization informed by a critical understanding of key clinical adverse effect profiles. We present preclinical and clinical evidence of MK-8262 safety and efficacy by means of HDL increase and LDL reduction as biomarkers for reduced CHD risk.

Synthesis and Modeling of Ezetimibe Analogues

Ezetimibe is a well-known drug that lowers blood cholesterol levels by reducing its absorption in the small intestine when joining to Niemann-Pick C1-like protein (NPC1L1). A ligand-based study on ezetimibe analogues is reported, together with one-hit synthesis, highlighted in the study. A convenient asymmetric synthesis of (2S,3S)-N-α-(R)-methylbenzyl-3-methoxycarbonylethyl-4-methoxyphenyl β-lactam is described starting from Baylis-Hillman adducts. The route involves a domino process: allylic acetate rearrangement, stereoselective Ireland-Claisen rearrangement and asymmetric Michael addition, which provides a δ-amino acid derivative with full stereochemical control. A subsequent inversion of ester and acid functionality paves the way to the lactam core after monodebenzylation and lactam formation. It also shows interesting results when it comes to a pharmacophore study based on ezetimibe as the main ligand in lowering blood cholesterol levels, revealing which substituents on the azetidine-2-one ring are more similar to the ezetimibe skeleton and will more likely bind to NPC1L1 than ezetimibe.

Anti-hyperlipidemic potential of natural product based labdane-pyrroles via inhibition of cholesterol and triglycerides synthesis

Hyperlipidemia is the clinical condition where blood has an increased level of lipids, such as cholesterol and triglycerides. Therefore controlling hyperlipidemia is considered to be a protective strategy to treat many associated diseases. Thus, a novel natural product derived pyrrole, and pyrazole-(E)-Labda-8(17),12-diene-15,16-dial conjugates with cholesterol and triglycerides synthesis inhibition potential was designed through scaffold hopping approach and synthesized via one-pot selective cycloaddition. Amongst the tested hybrids, 3i exhibited excellent activity against triglyceride and cholesterol synthesis with the percentage inhibition of 71.73 ± 0.78 and 68.61 ± 1.19, which is comparable to the positive controls fenofibrate and atorvastatin, respectively. Compounds 3j and 3k also exhibited the considerable potential of promising leads. The HMG CoA reductase inhibitory activity of the compounds was consistent with that of inhibitory activity of cholesterol synthesis. Compound 3i showed the highest inhibitory potential (78.61 ± 2.80) percentage of suppression, which was comparable to that of the positive control pravastatin (78.05 ± 5.4). Favourably, none of the compounds showed cytotoxicity (HepG2) in the concentration ranging from 0.5 to 100 μM.

Phytosterol and γ-Oryzanol Conjugates: Synthesis and Evaluation of their Antioxidant, Antiproliferative, and Anticholesterol Activities

Fifteen new multifunctional conjugates were designed and synthesized by chemically linking the steroidal framework of natural occurring γ-oryzanol and γ-oryzanol-derived phytosterols to a wide range of bioactive natural compounds (fatty acids, phenolic acids, amino acids, lipoic acid, retinoic acid, curcumin, and resveratrol). Starting from γ-oryzanol, which is the main component of rice bran oil, this study was aimed at assessing if the conjugation strategy might enhance some γ-oryzanol bioactivities. The antioxidant activity was evaluated through three different mechanisms, namely, DPPH-scavenging activity, metal-chelating activity, and β-carotene-bleaching inhibition. Measurement of the in vitro cell growth inhibitory effects on three different human cancer cellular lines was also carried out, and the potential hypocholesterolemic effect was studied. Compounds 10 and 15 displayed an improved antioxidant activity, with respect to that of γ-oryzanol. Compounds 2, 6, and 12 exerted an antiproliferative activity in the low micromolar range against HeLa and DAOY cells (GI₅₀ < 10 μM). As for the claimed hypocholesterolemic effect of γ-oryzanol, none of the synthesized compounds inhibited the 3-hydroxy-3-methylglutaryl-coenzyme A reductase, a key enzyme in cholesterol biosynthesis.

Molecular Diversity by Olefin Cross-Metathesis on Solid Support. Generation of Libraries of Biologically Promising β-Lactam Derivatives

The application of the reagent-based diversification strategy for generation of libraries of biologically promising β-lactam derivatives is described. Key features are the versatility of the linker used and the cross-metathesis functionalization at the cleavage step. From an immobilized primary library, diversity was expanded by applying different cleavage conditions, leading to a series of cholesterol absorption inhibitor analogues together with interesting hybrid compounds through incorporation of a chalcone moiety.

New pyripyropene A derivatives, highly SOAT2-selective inhibitors, improve hypercholesterolemia and atherosclerosis in atherogenic mouse models

Sterol O-acyltransferase 2 (SOAT2; also known as ACAT2) is considered as a new therapeutic target for the treatment or prevention of hypercholesterolemia and atherosclerosis. Fungal pyripyropene A (PPPA: 1,7,11-triacyl type), the first SOAT2-selective inhibitor, proved orally active in vivo using atherogenic mouse models. The purpose of the present study was to demonstrate that the PPPA derivatives (PRDs) prove more effective in the mouse models than PPPA. Among 196 semisynthetic PPPA derivatives, potent, SOAT2-selective, and stable PRDs were selected. In vivo antiatherosclerotic activity of selected PRDs was tested in apolipoprotein E knockout (Apoe(-/-)) mice or low-density lipoprotein receptor knockout (Ldlr(-/-)) mice fed a cholesterol-enriched diet (0.2% cholesterol and 21% fat) for 12 weeks. During the PRD treatments, no detrimental side effects were observed. Among three PRDs, Apoe(-/-) mice treated with PRD125 (1-,11-O-benzylidene type) at 1 mg/kg/day had significantly lower total plasma cholesterol concentration by 57.9 ± 9.3%; further, the ratio of cholesteryl oleate to cholesteryl linoleate in low-density lipoprotein was lower by 55.6 ± 7.5%, respectively. The hepatic cholesteryl ester levels and SOAT2 activity in the small intestines and livers of the PRD-treated mice were selectively lowered. The atherosclerotic lesion areas in the aortae of PRD125-treated mice were significantly lower at 62.2 ± 13.1%, respectively. Furthermore, both PRDs were also orally active in atherogenic Ldlr(-/-) mice. Among the PRDs tested, PRD125 was the most potent in both mouse models. These results suggest that SOAT2-selective inhibitors such as PRD125 have a high potential as poststatin agents for treatment and/or prevention in patients with atherosclerosis and hypercholesterolemia.

Synthesis and investigation of biological properties of modified 6-oxa-estra-1,3,5(10),8(9)-tetraenes

To investigate the relationship between structure and biological activity of analogues of steroid estrogens we have developed the synthesis of 7α-methyl-6-oxa-estra-1,3,5(10),8(9)-tetraenes with cis- and trans-junction of C and D rings. We found that such compounds have stronger osteoprotective, cholesterol-lowering and antioxidant properties in comparison with uterotrophic activity; that is the advantage in comparison with clinically used 17α-ethynylestradiol.

The thyroid receptor modulator KB3495 reduces atherosclerosis independently of total cholesterol in the circulation in ApoE deficient mice

BACKGROUND

Thyroid hormones (TH) regulate cholesterol metabolism but their use as lipid-lowering drugs is restricted due to negative cardiac effects. TH mimetic compounds modulating TH receptor β (THRβ) have been designed as potential drugs, reducing serum cholesterol levels while avoiding apparent deleterious cardiac effects.

OBJECTIVE

Using ApoE deficient mice, we examined whether KB3495, a TH mimetic compound, reduces atherosclerosis and if there is a synergistic effect with atorvastatin. The effect of KB3495 was investigated after 10 and 25 weeks.

RESULTS

KB3495 treatment reduced atherosclerotic plaque formation in aorta and decreased the cholesteryl ester (CE) content by 57%. Treatment with KB3495 was also associated with a reduction of macrophage content in the atherosclerotic plaques and reduced serum levels of IL-1β, TNFalpha, IL-6, Interferon γ, MCP-1 and M-CSF. Serum lipoprotein analysis showed no change in total cholesterol levels in ApoB-containing lipoproteins. KB3495 alone increased fecal BA excretion by 90%. The excretion of neutral sterols increased in all groups, with the largest increase in the combination group (350%). After 25 weeks, the animals treated with KB3495 showed 50% lower CE levels in the skin and even further reductions were observed in the combination group where the CE levels were reduced by almost 95% as compared to controls.

CONCLUSION

KB3495 treatment reduced atherosclerosis independently of total cholesterol levels in ApoB-containing lipoproteins likely by stimulation of sterol excretion from the body and by inhibition of the inflammatory response.

[Progress in the ligands and their complex structures of farnesoid X receptor]

Farnesoid X receptor (FXR) belongs to the nuclear receptor superfamily. It is highly related to the formation of metabolic syndrome and the glucose homeostasis, and therefore represents an important drug target against metabolic diseases and diabetes. In recent years, great progress has been made in the agonists, antagonists, and crystal structures of FXR. The diverse FXR ligands and their structure-activity relationship are reviewed in this article. The advances in the crystal structures of FXR in complex with different ligands are also introduced.

Relationships between lipophilicity and biological activities in a series of indoline-based anti-oxidative acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors

A novel series of 1-alkyl-7-amido-indoline-based anti-oxidative acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors have been reported and are expected to lower plasma cholesterol levels due to the inhibition of intestinal and hepatic ACAT, and to inhibit cholesterol accumulation in macrophages due to the inhibition of low density lipoprotein (LDL) oxidation. In the present study, relationships between lipophilicity and biological activities were examined in 13 derivatives. Lipophilicity (logP) increased and water solubility decreased with dependence on the number of carbons in the 1-alkyl chain. Inhibitory activity against both in vitro intestinal ACAT and LDL oxidation positively correlated with logP; however, the optimum logP, at which the level of activity is maximal, differed between these two effects. Inhibitory activity against in vitro plasma oxidation was weakly dependent on logP. Plasma concentrations of the derivatives after oral administration at 10 mg/kg correlated negatively with logP and positively with water solubility. Hypocholesterolemic activity in rats fed a high-cholesterol diet, and the ratio of Cmax and IC50 values for ACAT inhibition, an index of effective plasma concentration, positively and highly correlated with logP, while ex vivo inhibitory activity against plasma oxidation in rats, and the ratio of Cmax and IC50 values for the inhibition of plasma oxidation negatively correlated with logP. In conclusion, in vitro ACAT inhibitory and anti-oxidative activity were differently dependent on logP, and intestinal absorption was inversely dependent on lipophilicity in indoline-based anti-oxidative ACAT inhibitors. The hypocholesterolemic effect positively correlated and the ex vivo anti-oxidative effect negatively correlated with lipophilicity. Optimum logP as a bioavailable dual inhibitor against in vivo ACAT and lipid peroxidation was estimated to be 3.8 (1-pentyl and 1-isopentyl derivatives) in the present series of derivatives.

Synthesis and HMG CoA reductase inhibition of 4-thiophenyl quinolines as potential hypocholesterolemic agents

A series of novel 4-thiophenyl quinoline-based mevalonolactone derivatives were synthesized from ethyl 6,7,8-trisubstituted-4-chloro-quinoline-3-carboxylates by several reactions and evaluated for their ability to inhibit the rat HMG CoA reductase in vitro. It was found that substitution with a variety of thiophenyl groups at position 4 in quinoline resulted in retention or enhancement of the inhibition and the preferable groups were 4-isopropyl-thiophenyl and 3-methoxy-thiophenyl. (4R,6S)-6-[(E)-2-(6,7,8-trifluoro-4-isopropylthiophenyl-quinoline-3-yl)-ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one (A16) and (4R, 6S)-6-[(E)-2-(6-fluoro-4,7-di-(3-methoxy-thiophenyl)-quinoline-3-yl)-ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-2H-pyran-2-one (A23) were approximately three times more potent than rosuvastatin or pitavastatin in inhibiting HMG CoA reductase and selected as the hypocholesterolemic candidates for further evaluation.

[Synthesis and biological properties of 6-oxa-D-homo-8alpha analogues of steroid estrogens]

Modifications of 6-oxa-D-homo-8alpha-analogues of steroid estrogens were found to lead to a complete loss of the uterotropic and hypertriglyceridemic activities. These compounds may be promising for the design on their basis of inhibitors of the steroid hormone metabolism and transporters of other compounds to the estrogen target organs.

[Synthesis, structure, and biological properties of some 8alpha-analogues of steroid estrogens with fluorine in position 2]

A total synthesis of 8alpha analogues of steroid estrogens with fluorine in position 2 was achieved. Structural features of these compounds were studied by the example of 17beta-acetoxy-2-fluoro-3-methoxy-8alpha-estra-1,3,5(10)-triene. It was shown that the 8alpha analogues of 2-fluorosubstituted steroid estrogens have a low uterotropic activity and retain the osteoprotective and hypocholesterolemic activities.

Influence of HDL-cholesterol-elevating drugs on the in vitro activity of the HDL receptor SR-BI

Treatment of atherosclerotic disease often focuses on reducing plasma LDL-cholesterol or increasing plasma HDL-cholesterol. We examined in vitro the effects on HDL receptor [scavenger receptor class B type I (SR-BI)] activity of three classes of clinical and experimental plasma HDL-cholesterol-elevating compounds: niacin, fibrates, and HDL376. Fenofibrate (FF) and HDL376 were potent (IC(50) approximately 1 microM), direct inhibitors of SR-BI-mediated lipid transport in cells and in liposomes reconstituted with purified SR-BI. FF, a prodrug, was a more potent inhibitor of SR-BI than an activator of peroxisome proliferator-activated receptor alpha, a target of its active fenofibric acid (FFA) derivative. Nevertheless, FFA, four other fibrates (clofibrate, gemfibrozil, ciprofibrate, and bezafibrate), and niacin had little, if any, effect on SR-BI, suggesting that they do not directly target SR-BI in vivo. However, similarities of HDL376 treatment and SR-BI gene knockout on HDL metabolism in vivo (increased HDL-cholesterol and HDL particle sizes) and structure-activity relationship analysis suggest that SR-BI may be a target of HDL376 in vivo. HDL376 and other inhibitors may help elucidate SR-BI function in diverse mammalian models and determine the therapeutic potential of SR-BI-directed pharmaceuticals.

Hypocholesterolemic and antioxidant properties of 3-(4-hydroxyl)propanoic acid derivatives in high-cholesterol fed rats

The purpose of the present study was to evaluate the in vivo efficacy of two cinnamic acid synthetic derivatives (allyl 3-[4-hydroxyphenyl]propanoate; HPP304, 1-naphthyl-methyl 3-[4-hydroxyphenyl]propanoate; HPP305) in high-cholesterol fed rats and compare their actions to that of cinnamic acid. Cinnamic acid and its synthetic derivatives were supplemented with a high-cholesterol diet for 42 days at a dose of 0.135 mmol/100g of diet. The supplementation of HPP304 and HPP305 significantly lowered cholesterol and triglyceride levels in the plasma and liver with a simultaneous increase in the HDL-cholesterol concentration, whereas cinnamic acid only lowered the plasma cholesterol concentration. Cinnamic acid lowered hepatic HMG-CoA reductase activity in high-cholesterol fed rats, however, its synthetic derivatives (HPP304 and HPP305) did not affect HMG-CoA reductase activity compared to the control group. Instead, the HPP304 and HPP305 supplements significantly lowered hepatic acyl coenzyme A:cholesterol acyltransferase activity and increased the fecal bile acid. The SOD activity of the erythrocytes and liver was not different between the groups, however, the activities of CAT and GSH-Px, and the level of GSH in the erythrocytes were significantly higher in the HPP304 and HPP305 groups than in the control group. On the other hand, the activities of CAT and GSH-Px, and the level of malondialdehyde in the liver were significantly lower in the HPP304 and HPP305 groups. The antioxidant activities of these cinnamic acid synthetic derivatives were similar to the cinnamic acid in the high-cholesterol fed rats. In addition, HPP304 and HPP305 lowered amniotransferase activity in the plasma. These results suggest that two cinnamic acid synthetic derivatives (HPP304 and HPP305) exert lipid-lowering action and antioxidant properties without hepatotoxicity in high-cholesterol fed rats.

Novel side chain modified Delta8(14)-15-ketosterols

Synthesis of five novel Delta8(14)-15-ketosterols comprising modified side chains starting from ergosterol is described. Ergosteryl acetate was converted into (22E)-3beta-acetoxy-5alpha-ergosta-8(14),22-dien-15-one through three stages in 32% overall yield; further transformations of the product obtained led to (22E)-3beta-hydroxy-5alpha-ergosta-8(14),22-dien-15-one, (22S,23S)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one, (22R,23R)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one, (22R,23R)-5alpha-ergost-8(14)-en-15-on-3beta,22,23-triol and (22R,23R)-3beta-hydroxy-22,23-isopropylidenedioxy-5alpha-ergost-8(14)-en-15-one. New Delta8(14)-15-ketosterols were evaluated for their cytotoxicity and effects on sterol biosynthesis in human hepatoma Hep G2 cells in comparison with known 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one. Among the compounds tested, (22R,23R)-3beta-hydroxy-22,23-oxido-5alpha-ergost-8(14)-en-15-one was found to be the most potent inhibitor of sterol biosynthesis (IC(50)=0.6+/-0.2microM), whereas (22R,23R)-5alpha-ergost-8(14)-en-15-on-3beta,22,23-triol exhibited the highest cytotoxicity (TC(50)=12+/-3microM at a 24h incubation).

Improving catalytic function by ProSAR-driven enzyme evolution

We describe a directed evolution approach that should find broad application in generating enzymes that meet predefined process-design criteria. It augments recombination-based directed evolution by incorporating a strategy for statistical analysis of protein sequence activity relationships (ProSAR). This combination facilitates mutation-oriented enzyme optimization by permitting the capture of additional information contained in the sequence-activity data. The method thus enables identification of beneficial mutations even in variants with reduced function. We use this hybrid approach to evolve a bacterial halohydrin dehalogenase that improves the volumetric productivity of a cyanation process approximately 4,000-fold. This improvement was required to meet the practical design criteria for a commercially relevant biocatalytic process involved in the synthesis of a cholesterol-lowering drug, atorvastatin (Lipitor), and was obtained by variants that had at least 35 mutations.

Ezetimibe analogs with a reorganized azetidinone ring: Design, synthesis, and evaluation of cholesterol absorption inhibitions

The underlying principle of drug design in this paper is that the maximum retention of the functional groups that exist in the marketed drug would provide a higher probability for comparable safety while the conformational changes in the newly created analogs should not constitute a significant structural variation to adversely affect biological activity. Four individual isomers of backbone re-organized ezetimibe analogs were designed and synthesized. Their effects on the cholesterol levels in rat serum were evaluated by a high-cholesterol and high-fat diet feeding experiment. All the new analogs showed significant effect in lowering the levels of total cholesterol in serum.

Synthesis of 3-(Aryl)alkenyl-β-lactams by an Efficient Application of Olefin Cross-Metathesis on Solid Support

[reaction: see text] An efficient cross-metathesis on solid support for the synthesis of beta-lactam analogues of cholesterol absorption inhibitors is described. The applied strategy allows the introduction of diversity in positions 3 and 4 of the beta-lactam ring with excellent 3,4-trans selectivity and complete E selectivity at the C-3 side chain.

Discovery of Phenyl Acetic Acid Substituted Quinolines as Novel Liver X Receptor Agonists for the Treatment of Atherosclerosis

A structure-based approach was used to optimize our new class of quinoline LXR modulators leading to phenyl acetic acid substituted quinolines 15 and 16. Both compounds displayed good binding affinity for LXRbeta and LXRalpha and were potent activators in LBD transactivation assays. The compounds also increased expression of ABCA1 and stimulated cholesterol efflux in THP-1 cells. Quinoline 16 showed good oral bioavailability and in vivo efficacy in a LDLr knockout mouse model for lesions.

Synthesis and pharmacochemical study of novel polyfunctional molecules combining anti-inflammatory, antioxidant, and hypocholesterolemic properties

We have designed and synthesized a series of novel molecules having a residue of a classical NSAID and an antioxidant moiety, both attached through amide bonds to a known nootropic structure, an L-proline, trans-4-hydroxy-L-proline or DL-pipecolinic acid residue. The compounds were found to retain anti-inflammatory and antioxidant activities, to acquire hypocholesterolemic action, and to possess a greatly reduced gastrointestinal toxicity. The novel molecules could find useful applications, among others, in slowing the progression or delaying the onset of neurodegenerative diseases.

A Selective Estrogen Receptor Modulator for the Treatment of Hot Flushes

A selective estrogen receptor modulator (SERM) for the potential treatment of hot flushes is described. (R)-(+)-7,9-difluoro-5-[4-(2-piperidin-1-ylethoxy)phenyl]-5H-6-oxachrysen-2-ol, LSN2120310, potently binds ERalpha and ERbeta and is an antagonist in MCF-7 breast adenocarcinoma and Ishikawa uterine cancer cell lines. The compound is a potent estrogen antagonist in the rat uterus. In ovariectomized rats, the compound lowers cholesterol, maintains bone mineral density, and is efficacious in a morphine dependent rat model of hot flush efficacy.

Synthesis and in vitro evaluation of inhibitors of intestinal cholesterol absorption

We have utilized our recently developed in vitro assay to address two key questions in the design of small-molecule cholesterol absorption inhibitors using ezetimibe, the only drug yet approved for the inhibition of cholesterol absorption in the small intestine, as a starting point: (1) the role of glycosylation and (2) the importance of the beta-lactam scaffold of ezetimibe for inhibitory activity. A wide range of nonhydrolyzable phenolic glycosides of ezetimibe were synthesized and demonstrated to be active inhibitors of cholesterol absorption using the brush border membrane vesicle assay. The analogous azetidines provided access to a variety of inhibitors in vitro, suggesting that the beta-lactam of ezetimibe merely serves as a ring scaffold to appropriately position the required substituents. Our findings highlight several promising strategies for the design of alternative small-molecule cholesterol absorption inhibitors that could ultimately be useful in preventing cardiovascular disease by lowering blood cholesterol levels.

Discovery of potent, nonsystemic apical sodium-codependent bile acid transporter inhibitors (Part 1)

Elevated plasma levels of low-density lipoprotein (LDL) cholesterol are a major risk factor for atherosclerosis leading to coronary artery disease (CAD), which remains the main cause of mortality in Western society. We believe that by preventing the reabsorption of bile acids, a minimally absorbed apical sodium-codependent bile acid transporter (ASBT) inhibitor would lower the serum cholesterol without the potential systemic side effects of an absorbed drug. A series of novel benzothiepines (3R,3R'-2,3,4,5-tetrahydro-5-aryl-1-benzothiepin-4-ol 1,1-dioxides) were synthesized and tested for their ability to inhibit the apical sodium dependent bile acid transport (ASBT)-mediated uptake of [(14)C]taurocholate (TC) in H14 cells. A 3R,4R,5R/3S,4S,5S racemate was found to have greater potency than the other three possible racemates. Addition of electron-donating groups such as a dimethylamino substituent at the 7 position greatly enhanced potency, and incorporation of a long-chain quaternary ammonium substituent on the 5-phenyl ring was useful in minimizing systemic exposure of this locally active ASBT inhibitor while also increasing water solubility and maintaining potency. The reported results describe the synthesis and SAR development of this benzothiepine class of ASBT inhibitors resulting in an 6000-fold improvement in ASBT inhibition with desired minimal systemic exposure of this locally acting drug candidate.

Effect of Some Biologically Interesting Substituted Tetrahydro-1,4- Oxazines on Drug Metabolising Enzymes and on Inflammation

The effect on hepatic drug metabolising enzymes was evaluated for three representative structures and that were selected from a series of substituted oxazine derivatives designed to possess particular pharmacological properties such as analgesic, antioxidant and hypolipidemic activity. In addition, since xenobiotic metabolism, reactive oxygen and nitrogen species, atherosclerosis and inflammation are interrelated and mutually affected, the effects of and on acute inflammation in vivo and lipoxygenase activity in vitro were also investigated. It was found that treatment of rats with caused induction of cytochrome P450, enhancement of the metabolism of aminopyrine in vitro and of zoxazolamine and hexobarbital in vivo. Compound appeared to induce particularly erythromycin N-demethylation, while, a nitric ester, reduced the catalytically active cytochrome P450, although it increased the metabolism of specific cytochrome P450 substrates, i.e. 4-nitrophenol and erythromycin. Compounds and with strong hypolipidemic and antioxidant properties, reduced acute inflammatory response in two inflammation models and inhibited lipoxygenase activity in vitro. These results are helpful in optimising the biological profile as well as the potential applications of substituted oxazines.

Anticholesterolemic effect of 3,4-di(OH)-phenylpropionic amides in high-cholesterol fed rats

Two amide synthetic derivatives of 3,4-di(OH)-hydrocinnamate (HC), 3,4-dihydroxyphenylpropionic (l-serine methyl ester) amide (E030) and 3,4-dihydroxyphenylpropionic (l-aspartic acid) amide (E076), were investigated to compare their lipid-lowering efficacy with HC. Male rats were fed a 1 g/100 g high-cholesterol diet for 6 weeks with supplements of either clofibrate (0.02%, w/w), HC (0.025%, w/w), E030 (0.039%, w/w) or E076 (0.041%, w/w). The clofibrate supplement was used as a positive control for the lipid-lowering efficacy. The food intakes and body weight gains were not significantly different among the groups. The plasma and hepatic cholesterol and triglyceride levels were lower in clofibrate, HC, E030, and E076-supplemented groups compared to the control group. The supplementation of HC and its amide derivatives was as effective as clofibrate in increasing the ratio of HDL-cholesterol to total plasma cholesterol and reducing the atherogenic index (AI). The hepatic cholesterol level in the HC and E076 groups was significantly lower than that in the clofibrate group. The hepatic 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA reductase) and acyl-CoA:cholesterol acyltransferase (ACAT) activities were significantly lower in the all test groups than in the control group. The excretion of neutral sterol was significantly higher in the HC, E030, and E076-supplemented groups compared to the control group. The plasma AST and ALT activities, indirect indexes of hepatic toxicity, were significantly lower in the HC, E030, and E076-supplemented groups than in the control group. Accordingly, the current results suggest that E030 and E076, two amide synthetic derivatives of HC, are effective in lowering lipid activity.

Discovery of Potent, Nonsystemic Apical Sodium-Codependent Bile Acid Transporter Inhibitors (Part 2)

In the preceding paper several compounds were reported as potent apical sodium-codependent bile acid transporter (ASBT) inhibitors. Since the primary site for active bile acid reabsorption is via ASBT, which is localized on the luminal surface of the distal ileum, we reasoned that a nonsystemic inhibitor would be desirable to minimize or eliminate potential systemic side effects of an absorbed drug. To ensure bioequivalency and product stability, it was also essential that we identify a nonhygroscopic inhibitor in its most stable crystalline form. A series of benzothiepines were prepared to refine the structure-activity relationship of the substituted phenyl ring at the 5-position of benzothiepine ring and to identify potent, crystalline, nonhygroscopic, and efficacious ASBT inhibitors with low systemic exposure.

[New delta8(14)-ketosterols with an oxygenated side chain]

New analogues of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one (15-ketosterol) with modified 17-chains [(22S,23S,24S)- and (22R,23R,24S)-3beta-hydroxy-24-methyl-22,23-oxido-5alpha-cholest-8(14)-en-15-ones and (22RS,23xi,24S)-24-methyl-5alpha-cholesta-3beta,22,23-triol-15-one] were synthesized from (22E,24S)-3beta-acetoxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one. The chiralities of their 22 and 23 centers were determined by NMR spectroscopy. The isomeric 22,23-epoxides effectively inhibited cholesterol biosynthesis in hepatoma Hep G2 cells (IC50 0.9 +/- 0.2 and 0.7 +/- 0.2 microM, respectively), and their activities significantly exceeded those of 15-ketosterol (IC50 4.0 +/- 0.5 microM), (22E,24S)-3beta-hydroxy-24-methyl-5alpha-cholesta-8(14),22-dien-15-one (IC50 3.1 +/- 0.4 microM), and the 3beta,22,23-triol synthesized (IC50 6.0 +/- 1.0 microM). The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 3; see also http://www.maik.ru.

Saucerneol B derivatives as human acyl-CoA: cholesterol acyltransferase inhibitors

A series of 2a-i were prepared from a lead compound, saucerneol B (1) for evaluating their acyl-CoA: cholesterol acyltransferase inhibitory activities. Compounds 2a-g exhibited the high specificity of hACAT-1 than hACAT-2, whereas 2h and 2i showed very weak inhibitory activities in both hACAT-1 and hACAT-2. Saucerneol B (1) exhibited strong cholesterol-lowering effect in high cholesterol-fed mice.

Hypocholesterolemic activity of some novel azetidin-2-ones in diet and diabetes induced hypercholesterolemia in rats

Some novel substituted azetidin-2-ones (5-8) were synthesized via [2 + 2] cycloaddition reactions of imines and ketenes and evaluated for their ability to prevent diet and diabetes induced hypercholesterolemia. The test compounds 5a and 7a significantly (p < 0.01) inhibited the rise in serum total cholesterol induced by peanut oil (5.5%), cholesterol (1.5%) and cholic acid (0.5%) diet in both acute and chronic models in a dose dependent manner. Compound 5a also raised the high density lipoprotein-cholesterol levels in chronic diet models by peanut oil (5.5%), cholesterol (1.5%) and cholic acid (0.5%). In a diabetes induced model of hypercholesterolemia, the test compounds were evaluated for preventing diabetes-induced hypercholesterolemia (protocol 1) as well as for lowering post diabetic hypercholesterolemia (protocol 2). Test compounds 5a-g and 7a-d significantly (p < 0.05) reduced serum total cholesterol with a greater reduction in protocol 1 as compared with protocol 2. Based on SAR studies, the substituents that favor hypocholesterolemic activity around the azetidin-2-one nucleus are discussed and a possible mechanism of action is proposed on the basis of their differential effects in two protocols of diabetes-induced hypercholesterolemia.

Dual-action hypoglycemic and hypocholesterolemic agents that inhibit glycogen phosphorylase and lanosterol demethylase

Diabetic dyslipidemia requires simultaneous treatment with hypoglycemic agents and lipid-modulating drugs. We recently described glycogen phosphorylase inhibitors that reduce glycogenolysis in cells and lower plasma glucose in ob/ob mice (J. Med. Chem., 41: 2934, 1998). In evaluating the series prototype, CP-320626, in dogs, up to 90% reduction in plasma cholesterol was noted after 2 week treatment. Cholesterol reductions were also noted in ob/ob mice and in rats. In HepG2 cells, CP-320626 acutely and dose-dependently inhibited cholesterolgenesis without affecting fatty acid synthesis. Inhibition occurred together with a dose-dependent increase in the cholesterol precursor, lanosterol, suggesting that cholesterolgenesis inhibition was due to lanosterol 14alpha-demethylase (CYP51) inhibition. In ob/ob mice, acute treatment with CP-320626 resulted in a decrease in hepatic cholesterolgenesis with concomitant lanosterol accumulation, further implicating CYP51 inhibition as the mechanism of cholesterol lowering in these animals. CP-320626 and analogs directly inhibited rhCYP51, and this inhibition was highly correlated with HepG2 cell cholesterolgenesis inhibition (R2 = 0.77). These observations indicate that CP-320626 inhibits cholesterolgenesis via direct inhibition of CYP51, and that this is the mechanism whereby CP-320626 lowers plasma cholesterol in experimental animals. Dual-action glycogenolysis and cholesterolgenesis inhibitors therefore have the potential to favorably affect both the hyperglycemia and the dyslipidemia of type 2 diabetes.

Carbohydrate Sulfonyl Chlorides for Simple, Convenient Access to Glycoconjugates

[reaction: see text] The use of carbohydrate sulfonyl chlorides is introduced as a new, facile glycoconjugation method which could find broad applications. We demonstrate the approach by synthesizing a number of glycosylated cholesterol absorption inhibitors which display high inhibitory efficacies in our recently established in vitro assay. Furthermore, we highlight an advantage of the electron-withdrawing nature of the sulfonyl linkage which allowed the synthesis of otherwise unstable azetidine conjugates.

Beta-lactam cholesterol absorption inhibitors

beta-Lactams have recently been identified as potent, highly efficacious cholesterol absorption inhibitors (CAIs). The discovery, SAR, and asymmetric synthesis of this class of hypolipidemic agents are described. Metabolism studies of the first clinical candidate, Sch 48461, led to the identification of a more potent second generation clinical candidate, Sch 58235 (ezetimibe) incorporating key structural elements of the active metabolites. A summary of preclinical and early clinical studies of ezetimibe as monotherapy and in combination with statins is also presented. Efforts to identify a pharmacophore model has led to the development of conformationally constrained analogs and analogs with conformational biases based on intramolecular hydrogen bonding possibilities. Finally, mechanism of action studies have led to the development of many biochemical tools for the investigation and identification of novel proteins involved in cholesterol uptake.

Heterocyclic ring scaffolds as small-molecule cholesterol absorption inhibitors

Enantio- and diastereoselective syntheses of a substituted oxazolidinone, isoxazoline and pyrazoline as beta-lactam surrogates are described. The substituted heterocycles were designed to incorporate side chains closely resembling those found in the beta-lactam cholesterol absorption inhibitor ezetimibe (1). Additionally, the in vitro inhibitory efficacy of the novel compounds as cholesterol absorption inhibitors is reported using a brush border membrane vesicle assay.

Discovery of Novel Phenolic Antioxidants as Inhibitors of Vascular Cell Adhesion Molecule-1 Expression for Use in Chronic Inflammatory Diseases

Vascular cell adhesion molecule-1 (VCAM-1) mediates recruitment of leukocytes to endothelial cells and is implicated in many inflammatory conditions. Since part of the signal transduction pathway that regulates the activation of VCAM-1 expression is redox-sensitive, compounds with antioxidant properties may have inhibitory effects on VCAM-1 expression. Novel phenolic compounds have been designed and synthesized starting from probucol (1). Many of these compounds demonstrated potent inhibitory effects on cytokine-induced VCAM-1 expression and displayed potent antioxidant effects in vitro. Some of these derivatives (4o, 4p, 4w, and 4x) inhibited lipopolysaccharide (LPS)-induced secretion of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 from human peripheral blood mononuclear cells (hPBMCs) in a concentration-dependent manner in vitro and showed antiinflammatory effects in an animal model. Compounds 4ad and 4ae are currently in clinical trials for the treatment of rheumatoid arthritis (RA) and prevention of chronic organ transplant rejection, respectively.

Design and Synthesis of Novel N-Acetylgalactosamine-Terminated Glycolipids for Targeting of Lipoproteins to the Hepatic Asialoglycoprotein Receptor

A novel glycolipid has been prepared that contains a cluster glycoside with an unusually high affinity for the asialoglycoprotein receptor (ASGPr) and a bile acid moiety that mediates stable incorporation into lipidic particles. The glycolipid spontaneously associated with low-density lipoproteins (LDL) and high-density lipoproteins (HDL) within human and murine plasma, and loading of lipoproteins with this glycolipid resulted in an efficient dose-dependent recognition and uptake of LDL and HDL by the liver (and not by spleen) upon intravenous injection into wild-type mice. Preinjection with asialoorosomucoid largely inhibited the uptake, establishing that both HDL and LDL were selectively recognized and processed by the ASGPr on liver parenchymal cells. Finally, repeated intravenous administration of the glycolipid to hyperlipidemic LDL receptor-deficient mice evoked an efficient and persistent cholesterol-lowering effect. These results indicate that the glycolipid may be a promising alternative for the treatment of hyperlipidemic patients who do not respond sufficiently to current cholesterol-lowering therapies.

CETi-1. AVANT

CETi-1, a vaccine that stimulates antibodies specific for cholesteryl ester transfer protein, is under development by AVANT Immunotherapeutics for potential use in reducing risk factors for atherosclerosis. Phase II trials with CETi-1 in hypercholesterolemia and atherosclerosis had been initiated by August 2001.

Synthesis and Biological Evaluation of Quinuclidine Derivatives Incorporating Phenothiazine Moieties as Squalene Synthase Inhibitors

Squalene synthase inhibitors have the potential to be superior hypocholesterolemic agents. A series of quinuclidine derivatives incorporating phenothiazine systems was synthesized in order to investigate the effects of their structure on the inhibition of hamster liver microsomal enzyme. (+/-)-3-(10-Methyl-10H-phenothiazin-3-ylmethoxy)quinuclidine hydrochloride (19) was the most potent inhibitor in this series with an IC(50) value of 0.12 microM. Oral dosing of compound 19 to hamsters demonstrated effective reduction of both plasma total cholesterol levels and plasma triglyceride levels. Compound 19 showed a reduced tendency to elevate plasma transaminase levels, an indicator of hepatotoxicity. Enantiomerically pure (-)-19, YM-53546, was found to be more potent than the corresponding (+)-enantiomer.

Synthesis and hypolipidemic activity of N-substituted phthalimides. Part V

A series of N-aryl- or N-(1,2,4-triazol-yl)-phthalimides (4a-4i) have been synthesized starting from phthalic anhydride (1) and an appropriate amine (2a-2i). All compounds presented hypolipidemic activity, but compound 4d proved to be the most active and reduced plasma cholesterol and triglyceride levels in Swiss white mice significantly.

Microbial/enzymatic synthesis of chiral drug intermediates

Biocatalytic processes were used to prepare chiral intermediates for pharmaceuticals. These include the following processes. Enzymatic synthesis of [4S-(4a,7a,10ab)]1-octahydro-5-oxo-4-[[(phenylmethoxy) carbonyl]amino]-7H-pyrido-[2,1-b] [1,3]thiazepine-7-carboxylic acid methyl ester (BMS-199541-01), a key chiral intermediate for synthesis of a new vasopeptidase inhibitor. Enzymatic oxidation of the epsilon-amino group of lysine in dipeptide dimer N2-[N[[(phenylmethoxy)carbonyl] L-homocysteinyl] L-lysine)1,1-disulfide (BMS-201391-01) to produce BMS-199541-01 using a novel L-lysine epsilon-aminotransferase from S. paucimobilis SC16113 was demonstrated. This enzyme was overexpressed in E. coli, and a process was developed using recombinant enzyme. The aminotransferase reaction required alpha-ketoglutarate as the amine acceptor. Glutamate formed during this reaction was recycled back to alpha-ketoglutarate by glutamate oxidase from S. noursei SC6007. Synthesis and enzymatic conversion of 2-keto-6-hydroxyhexanoic acid 5 to L-6-hydroxy norleucine 4 was demonstrated by reductive amination using beef liver glutamate dehydrogenase. To avoid the lengthy chemical synthesis of ketoacid 5, a second route was developed to prepare the ketoacid by treatment of racemic 6-hydroxy norleucine (readily available from hydrolysis of 5-(4-hydroxybutyl) hydantoin, 6) with D-amino acid oxidase from porcine kidney or T. variabilis followed by reductive amination to convert the mixture to L-6-hydroxynorleucine in 98% yield and 99% enantiomeric excess. Enzymatic synthesis of (S)-2-amino-5-(1,3-dioxolan-2-yl)-pentanoic acid (allysine ethylene acetal, 7), one of three building blocks used for synthesis of a vasopeptidase inhibitor, was demonstrated using phenylalanine dehydrogenase from T. intermedius. The reaction requires ammonia and NADH. NAD produced during the reaction was recycled to NADH by oxidation of formate to CO2 using formate dehydrogenase. Efficient synthesis of chiral intermediates required for total chemical synthesis of a beta 3 receptor agonist was demonstrated. These include: (a) microbial reduction of 4-benzyloxy-3-methanesulfonylamino-2'-bromoacetophenone 9 to corresponding (R)-alcohol 10 by S. paucimobilis SC16113, (b) enzymatic resolution of racemic alpha-methyl phenylalanine amide 11 and alpha-methyl-4-hydroxyphenylalanine amide 13 by amidase from M. neoaurum ATCC 25795 to prepare corresponding (S)-amino acids 12 and 14, and (c) asymmetric hydrolysis of methyl-(4-methoxyphenyl)-propanedioic acid ethyl diester 15 to corresponding (S)-monoester 16 by pig liver esterase. (S)[1-(acetoxyl)-4-(3-phenyl)butyl]phosphonic acid diethyl ester 21, a key chiral intermediate required for total chemical synthesis of BMS-188494 (an anticholesterol drug) was prepared by stereoselective acetylation of racemic [1-(hydroxy)-4-(3-phenyl)butyl]phosphonic acid diethyl ester 22 using G. candidum lipase. Lipase-catalyzed stereoselective acetylation of racemic 7-[N,N'-bis-(benzyloxy-carbonyl)N-(guanidinoheptanoyl)]-alpha-hydroxy-glycine 24 to corresponding S-(-)-acetate 25 was demonstrated. S-(-)-acetate 25 is a key intermediate for total chemical synthesis of (-)-15-deoxyspergualin 23, an immunosuppressive agent and antitumor antibiotic. Stereoselective microbial reduction of (1S)[3-chloro-2-oxo-1-(phenyl-methyl)propyl] carbamic acid, 1,1-dimethyl-ethyl ester 26 to corresponding chiral alcohol 27a (a key chiral intermediate for HIV protease inhibitors) was also demonstrated. Stereospecific enzymatic hydrolysis of racemic epoxide RS-1-[2',3'-dihydro benzo[b]furan-4'-yl]-1,2-oxirane 29 the corresponding R-diol 30 and unreacted chiral S-epoxide 28 was demonstrated using R. glutinis and A. niger. Dynamic resolution of racemic diol RS-1-[2',3'-dihydrobenzo[b]furan-4'-yl]-ethane-1,2-diol 32 to corresponding S-diol S-1-[2',3'-dihydrobenzo[b]furan-4'-yl]-ethane-1,2-diol 31 was demonstrated using C. boidinii and P. methanolica. Chiral (S)-epoxide 28 and (S)-diol 31 are key intermediates for a new prospective circadian modulator drug. Enzymatic resolution of racemic 2-pentanol and 2-heptanol by lipase B from Candida antarctica was demonstrated. S-(+)-2-pentanol is a key chiral intermediate required for synthesis of anti-Alzheimer's drugs.

Hypocholesterolemic activity of hesperetin derivatives

Hesperetin ester and ether derivatives possessing a long alkyl chain were synthesized for examining their hypocholesterolemic activities in high cholesterol-fed mice. Hesperetin 7-O-lauryl ether (4b) and hesperetin 7-O-oleyl ether (4e) exhibited strong cholesterol-lowering effects.

Synthesis and structure-activity studies of novel orally active non-terpenoic 2,3-oxidosqualene cyclase inhibitors

New orally active non-terpenoic inhibitors of human 2,3-oxidosqualene cyclase (hOSC) are reported. The starting point for the optimization process was a set of compounds derived from a fungicide project, which in addition to showing high affinity for OSC from Candida albicans showed also high affinity for human OSC. Common structural elements of these inhibitors are an amine residue and an electrophilic carbonyl C atom embedded in a benzophenone system, which are at a distance of about 10.7 A. Considering that the keto moiety is in a potentially labile position, modifications of the substitution pattern at the benzophenone as well as annelated heteroaryl systems were explored. Our approach combined testing of the compounds first for increased binding affinity and for increased stability in vitro. Most promising compounds were then evaluated for their efficacy in lowering plasma total cholesterol (TC) and plasma low-density lipoprotein cholesterol (LDL-C) in hyperlipidemic hamsters. In this respect, the most promising compounds are the benzophenone derivative 1.fumarate and the benzo[d]isothiazol 24.fumarate, which lowered TC by 40% and 33%, respectively.

Syntheses and biological evaluation of novel quinuclidine derivatives as squalene synthase inhibitors

Squalene synthase (E.C. 2.5.1.21) catalyses the reductive dimerization of two molecules of farnesyl diphosphate to form squalene and is involved in the first committed step in cholesterol biosynthesis. Inhibition of this enzyme is therefore an attractive target for hypocholesterolemic strategies. A series of quinuclidine derivatives incorporating a tricyclic system was synthesized and evaluated for their ability to inhibit squalene synthase in vitro. A 9H-fluorene moiety was found to be optimal as the tricyclic system for potent inhibitory activity. Improved activity can be achieved with a conformationally constrained three-atom linkage connecting the tricyclic system with the quinuclidine nucleus. Among these compounds, (Z)-3-[2-(9H-fluoren-2-yloxy)ethylidene]-quinuclidine hydrochloride 31 was found to be a potent inhibitor of squalene synthase derived from hamster liver and human hepatoma cells with IC(50) values of 76 and 48 nM, respectively. Oral dosing of compound 31 demonstrated effective reduction of plasma non-HDL cholesterol levels in hamsters.

Synthesis of a biotin-tagged photoaffinity probe of 2-azetidinone cholesterol absorption inhibitors

The design and synthesis of a biotin-tagged photoreactive analogue C-4 of the cholesterol absorption inhibitor Ezetimibe is described. Photoaffinity labeling of intestinal brush border membrane vesicles with C-4 and subsequent streptavidin-biotin chromatography leads to selective extraction of a 145 kDa integral membrane protein as the molecular target for cholesterol absorption inhibitors.

Microsomal triglyceride transfer protein inhibitors: discovery and synthesis of alkyl phosphonates as potent MTP inhibitors and cholesterol lowering agents

A series of newly synthesized phosphonate esters were evaluated for their effects on microsomal triglyceride transfer protein activity (MTP). The most potent compounds were evaluated for their ability to inhibit lipoprotein secretion in HepG2 cells and to affect VLDL secretion in rats. These inhibitors were also found to lower serum cholesterol levels in a hamster model upon oral dosing.

Synthesis of novel 4,1-benzoxazepine derivatives as squalene synthase inhibitors and their inhibition of cholesterol synthesis

Modification of the carboxyl group at the 3-position and introduction of protective groups to the hydroxy group of the 4,1-benzoxazepine derivative 2 (metabolite of 1) were carried out, and the inhibitory activity for squalene synthase and cholesterol synthesis in the liver was investigated. Among these compounds, the glycine derivative 3a and beta-alanine derivative 3f exhibited the most potent inhibition of squalene synthase prepared from HepG2 cells (IC(50) = 15 nM). On the other hand, the piperidine-4-acetic acid derivative 4a, which was prepared by acetylation of 3j, was the most effective inhibitor of cholesterol synthesis in rat liver (ED(50) = 2.9 mg/kg, po). After oral administration, 4a was absorbed and rapidly hydrolyzed to deacylated 3j. Compound 3j was detected mainly in the liver, but the plasma level of 3j was found to be low. Compounds 3j and 4a were found to be competitive inhibitors with respect to farnesyl pyrophosphate. Further evaluation of 4a as a cholesterol-lowering and antiatherosclerotic agent is underway.

6alpha-ethyl-chenodeoxycholic acid (6-ECDCA), a potent and selective FXR agonist endowed with anticholestatic activity

A series of 6alpha-alkyl-substituted analogues of chenodeoxycholic acid (CDCA) were synthesized and evaluated as potential farnesoid X receptor (FXR) ligands. Among them, 6alpha-ethyl-chenodeoxycholic acid (6-ECDCA) was shown to be a very potent and selective FXR agonist (EC(50) = 99 nM) and to be endowed with anticholeretic activity in an in vivo rat model of cholestasis.

[Crystalline polymorphism of eflucimibe]

The importance, in therapeutics, of the concept of bioavailability and on-going quality research in the formulation of a drug has prompted us to examine the crystalline polymorphism of eflucimibe as from the research phase. This study has been carried out by re-crystallization of the product in organic solvents having a different polarity in a variety of experimental temperature and pressure conditions, then, subsequently, by re-cooling the previously dissolved substance. The analytical methods applied to identify and then describe the polymorphic forms are thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction from synchrotron radiation (XRPD), infrared spectrometry (IR), solid-state nuclear magnetic resonance spectrometry (SSNMR) and lastly maximum solubility measurements. By means of XRPD, two polymorphic forms called A and B have been clearly identified at ambient temperature. These two crystalline forms were obtained in a reproducible way, then described by DSC, XRPD, IR and SSNMR. Differential scanning calorimetry analysis has shown for polymorphic form A two endothermic phenomena with low energy at about 35 masculine and 118 degrees C attributed by XRDP to conformational polymorphism. The complex endothermic event that extends between 75 masculine and 105 degrees C appears to correspond to successive alterations of a lamellar structure. The solid-solid transition observed at 110 degrees C is due to a change of crystalline phase, then the melting point occurring at about 130 degrees C. For form B, two changes of crystalline phase are clearly observed at about 80 masculine and 120 degrees C. The reversibility of these changes was observed by thermomicroscopy in polarized light. Form A, which is less soluble in absolute ethanol than form B, is the more stable thermodynamically in the temperature range from 25 masculine to 50 degrees C where the data have been obtained. The Van't Hoff diagram layout for each polymorphic form appears to reveal an A<-->B transition temperature in a temperature range lower than 25 degrees C. This study, undertaken as from the research phase, has enabled us to highlight the polymorphism of this new chemical entity by means of XRDP by explaining the nature of the endothermic phenomena observed by DSC, and lastly identify the thermodynamically more stable polymorphic form, thus contributing to a better knowledge of this future drug.

Ezetimibe. Schering-Plough

Ezetimibe (Sch-58235) is a cholesterol absorption inhibitor under development by Schering-Plough (SP), in collaboration with Merck, for the potential treatment of hypercholesterolemia. In late December 2001, the companies filed an NDA in the US for this indication. SP is studying ezetimibe as a monotherapy for lowering lipid levels, and also in combination with commonly used statins therapies. The company believes that ezetimibe will have additive effects with the statins, inhibiting the absorption of cholesterol in the intestine, while the statins work by inhibiting the production of cholesterol in the liver. In May 2000, SP and Merck signed an agreementfor the codevelopment of ezetimibe covering its uses as a monotherapy, in combination with statins, and as a fixed combination with simvastatin. In December 2001, Merck and SP expanded their partnership launched in the US in 2000, to develop and market ezetimibe. In August and September 2001, Credit Suisse First Boston predicted ezetimibe sales of US $420 million in 2003 and US $959 million in 2004. Analysts at Salomon Smith Barney predicted in November 2001 that the product would be launched in 2003.

Synthesis of the C1-C21 (C1'-C21') fragment of the dimeric polyketide natural product SCH 351448

[structure: see text] A convergent, stereoselective assembly of the C1-C21 (C1'-C21') fragment of SCH 351448, a 28-membered bis-lactone natural product, has been developed. A highly efficient approach to this fragment assembles 75% of the carbon skeleton and all the stereochemical elements present in the natural product. In addition, an interesting boron ligand effect on the diastereoselectivity of a key aldol reaction with methyl ketone-derived enolborinates is reported.