Anti-inflammatory 17beta-thioalkyl-16alpha,17alpha-ketal and -acetal androstanes: a new class of airway selective steroids for the treatment of asthma.

The synthesis and anti-inflammatory potencies of a new class of 17beta-thioalkyl-16alpha,17alpha-ketal and -acetal androstanes are described. This new class of steroids was made by fragmentation of 2-thioxo-1,2-dihydropyrid-1-yl esters of the corresponding 17-acids to the 17-radical. The radical generated was trapped using a variety of radicophilic disulfides, giving a steroidal D-ring having acetal or ketal functionality at C-16 and C-17, together with a sulfide link at C-17. Compounds from this series bind to the glucocorticoid receptor with high potency and are functional agonists as measured by their ability to induce tyrosine aminotransferase activity in a rat hepatic cell line in vitro. These 17beta-thioalkyl androstanes potently inhibit Sephadex-induced rat lung inflammation when administered directly into the airways. The high topical potency, together with a low propensity to induce systemic glucocorticoid-like side effects (rat thymus involution), provides the present compounds with a high degree of airway selectivity compared with currently available inhaled glucocorticoids. The presently described 17beta-thioalkyl-16alpha,17alpha-ketal androstanes may be useful for therapies for inflammatory diseases such as asthma.

New low-density lipoprotein receptor upregulators acting via a novel mechanism.

The synthesis and biological activity of a new series of benzamides and related compounds that upregulate the expression of the low-density lipoprotein (LDL) receptor in human hepatocytes (HepG2 cells) by a novel mechanism are described. The lead compound, N-[5-[(3-cyclohexylpropionyl)amino]-2-methylphenyl]-4-hydroxybe nzamide (1, RPR102359), increased the expression of the LDL receptors in HepG2 cells by 80% when tested at a concentration of 3 microM. Mevinolin (lovastatin) was found to increase the LDL receptor expression by 70% at the same concentration. In contrast to mevinolin, 1 was found to have no effect on cholesterol biosynthesis in liver homogenates or in HepG2 cells at doses where substantial upregulation of the LDL receptor was observed and thus stimulated LDL receptor expression by a novel mechanism.

Acyl-CoA:Cholesterol O-acyltransferase (ACAT) inhibitors. 2. 2-(1,3-Dioxan-2-yl)-4,5-diphenyl-1H-imidazoles as potent inhibitors of ACAT.

The second in this series of papers concerns our further investigations into the search for a potent bioavailable acyl-CoA:cholesterol O-acyltransferase (ACAT) inhibitor suitable for the treatment of atherosclerosis. The design, synthesis, and structure-activity relationship for a series of ACAT inhibitors based on the 2-(1,3-dioxan-2-yl)-4,5-diphenyl-1H-imidazole pharmacophore are described. Compounds such as 13a bearing simple alkyl or hydroxymethyl substituents at the 5-position of the 1,3-dioxane ring are potent bioavailable inhibitors of the rat hepatic microsomal enzyme in vitro (IC50 < 100 nM) but are only weak inhibitors of the human hepatic enzyme. We have found however that 1,3-dioxanes substituted at the 5-cis position with pyrazolylalkyl or aminoalkyl groups are potent inhibitors in vitro of human macrophage ACAT, the potency depending on the nature of the terminal heterocycle and the length of the alkyl chain. An ex vivo bioassay herein demonstrates that potent inhibitors such as 13t (IC50 = 10 nM) which contain lipophilic terminal heterocycles do not appear to be systematically available. Less potent but more water soluble compounds such as 13h (IC50 = 60 nM) and 13n (IC50 = 70 nM) are absorbed following oral dosing and achieve plasma levels significantly in excess of their IC50 for ACAT inhibition. These compounds are therefore possible candidates for further investigation as oral antiatherosclerotic agents.

Suppression of eosinophil function by RP 73401, a potent and selective inhibitor of cyclic AMP-specific phosphodiesterase: comparison with rolipram.

1. We have investigated the inhibitory potency of RP 73401, a novel, highly selective and potent inhibitor of cyclic AMP-specific phosphodiesterase (PDE IV), against partially-purified PDE isoenzymes from smooth muscle and the particulate PDE IV from guinea-pig eosinophils. The inhibitory effects of RP 73401 on the generation of superoxide (.O2-), major basic protein (MBP) and eosinophil cationic protein (ECP) from guinea-pig eosinophils have also been studied. 2. RP 73401 potently inhibited partially-purified cyclic AMP-specific phosphodiesterase (PDE IV) from pig aortic smooth muscle (IC50 = 1.2 nM); it was similarly potent against the particulate PDE IV from guinea-pig peritoneal eosinophils (IC50 = 0.7 nM). It displayed at least a 19000 fold selectivity for PDE IV compared to its potencies against other PDE isoenzymes. Rolipram was approximately 2600 fold less potent than RP 73401 against pig aortic smooth muscle PDE IV (IC50 = 3162 nM) and about 250 times less potent against eosinophil PDE IV (IC50 = 186 nM). 3. Solubilization of the eosinophil particulate PDE IV increased the potency of rolipram 10 fold but did not markedly affect the potency of RP 73401. A similar (10 fold) increase in the PDE IV inhibitory potency of rolipram, but not RP 73401, was observed when eosinophil membranes were exposed to vanadate/glutathione complex (V/GSH). 4. Reverse transcription polymerase chain reaction (RT-PCR), using primer pairs designed against specific sequences in four distinct rat PDE IV subtype cDNA clones (PDE IVA-D), showed only mRNA for PDE IVD in guinea-pig eosinophils. PDE IVD was also the predominant subtype expressed in pig aortic smooth muscle cells. 5. RP 73401 (Kiapp = 0.4 nM) was 4 fold more potent than (+/-)-rolipram (Kiapp = 1.7 nM) in displacing[3H]-(+/-)-rolipram from guinea-pig brain membranes.6. In intact eosinophils, RP 73401 potentiated isoprenaline-induced cyclic AMP accumulation(EC50 = 79 nM). RP 73401 also inhibited leukotriene B4-induced generation of *02- (IC50 = 25 nM), and the release of major basic protein (ICo = 115 nM) and eosinophil cationic protein (IC50 = 7 nM). Rolipram was 3-14 times less potent than RP 73401.7. Thus RP 73401 is a very potent and selective PDE IV inhibitor which suppresses eosinophil function suggesting that it may be a useful agent for the treatment of inflammatory diseases such as asthma. The greatly different inhibitory potencies of rolipram against PDE IV from smooth muscle and eosinophils(in contrast to the invariable effects of RP 73401) are unlikely to be attributable to diverse PDE IV subtypes but suggest distinct interactions of the two inhibitors with the enzyme.

Selective type IV phosphodiesterase inhibitors as antiasthmatic agents. The syntheses and biological activities of 3-(cyclopentyloxy)-4-methoxybenzamides and analogues.

The syntheses and biological activities of a number of benzamide derivatives, designed from rolipram, which are selective inhibitors of cyclic AMP-specific phosphodiesterase (PDE IV), are described. The effects of changes to the alkoxy groups, amide linkage, and benzamide N-phenyl ring on the inhibition of the cytosolic PDE IV from pig aorta have been investigated. As a result, some highly potent and selective PDE IV inhibitors have been identified. The most potent compounds have been further evaluated for their inhibitory potencies against PDE IV obtained from and superoxide O2- generation from guinea pig eosinophils in vitro. Selected compounds have also been examined for their activities in inhibiting histamine-induced bronchospasm in anaesthetized guinea pigs. 3-(Cyclopentyloxy)-N-(3,5-dichloro-4-pyridyl)-4-methoxybenzamide (15j) showed exceptional potency in all tests and may have therapeutic potential in the treatment of asthma.

Acyl-CoA:cholesterol O-acyl transferase (ACAT) inhibitors. 1. 2-(Alkylthio)-4,5-diphenyl-1H-imidazoles as potent inhibitors of ACAT.

A potent, bioavailable ACAT inhibitor may have beneficial effects in the treatment of atherosclerosis by (i) reducing the absorption of dietary cholesterol, (ii) reducing the secretion of very low density lipoproteins into plasma from the liver, and (iii) preventing the transformation of arterial macrophages into foam cells. We have found that a mevalonate derivative 2, which contains a 4,5-diphenyl-1H-imidazol-2-yl moiety, inhibits rat hepatic microsomal ACAT in vitro and produces a significant hypocholesterolemic effect in the cholesterol-fed rat. Structure-activity relationships for analogues of 2 demonstrate that the 4,5-diphenyl-1H-imidazole moiety is a pharmacophore for inhibition of rat microsomal ACAT.

Salmonella infections in infants in Hawaii.

In a 10-year cohort of 117 infants hospitalized in Honolulu with Salmonella infections, there were 12 infants with bacteremia or complications (simple bacteremia, 7; bacteremia with probably unrelated concurrent infection, 2; serious complications, 3). The rate of serious complications in this cohort was low and occurred only in infants with previous chronic illness or clinically obvious extraintestinal infection at the time of presentation. Antibiotics were not shown to be of benefit in reducing the frequency of complications; however, the sample size was too small to make definitive conclusions. These data do not support the contention that infants with Salmonella gastroenteritis are at increased risk of complications and should therefore be treated with antibiotics. Rather, the same clinical risk factors for sepsis that apply to all infants also apply to infants with Salmonella gastroenteritis and the decision to begin antibiotic treatment should be based on similar clinical information.

Effect of sodium 2-n-pentadecyl-benzimidazole-5-carboxylate (M & B 35347B), an inhibitor of acetyl-CoA carboxylase, on lipogenesis and fat deposition in obese hyperglycaemic (ob/ob) and lean mice.

A high rate of lipogenesis in obese mice plays a major role in their excessive deposition of body lipid. Inhibition of lipogenesis may decrease their obesity. Therefore, we have investigated the effects of sodium 2-n-pentadecyl-benzimidazole-5-carboxylate (M & B 35347B), an inhibitor of acetyl-CoA carboxylase, on in-vivo lipogenesis in obese and lean mice. It significantly inhibited hepatic cholesterol and fatty acid synthesis, measured using 3H2O, in both lean and obese mice, with or without a glucose load. Brown adipose tissue (scapular) lipogenesis was decreased by M & B 35347B in obese mice but not in lean mice. In white adipose tissue, M & B 35347B did not affect the rates of lipogenesis in either scapular white, inguinal or epididymal depots of obese mice, or the inguinal and scapular white depot of lean mice. However, it doubled lipogenesis in the epididymal fat pad of lean mice. After a glucose load, lipogenesis in the lean epididymal fat pad was not inhibited but that in the inguinal depot was. M & B 35347B inhibited acetyl CoA carboxylase of adipose tissue in vitro but only a small inhibition was detected after in-vivo treatment. These different responses according to type of mouse, treatment and tissue site appear to stem from differences in inhibitor concentration and the importance of acetyl CoA carboxylase as the rate-limiting enzyme of lipogenesis. The weight gain of obese mice dosed orally (200 mg M & B 35347B/kg daily) for 60 days was unaffected and they continued to deposit excess body fat. This presumably occurred because of the lack of inhibition of fatty acid synthesis in white adipose tissue.

Heterocyclic analogues of chlorcyclizine with potent hypolipidemic activity.

A series of [alpha-(heterocyclyl)benzyl]piperazines was synthesized and their effect of reducing serum cholesterol and triglyceride levels in the rat was evaluated. A systematic exploration of the structure-activity relationships led to the synthesis of (R,S)-(3,5-dimethylisoxazol-4-yl)[4-(1-methylethyl)phenyl] (4-methylpiperazin-1-yl)methane dihydrochloride (M&B 31 426), which had potent activity in lowering serum lipid levels at a daily oral dose of 2 mg/kg and was 100 times more potent than clofibrate.

Acylthioxanthenes: agents which selectively reduce decerebrate rigidity in the cat.

A series of 2-acylthioxanthene-delta 9 (gamma)-propylamines was synthesized, and their effect of reducing the intercollicular decerebrate rigidity in the cat was evaluated. The compound exhibiting the greatest separation between the dosage that reduced rigidity and that which caused sedation was (Z)-2-propionyl-9-[3-(dimethylamino)propylidene]thioxanthene. The separation of Z and E isomers was monitored by 1H NMR spectroscopy, using an europium shift reagent.