N-imidazolyl derivatives of the napththalene and chroman rings as thromboxane A2 synthase inhibitors

Synthesis and evaluation of heteroaryl-substituted dihydronaphthalenes and indenes: potent and selective inhibitors of aldosterone synthase (CYP11B2) for the treatment of congestive heart failure and myocardial fibrosis

In this study, the synthesis and biological evaluation of heteroaryl-substituted dihydronaphthalenes and indenes (1-16) is described. The compounds were tested for activity by use of human CYP11B2 expressed in fission yeast and V79 MZh cells and for selectivity by use of human CYP11B1, CYP17, and CYP19. The most active inhibitor was the 6-methoxydihydronaphthalene 4 (IC(50) = 2 nM), showing a K(i) value of 1.3 nM and a competitive type of inhibition. The 5-methoxyindene 3 was found to be the most selective CYP11B2 inhibitor (IC(50) = 4 nM; CYP11B1 IC(50) = 5684 nM), which also showed only marginal inhibition of human CYP3A4 and CYP2D6. Docking and molecular dynamics studies using our homology-modeled CYP11B2 structure were performed to understand some structure-activity relationships. Caco-2 cell experiments revealed highly cell-permeable compounds, and metabolic studies with 4 using rat liver microsomes showed sufficient stability.

1-imidazolyl(alkyl)-substituted di- and tetrahydroquinolines and analogues: syntheses and evaluation of dual inhibitors of thromboxane A(2) synthase and aromatase

A series of 1-imidazolyl(alkyl)-substituted quinoline, isoquinoline, naphthalene, benzo[b]furan, and benzo[b]thiophene derivatives was synthesized as dual inhibitors of thromboxane A(2) synthase (P450 TxA(2)) and aromatase (P450 arom). Dual inhibition of these enzymes could be a novel strategy for the treatment of mammary tumors and the prophylaxis of metastases. The most potent dual inhibitors, 5-(2-imidazol-1-ylethyl)-7,8-dihydroquinoline (31) (P450 TxA(2): IC(50) = 0.29 microM; P450 arom: IC(50) = 0.50 microM) and its 5, 6-saturated analogue 30 (P450 TxA(2): IC(50) = 0.68 microM; P450 arom: IC(50) = 0.38 microM), showed a stronger inhibition of both target enzymes than the reference compounds (dazoxiben: IC(50) = 1.1 microM; aminoglutethimide: IC(50) = 18.5 microM). For the determination of the in vivo activity, the influence of selected compounds on serum TxB(2) concentration was examined in rats. Compound 30 (8.5 mg/kg body weight) led to a reduction of the TxB(2) serum level of 78%, 71%, and 51% after 3, 5, and 8 h, respectively (dazoxiben: 60%, 34%, and 36%). Selectivity was studied toward some enzymes of the steroidogenic and eicosanoid pathways. P450 17 was inhibited by selected compounds only at high concentrations. Compound 30 inhibited P450 scc by 13% (25 microM). Compound 31 did not affect cyclooxygenase and lipoxygenase.

Synthesis and evaluation of azole-substituted tetrahydronaphthalenes as inhibitors of P450 arom, P450 17, and P450 TxA2

In search of potential drugs for the treatment of estrogen- and androgen-dependent cancer as well as the prophylaxis of metastases, tetralones, tetralins, and dihydronaphthalenes bearing a OCH3 substituent at the benzene nucleus and an imidazol-4-yl, imidazol-1-yl, or 1,2,4-triazol-1-yl substituent in 2-position were synthesized with and without C1-spacer between the rings (compounds 2-26). The compounds were tested in vitro for inhibition of the three targets enzymes P450 arom (human placental microsomes), P450 17 (rat testicular microsomes), and P450 TxA2 (citrated human whole blood). To examine selectivity, some compounds were further tested in vitro for inhibition P450 18 (bovine adrenal mitochondria), P450 scc (bovine adrenal mitochondria) and corticoid formation (aldosterone, corticosterone; ACTH stimulated rat adrenal tissue). In vitro, selected compounds were examined in Sprague Dawley rats regarding P450 TxA2 inhibition, reduction of plasma testosterone concentration, antiuterotrophic activity (inhibition of the uterotrophic activity of androstenedione), reduction of plasma estradiol concentration (pregnant mares' serum gonadotropin-primed rats), and mammary tumor inhibiting activity (dimethylbenzanthracene-induced tumor; pre-and postmenopausal model). In the series of imidazol-4-yl compounds, which represent a novelty in the field of azole inhibitors of steroidogenic P450 enzymes, strong inhibitors of P450 arom and/or P450 17 were found; 7-OCH3-2-(imidazol-4-ylmethylene)-1-tetralone (4) and 7-OCH3-2-(imidazol-4-ylmethyl)-tetralin (12) are among the most potent inhibitors of P450 arom in vitro known so far. Compound 4 is a selective inhibitor, whereas 12 shows in addition strong inhibition of P450 17. In contrast to 12, the 6-OCH3 derivative (compound 11) is a selective inhibitor of P450 17, being 50 times more potent than ketoconazole. Some imidazol-1-yl compounds show a marked inhibition of P450 TxA2: 2-(imidazol-1-ylmethyl)-1-tetralone (13) is a selective inhibitor of P450 TxA2, whereas 7-OCH3-2-(imidazol-1-ylmethyl)-tetralin (17) as well 2-(imidazol-1-ylmethyl)-tetralin (16) and 7-OCH3-2-imidazol-1-yl-3, 4-dihydronaphthalene (25) additionally show strong inhibition of P450 arom and P450 17. Regarding the other steroidogenic P450 enzymes as well as corticosterone formation, the compounds show only little inhibitory activity. Aldosterone formation, however, is inhibited at low concentrations. Nevertheless, 4 and 12 are more selective, i.e. inhibit aldosterone synthesis less than the well known inhibitor of P450 arom fadrozole. The compounds show activity in the aforementioned in vivo tests.

Tetrahydronaphthalenes: influence of heterocyclic substituents on inhibition of steroid enzymes P450 arom and P450 17

In search of new leads for selective inhibition of estrogen and androgen biosynthesis, respectively, heterocyclic substituted 2-(arylmethylene)-1-tetralones (1-4, 9-17), 2-(aryl-hydroxymethyl)-1-tetralones (5-8), exo-1a,2,3,7b-tetrahydro-1H-cyclopropa[alpha] naphthalenes (18-24), and 3-alkyl substituted 4,5-dihydronaphtho[1,2-c]pyrazoles (25-27) were synthesized and tested for inhibitory activity toward four steroidogenic enzymes (P450 arom, P450 17, P450 18, and P450 scc, as well as another P450 enzyme, thromboxane A(2) (TXA(2)) synthase. The test compounds inhibited human placental P450 arom, showing a wide range of inhibitory potencies. (Z)-4-Imidazolyl compound 17 was the most potent inhibitor, with a relative potency (rp) of 110 [rp of aminoglutethimide (AG) = 1), rp of fadrozole = 359]. A competitive type of inhibition was shown by the (E)-4-imidazolyl compound 16(rp = 71). On the other hand some of these compounds inhibited rat testicular P450 17. Maximum activity was shown by the 3-pyridyl compound 20 (rp = 10, ro of ketoconazole = 1). 20 was the only compound which exhibited a marked inhibition of TXA(2) synthase (IC(50) = 14.5 microM; IC(50) of dazoxiben = 1.1 microM). Regarding selectivity toward the steroidogenic enzymes, compound 16 was relatively selective toward P450 arom, whereas compound 20 was relatively selective toward P450 17. (P450 arom: K(m) testosterone = 42 nM, K(i)16 = 33 nM, K(i)20 = 3 microM. P450 17: K(m)progesterone = 7 microM, K(i)16 = 9 microM, K(i)20 = 80 nM). 17 and 24 were not selective since they showed strong inhibition of P450 arom (K(i)17 = 26 nM, K(i)24 = 0.12 microM) and P450 17 (K(i) 17 = 0.7 microM, K(i)24 = 0.11 microM).

Long-term thromboxane-synthase inhibition prolongs survival in murine lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease, characterized by nephritis, in which mortality is largely influenced by the severity of renal involvement. As there are evidences that thromboxane (TX)A2 plays an important role in the pathogenesis of lupus nephritis, we decided to assess the effects of long-term suppression of TXA2 synthesis on the progression of the disease, by designing a study of TXA2-synthase inhibition having adequate size to detect an effect on mortality as the primary end-point. Thus, we randomized 362 NZBxNZW mice (11-week-old at entry) to one of the following treatments: a TXA2 synthase inhibitor, FCE 22178 (300 mg/kg daily), saline or cyclophosphamide (5 mg/mouse weekly x 4 weeks) used as reference treatment. The TXA2 synthase inhibitor suppressed TXA2 biosynthesis, as reflected by urinary TXB2 and 2,3-dinor-TXB2 excretion (by 78% and 90%, respectively) and significantly reduced mortality (death rate: 34% vs. 61% in controls, at 37 weeks, P < 0.01). A significant reduction in proteinuria (9 +/- 1.6 vs. 17.3 +/- 2.4 mg/24 hr in FCE 22178 vs. saline, P < 0.01) and glomerular lesions was observed up to 30 weeks but not at 37 weeks. In contrast, cyclophosphamide prevented the development of proteinuria and histologic lesions, and reduced mortality to 8% at 37 weeks. Renal plasma flow and glomerular filtration rate were lower (by 29% and 52%, respectively) in 37-week-old as compared to young NZBxNZW mice. These parameters were further depressed by cyclophosphamide (by 48% and 45% vs. age-matched controls, respectively, P < 0.01) but were not altered significantly by FCE 22178.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a screening assay for the in vitro evaluation of thromboxane A2 synthase inhibitors

Inhibitors of thromboxane A2 (TxA2) synthase are regarded as potentially useful agents in the treatment of cardiovascular diseases and in the prevention of tumour cell metastases. We report here a novel in vitro assay for the evaluation of TxA2 synthase inhibitors. For the determination of inhibitory activity, malondialdehyde (MDA) formation by TxA2 synthase in whole blood was utilized. After reaction with thiobarbituric acid MDA was quantified spectrofluorimetrically. The blank value was obtained by incubation with a selective TxA2 synthase inhibitor. For the screening of compounds the simple MDA assay represents an alternative to the rather expensive and time consuming radioimmunoassay, HPLC and TLC methods. Only for compounds which have been shown to be good inhibitors in the MDA assay should a radioimmunoassay for selective inhibition of TxA2 synthase be performed.

Thromboxane A2 biosynthesis inhibitors: synthesis and evaluation of pyrazolotriazinyl alkanoic acids

A novel series of (6-aryl-4-oxo-pyrazolo 2,3-d] [1,2,5] triazin-3-yl) alkanoic acids was synthesized and evaluated in vitro as thromboxane A2 (TXA2) biosynthesis inhibitors. The experiments were carried out using arachidonic acid (32.8 microM) as a substrate and horse platelet microsomes (HPM) as sources of TXA synthetase. TXB2, a stable breakdown product of TXA2, was determined by radioimmunoassays (RIA). The substances under study, at concentrations ranging from 1.10(-6) M to 1.10(-4) M, significantly inhibited the biosynthesis of TXA2 in vitro. This activity was found to be dose-dependent, the potency of which could be related to structural features of the molecules. Compound 3b, bearing a butanoic side chain in the 3-position and a 4-chloro phenyl ring in the 6-position of the bicyclic system, was the most active derivative in in vitro enzyme inhibition (ID50 = 2.81 x 10(-5) M). Comparison of the spatial configurations of prostaglandin H2 (PGH2 and 3b displayed a good correlation between essential structural moieties of both molecules. In addition, conceptual model for the PGH2 and TX synthetase interactions was applied to compound 3b.