Benzothiazole hydroxy ureas as inhibitors of 5-lipoxygenase: use of the hydroxyurea moiety as a replacement for hydroxamic acid.

A novel series of N-[(2-benzothiazolylthio)alkyl]-N'-hydroxyurea derivatives (9-25) was synthesized and evaluated for biological activity as inhibitors of 5-lipoxygenase both in vivo (mouse zymosan peritonitis assay) and in vitro (Ca2+ ionophore-stimulated human peripheral blood leukocyte model). The compounds of this series were based on the corresponding hydroxamic acid derivatives (1, 3, 4, and 5) which were moderately active in vitro but inactive in vivo. A number of compounds in the hydroxyurea series exhibited oral activity for 5-lipoxygenase inhibition. Results of studies relating structure to in vivo and in vitro 5-lipoxygenase activity are reported.

Enhancement of in vitro lipopolysaccharide-stimulated interleukin-1 production by levamisole.

The production of interleukin-1 (IL-1) by the P388D1 mouse macrophage cell line and by adherent peritoneal exudate cells (PMs) was examined. In vitro IL-1 production by P388D1 cells treated with lipopolysaccharide (LPS) was enhanced by coculture with levamisole (0.1 to 10 microM). Oral administration of levamisole (3 mg/kg) to mice also resulted in potentiation of in vitro IL-1 production by thioglycollate-elicited peritoneal macrophages in response to in vitro LPS stimulation. Potentiation was approximately twofold. IL-1 production in the absence of LPS by either the P388D1 cells or the PMs was nil, and levamisole did not directly stimulate IL-1 production in these cases. IL-1 activity in the culture supernatants was measured by thymocyte comitogenic assays. The immunochemical identify of the thymocyte comitogenic activity as IL-1 alpha was confirmed by neutralization with a specific goat anti-mouse IL-1 alpha antiserum. These results suggest that one mechanism by which levamisole acts to normalize and restore immune responses may be enhancing the signals which enable activated macrophages to secrete IL-1.

Antinociceptive action of McN-5195 in rodents: a structurally novel (indolizine) analgesic with a nonopioid mechanism of action.

McN-5195 [(+/-)-trans-3-(2-bromophenyl)-octahydroindolizine] inhibited at nontoxic doses the nociceptive response in tail-pinch, tail-flick and 48 degrees C hot-plate tests of mice, with ED50 values of 38.2, 33.9 and 30.9 mg/kg i.p., respectively, and of rats, with ED50 values (i.p.) of 33.2 mg/kg (tail-flick) and 33.3 mg/kg (hot-plate). The compound was p.o. active in the acetylcholine-induced irritant test (ED50 = 20.1 mg/kg) in mice and the air-induced irritant test (ED50 = 33.2 mg/kg) in rats. McN-5195 blocked thalamic activity (multiunit recordings from the ventral posterolateral nucleus) evoked by noxious stimulation of the contralateral hindlimb of anesthetized rats, but did not alter thalamic activity during non-noxious stimulation. The antinociceptive action of McN-5195 was not blocked by naloxone and was not diminished in morphine-tolerant animals. McN-5195 did not affect arachidonate metabolism and was not active against carrageenan-induced paw edema or in an adjuvant arthritis test in rats. McN-5195 did not bind to opiate, serotonin S1 or S2, dopamine D2, alpha-1, alpha-2, beta adrenergic or gamma-aminobutyric acid-A receptors and did not inhibit the synaptic uptake of norepinephrine, serotonin, dopamine or gamma-aminobutyric acid. McN-5195-induced antinociception was not affected by reserpine or phentolamine pretreatment and was not reduced in clonidine-tolerant animals. Ketanserin and yohimbine inhibited McN-5195-induced antinociception by an indirect mechanism. Tolerance did not develop to chronic administration of McN-5195 (120 mg/kg 3 times per day for 10 days). We conclude that McN-5195 is a structurally novel (indolizine) antinociceptive agent that produces its analgesic action via a nonopioid mechanism, not involving products of arachidonate metabolism.

Effect of tolmetin glycine amide (McN-4366), a prodrug of tolmetin sodium, on adjuvant arthritis in the rat.

The glycine amide of tolmetin sodium (TGA) functions as a prodrug and was demonstrated to be more potent than the parent compound as an inhibitor of developing and established adjuvant arthritis in the female Lewis rat. In contrast, the glycine amide of indomethacin was less potent than indomethacin. The superiority of TGA relative to tolmetin sodium in alleviating this condition was demonstrated by inhibition of paw swelling and reduction of the degenerative bone changes that are associated with the progression of this chronic animal model of rheumatoid arthritis in humans. These properties were not evident when equimolar mixtures of tolmetin sodium and glycine were administered concurrently. Pharmacokinetic analyses revealed that TGA was absorbed completely and hydrolyzed to tolmetin in the female adjuvant arthritic rat. The combined effects of absorption, distribution and hydrolysis of TGA produced lower peak plasma tolmetin levels than an equivalent dose of tolmetin sodium, but plasma concentrations were sustained for a longer period of time contributing to an apparent increase in potency. Furthermore, TGA displayed a decreased propensity to cause gastrointestinal irritation compared to tolmetin sodium. Several additional amino acid amides of tolmetin were similar to the glycine amide in exhibiting increased potency and reduced gastrointestinal toxicity in comparison to equivalent doses of tolmetin sodium.

Substance P, neurokinin A, and neurokinin B induce generation of IL-1-like activity in P388D1 cells. Possible relevance to arthritic disease.

Near nanomolar concentrations of substance P induce production of IL-1 or an IL-1-like activity in the mouse macrophage cell line P388D1. Moreover, this could be accomplished with the carboxyl-terminal octapeptide substance P4-11, and could be inhibited with the substance P antagonist [D-Pro2, D-Trp7,9]-substance P. Two other mammalian neurokinins, neurokinin A and neurokinin B, were also found to induce secretion of IL-1-like activity in P388D1 cells. These findings suggest that activation of immune cells by neuromodulators can contribute to the maintenance of the chronic inflammatory state and the immunopathology observed in arthritic disease mediated by IL-1. The results also suggest that one approach to the treatment of rheumatoid arthritis might be to attempt to inhibit the local effects of immuno-modulatory neuropeptides, specifically the neurokinins, in affected joints.

Potentiation of Balb/3T3 fibroblast proliferative response by interleukin-1 and epidermal growth factor.

Balb/3T3 fibroblasts respond to interleukin-1 (IL-1) by proliferating in a dose-dependent fashion. Increasing proliferative responses were observed with increasing IL-1 concentration in serum-free medium when the medium was supplemented with insulin, transferrin, and selenium. This response was evident only if the cell culture medium also contained the cyclooxygenase inhibitor indomethacin. When another fibroblast mitogen, epidermal growth factor (EGF) was cocultured with either purified monocyte-derived IL-1 beta or recombinant IL-1 beta, there was a potentiation of proliferation above the expected additive response. Unexpectedly, the response to recombinant IL-1 alpha was only additive with EGF. This suggests that IL-1-mediated activation of synovial fibroblasts in rheumatoid arthritis may be compounded by EGF as well as by other fibroblast mitogens secreted by cells found in the joint. The results further suggest that IL-1 and EGF interactions may play a significant role in wound healing, scarring, and bone resorption. In addition, these results imply that there may be different cellular activation pathways brought to bear in vivo which may depend, in part, on the IL-1 isotype available.

Non-selective inhibition of mammalian protein kinases by flavinoids in vitro.

In vitro, the flavinoids quercetin, morin, and rutin produced comparable inhibition of protein kinase C prepared from bovine brain, the epidermal growth factor (EGF)-stimulated tyrosine specific protein kinase associated with A431 cell membranes, and the cAMP-stimulated protein kinase activity associated with rat brain tubulin. Concentrations producing 50% inhibition (IC50's) were in the 10 microM range. These findings demonstrate the lack of specificity of the flavinoids toward cyclic nucleotide-dependent vs cyclic nucleotide-independent protein kinases.

Identification of some interleukin-1 (IL-1) sensitive organs in vivo using the induction of ornithine decarboxylase (ODC) following injection of recombinant IL-1 beta in mice.

Intraperitoneal (i.p.) and intravenous (i.v.) injection of human recombinant interleukin-1 beta (rIL-1 beta) in mice produced a 2-4 fold induction of ornithine decarboxylase (ODC) in liver and heart six hours after administration. Lymphoid organs (thymus and spleen) and brain did not respond to rIL-1 beta administration with significant increases in ODC. IL-1-induced responses in heart seemed not to be secondary to stress induced catecholamine release since the beta-adrenergic antagonist propranolol did not inhibit the induction of ODC produced by injection rIL-1 beta. Injection of 10 micrograms bacterial lipopolysaccharide (LPS), an inducer of IL-1 synthesis, exhibited a pattern of tissue responsiveness which was distinct from the responses elicited by rIL-1 beta, most notably a marked 5-fold induction of ODC in spleen. The differences in the responses of various organs to rIL-1 beta vs. LPS suggested that the in vivo effects of LPS may involve more than stimulation of the release of IL-1. The identification of heart as an IL-1 sensitive tissue merits further study to define the contribution of IL-1 to cardiac physiology and pathophysiology.

Antagonism by ETYA of the effects of leukotrienes on ileum and lung parenchymal strips independent of effects on arachidonic acid metabolism.

5,8,11,14-Eicosatetraynoic acid (ETYA), a compound which inhibits both the cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism, antagonized the contraction of segments of guinea-pig ileal longitudinal muscle produced by SRS-A (IC50 = 2.73 microM). This activity was unaffected by pretreatment of the tissues with 10 microM indomethacin. Phenidone, another mixed cyclooxygenase-lipoxygenase inhibitor, was inactive. FPL-55712, an SRS-A antagonist, was a very potent inhibitor (IC50 = 0.011 microM). BW755C and NDGA nonselectively inhibited the contractions of the guinea-pig ileal longitudinal muscle induced by SRS-A or histamine. ETYA antagonized the contraction of the guinea-pig ileal strip produced by 6 nM synthetic LTC4 (IC50 = 9.3 microM). FPL-55712 demonstrated an IC50 of 0.3 microM in a similar series of experiments. ETYA, 1, 3 or 10 microM did not inhibit the contractions elicited by 0.5 microM of histamine. This was not a tissue-selective effect since 100 microM ETYA antagonized the LTC4-induced contraction of the guinea-pig lung parenchymal strip preparation. These data demonstrate that ETYA antagonized the contractile effect of the leukotrienes on tissues from the gastrointestinal tract and lung. Furthermore, the inability of indomethacin or phenidone to inhibit the contractile response suggests that antagonism by ETYA may occur by a mechanism independent of cyclooxygenase and lipoxygenase enzymes.

Indolo[2,1-c][1,4]benzodiazepines: a new class of antiallergic agents.

A series of 12-(cyclic alkylamino)-6H-indolo[2,1-c][1,4]benzodiazepines were synthesized that possess antihistamine and antiserotonin activities as well as ability to inhibit mediator release. Compound 6a, 12-(4-methyl-1-piperazinyl)-6H-indolo[2,1-c][1,4]benzodiazepine was a more potent inhibitor of serotonin release than disodium cromoglycate (DSCG) and ketotifen and approximately equivalent to oxatomide. In the in vivo tests (PCA and ALA), compound 6a was equivalent or superior to DSCG and oxatomide. These agents have potential for the treatment of a variety of allergic conditions.

Replacement of aromatic or heteroaromatic groups in nonsteroidal antiinflammatory agents with the ferrocene group.

Ferrocene analogues of the antiinflammatory agents tolmetin (1), fenbufen (2), flurbiprofen (3), and fenclofenac (4) were synthesized and tested for biological activity. The derivatives exhibited little or no antiarthritic or platelet antiaggregatory activity, indicating that the ferrocene moiety is a poor bioisostere for aromatic or heteroaromatic groups in nonsteroidal antiinflammatory agents.