Pharmacologic characterization of the antiinflammatory properties of a new dual inhibitor of lipoxygenase and cyclooxygenase

Antioxidant, anti-inflammatory activities and acute toxicity of the polyherbal formulation: Romix®

CONTEXT

Polyherbal formulations containing different plants are used for the treatment of various diseases. Romix® powder is a polyherbal formulation consisting of 14 traditionally used herbs and is used as a food supplement. There is no information about pharmaceutical activities of Romix®.

OBJECTIVE

This study determined the total phenolic and total flavonoid content, and investigated the antioxidant and anti-inflammatory activities and acute toxicity of Romix®.

MATERIAL AND METHODS

The total phenolics in the extracts were determined colorimetrically by using the Folin-Ciocalteu reagent. The total flavonoid content of the extracts was evaluated by a spectrophotometric method. The quercetin content of the extract was analyzed using the high-performance liquid chromatography (HPLC) method. Antioxidant activity of the extracts was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assays. The anti-inflammatory activity was evaluated by the carrageenan-induced paw edema test in the rat.

RESULTS

The flavonoid and phenolics contents of Romix® were 50.58 and 265.83 mg/g in ethanol extract and 18.60 and 222.50 mg/g in water extract, respectively. Total quercetin content of Romix® was determined as 2.857 mg/g. Antioxidant activity results showed that ethanol extract in 1 mg/mL concentration (4.49775 µg/mL) had moderate antioxidant activity than water extract in the same concentration (4.28191 µg/mL). Intraperitoneal administration of 25 mg/kg Romix® extract exhibited anti-inflammatory activity and inhibited paw swelling at 1, 2, 3, 4, 5 and 6 h in rats with no acute toxicity.

CONCLUSION

These findings suggest that Romix® due to its antioxidant and anti-inflammatory activities may be useful in the prevention or treatment of aging-related and inflammatory diseases.

Inhibitors of p38 mitogen-activated protein kinase: potential as anti-inflammatory agents in asthma?

Asthma is an inflammatory disease of the airways, which in patients with mild to moderate symptoms is adequately controlled by either beta(2)-adrenoceptor agonists or corticosteroids, or a combination of both. Despite this, there are classes of patients that fail to respond to these treatments. In addition, there is a general trend towards increasing morbidity and mortality due to asthma, which suggests that there is a need for new and improved treatments. The p38 mitogen-activated protein kinases (MAPKs) represent a point of convergence for multiple signalling processes that are activated in inflammation and that impact on a diverse range of events that are important in inflammation. Small molecule pyridinyl imidazole inhibitors of p38 MAPK have proved to be highly effective in reducing various parameters of inflammation, in particular cytokine expression. Like corticosteroids, inhibitors of p38 MAPK appear to be able to repress gene expression at multiple levels, for example, by transcriptional, posttranscriptional and translational repression, and this raises the possibility of a similarly broad spectrum of anti-inflammatory activities. Indeed these molecules have proved to be effective in numerous in vitro and in vivo models of inflammation and septicaemia, which suggests that such compounds may be effective as therapeutic agents against inflammatory disorders. Despite these very promising indications of the possible therapeutic use of p38 MAPK inhibitors, a number of events that are p38-dependent are in fact also beneficial to the resolution or modulation of diseases such as asthma. We conclude that the overall effect of p38 MAPK inhibition would be beneficial in inflammatory diseases such as rheumatoid arthritis and asthma. However, these drugs may result in a complex phenotype that will require careful evaluation. Currently, a number of second or third generation inhibitors of p38 MAPK are being tested in phase I and phase II clinical trials.

Preliminary studies on the anti-inflammatory and analgesic activity of the methanolic fraction of the root extract of Tragia involucrata Linn

Tragia involucrata has been widely used in the traditional medicinal system for the treatment of a variety of diseases. The effect of methanolic extract of T. involucrata was studied in different experimental animal models and it was revealed that the extract possesses significant analgesic and anti-inflammatory activity.

Effect of fepradinol on rat hind paw oedema induced by several inflammatory agents

Fepradinol is an effective non-steroidal anti-inflammatory agent. The effect on rat paw oedema induced by various phlogistic agents was investigated. The inhibitory effect of fepradinol (25 mg kg-1, p.o.) on dextran-induced oedema was nearly equal to that of cyproheptadine (10 mg kg-1, p.o.). On oedema induced by platelet-activating factor only fepradinol (25 mg kg-1, p.o.) and phenidone (100 mg kg-1, p.o.) clearly inhibited the inflammatory process. Both the above induced oedemas are thought to be unrelated to prostaglandins in the rat system and therefore, the anti-inflammatory activity against them is not shared by selective cyclo-oxygenase inhibitors. Fepradinol (25 mg kg-1, p.o.) displayed an inhibitory effect on the early and late stage of kaolin- and nystatin-induced oedemas in contrast with indomethacin (10 mg kg-1, p.o.) and piroxicam (10 mg kg-1, p.o.) which only inhibited the late stage. The results obtained in this study confirm that fepradinol is a potent anti-inflammatory agent and indicate that its mechanism of action is different from that of other anti-inflammatory compounds.

Antiarthritic profile of BF-389--a novel anti-inflammatory agent with low ulcerogenic liability

BF-389, dihydro-4-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2-methyl-2H-1,2- oxazin-3(4H)-one, is a potent, orally active, antiarthritic and analgesic agent with low ulcerogenic potential. A comparison of the activity profiles of BF-389 and naproxen showed similarities in: (1) suppression of developing and chronic adjuvant arthritis (AA); (2) maximal inhibitory response, as shown by the E(max) values in the developing and established AA models; (3) inhibition of bone degenerative changes associated with chronic adjuvant arthritis; and (4) analgesic activity in the acetic acid and phenylquinone writhing assays. Though BF-389 has been shown to be a potent inhibitor of cyclooxygenase, IC50 = 0.84 +/- 0.25 microM against the production of PGE2 in vitro, there is a great difference from most cyclooxygenase inhibitors; it also inhibits the 5-lipoxygenase enzyme. For BF-389, the IC50 for in vitro LTB4 formation was found to be 3.65 +/- 1.19 microM. The ulcerogenic potential of BF-389 was compared to that of naproxen using a five-day in vivo ulcerogenic rat assay. The UD50 for naproxen was found to be approximately 30 mg/kg/day, p.o. Based upon efficacy in the DEV AA and EST AA models, UD50/ED50 values for naproxen were estimated to be 0.7 and 1.9, respectively. For BF-389 the UD50 was shown to be 520 (389-695) mg/kg/day, p.o., and the corresponding UD50/ED50 values were calculated to be 84 and 28, respectively, thus demonstrating the wide margin of safety between efficacy and ulcerogenicity in rats.

5-lipoxygenase inhibitors and their anti-inflammatory activities

A wide variety of agents have been reported as 5-LO inhibitors. The majority of the series appear to be lipophilic reducing agents, including phenols, partially saturated aromatics, and compounds containing heteroatom-heteroatom bonds. Many of these are not selective 5-LO inhibitors, but often affect CO and other LOs as well. In vivo systemic activity for many of these has been, in general, disappointing, probably because of poor bioavailability caused by lipophilicity and metabolic instability (oxidation, and conjugation of phenolic compounds). However, topically a number of agents have shown promise for skin inflammation, with Syntex's lonapalene the most advanced of these. Most results published to date appear more disappointing in the allergy/asthma field. More excitingly, a few structural types are selective 5-LO inhibitors which have shown systemic activity in vivo and in the clinic. Abbott's zileuton (136) appears to be one of the leading compounds in this category, along with other hydroxamates such as BW-A4C (129) from Burroughs-Wellcome. Recent selective non-reducing agents such as Wyeth-Ayerst's Wy-50,295 (143) and the similar ICI compounds such as ICI 216800 (145) also hold promise. The enantiospecific effects of (106) and (145) are especially interesting for the design of new inhibitors. If compounds like these validate the hypothesis that inhibition of 5-LO will have a significant anti-inflammatory effect, a redoubling of effort throughout the industry to find second- and third-generation selective agents may be expected. Part of the difficulty in interpreting and comparing the 5-LO literature is the plethora of test methods and activity criteria. As pointed out in the introduction, inhibition of product release from cells, often stimulated with A23187, has commonly been used to demonstrate 5-LO inhibition. However, this type of assay cannot be assumed to be diagnostic for 5-LO inhibition. Only if specificity for 5-LO product generation and (ideally) activity in cell-free enzymes is also shown should mechanistic interpretations be made. Recently, a new class of compounds was found at Merck which inhibited LT biosynthesis without inhibiting 5-LO, but apparently by a novel, specific mechanism. L-655,240 (169) and L-663,536 (MK-886) (170) were both active in human ISN, with IC50 values in the low micromolar range. Both also orally inhibited GPB (< 1 mg/kg). MK-886 was effective in Ascaris-induced asthma in squirrel monkeys, in rat carrageenan pleurisy, in rat Arthus pleurisy, and (topically) in guinea-pig ear oedema induced by A23187.(ABSTRACT TRUNCATED AT 400 WORDS)

Determination of tebufelone, a new anti-inflammatory drug, in plasma and tissue using capillary gas chromatography/stable isotope dilution mass spectrometry

A capillary gas chromatographic/mass spectrometric method for the determination of tebufelone, a new anti-inflammatory drug, in plasma and rat paw tissue is described. Trideuteriated tubufelone was employed as an internal standard and the drug quantified by selected ion monitoring using a mass-selective detector following positive electron ionization (70 eV). Tebufelone was recovered from plasma (greater than 93%) and pulverized paw tissue (greater than 88%) by ethereal extraction. Standard curves were linear between 5 ng ml-1 and 5 micrograms ml-1 with a detection limit (S/N = 2) of 2 ng ml-1. The coefficient of variation for successive injections of standards (200 ng ml-1) or samples (10-1500 ng ml-1) was 7.3% and 8.5%, respectively.

Drug actions on delayed-type hypersensitivity in rats with developing and established adjuvant arthritis

Rats were sensitized by i.d. injection in the base of the tail with Freund's complete adjuvant (FCA) and were challenged i.d. in the dorsal skin with mycobacterial antigen. The 24 hour dermal delayed-type hypersensitivity (DTH) response increased up to 10 days after FCA injection followed by a decrease by day 15 which coincided with the development of adjuvant arthritis (AA). Drug studies were performed, using a 4-day dosing schedule, on optimal DTH elicited on day 10, suboptimal DTH elicited on day 15, and AA (day 16). Cyclosporine, leflunomide and prednisolone significantly inhibited day 10 DTH and AA with no effect on day 15 DTH. Indomethacin and tiaprofenic acid significantly inhibited AA with no effect on either DTH response. Chloroquine, levamisole, D-penicillamine, diazepam and RU38468 had no significant effect on DTH or AA. These findings suggest a complex temporal relationship between AA, DTH and drug actions.

2-substituted indazolinones: orally active and selective 5-lipoxygenase inhibitors with anti-inflammatory activity

1. This paper describes the pharmacological profile of ICI207968, a novel, orally-active and selective inhibitor of 5-lipoxygenase. 2. Inhibition of leukotriene B4 (LTB4) synthesis by 2-substituted indazolinones was not directly related to redox potential but was critically dependent on the nature of the N2 substituent. 2-(3-Pyridylmethyl)-indazolinone (ICI207968) combined selectivity and oral potency. 3. In several in vitro systems ICI207968 exhibited similar lipoxygenase inhibitory potency (IC50 values from 1.5 microM to 6.0 microM) and was approximately 300 times less potent against cyclo-oxygenase, as measured by inhibition of prostaglandin E2 (PGE2) synthesis. 4. ICI207968 also produced selective lipoxygenase inhibition following oral administration in the rat. ED50 values of 2.5, 10 and 25 mg kg-1 p.o. for inhibition of LTB4 release from A23187-stimulated blood were obtained 1, 3 and 5 h after dosing. The compound did not inhibit PGE2 synthesis at oral doses up to 300 mg kg-1. 5. Co-administration of ICI207968 with arachidonic acid, into rabbit dermis, potently inhibited both plasma extravasation and polymorphonuclear leucocyte (PMNL) infiltration induced by this inflammatory fatty acid. The anti-inflammatory potency of a number of intradermally administered indazolinones, with similar redox potentials, was related to their inhibitory potency against leukotriene generation in blood. Oral administration of ICI207968 (100 mg kg-1) in the rabbit inhibited ex vivo leukotriene generation in blood and arachidonic acid-induced skin inflammation. 6. These data demonstrate that ICI207968 is an orally active and selective inhibitor of 5-lipoxygenase which has anti-inflammatory properties. IC1207968 will be a valuable agent for clarifying the biological roles of leukotrienes and the therapeutic potential of 5-lipoxygenase inhibitors.

Inhibition of inflammatory cell infiltration by bicyclic imidazoles, SK&F 86002 and SK&F 104493

The mode of action of the dual inhibitors of eicosanoid metabolism, SK&F 86002 and SK&F 104493 was evaluated on inflammatory cell infiltration induced in mice by carrageenan, monosodium urate crystals, and arachidonic acid. The results were compared to those seen with standard antiinflammatory compounds. Inflammatory cell infiltration was inhibited by SK&F 86002. SK&F 104493, colchicine, and phenidone but not naproxen. In vivo, PMN infiltration induced by LTB4 was inhibited by colchicine but not by SK&F 86002, SK&F 104493, or phenidone treatment. Similarly, in vitro chemotaxis to LTB4 was not inhibited by SK&F 86002. The 5-lipoxygenase inhibitors, SK&F 86002, SK&F 104493, and phenidone inhibited LTB4 production in vivo as well as inflammatory cell infiltration induced by arachidonic acid. The data are consistent with the suggestion that the bicyclic imidazoles inhibit PMN infiltration by virtue of inhibition of LTB4 production.

Depression of the immune responsiveness in mice treated with thioacetamide after antigen exposure

The effects of the weak carcinogen thioacetamide (TAA) on the mouse immune response have been investigated. TAA administration up to 1 day after antigen priming markedly suppressed the antibody response to both T-dependent (sheep erythrocytes) and T-independent (trinitrophenyl-Ficoll) antigens; the compound was ineffective when given 3 or 4 days after immunization. A significant suppression of the in vitro lymphoproliferative response to the B-cell mitogen S. aureus Cowan I was evident from 3 to 48 h after TAA treatment. On the other hand, cell-mediated immune response to oxazolone was suppressed by TAA at each time tested, including that of challenge. The in vitro lymphoproliferative response to concanavalin A was decreased 12 h after TAA administration only, when adenosine deaminase activity within lymphocytes was increased. Furthermore, TAA is endowed with anti-inflammatory activity, as shown by the decreased footpad swelling and by evaluation of the inflammatory cell infiltration upon carrageenan injection. Taken together, these findings suggest selective TAA interaction with multiple targets within the immune system, including B- and T-lymphocytes, while non-specific cytotoxicity can be reasonably ruled out, since hematological determinations and phenotypic analysis of spleen lymphocyte subsets showed no relevant changes.

Inflammatory mediators of experimental colitis in rats

Colonic inflammation was induced in rats by intracolonic administration of 0.25 ml of 50% ethanol containing 30 mg of trinitrobenzene sulfonic acid (TNB). Control rats were treated with 0.25 ml of 50% ethanol or with 30 mg of TNB in 0.25 ml of saline. After 24 h, mucosal ulceration and hemorrhage were observed in TNB/ethanol-, 50% ethanol-, and to a lesser extent, in TNB/saline-treated rats. After 1 wk, mucosal damage was completely resolved in the 50% ethanol and TNB/saline-treated rats but the lesions in the TNB/ethanol-treated rats persisted and progressed to a chronic active inflammatory process after 3 wk. Myeloperoxidase activity was significantly elevated in mucosal scrapings from all treatment groups at all time intervals when macroscopic and microscopic mucosal injury was evident. Interleukin-1 was found to be the most sensitive indicator of mucosal inflammation, and its mucosal values correlated with myeloperoxidase activity. Leukotriene B4 was increased in control rats at 1 wk and in TNB/ethanol-treated rats at all time intervals. The maximal increase in leukotriene B4 was observed at 1 wk. Thromboxane B2 generation was reduced while platelet activating factor generation was not increased in TNB/ethanol-treated rats. These results indicate that in this TNB/ethanol model of gut inflammation, myeloperoxidase activity and interleukin-1 are reliable and sensitive indicators of colonic inflammation, and that thromboxane B2 is not involved in the acute lesions, whereas leukotriene B4 appears in the chronic active inflammatory response.

Inhibitory effect of SK&F 86002 on monocyte IL-1 production

The effects of several anti-inflammatory and anti-arthritic drugs on the in vitro production of interleukin-1 by human monocytes were examined. SK&F 86002-A2 was shown to be a potent inhibitor of IL-1 production with a 50% inhibitory concentration (IC50) of 1.3 +/- 0.5 microM. Standard compounds which inhibit the cyclooxygenase (CO) or CO and 5-lipoxygenase (5LO) pathways of arachidonic acid metabolism did not inhibit IL-1 production at nontoxic concentrations. Analysis of SK&F 86002 analogs also showed no clear correlation between 5LO and IL-1 synthesis inhibitory activity. The precise mechanism of action is not known except that it is post-transcriptional. Thus, SK&F 86002 may serve as a useful reagent in the understanding of the synthetic, processing and/or secretory pathways of interleukin-1, and may provide important insight into the treatment of disease states where aberrant IL-1 production is implicated.

Pharmacological evaluation of rat paw oedema induced by Bothrops jararaca venom

The mechanism involved in the genesis of the rat paw oedema caused by intraplantar (IPL) injection of Bothrops jararaca venom (BJV) has been investigated. IPL injection of BJV (1 to 30 micrograms/paw) caused a dose- and time-related oedematogenic effect. Oedema was maximal within 1 h after BJV injection, was partially reduced at 6 h and disappeared completely within 24 h. No systemic effect was observed. Previous heating of BJV at 100 degrees C for 3 to 30 min caused a significant inhibition (25%) of its oedematogenic activity. Daily IPL injections of BJV (10 micrograms/paw) for 4 days attenuated BJV-induced oedema (26%), but did not influence oedema-induced by PAF-acether, serotonin (5-HT) and histamine (His), indicating the absence of cross desensitization. In the paw desensitized by daily IPL injections of PAF-acether, BJV induced a full oedematogenic response also indicating absence of cross desensitization. Different groups of drugs including alpha 1- and alpha 2-adrenoceptor antagonists (prazosin and yohimbine), inhibitors of both cyclo- and lipo-oxygenase (indomethacin, nordihydroguaiaretic acid), inhibitors of phospholipase A2 (dexamethasone and mepacrine) caused marked inhibition of BJV-induced rat paw oedema, whereas antagonists of 5-HT, PAF-acether and H1-histamine receptors were less effective. Pre-treatment with a beta-adrenoceptor antagonist, a Ca2+ channel blocker and a H2-histamine antagonist failed to affect BJV-induced oedema. Pre-treatment of the animals with captopril did not interfere with BJV-induce oedema, suggesting that kinins are not insolved in the genesis of oedema. Association of BJV with 5-HT and PAF did not potentiate the BJV-induced oedema.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of inhibitors of eicosanoid metabolism in murine collagen-induced arthritis

The dual inhibitors of arachidonic acid metabolism, Smith Kline & French (SK&F) 86002, SK&F 104351, and phenidone; the corticosteroid, dexamethasone; and the selective cyclooxygenase inhibitors, ibuprofen, indomethacin, naproxen, and piroxicam were evaluated for their antiarthritic potency in the murine, collagen-induced arthritis model. The ability of these compounds to alter the severity of arthritic lesions and to reduce serum levels of the acute-phase reactant, serum amyloid P component (SAP) were monitored. Serum concentrations of SAP were found to correlate strongly (r = 0.985) with disease severity at day 35 postimmunization. Treatment with SK&F 86002, SK&F 104351, phenidone, or dexamethasone significantly reduced disease severity, as judged by clinical score (55%, 72%, 41%, and 45% inhibition, respectively) and SAP levels (62%, 94%, 52%, and 94% inhibition, respectively) in arthritic mice. This profile of activity was not shared by the selective cyclooxygenase inhibitors, which did not uniformly inhibit disease activity by both parameters. The results suggest that dual inhibitors of 5-lipoxygenase and cyclooxygenase may prove more effective than selective cyclooxygenase inhibitors as anti-arthritic agents.

Immunomodulatory activity and non-specific suppressor cell generation by spirogermanium in murine and rat models of cell-mediated immunity

Spirogermanium (SG) is a metal-containing compound reported to have antitumor, antiarthritic, antimalarial and immunoregulatory activity. In this study we have demonstrated that treatment of mice and rats with spirogermanium results in an inhibition of autoimmune disease and cell-mediated immune (CMI) responses. Prophylactic administration of SG inhibited the development of adjuvant-induced arthritis and the DTH response to purified protein derivative (PPD) in Lewis strain rats. SG treatment was also able to alleviate the symptoms of experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats. In two strains of mice, BDF1 and C57B1/6, the DTH response to sheep red blood cells could be suppressed by intraperitoneal (i.p.) administration of SG. The spleens of both mice and rats that have been treated with this drug contain suppressor cells which inhibit the response of normal cells to concanavalin A (Con A) and the mixed lymphocyte reaction. In addition, the generation of cytotoxic T cells (CTL) in the murine MLR is abrogated in the presence of these suppressor cells. The suppressor cells were radiation-resistant (2000 rad), indomethacin-insensitive and were not depleted by treatment with anti-Thy-1.2 antiserum plus complement. These results suggest that SG modulates cell-mediated immune responses in vivo by the induction of non-specific suppressor cells.

Ovarian effects of SK&F 86002-A2 in the rat: site of action

In a preliminary 30-day study, oral administration of SK&F 86002-A2, an inhibitor of prostaglandin and leukotriene synthesis, blocked ovulation and altered ovarian structure and hormone production in rats. The purpose of the present study was to determine if the locus of action of SK&F 86002-A2 for these effects was the ovary or some other site in the female reproductive system, using a number of experimental approaches. A single sc or intraovarian injection of SK&F 86002-A2 did not block spontaneous or gonadotropin-induced ovulation in proestrous rats, whereas indomethacin, a positive control, acutely disrupted the ovulatory process. Since neither route of administration blocked ovulation, integrated pituitary and ovarian events were not negatively affected by a single injection of SK&F 86002-A2 at doses which caused ovarian dysfunction when administered repeatedly for 30 days. In contrast to a single dose, oral administration of SK&F 86002-A2 to hypophysectomized rats for 2 weeks suppressed follicular growth and estradiol production in response to sc administration of pregnant mare serum gonadotropin. Although ovarian function was suppressed in hypophysectomized rats, LH surges induced by estradiol in ovariectomized rats were not affected by administration of SK&F 86002-A2 for 2 weeks. Thus, hypothalamic/pituitary dysfunction did not contribute to the ovarian effects of SK&F 86002 that occurred after repeated dosing. In conclusion, these results indicate that disruption of ovarian cycles by SK&F 86002-A2 is related to a direct effect on the ovary, and not to altered hypothalamic/pituitary function and LH release. Specifically, SK&F 86002-A2 may suppress the ovarian response to gonadotrophin, retarding follicular growth and estrogen production. The ovarian effects are consistent with a pharmacological expression of the inhibitory action of SK&F 86002-A2 on prostaglandin and leukotriene synthesis.

Ovarian effects of an anti-inflammatory-immunomodulatory drug in the rat

The purpose of this study was to determine whether a 30-day administration of SK&F 86002-A2, an inhibitor of cyclooxygenase and 5-lipoxygenase pathways of arachidonate metabolism, adversely affected reproductive cycles, ovarian structure, and/or pituitary/ovarian hormone secretion. Cyclooxygenase and 5-lipoxygenase enzymes catalyze the reactions leading to the synthesis of prostaglandins and leukotrienes, respectively, which are physiological regulators of ovarian function. Female rats were dosed once daily by gavage with 0, 1, 5, 10, 30, or 60 mg (base)/kg/day of SK&F 86002-A2 for 30 consecutive doses beginning on the day of vaginal proestrus. Vaginal smears were then examined daily until necropsy, when ovaries and uteri were collected for macroscopic and histological examination. In addition, serum concentrations of estradiol, progesterone, luteinizing hormone, follicle stimulating hormone, and prolactin were estimated by radioimmunoassay. Estrous cycle irregularity, resulting from a dose-related lengthening of the interestrous interval, significantly (p less than 0.05) reduced the number of cycles in rats receiving 60 mg/kg/day of SK&F 86002-A2 compared to controls. Furthermore, the ovaries from this group of rats weighed significantly more (p less than 0.05) than controls, apparently due to an increased occurrence of enlarged, cystic follicles that occasionally contained blood. Luteinized follicles with entrapped ova were also detected during histological examination. Dilatation of the uterine lumen was observed in some rats receiving doses of SK&F 86002-A2 greater than 1 mg/kg/day. Serum progesterone in rats receiving 60 mg/kg/day of SK&F 86002-A2 was significantly (p less than 0.05) lower than controls. In contrast, mean levels of serum estradiol were elevated in rats receiving 30 mg/kg/day of SK&F 86002-A2. Serum concentrations of FSH, LH, and prolactin were not significantly different in any group. The results of this study suggest that SK&F 86002-A2 disrupts cyclic ovarian function by a local, cumulative action that inhibits ovulation and alters steroid secretion.

Inhibition of monocyte IL-1 production by the anti-inflammatory compound, SK&F 86002

The effects of several anti-inflammatory/anti-arthritic drugs on the in vitro production of interleukin-1 (IL-1) by human monocytes were examined. SK&F 86002, a novel dihydroimidazo thiazoline which inhibits both 5-lipoxygenase- and cyclooxygenase-mediated arachidonate metabolism was shown to be a potent inhibitor of IL-1 production by LPS-stimulated human monocytes. The inhibition was dose-dependent (IC50 = 1.30 +/- 1 microM), reversible and was independent of the concentration or type of stimulus used. The compound also inhibited cell-associated IL-1 activity. The compound did not exert general inhibitory effects on such parameters as adherence, cytotoxic function and protein synthesis of the monocytes. Other cyclooxygenase and/or 5-lipoxygenase inhibitors of arachidonic acid metabolism tested, with the exception of nordihydroguaiaretic acid, were inactive in inhibiting monocyte IL-1 production suggesting that the inhibition of IL-1 production by 86002 may be dissociated from its inhibition of the fatty acid oxygenases. The inhibition of IL-1 production by SK&F 86002 adds another facet of drug action contributing to its spectrum of anti-inflammatory activities.

The role of arachidonic acid metabolism in IL-3-induced proliferation

The role of arachidonic acid metabolites as second messengers in the IL-3-induced activation of DA-1 cells was examined. By using inhibitors of either the cyclooxygenase (CO) or lipoxygenase (LPO) pathways, we determined that neither prostaglandins nor leukotrienes were involved in signal transduction, since aspirin, indomethacin, meclofenamic acid, and nordihydroguaiaretic acid (NDGA) failed to inhibit the proliferation response of DA-1 cells to IL-3. Furthermore, two combination CO/LPO inhibitors, benoxaprofen and BW755c, failed to inhibit DA-1 proliferation. A new CO/LPO compound examined, SK&F 86002, did inhibit proliferation (IC50 = 30 microM +/- 14, N = 11), leading us to conclude this drug has other actions besides CO/LPO inhibition. Finally, direct measurement of 3H-arachidonic acid uptake by DA-1 cells failed to show a difference in the amount of 3H-arachidonic acid incorporated in the presence of limiting or saturating amounts of IL-3. We conclude from these data that arachidonic acid metabolites are not involved in transmembrane signalling by IL-3 in DA-1 cells.

SK&F 86002: a structurally novel anti-inflammatory agent that inhibits lipoxygenase- and cyclooxygenase-mediated metabolism of arachidonic acid

The effects of SK&F 86002 [5-(4-pyridyl)-6 (4-fluorophenyl)-2,3-dihydroimidazo (2,1-b) thiazole] on the generation of eicosanoids in vitro and on inflammatory responses in vivo are described and compared to other non-steroidal anti-inflammatory drugs. SK&F 86002 inhibited prostaglandin H2 (PGH2) synthase activity (IC50 120 microM) as well as prostanoid production by rat basophilic leukemia (RBL-1) cells (IC50 70 microM) and its sonicate (IC50 100 microM) and human monocytes (IC50 1 microM). In addition, SK&F 86002 inhibited the generation of dihydroxyeicosatetraenoic acid (diHETE) and 5-hydroxyeicosatetraenoic acid (5-HETE) by a high speed supernatant fraction of RBL-1 cells (IC50 10 microM). Cellular production of 5-lipoxygenase products was inhibited by SK&F 86002 as measured by leukotriene B4 (LTB4) generation from human neutrophils (IC50 20 microM), leukotriene C4 (LTC4) generation by human monocytes (IC50 20 microM), and 5-HETE production by RBL-1 cells (IC50 40 microM). The in vivo profile of anti-inflammatory activity of SK&F 86002 supports the dual inhibition of arachidonate metabolism as indicated by its activity in inflammation models that are insensitive to selective cyclooxygenase inhibitors. The responses of arachidonic-acid-induced edema in the mouse ear and rat paw, as well as the cell infiltration induced by carrageenan in the mouse peritoneum and by arachidonic acid in the rat air pouch, were inhibited by SK&F 86002 and phenidone but not by the selective cyclooxygenase inhibitors naproxen and indomethacin.