The pharmacology of arachidonic acid-induced rat paw edema

Inhibitory effect of 4-acylaminophenol derivatives (T-0799 and T-0757), novel lipoxygenase inhibitors, on arachidonic acid-induced infiltration of polymorphonuclear leukocytes in rat skin

Effects of 4-acylaminophenol derivatives, novel 5-lipoxygenase inhibitors, on the neutrophil infiltration in arachidonic acid (AA) (10 mg/site)-induced skin inflammation in rats were examined. Myeloperoxidase (MPO) activity in the skin lesion, used as an indicator of neutrophil infiltration, was significantly increased after intradermal injection of AA. Dual inhibitors of cyclooxygenase and 5-lipoxygenase, phenidone (100 mg/kg x 2, i.p. and p.o.) and BW-755C (50 mg/kg x 2, p.o.), and 5-lipoxygenase inhibitors, AA-861 (100 mg/kg x 2, i.p.) and the 4-acylaminophenol derivatives T-0799 and T-0757 (10-100 mg/kg x 2, p.o.), inhibited the increase in MPO activity 5 hr after AA-injection, but the cyclooxygenase inhibitor indomethacin (5 mg/kg, i.p.) showed no effect. These results suggest that products of lipoxygenase, but not of cyclooxygenase, are involved in the MPO activity increase (i.e., neutrophil infiltration), and that this model is useful for in vivo evaluation of 5-lipoxygenase inhibitors. It is suggested that the 4-acylaminophenol derivatives may be useful as orally active drugs for treatment of some leukotriene-mediated diseases.

Studies on the mechanism of anti-inflammatory and anti-ulcer activity of Pluchea indica--probable involvement of 5-lipooxygenase pathway

The effect of the methanolic fraction of Pluchea indica Less. root extract was evaluated on various models of inflammation and ulcer in vivo to assess the role of P. indica on the 5-lipoxygenase pathway of prostaglandin synthesis. Studies presented here reveal significant antiinflammatory activity of the fraction on Arachidonic acid, Platelet activation factor and Compound 48/80-induced paw oedema. There was significant inhibition of spontaneous as well as compound 48/80-induced histamine release from mast cells. Ulcer studies revealed significant protective action of the fraction on indomethacin, alcohol and indomethacin-alcohol induced ulceration. There was significant decrease of gastric volume and acidity in pylorus ligated rats. Studies also showed, significant protective action of the same on gastric mucosa.

The role of chemical mediators in the pathogenesis of inflammation with emphasis on the kinin system

In recent years, numerous agents have been recognized as inflammatory mediators. In this review, however, we discuss only those having direct relevance to human inflammatory diseases These mediators are clinically important due to their proinflammatory properties such as vasodilatation, increased vascular permeability, pain and chemotaxis. They may lead to the fifth cardinal sign, loss of function in inflammatory diseases. Agonists and non-specific antagonists are used as pharmacological tools to investigate the inflammatory role of PGs, LTs, PAF, IL-1, histamine, complement, SP, PMN-leukocytes, and kallikrein-kininogen-kinin systems. Unfortunately, no compound is known which concurrently abolishes all actions and interactions of inflammatory mediators. Therefore it would be highly useful to promote efforts in developing selective and competitive antagonists against proinflammatory actions of these chemical mediators. This may help to a better understanding of the pathogenesis of inflammatory reactions, and it may also be useful for the therapy of inflammatory diseases.

The pharmacology of arachidonic acid-induced rat PMN leukocyte infiltration

Arachidonic Acid (AA) injected into a hindpaw of Lewis rats produces high levels of tissue myeloperoxidase (MPO), a biochemical marker for PMN leukocytes. Treatment with a corticosteroid (prednisolone) or dual 5-LO/CO inhibitors of AA metabolism (phenidone, SKF 86002) produced dose-related inhibition of AA-induced elevations in paw tissue MPO levels. In contrast, administration of high pharmacologic doses of selective cyclooxygenase inhibitors (indomethacin, ibuprofen, naproxen), anti-histamine/serotonin agents (cyproheptadine, chlorpheniramine) or an anti-arthritic gold compound (auranofin) produced only slight or moderate effects. Thus, AA-induced hindpaw inflammation is a useful method for determining pharmacologic effects of 5-LO/CO inhibitors on PMN leukocyte infiltration in vivo.