ABSTRACT
3-Hydroxy-5-trifluoromethyl-N-(2-(2-thienyl)-2-phenyl-ethenyl)- benzo (b) thiophene-2-carboxamide (L-652,343) is an inhibitor of cyclooxygenase and 5-lipoxygenase in vitro and inhibits the synthesis of the products of both these pathways in whole cells. L-652,343 is an inhibitor of the acute edema induced by carrageenan in vivo and is active topically in suppressing arachidonic acid induced inflammation in the skin. The compound is an effective inhibitor of the chronic inflammation of adjuvant and type II collagen induced polyarthritis. L-652,343 is an extremely potent analgesic in models of yeast and platelet activating factor induced hyperalgesia in rats and phenylbenzoquinone-induced writhing in mice. The fever induced by Brewer's yeast is lowered by L-652,343. The ulcerogenicity and gastric bleeding induced by L-652,343 is extremely low, providing a favorable therapeutic index which is superior to that of indomethacin, piroxicam and phenylbutazone.
Subject(s)
Arachidonate Lipoxygenases/antagonists & inhibitors , Cyclooxygenase Inhibitors , Lipoxygenase Inhibitors , Thiophenes/pharmacology , Analgesics , Animals , Anti-Inflammatory Agents , Anti-Inflammatory Agents, Non-Steroidal , Dogs , Female , Male , Mice , Mice, Inbred Strains , Rats , Rats, Inbred Strains , Stomach Ulcer/chemically induced , Thiophenes/toxicityABSTRACT
L-656,224 (7-chloro-2-[(4-methoxyphenyl)methyl]-3-methyl-5-propyl-4-benzofuranol) was a potent inhibitor of leukotriene biosynthesis in intact rat and human leukocytes and CXBG mastocytoma cells (IC50 values, 18-240 nM) and of crude human leukocyte and highly purified porcine leukocyte 5-lipoxygenase (IC50 value, 4 X 10(-7) M). The selectivity of L-656,224 for 5-lipoxygenase was shown through the relative lack of activity of the compound on 12-lipoxygenase, 15-lipoxygenase, cyclooxygenase, catalase, and myeloperoxidase. The compound showed (i) oral activity against hyperalgesia induced in the rat paw by injection of yeast or platelet-activating factor, (ii) dyspnea in sensitized inbred rats induced by an aerosol of antigen, and (iii) bronchoconstriction induced by an aerosol of Ascaris in squirrel monkeys, suggesting a role for 5-lipoxygenase inhibitors in the treatment of asthma and peripheral pain.
Subject(s)
Arachidonate Lipoxygenases/antagonists & inhibitors , Benzofurans/pharmacology , Lipoxygenase Inhibitors , Animals , Blood Platelets/enzymology , Catalase/antagonists & inhibitors , Cattle , Cells, Cultured , Eating/drug effects , Female , Humans , Leukocytes/enzymology , Neutrophils/enzymology , Peroxidase/metabolism , Prostaglandin-Endoperoxide Synthases/metabolism , Rats , Saimiri , Glycine max/enzymology , Species Specificity , SwineABSTRACT
Treatment of intact human platelets with the tumour-promoting phorbol ester, phorbol 12-myristate 13-acetate (PMA), specifically inhibited PGD2-induced cyclic AMP formation without affecting the regulation of cyclic AMP metabolism by PGI2, PGE1, 6-keto-PGE1, adenosine or adrenaline. This action of PMA was: (i) concentration-dependent; (ii) not mediated by evoked formation or release of endogenous regulators of adenylate cyclase activity (thromboxane A2 or ADP); (iii) mimicked by 1,2-dioctanoylglycerol (DiC8) but not by 4 alpha-phorbol 12,13-didecanoate (which does not activate protein kinase C); (iv) attenuated by Staurosporine. These results indicate that activation of protein kinase C in platelets may provide a regulatory mechanism to abrogate the effects of the endogenous adenylate cyclase stimulant PGD2 without compromising the effects of exogenous stimulants of adenylate cyclase (PGI2, 6-keto-PGE1, adenosine).
Subject(s)
Blood Platelets/metabolism , Cyclic AMP/blood , Protein Kinase C/blood , Adenosine Diphosphate/pharmacology , Adenylyl Cyclases/blood , Alprostadil/analogs & derivatives , Alprostadil/pharmacology , Blood Platelets/enzymology , Enzyme Activation , Epinephrine/pharmacology , Humans , In Vitro Techniques , Prostaglandin D2 , Prostaglandins D/pharmacology , Tetradecanoylphorbol Acetate/pharmacologyABSTRACT
Gastric bleeding caused by cyclooxygenase inhibitors has been assessed by a novel method. Rats are adapted to a strict light-dark cycle with limited access to food to reduce the stress associated with starvation. Such animals are then labeled with 51Cr-red blood cells from donor animals and dosed with the compound under evaluation. After 24 hr. animals are sacrificed and the amount of blood that has accumulated in the lumen of the cecum is quantitated. The potency of cyclooxygenase inhibitors in this assay to cause gastric bleeding is as follows: indomethacin greater than piroxicam greater than naproxen greater than ibuprofen greater than diflunisal which is similar to their antiinflammatory potency in the rat. In addition, the protective activity of PGE2 on indomethacin-induced gastric bleeding is clearly shown by this method.
