EFFECT OF LOBARIC ACID ON CYSTEINYL-LEUKOTRIENE FORMATION AND CONTRACTILE ACTIVITY OF GUINEA-PIG TAENIA-COLI

Lobaric acid, a constituent of the lichen Stereocaulon alpinum, was in vestigated for effects on the smooth muscle taenia coli from guinea pi gs. Inhibitory effects of lobaric acid on spontaneous contractile acti vity and on contractile activity stimulated by ionophore A23187 were s tudied. In addition, the activity of lobaric acid on ionophore-induced generation of cysteinyl-leukotrienes in taenia coli was determined by enzyme immunoassay. Lobaric acid significantly reduced spontaneous co ntractile activity of the muscle and inhibited contractions caused by ionophore A23187 with an effective dose of 5.8 mu M. Increased contrac tility caused by leukotriene D-4 was not influenced by lobaric acid. L obaric acid inhibited the formation of cysteinyl-leukotrienes as deter mined by enzyme immunoassay with an effective dose of 5.5 mu M.