New beta-diketone and 3,5-dimethyl isoxazole derivatives of theophylline as potential bronchodilator agents.

Ten new compounds having 7-[(2,4-pentanedione-3-yl)alkyl]- and 7-[(3,5-dimethylisoxazole-4-yl)alkyl]-3,7-dihydro-1,3-dimethyl-1H- purine-2, 6-dione structures were synthesized and their bronchodilator activities investigated using the method based on inhibition of acetylcholine and histamine-induced contractions in guinea pig trachea. None of the compounds were effective on acetylcholine-induced contractions. However, the compounds 4d, 4e, 5d and 5c were potent inhibitors of the bronchospasm induced by histamine, whereas the others (4b, 4c, 5b and 5c) were weak inhibitors.