THE INVOLVEMENT OF A CA2-VISNAGA FRUITS( CHANNEL BLOCKING MODE OF ACTION IN THE PHARMACOLOGY OF AMMI)

Based on a screening program of medicinal plants for their possible ca lcium antagonistic mode of action, the most active lipophilic extract of Ammi visnaga fruits (DAB 10) was fractionated by CC and investigate d pharmacologically at K+ (60 mM)-depolarized guinea-pig aortic strips . Visnadin, khellin, and visnagin were identified and determined as th e effective principles in this testing model with the dihydropyranocou marin visnadin being the most active. Further selectivity tests agains t norepinephrine (100 mu M)-induced contractions evaluated a possible pharmacological differentiation between these compounds as the furanoc hromones khellin and visnagin inhibited both spasms to a similar exten t while visnadin's activity was significantly higher against K+-spasms , suggesting an involvement of a calcium channel blocking mode of acti on for visnadin.