RT Journal Article SR Electronic T1 3-(Hydroxymethyl)-8-methoxychromone and unconjugated metabolites in rat plasma. Identification of the biologically active species. JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 368 OP 371 VO 4 IS 4 A1 F J De Carlo A1 D J Herzig A1 E J Kusner A1 P R Schumann A1 M D Melgar A1 S George A1 M C Crew YR 1976 UL http://dmd.aspetjournals.org/content/4/4/368.abstract AB After administering 14C-labeled 3-(hydroxymethyl)-8-methoxychromone to rats by gavage, plasma was found to contain unchanged compound and three unconjugated metabolites. These metabolites were identified as 3-carboxy-8-methoxychromone, 8-methoxychromone, and 2-hydroxy-3-methoxyactophenone. The plasma levels of all four labeled compounds were determined from 30 min to 48 hr after drug administration. Only the levels of 3-(hydroxymethyl)-8-methoxychromone and 3-carboxy-8-methoxychromone correlated with the expression of antiallergy activity in the rat, and only these compounds were found to be active in vivo. However, a test system for the inhibition of anaphylactic histamine release in vitro showed activity only for 3-carboxy-8-methoxychromone.