(Science: chemical) 2,3,7,8-tetrahydroxy(1)benzopyrano(5,4,3-cde)(1)-benzopyran-5,10-dione. A fused four ring compound occurring free or combined in galls. Isolated from the kino of eucalyptus maculata hook and e. Hemipholia f. Muell. Activates factor xii of the blood clotting system which also causes kinin release; used in research and as a dye.
chemical name: (1)Benzopyrano(5,4,3-cde)(1)benzopyran-5,10-dione, 2,3,7,8-tetrahydroxy-