Novel acridone compounds represented by the general formula (I) or pharmaceutically acceptable salts thereof efficacious in the prevention and treatment of diseases in which chemical transmitters such as histamine and leukotriene participate, typified by asthma, allergic rhinitis, atopic dermatitis, urticaria, hay fever, digestive tract allergy and food allergy:
wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are the same or different and each represents hydrogen, hydroxy, halogeno, lower alkyl, cycloalkyl, lower alkoxy, etc.; Y represents -(CH 2 ) t -(B) m -(CH 2 ) n -Z {wherein m is 0 or 1; t and n represent each an integer of 0 to 6; B represents lower alkylene, optionally substituted arylene, etc.; and Z represents cyano, optionally protected carboxy, acyl, -NR 7 R 8 [wherein R 7 and R 8 are the same or different and each represents hydrogen, lower alkyl, lower alkoxy, hydroxyalkyl, etc.]}; and D represents oxygen or sulfur.