Compositions containing and methods employing, as the essential ingredient, novel disubstituted xanthone carboxylic acid compounds which are useful in the treatment of allergic conditions. Methods for preparing these compounds and compositions and intermediates therein are also disclosed. 5-Methylthio-7-isopropoxyxanthone-2-carboxylic acid and 5,7-di-(methylthio)xanthone-2-carboxylic acid are illustrated as representative compounds.
This is a division of application Ser. No. 450,351, filed March 12, 1974, which is in turn a division of appliction Ser. No. 217,300, filed January 12, 1972, now U.S. Pat. No. 3,821,251.
Xanthene compounds represented by the formula: ##STR1## wherein R.sup.1 is a carboxyl group which may be esterified or amidated; R.sup.2 is a hydrogen atom, a hydroxyl group, or a hydrocarbon group which may be substituted; R.sup.3 and R.sup.4 are the same or different and are a hydroxyl group which may be substituted; R.sup.5 and R.sup.6 are a hydrogen atom or a halogen atom; R.sup.7 is a hydrogen atom, a nitro group, a halogen atom, a hydrocarbon group which may be substituted, a heterocyclic group which may be substituted, or an acyl group which may be substituted; n is an integer of 0 to 2; and Y is an oxygen atom or two hydrogen atoms; and when n is 0, R.sup.2 may be a group represented by the formula: ##STR2## wherein the symbols have the same meanings as defined above, or a salt thereof inhibit a binding of B7-1 to CD28, prevent the B7-1-dependent activation of T cells and inhibit IL-2 production from T cells, thus being used as an immunomodulator such as a graft rejection inhibitor or a pharmaceutical composition for therapeutic treatment of allergy, rheumatoid arthritis, autoimmune disease, nephritis, diabetes mellitus and so on.
