PROBLEMS TO BE SOLVED BY THE INVENTIONTo provide aqueous solutions of conophylline and/or conophyllidine methods for purifying conophylline and/or conophyllidine from the aqueous solutions methods for producing the aqueous solutions, water-soluble compositions containing conophylline and/or a conophyllidine useful for food compositions or pharmaceutical compositions or methods for preparing the same as well as food compositions or pharmaceutical compositions containing the water-soluble compositions.MEANS OF SOLVING THE PROBLEMSIt has been found that conophylline and/or conophyllidine can be efficiently extracted from a plant producing conophylline and/or conophyllidine with an acidic aqueous solution having a pH equal to or less than 4. The extract thus obtained, i.e., aqueous solution of conophylline, and/or conophyllidine is useful for production of, for instance, food compositions, pharmaceutical compositions, etc.
