Abstract: Compounds represented by formula (1), wherein X is, for example, CH, CH2, CHR (wherein R is a lower alkyl group or a substituted lower alkyl group) or CRR? (wherein R and R? are the same as the above defined R); Y is, for example, CH, CH2 or C?O; Z is, for example, O, S, S?O or SO2; U is C or N; R1 to R4 are each independently, for example, a hydrogen atom, OR, SR (wherein R is the same as defined above), or an aromatic ring, a substituted aromatic ring or a heterocycle; at least one of R5 and R8 is, for example, OH and the remaining of R5 and R8 are each independently, for example, a hydrogen atom or OH, optical isomers thereof, conjugates thereof or pharmaceutically acceptable salts thereof are provided. These compounds are characterized in having a wide range of pharmacological actions such as an excellent relaxing action of tracheal smooth muscles, an inhibition of airway hypersensitivity and an inhibition of infiltration of inflammatory cells into the airway and, in addition, high safety.