The invention relates to compounds of structural formulas (I) and (XVI):or a pharmaceutically acceptable salt, solvate, clathrate, or prodrug thereof, wherein X1, X2, Z, L, L2, R1, R2, R3, R21, n, q, and t are defined herein. These compounds are useful as immunosuppressive agents and for treating and preventing inflammatory conditions, allergic disorders, and immune disorders.本發明係有關結構式(I)和(XVI)化合物:或其醫藥上可接受之鹽、溶劑合物、晶籠化合物或前藥,其中X1、X2、Z、L、L2、R1、R2、R3、R21、n、q、及t係如本文中所定義。此等化合物係有用於作為免疫抑制劑,及用於治療與預防炎症、過敏病症、及免疫病症。