Quantum-chemical study of relationships between immunological activity andmolecular structure of 5-amino-3-methylisoxazole-4-carboxylic acid phenylamides.

Methods for investigating relations :between biological activity and molecu lar structure give many important clues about quantitative correlations, wh ich can be used to determine biological activity and related pharmacologica l effects. The quantum-chemical study is presented for 5-amino-3-methylisox azole-4-carboxylic acid phenylamides, which exhibit experimentally observed immunosuppresing properties. Derivatives presented in this study differ am ong themselves by substituents in the phenyl ring. Change of the substituen ts has a strong influence on biological activity. ((1) under bar) Gas phase calculations were carried out which consisted from semiempirical AM1 and P M3 to DFT methods. Moreover calculations at the AM1 semiempirical method, i ncluding solvent effects, were performed. For this purpose the COSMO model was employed.