| 摘要 |
The invention relates to compounds of the formula <IMAGE> in which R1 is absent or denotes hydrogen, alkyl or acyl, A denotes an acyl radical or an amino acid residue, B denotes an amino acid residue, and R2, R3 and R4 are as defined in the specification, and to their salts, to a process for their preparation, to pharmaceutical products containing them, and to their use as medicaments, and intermediates for the preparation of these compounds. |
