The invention relates to chemistry of organic substances, pharmacology and medicine, and concerns treating diseases associated and with aberrant activity of cells of the immune system, more particularly for treating lung, respiratory tract and abdominal diseases, radiation sickness and pain syndrome, and also other diseases by using compounds of formula (A)






wherein
R1 is —C(O)—R2—(O)— or —R2—C(O)— group, where R2 is —(CH2)n-group optionally substituted with one or two C1-C6 alkyls, or phenyl,
n is an integer from 0 to 4;
wherein compounds are selected from the group consisting of the group of compounds as set out in the description. These compounds, as well as pharmaceutically acceptable salts thereof, are highly effective in inhibiting glutaminyl cyclase, which is involved, in particular, in processes of post-translational modification of chemokines and chemotaxis of monocytes, macrophages and other cells of the immune system. This invention also relates to pharmaceutical compositions comprising a therapeutically effective amount of the compounds of formula (A) as defined above.