Inhibition by 2- or/and 8-substituted adenosine derivatives of adenosine deaminase and calmodulin-dependent phosphodiesterase.

Several 2- or/and 8-substituted adenosine derivatives were tested for their ability to inhibit the adenosine deaminase activity in hog heart and Ca++, calmodulin-dependent phosphodiesterase activity in hog brain. Among these derivatives, 2-piperidyladenosine competitively inhibited not only the adenosine deaminase activity but also the phosphodiesterase activity. Further substitution of this compound with a bulky group at 8-position, 2-piperidyl-8-(8-aminooctylamino)-adenosine, abolished its ability to inhibit the adenosine deaminase activity, but progressively increased in the ability to inhibit the phosphodiasterase activity. On the other hand, 8-monosubstituted adenosine derivatives did not inhibit the adenosine deaminase activity.