A novel adenine compound represented by the formula (1):
wherein A represents an (un)substituted aromatic carbocycle or (un)substituted aromatic heterocycle; L
1
, L
2
, and L
3
each independently represents linear or branched alkylene, etc.; R
1
represents (un)substituted alkyl, (un)substituted aryl, etc.; R
2
represents hydrogen or (un) substituted alkyl; R
3
represents (un)substituted alkyl, etc., provided that R
3
may be bonded to L
2
or L
3
to form a nitrogenous saturated heterocycle; and X represents oxygen, etc.; or a pharmaceutically acceptable salt of the compound. The compound and salt are useful as a medicine.