The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Inhibition of various cyclic AMP phosphodiesterases by pentifylline and theophylline》. Authors are Stefanovich, V.; Von Poelnitz, M.; Reiser, M..The article about the compound:1-Hexyl-3,7-dimethyl-1H-purine-2,6(3H,7H)-dionecas:1028-33-7,SMILESS:CN1C=NC(N(C(N2CCCCCC)=O)C)=C1C2=O).Formula: C13H20N4O2. Through the article, more information about this compound (cas:1028-33-7) is conveyed.
The inhibiting effect of pentifylline (1-hexyl-3,7-dimethylxanthine) (I) and theophylline (II) was tested on 3′,5′-AMP-phosphodiesterase (III) of 7 organs of guinea pigs, of rat brain, and bovine heart. I was a better inhibitor than II of III of rat brain and bovine heart. The difference between the degrees of inhibition by I and II was largest in the case of III of rat brain. I inhibited III of bovine heart noncompetitively and II did so competitively. Serum albumin affected the I inhibition of bovine heart III more than it did the inhibition by II. II exhibited the highest effect on guinea pig heart III while I did so on III of brain.
Compounds in my other articles are similar to this one(1-Hexyl-3,7-dimethyl-1H-purine-2,6(3H,7H)-dione)Formula: C13H20N4O2, you can compare them to see their pros and cons in some ways,such as convenient, effective and so on.
Reference:
Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem