2-Methylpropyl ester of 3-(adenin-9-yl)-2-hydroxypropanoic acid. Mechanism of antiviral action in vaccinia virus-infected L929 cells.
Alkyl esters of (RS)-3-(adenin-9-yl)-2-hydroxypropanoic acid (AHPA) were shown recently to be broad spectrum antiviral agents (De Clercq E and Holy A, J Med Chem 28: 282-287, 1985). It was postulated that these alkyl esters function as prodrugs by undergoing hydrolysis catalyzed by cellular esters to AHPA, a known inhibitor of S-adenosyl-L-homocysteine (AdoHcy) hydrolase. In this study, we describe the metabolic fate of the 2-methylpropyl ester of AHPA (AHPA-iBu) in murine L929 cells. When AHPA-iBu was included in the culture medium, it was taken up rapidly by murine L929 cells. The uptake was time- and concentration-dependent, resulting in the intracellular accumulation of the free acid, AHPA. Treatment with AHPA-iBu caused inhibition of cellular AdoHcy hydrolase in both a time- and a dose-dependent manner. Complete inhibition of the enzyme was achieved after a 1-hr incubation in culture medium containing 50 microM AHPA-iBu. The inhibition of the enzyme caused cellular accumulation of AdoHcy and a significant increase in the ratio of AdoHcy/S-adenosyl-L-methionine (AdoMet). Partial recovery of the AdoHcy hydrolase activity in L929 cells treated with 50 microM AHPA-iBu was observed after 24 hr. This recovery of enzyme activity was paralleled by a significant decrease in the cellular levels of AdoHcy and the ratio of AdoHcy/AdoMet. AHPA-iBu also exerted an inhibition (IC50 = 0.17 microM) of vaccinia virus plaque formation in monolayers of L929 cells. A 1 microM concentration of AHPA-iBu, which caused 80% inhibition of plaque formation, produced a 17-fold increase in AdoHcy content in drug-treated, virus-infected cells versus non-drug-treated, virus-infected cells and a 15% undermethylation of the poly(A)+ RNA. These data show that AHPA-iBu is a prodrug for AHPA which inhibits cellular AdoHcy hydrolase. The inhibition of this enzyme elevates cellular levels of AdoHcy, creating an unfavorable environment which suppresses replication of vaccinia virus.
Votruba
I
I
Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66045.
Hasobe
M
M
Holý
A
A
Borchardt
R T
RT
D000225:Adenine / Q000031:analogs & derivatives* / Q000032:analysis / Q000494:pharmacology; D043383:Adenosylhomocysteinase; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006867:Hydrolases / Q000037:antagonists & inhibitors; D007739:L Cells / Q000187:drug effects*; D051379:Mice; D012435:S-Adenosylhomocysteine / Q000032:analysis; D012436:S-Adenosylmethionine / Q000032:analysis; D014615:Vaccinia / Q000382:microbiology; D014616:Vaccinia virus / Q000187:drug effects*; D014779:Virus Replication / Q000187:drug effects
D000998:Antiviral Agents; D012436:S-Adenosylmethionine; C048336:3-adenin-9-yl-2-hydroxypropanoic acid isobutyl ester; C045526:3-adenin-9-yl-2-hydroxypropanoic acid; D012435:S-Adenosylhomocysteine; D006867:Hydrolases; D043383:Adenosylhomocysteinase; D000225:Adenine