Computer-aided design, synthesis, and anti-HIV-1 activity in vitro of 2-alkylamino-6-[1-(2,6-difluorophenyl)alkyl]-3,4-dihydro-5-alkylpyrimidin-4(3H)-ones as novel potent non-nucleoside reverse transcriptase inhibitors, also active against the Y181C variant.
Dihydro-alkoxy-benzyl-oxopyrimidines (DABOs) are a family of potent NNRTIs developed in the past decade. Attempts to improve their potency and selectivity led to thio-DABOs (S-DABOs), DATNOs, and difluoro-thio-DABOs (F(2)-S-DABOs). More recently, we reported the synthesis and molecular modeling studies of a novel conformationally constrained subtype of the S-DABO series characterized by the presence of substituents on the methylene linkage connecting the pyrimidine ring to the aryl moiety (Mai, A., et al. J. Med. Chem. 2001, 44, 2544-2554). Now we report the computer-aided design, synthesis, and biological evaluation of four new DABO prototypes (5-alkyl-2-cyclopentylamino-6-[1-(2,6-difluorophenyl)alkyl]-3,4-dihydropyrimidin-4(3H)-ones, F(2)-NH-DABOs) in which the sulfur atom of the related F(2)-S-DABOs is replaced by an amino group. For these studies, we used as a reference model the cocrystallized MKC-442/RT complex. Docking studies with Autodock of the newly designed F(2)-NH-DABOs on the ligand-derived RT confirmed the findings previously described for the F(2)-S-DABOs. The F(2)-NH-DABO binding mode resembles that reported for F(2)-S-DABOs, with the difference that the NH moiety at the C-2 position represents a new anchor site for ligand/enzyme complexation. The predicted inhibition constant (K(i)) values by the internal scoring function of Autodock, and the predicted IC(50) values by the application of a VALIDATE II/HIV-RT model strongly suggested the synthesis of the designed amino-DABOs. F(2)-NH-DABOs were shown to be highly active in both anti-RT and anti-HIV biological assays with IC(50) and EC(50) comparable with that of the reference compound MKC-442. Interestingly, 2-cyclopentylamino-6-[1-(2,6-difluorophenyl)ethyl]-3,4-dihydro-5-methyl pyrimidin-4(3H)-one (9d) was active against the Y181C HIV-1 mutant strain at submicromolar concentration, with a resistance value similar to that of efavirenz, the last FDA-approved NNRTI for AIDS therapy, and 2-fold lower than that of its 2-cyclopentylthio counterpart 8d. The introduction in 9d of a new anchor point (pyrimidine C-2 NH group), with the formation of a new hydrogen bond with Lys101, could compensate for the lack of positive hydrophobic ligand/NNBP interactions due to the Tyr181 to Cys181 mutation.
Ragno
Rino
R
Dipartimento di Studi di Chimica e Tecnologie delle Sostanze Biologicamente Attive, Università degli Studi di Roma "La Sapienza", P.le A. Moro 5, I-00185 Roma, Italy.
Mai
Antonello
A
Sbardella
Gianluca
G
Artico
Marino
M
Massa
Silvio
S
Musiu
Chiara
C
Mura
Massimo
M
Marturana
Flavia
F
Cadeddu
Alessandra
A
La Colla
Paolo
P
D002460:Cell Line; D003198:Computer Simulation; D015195:Drug Design; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000378:metabolism*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics; D015498:HIV-2 / Q000187:drug effects; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D011744:Pyrimidinones / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D021281:Quantitative Structure-Activity Relationship; D018894:Reverse Transcriptase Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
C483197:2-cyclopentylamino-6-(1-(2,6-difluorophenyl)ethyl)-3,4-dihydro-5-methylpyrimidin-4(3H)-one; D011744:Pyrimidinones; D018894:Reverse Transcriptase Inhibitors; D054303:HIV Reverse Transcriptase