Pyrimidotriazine derivatives as selective inhibitors of HBV capsid assembly

Chronic hepatitis B virus (HBV) infection is currently treated with nucleoside/nucleotides analogs. They are potent inhibitors of HBV DNA polymerase, which also functions as reverse transcriptase. Although nucleoside/nucleotide analogs efficiently suppress HBV replication in liver cells, they cannot eradicate HBV DNA from liver cells and cure the disease. Therefore, it is still mandatory to identify and develop effective inhibitors that target a step other than reverse transcription in the viral replication cycle. HBV capsid assembly is a critical step for viral replication and an attractive target for inhibition of HBV replication. We conducted in silico screening of compounds expected to bind to the HBV capsid dimer-dimer interaction site. The selected compounds were further examined for their anti-HBV activity in vitro. Among the test compounds, novel pyrimidotriazine derivatives were found to be selective inhibitors of HBV replication in HepG2.2.15.7 cells. Among the compounds, 2-[(2,3-dichlorophenyl)amino]-4-(4-tert-butylphenyl)-8-methyl-4H,9H-pyrimido[1,2-a][1,3,5]triazin-6-one was the most active against HBV replication. Studies on its mechanism of action revealed that the compound interfered with HBV capsid assembly determined by a cell-free capsid assembly system. Thus, the pyrimidotriazine derivatives are considered to be potential leads for novel HBV capsid assembly inhibitors.

Synthesis and anticancer evaluation of some novel pyrimido[5,4-e][1,2,4]triazines and pyrazolo[3,4-d]pyrimidine using DMF-DMA as methylating and cyclizing agent

Background

Described a series of main target compounds pyrimido[5,4-e][1,2,4]triazines is obtained via condensation of 6-hydrazinyluracil with different aromatic aldehydes to give the hydrazones followed by nitrosation with HNO₂ then intramolecular cyclization. On the other hand, pyrazolopyrimidines can be obtained by the reaction of hydrazones with dimethylformamide-dimethylacetal (DMF-DMA), DMF-DMA in the presence of DMF or by refluxing the hydrazinyluracil with DMF-DMA in the presence of DMF directly. The newly synthesized compounds are evaluated in vitro for their anticancer activity against human lung carcinoma (A549).

Results

A newly substituted compounds of benzaldehyde-pyrimidin-4-yl)hydrazones (5a–f), pyrimido[5,4-e][1,2,4]triazines 6a–e, arylethylidenehydrazinylpyrimidine 7a,b and pyrazolopyrimidines 9,11 are screened for cytotoxic activity against human lung carcinoma (A549) cell line. They exhibited a good yield. Compound 6b shows the highest effect with IC₅₀ value 3.6 μM, followed by compounds 9, 5a, 8, 5e, 6e, 5b, 5f, 7a, 5c, 6c, 7b, 6a, 11, 5d and 6d.

Conclusion

A simple and efficient route is used for the synthesis of pyrimido[5,4-e][1,2,4]triazines and pyrazolopyrimidines. The synthesized compounds are screened for antitumor activity.