Identification of substituted [3, 2-a] pyrimidines as selective antiviral agents: Molecular modeling study

► Biological activity of thiazolo [3, 2-a] pyrimidine derivatives was studied. ► The molecular descriptors of 4b, 5b and 6b explained their drug like properties. ► 4b, 5b and 6b showed best docking scores in silico with HN viral envelop protein. ► 4b, 5b and 6b showed antiviral activity against NDV virus infected chicks in vivo. ► Both in silico, in vivo assays ensures 4b, 5b and 6b as potential antiviral drugs. A series of novel substituted dihydropyrimidine and 5H-thiazolo [3, 2-a] pyrimidine derivatives were designed and synthesized as a potential target to discover drugs fighting against the viral diseases. The main objective of the present work is to carry out the QSAR studies for all the series of the compounds starting from 4a to 6j to find out their molecular descriptors and predict the biological properties. All of them are showing the best QSAR descriptors, hence chosen for the prediction of anti-viral activity against Newcastle disease virus (NDV). Initially their inhibitory activity was predicted by molecular docking of these compounds against haemaglutinin–neuraminidase (HN) protein using molecular operating environment (MOE) software. Based on the best affinity and highest docking scores 4b, 5b and 6b were assayed in vivo on NDV infected chicks and it was found that there is significant improvement in the survival of the chicks with the treatment (P