Synthetic Nitrogen Base Analogues (SNBA) fused heterocyclic purine and pyrimidine  derivatives are of great biological interest, especially as antiviral, antitumor and antimicrobial agents. The viruses are one of the risk   factors for plants resulting in gigantic economic losses  . Four SNBA compounds were assayed antiviral activity, plant cytotoxicity as well as determining their mode of action against Tomato mosaic tobamovirus (ToMV) by using the local lesion   on Datura metel as well as infectivity assayed on tomato plants . The cytotoxicity of Ph-Oxanzolo and Oxazalone compounds at concentrations 15 and 20μg/mL showed   chlorosis, mottling, necrosis, wilting, and curling  at  three to four days after spraying  while  Hippuric acid and Benzotriazolo compounds were safe on test plants and didn't show any signs of toxicity on D.metel and tomato plants . Ph-Oxanzolon and  Oxazalone had virucidal activity  where showed high percentage of inhibition at simultaneous- ToMV inoculation  at 5,10,15,20  ppm concentration and  low  percentage of inhibition at pre-and –post  ToMV inoculation  , as well as  they showed high ToMV concentration  and low  percentage disease severity  at   10  ppm concentration . While  another  Hippuric acid and Benzotriazol had affect the ToMV replication process , where showed weak inhibitory activity of inhibition at simultaneous - ToMV inoculation  at  5,10,15,20  ppm concentration  and  low   percentage of inhibition at pre-and –post  ToMV inoculation  , as well as  they showed very low doubtful  ToMV concentration  and disease severity  percentage at 15  ppm concentration  .