One‐Pot Synthesis of Pyrimido[4,5‐d]pyrimidine Derivatives and Investigation of Their Antibacterial, Antioxidant, DNA‐Binding and Voltammetric Characteristics

Dihydropyrimidinones (DHPMs), 4 a‐f and 6 a‐f is reported and were characterized by 1 H‐NMR, 13 C‐NMR, FT‐IR and LC–MS. The synthesized compounds were evaluated for their antibacterial activity against Staphylococcus aureus ( S.aureus) , Bacillus subtilis ( B. subtilis ), Salmonella typhi ( S. typhi ) and Pseudomonas aeruginosa ( P. aeruginosa ). Among the test samples compounds, 5‐(4‐hydroxy‐3‐methoxyphenyl)‐7‐imino‐1,3,5,6,8‐pentahydropyrimido[4,5‐d]pyrimidine‐2,4‐dione (6 c) and 5‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐1,3‐N,N‐dimethyl‐7‐thioxo‐5,6,8‐trihydropyrimido[4,5‐d]pyrimidine‐2,4‐dione (4 d) were more potent against S. aureus and B. subtilis . Whereas 5‐(4‐hydroxy‐3‐methoxyphenyl)‐1,3‐N,N‐dimethyl‐5,6,8‐trihydropyrimido[4,5‐d]pyrimidine‐2,4,7‐trione (6 e) and 5‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐1,3‐N,N‐dimethyl‐5,6,8‐trihydropyrimido[4,5‐d]pyrimidine‐2,4,7‐trione (4 e) showed good inhibition against S. typhi and P. aeruginosa which were well supported by computational interaction and DNA binding studies. Compound 5‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐7‐imino‐1,3,5,6,8‐pentahydropyrimido[4,5‐d]pyrimidine‐2,4,7‐trione (4 c) exhibited potent scavenging activity with IC 50 of 8.30 mg/ml. Furthermore, Cyclic Voltammetric analysis disclosed that 5 ‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐7‐thioxo‐1,3,5,6,8‐pentahydropyrimido[4,5‐d]pyrimidine‐2,4‐dione (4 a) , 5‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐1,3,5,6,8‐pentahydropyrimido[4,5‐d]pyrimidine‐2,4,7‐trione (4 b) , 4 c , 6 d , 6 e , and 6 f showed redox behavior.