Synthesis, Antioxidant, Antifungal and Antibacterial Activities of New Class of Fused Isoxazole-Pyrimidines and Pyrazole-Pyrimidines as Five and Six Membered Heterocyclic Compounds

Abstract: One series of total 5 phenylisoxazolo[4,3-d]pyrimidine and five series of total 22 pyrazolo[4,3-d]pyrimidine compounds were designed, synthesized and evaluated for anti-oxidant, antibacterial and antifungal activities. Compounds pyrazolo[4,3-d]pyrimidine derivatives (VIIIa'–d'), (IXa'–d') and (XIa'–d') exhibited significant antioxidant activity at 10 µg/mL better than compounds isoxazolo[4,3-d]pyrimidine derivatives (IIIa–e). The maximum anti-oxidant and anti-lipid peroxidation activities were showed for evaluated compound (IXb') 90% and 68% activities comparable to Vitamin-C and with Vitamin-E which showed 92% and 70% of activity respectively. Furthermore, compounds (VIIIa'–d') showed the highest antifungal activity against Botrytis cinerea and Alternaria solani species whereas compounds (IXa'–d') showed the highest antifungal activities against Cercospora arachidicola and Gibberellazeae zeae species. Finally as antibacterial activity the evaluated compounds (VIIIa'–d') showed pronounced antibacterial activities against Escherihia coli strain. All newly synthesized compounds structures were established on the basis of their elemental analysis and spectral IR, ¹H NMR and ¹³C NMR.