In the present work,we aimed to synthesize and evaluate in vitro antibacterial and antifungal activities of new 
heterocyclic compounds bearing sulfadiazine moiety. Among the synthesized compounds, arylidine (3f) displayed 
significant antibacterial activity against S.pneumoniae (IC50, 22.46µg/mL, comparable to ampicillin IC50 value, 22.76 
µg/mL),whereas, 2-pyridone (4f)showed the highest antifungal activity against G.candidum (IC50,8.63µg/mL, comparable 
to amphotericin B,IC50, 11.63 µg/mL).Its antibacterial activity against S.pneumoniae was (IC50,13.84 µg/mL, comparable to 
ampicillin, IC50, 22.76µg/mL) and E.coli (IC50,29.89 µg/mL, comparable to gentamycin ,IC50,29.42µg/mL) respectively.On 
the other hand 2-imino chromene (5a) displayed significant antibacterial activities against S.pneumoniae (IC50,19.84µg/mL, 
comparable to ampicillin , IC50, 22.76 µg/mL) and exhibited antifungal activity against G.candidum (IC50,12.63 µg/mL, 
comparable to amphotericin B, IC50 , 11.63 µg/mL) respectively.In general,all of the synthesized compounds exhibited 
better antimicrobial activities than sulfadiazine. Molecular docking studies indicated that the newly synthesized compounds 
could occupy both p-aminobenzoic acid (PABA) and pterin binding pockets of the dihydropteroate synthase (DHPS), 
suggesting that the target compounds could act by the inhibition of microbial DHPS enzyme.These derivatives contain 
sulfonamide moiety as well as heterocyclic moiety that increase the lipophilic characters of the synthesized compounds 
hence enhance its absorption.