Several new and known 6-(4-substituted-phenyl)-4-(4-substituted-phenyl)-2-phenyl-6H-1,3-thiazine (or selenazine) (Z4B7, Z4D5, Z4B7 and Z4D5) were prepared by US Pat 1,4-Michael addition reaction of chalcone derivatives with thiobenzamide or phenylselenocarboxamide in basic medium (the chalcones being formed by Claisen-Schimidt condensation of aromatic aldehydes with 4-substituted acetophenone in the presence of sodium hydroxide). These 6H-1,3-thia or selenazines were used for a new series of cephem and selenacephem compounds (i.e. 7-chloro-4-(4-substituted phenyl)-2-(4-substituted phenyl)-6- Phenyl5-thia (or 5-selena)-1-azabicyclo[4.2.0]oct-2-en-8-one; AZ4B7, AZ4D5, AZ4B7 and AZ4D5). All new compound derivatives were characterized by IR, 1 H NMR, 13 C NMR, mass spectroscopic techniques and elemental analysis. The toxicity of new compounds was assessed by determining their LD50 value using the Dixon up and down method. The antibacterial activity of cephem and selenacephem compounds was tested in vitro against Staphylococcus aureus, Bacillus, Escherichia coli and Pseudomonas aeruginosa. In addition, the antioxidant, anticancer, and DNA cleavage efficiencies of compounds were evaluated.