This work describes a novel purine derivatives incorporating tetrazole ring for biological applications. Initially, (6-aminopurin-9-yl)alkanenitrile compounds were synthesized. Then, 9-((1H-tetrazol-5-yl)alkyl)-9H-purin-6-amine compounds were synthesized via the addition of sodium azide to nitrile group. These novel purine analogues incorporating tetrazole ring were characterized by Fourier transform infrared, nuclear magnetic resonance and mass spectroscopic techniques. All the synthesized compounds were screened for their antibacterial activities against Gram-positive and Gram-negative bacteria and for their antifungal activities against yeast strains. The effect of the compounds on pBR322 plasmid DNA was studied by gel electrophoretic mobility measurements. The antibacterial activities and plasmid DNA interaction studies suggest that purine derivatives incorporating tetrazole ring cause DNA damages, and higher antibacterial activities than other derivatives.