A molecule that contains nitrogen and has the chemical properties of a base is called nitrogenous bases. There are two major types of nitrogenous bases that are the purine and the pyrimidine. Among them adenine and guanine is a purine base whereas cytosine and thymine or uracil is a pyrimidine base. So,adenine is a compound which is one of the four constituent bases of nucleic acids. It is a purine derivative, it is paired with thymine in double stranded DNA.