Amidines and guanidines in medicinal chemistry.

TLDR: The interesting finding for the present chapter is that the NO is formed by nitric oxide synthetase from arginine—the only essential amino acid which carries a guanidine group.

Abstract: Publisher Summary This chapter focuses on amidines and guanidines in medicinal chemistry. The drugs are classified under their main physiological activities and within each group are arranged roughly in order of increasing molecular complexity. Many of the compounds have given temporary excitement to their discoverers and then been dropped—the commonest experience in medicinal chemistry. There are important, clinically used, medicines in all the major categories of therapeutic action discussed in the chapter. This simple and very unstable compound is not only a neurotransmitter in the brain, but acts in the dilation of blood vessels and activates leucocytes to attack tumour cells, fungi, and bacteria. In addition, nitric oxide can inhibit blood coagulation by preventing platelet aggregation and appears to be the regulator of the male erection. No doubt other functions will be discovered in the future, but the interesting finding for the present chapter is that the NO is formed by nitric oxide synthetase from arginine—the only essential amino acid which carries a guanidine group. Since most of the active guanidine drugs have at least one unsubstituted =NH or NH 2 group, it is interesting to speculate that they will be shown to act by giving nitric oxide as well.