Importance of Heterocycles in Life

The importance of heterocycles in life was recognized as the nascent stage of organic chemistry two centuries ago with isolation of alkaloids such as morphine from poppy seeds, quinine from cinchona barks, and camptothecin from the Chinese joy tree. Today, heterocycles are found in numerous fields of biochemical and physiological such as photosynthesis, amino acids, DNA bases, vitamins, endogenous neurotransmitters, and so on. 

To begin with, chlorophyll is porphyrin (a tetramer of pyrrole) surrounding a magnesium atom. It is the molecule that absorbs sunlight and 

Several amino acids, the building block of life, are made of heterocycles. Histidine has an imidazole tryptophan has an indole yet proline has a pyrrolidine. 

Heterocycles also play an important role as endogenous neurotransmitters. Chief among them are serotonin and histamine, which are of paramount importance in modulating the body s physiological and biochemical processes. 

Melatonin regulates circadian rhythms, most noticeably sleep, whereas tryptamine is closely related to melatonin and the amino acid tryptophan. 

---