Heterocycles are parts of: * Biomolecules (nucleic bases in your DNA and RNA; amino acids Histidine and Tryptophan) * Important drugs (80% of top-selling drugs contain heterocycles: benzodiazepines, quinine, penicillin, etc.) * and even Food (sugar has heterocyclic rings too!) That's why it's so useful to know the structures of major heterocyclic compounds for molecular biologists, pharmacists, organic chemists and for general public interested in what the stuff is made from. This app is the