Introduction to Heterocyclic Chemistry 5 chlorophyllsessential for photosynthesis(Box 1.5).Similarly,the paired bases found in RNA and DNAare heterocycles,as are the sugars that in combination with phosphates provide the backbones and determine the topology of these nucleic acids Box 1.5 Some Heterocycles Important for Life Chlorophyll a Dyestuffs of plant origin include indigo blue,used to dye jeans.A poi- son of detective novel fame is strychnine,obtained from the plant resin curare (Box 1.6). Box 1.6 Some Other Natural Heterocycles ndigo (indigotin) trychn The biological properties of heterocycles in general make them one of the prime interests of the pharmaceutical and biotechnology indus- tries.A selection of just six biologically active pyridine or piperidineIntroduction to Heterocyclic Chemistry 5 chlorophylls essential for photosynthesis (Box 1.5). Similarly, the paired bases found in RNA and DNA are heterocycles, as are the sugars that in combination with phosphates provide the backbones and determine the topology of these nucleic acids. Dyestuffs of plant origin include indigo blue, used to dye jeans. A poi￾son of detective novel fame is strychnine, obtained from the plant resin curare (Box 1.6). The biological properties of heterocycles in general make them one of the prime interests of the pharmaceutical and biotechnology indus￾tries. A selection of just six biologically active pyridine or piperidine