Chapter 8: Purine- and Pyrimidine-derived Natural Products

Pyrimidine- and purine-based natural products could qualify as alkaloids (e.g. caffeine) but we take up these nucleoside natural products as a separate subclass, given the centrality of uracil/5-methyluracil, cytosine, adenine, and guanine in nucleic acid metabolism, and as starting points for varied nucleoside scaffolds and their roles as plant signaling molecules and natural antiviral and/or antibacterial agents. In the core tripartite structure of nucleobase, d-ribose sugar, and 5′-carbon substituent, one can find metabolites with altered nucleobase heterocycles (e.g. 7-deazguanines), altered sugar core (e.g. arabinose, 2′,3′-dideoxyribose, carbacycle in neplanocin A, glucose replacement for ribose), and a variety of 5′-substituents, including sugar and peptide-nucleoside tailorings (tunicamycin, jawsamycin, polyoxins).