[Frontiers in Bioscience 9, 1864-1876, May 1, 2004] 1864 DISTRIBUTION AND BIOSYNTHESIS OF CAFFEINE IN PLANTS

1. Abstract 2. Introduction 3. Structure and properties of purine alkaloids found in nature 4. Distribution of purine alkaloids 4.1. Coffee and related Coffea plants 4.2. Tea and related Camellia plants 4.3. Cacao and related Theobroma and Herrania plants 4.4. Other plants 5. The “core pathway” of caffeine biosynthesis: conversion of xanthosine to caffeine 5.1. Production of 7-methylxanthosine 5.2. Hydrolysis of 7-methylxanthosine to 7-methylxanthine 5.3. Production of caffeine from 7-methylxanthine via theobromine 5.4. Regulation of the “core pathway” 6. The “provider pathways” for xanthosine 6.1. De novo purine biosynthesis 6.2. S-Adenosyl-L-methionine (SAM) cycle 6.3. Degradation of adenine nucleotides (AMP pathway) 6.4. Degradation of guanine nucleotides (GMP pathway) 7. Diversity of purine alkaloid biosynthesis 7.1. Differences in products 7.2. Purine alkaloid synthesis in theobromine plants 7.3. Methyluric acid synthesis 8. Subcellular distribution and transport of purine alkaloids 9. Possible function of purine alkaloids in plants 10. Biotechnology of purine alkaloids 10.1. Caffeine production in cell and tissue cultures 10.2. Decaffeinated beverages 11. Summary and perspective 12. Acknowledgements 13. References