title: Distribution, biosynthesis and catabolism of methylxanthines in plants.
abstract: Methylxanthines and methyluric acids are purine alkaloids that are synthesized in quantity in a limited number of plant species, including tea, coffee and cacao. This review summarizes the pathways, enzymes and related genes of caffeine biosynthesis. The main biosynthetic pathway is a sequence consisting of xanthosine → 7-methylxanthosine → 7-methylxanthine → theobromine → caffeine. Catabolism of caffeine starts with its conversion to theophylline. Typically, this reaction is very slow in caffeine-accumulating plants. Finally, the ecological roles of caffeine and the production of decaffeinated coffee plants are discussed.
authors.affiliation: Department of Biological Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo, Japan. ashihara.hiroshi@ocha.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ashihara
authors.forename: Misako
authors.initials: M
authors.lastname: Kato
authors.forename: Alan
authors.initials: A
authors.lastname: Crozier
mesh_terms: D000595:Amino Acid Sequence; D002099:Cacao / Q000378:metabolism; D002110:Caffeine / Q000378:metabolism; D028244:Camellia / Q000378:metabolism; D040503:Coffea / Q000378:metabolism; D008780:Methyltransferases / Q000502:physiology; D008969:Molecular Sequence Data; D010944:Plants / Q000378:metabolism*; D013806:Theophylline / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism*
chemical_list: D014970:Xanthines; C008514:methylxanthine; D002110:Caffeine; D013806:Theophylline; D008780:Methyltransferases