Distribution, biosynthesis and catabolism of methylxanthines in plants.
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.
Ashihara
Hiroshi
H
Department of Biological Sciences, Ochanomizu University, Otsuka, Bunkyo-ku, Tokyo, Japan. ashihara.hiroshi@ocha.ac.jp
Kato
Misako
M
Crozier
Alan
A
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*
D014970:Xanthines; C008514:methylxanthine; D002110:Caffeine; D013806:Theophylline; D008780:Methyltransferases