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Xanthine Alkaloids: Occurrence, Biosynthesis, and Function in Plants.

Hiroshi Ashihara1, Kouichi Mizuno2, Takao Yokota3

  • 1Department of Biology, Ochanomizu University, Tokyo, 112-8610, Japan. ashihara.hiroshi@ocha.ac.jp.

Progress in the Chemistry of Organic Natural Products
|February 15, 2017
PubMed
Summary

Caffeine biosynthesis involves specific N-methyltransferases in a four-step pathway from xanthosine. Plants utilize caffeine for chemical defense against pests and pathogens.

Keywords:
BiosynthesisCaffeineCamellia sinensisCatabolismCoffea sppFunctionMethylxanthinesOccurrenceTheobroma cacaoTransgenics

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Area of Science:

  • Biochemistry
  • Plant Science
  • Molecular Biology

Background:

  • Caffeine, a xanthine alkaloid, is prevalent in beverages like tea and coffee.
  • Understanding caffeine biosynthesis pathways remained limited until the early 2000s.

Purpose of the Study:

  • To review the occurrence of xanthine alkaloids in plants.
  • To elucidate the molecular mechanisms of caffeine biosynthesis.
  • To discuss the role of caffeine in plant chemical defense.

Main Methods:

  • Review of existing literature on xanthine alkaloid occurrence.
  • Detailed analysis of the caffeine biosynthesis pathway, focusing on N-methyltransferases.
  • Examination of studies on transgenic plants demonstrating caffeine's defensive role.

Main Results:

  • Identified N-methyltransferases (motif B' methyltransferase family) catalyzing key steps in caffeine synthesis from xanthosine.
  • Outlined the four-step pathway of caffeine biosynthesis.
  • Demonstrated caffeine's role in plant defense against pathogens and herbivores via transgenic models.

Conclusions:

  • Caffeine biosynthesis is a well-defined pathway involving specific enzymes.
  • Caffeine plays a significant role in plant chemical defense mechanisms.
  • Future research could enable naturally decaffeinated crops and enhanced natural pesticides.