Sintesis De Cafeina

MINIREVIEW

Metabolism of alkaloids in coffee plants
Hiroshi Ashihara
Metabolic Biology Group, Department of Biology, Faculty of Science, Ochanomizu University, Tokyo, 112-8610, Japan;
E -mail: ashihara@cc.ocha.ac.jp

Coffee beans contain two types of alkaloids, caffeine and trigonelline, as major components. This review describes the distribution and metabolism of these compounds.Caffeine is synthesised from xanthosine derived from purine nucleotides. The major
biosynthetic route is xanthosine → 7-methylxanthosine → 7-methylxanthine → theobromine → caffeine. Degradation activity of caffeine in coffee plants is very low, but catabolism of theophylline is always present. Theophylline is converted to xanthine, and then enters the conventional purine degradation pathway. A recentdevelopment in caffeine research is the successful cloning of genes of N-methyltransferases and characterization of recombinant proteins of these genes. Possible biotechnological applications are discussed briefly. Trigonelline (N-methylnicotinic acid) is synthesised from nicotinic acid derived from
nicotinamide adenine nucleotides. Nicotinate N-methyltransferase (trigonelline synthase) activitywas detected in coffee plants,
but purification of this enzyme or cloning of the genes of this N-methyltransferase has not yet been reported. The degradation
activity of trigonelline in coffee plants is extremely low.
Key words: Coffea, caffeine, purine alkaloids, pyridine alkaloids, theobromine, trigonelline.

Metabolismo de alcalóides em plantas de café: Sementes de café possuem dois tipos dealcalóides, cafeína e trigonelina, como
principais componentes. Esta revisão descreve a distribuição e metabolismo desses compostos. Cafeína é sintetizada a partir da
xantosina derivada de nucleotídeos purínicos. A principal rota biossintética é xantosina → 7-metilxantosina → 7-metilxantina →
teobromina → cafeína. A atividade de degradação de cafeína em café é muito baixa, mas o catabolismo deteofilina está sempre
presente. Teofilina é convertida a xantina, que entra na via convencional de degradação de purinas. Um recente desenvolvimento na pesquisa com cafeína é a clonagem de genes de N-metiltransferases e a caracterização de proteínas recombinantes desses genes. Possíveis aplicações biotecnológicas são discutidas brevemente. Trigonelina (ácido N-metilnicotínico) é sintetizada apartir de ácido nicotínico derivado de nucleotídeos de nicotinamida adenina. Atividade de nicotinato N-metiltransferase (trigonelina sintase) foi detectada em plantas de café, mas a purificação desta enzima ou a clonagem dos genes desta N-metiltransferase ainda não foi relatada na literatura. A atividade de degradação de trigonelina em café é extremamente baixa.
Palavras-chave: Coffea, alcalóidespurínicos, alcalóides piridínicos, cafeína, teobromina, trigonelina.

INTRODUCTION
Coffee plants contain two different kinds of alkaloid de livered from nucleotides. One type is purine alkaloids, such
as caffeine (1,3,7- N -trimethylxanthine) and theobromine
(3,7- N -dimethylxanthine); the other is the pyridine alkaloid,
t rigonelline (1- N -methylnicotinic acid). The distribution ofcaffeine and trigonelline in the plant kingdom is different;
caffeine is present in both coffee and tea, but trigonelline is
found only in coffee. Large amounts of trigonelline are also
found in many leguminous plants. Although the metabo -

lism of purine and pyridine alkaloids has been investigated
in several plants, the present review focuses mainly on coffee plants. There are many species ofCoffea plant, but the
term ‘coffee plant’ is used here for Coffea arabica or Coffea
canephora plants.
Purine alkaloids
Distribution of purine alkaloids: Purine alkaloids are
distributed in 13 orders of plants within the plant kingdom.
By the end of the 20th century, caffeine had been found

Braz. J. Plant Physiol., 18(1):1-8, 2006

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H. ASHIHARA

in nearly 100 plant species....