Some thoughts on the physiology of caffeine in coffee: and a glimpse of metabolite profiling

Abstract

Human beings enjoy the flavor and stimulating activity of a cup of coffee without knowing that by doing so, they are part of a 'food web' and receive signals coffee plants build to improve their struggle for life. This review is centered in the first part on the purine alkaloid caffeine and its physiological role in the coffee plant's life cycle. Many of the thoughts and ideas presented here are plain speculation, because the real research revealing the secrets of plant physiology such as e.g. the formation of the coffee bean with all its ingredients, has just started. The recent achievements in molecular biology made it possible to tackle and answer new questions regarding the regulation of secondary metabolism in the coffee plant organs at selected stages of their development. Brazilian research groups have much contributed to the recent progress in molecular biology and physiology of coffee. Among them was Maro R. Söndahl, in commemoration of whom this article has been written. Thus, the second part reports on the very first steps Maro and I made together into a very new field of coffee, that is metabolite profiling. The outcome was amazing and gives an idea of the great potential of this technique to map in future the complex network of the coffee metabolom. Key words: Endosperm, flower, germination, metabolite profiling, purine alkaloid, perisperm.Alguns pensamentos sobre a fisiologia da cafeína em café -e uma rápida olhada no perfil metabólico: Humanos apreciam o sabor e a estimulante atividade de uma xícara de café sem saber que fazendo isto, eles fazem parte de uma teia alimentar e recebem sinais de plantas de café criados para melhorar sua sobrevivência. Esta revisão tem sua primeira parte centrada no alcalóide purínico cafeína e seu papel fisiológico no ciclo de vida da planta de café. Muitas das considerações e idéias apresentadas aqui são especulações, porque a pesquisa verdadeira revelando os segredos da fisiologia da planta de café, tal como a formação da semente de café com todos seus ingredientes, apenas começou recentemente. Os resultados recentes na biologia molecular tornou possível controlar e responder novas questões relatives à regulação do metabolismo secundário nos órgãos de plantas de café em estádios específicos de seu desenvolvimento. Grupos brasileiros de pesquisa contribuiram significativamente para o recente progresso em biologia molecular e fisiologia do café. Entre eles inclui-se Maro R. Söndahl, para quem este artigo é dedicado. Assim, a segunda parte deste artigo relata sobre os primeiros passos que Maro e eu fizemos juntos em uma área muito nova em café, que é o perfil metabólico. Os resultados foram surpreendentes e fornecem novas idéias para o grande potencial desta técnica para mapear futuramente a complexa rede do metaboloma do café. Palavras-chave: Alcalóides purínicos, endosperma, flor, germinação, perfil metabólico, perisperma.

Decaf and the Steeplechase Towards Decaffito—the Coffee from Caffeine-Free Arabica Plants

“…At second glance and to stick to our favorite, we may realize that accumulation of caffeine in the coffee bean is quite another cup of tea! It requires inter alia a concerted synthesis of the alkaloid and its complexors, the chlorogenic acids, their transport into the vacuole and finally the vacuolar storage of the complex [19,63,106,138]. This multifaceted allocation machinery starts already in the maternal perisperm, placeholder and template for the subsequent phytochemical and energetic asset of the endosperm, the coffee bean.…”

“…This assumption has never been tested experimentally. First steps in metabolite profiling of coffee seeds indicated-within some limits-an inverse coherence between the two alkaloids [19].…”

Ecophysiology of coffee growth and production

“…Several aspects of coffee (eco)physiology have recently been reviewed, including water relations and drought tolerance (Carr, 2001;Rena, 2001, 2002a;DaMatta, 2004c;DaMatta and Ramalho, 2006), photosynthetic acclimation to light availability (DaMatta, 2004a), nitrogen metabolism (Carelli et al, 2006), seed physiology (Eira et al, 2006), caffeine (Baumann, 2006), and impacts of extreme temperatures and drought on coffee physiology and production (DaMatta and Ramalho, 2006). Therefore, these aspects will not be examined here in detail.…”

Characterisation of AC1: a naturally decaffeinated coffee

“…In C. Arabica flowers during the anthesis stage, caffeine is the most abundant purine alkaloid, with 0.58 mg g -1 in the petals and gynoecium and 1.36 mg g -1 in the stamens (Baumann, 2006). The predominance of theobromine over caffeine was detected in all of the AC1 tissues analysed.…”