New Metabolites of Fairy Chemicals in Tea and Coffee: Methylated AHX and AOH

Fairy chemicals (FCs), such as 2-azahypoxanthine (AHX), 2-aza-8-oxohypoxanthine (AOH), and imidazole-4-carboxamide, are molecules with diverse functions in plants. Methylation of plant hormones is recognized to affect the physiological functions of plants. We predicted that plants regulate the physiological activity of FCs through methylation and launched a project searching for methyl derivatives of FCs. We synthesized 7-methyl-AHX (1), 9-methyl-AHX (2), 7- methyl-AOH (3), 9-methyl-AOH (4), and 1,7,9-trimethyl-AOH (5). 1-Methyl-AOH (6) and 1,9-dimethyl-AOH (7) were isolated from AOH-treated tea cells. By using these purines as authentic compounds to analyze tea plant and coffee plant, we found that 1, 2, and 4–7 are endogenously produced in tea plant and 5 in coffee plant. Furthermore, quantitative analysis revealed that 5 was accumulated in the highest amounts. Furthermore, 2 showed growth-promoting activity and 5–7 showed growth-inhibiting activity on tea cells. These results suggest that tea plants might methylate FCs to modulate their physiological activity.