四甲尿酸(Theacrine)全名是1,3,7,9-四甲基尿酸,是由古布阿苏及茶树叶子上提炼的生物碱[1][2]。四甲尿酸有抗炎性及镇痛的效果,其结构类似咖啡因,也会以类似的方式影响腺苷的信号[2][3]。一般认为在茶叶上,四甲尿酸是由三步骤的路径,由咖啡因所合成[2]。
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四甲尿酸很类似咖啡因,差异只有一个酮基,以及在9-碳上的甲基基团。
临床实验显示,健康人类可以每日安全服用 300 mg 四甲尿酸持续 8 周,且不会产生习惯。[4]实验中未发现四甲尿酸具有咖啡因等其他兴奋剂的快速耐受现象。[4]
在动物实验中,四甲尿酸的LD50为 810 mg/kg,[5][4]高于咖啡因的 265 mg/kg。[6]
- Liberine
- Methylliberine
- 可可碱
- 茶碱
Zheng, XQ; Ye, CX; Kato, M; Crozier, A; Ashihara, H. Theacrine (1,3,7,9-tetramethyluric acid) synthesis in leaves of a Chinese tea, kucha (Camellia assamica var. Kucha). Phytochemistry. 2002, 60 (2): 129–34. PMID 12009315. doi:10.1016/s0031-9422(02)00086-9.
Feduccia, Allison A.; Wang, Yuanyuan; Simms, Jeffrey A.; Yi, Henry Y.; Li, Rui; Bjeldanes, Leonard; Ye, Chuangxing; Bartlett, Selena E. Locomotor activation by theacrine, a purine alkaloid structurally similar to caffeine: Involvement of adenosine and dopamine receptors. Pharmacology Biochemistry and Behavior. 2012, 102 (2): 241. doi:10.1016/j.pbb.2012.04.014.
Wang, Yuanyuan; Yang, Xiaorong; Zheng, Xinqiang; Li, Jing; Ye, Chuangxing; Song, Xiaohong. Theacrine, a purine alkaloid with anti-inflammatory and analgesic activities. Fitoterapia. 2010, 81 (6): 627–31. PMID 20227468. doi:10.1016/j.fitote.2010.03.008.
Taylor L, Mumford P, Roberts M, Hayward S, Mullins J, Urbina S, Wilborn C. Safety of TeaCrine®, a non-habituating, naturally-occurring purine alkaloid over eight weeks of continuous use. Journal of the International Society of Sports Nutrition. 2016, 13: 2 [2016-05-14]. PMC 4711067 . PMID 26766930. doi:10.1186/s12970-016-0113-3. (原始内容存档于2016-06-04).
• These findings support the clinical safety and non-habituating neuro-energetic effects of TeaCrine® supplementation over 8 weeks of daily use (up to 300 mg/day). Moreover, there was no evidence of a tachyphylactic response that is typical of neuroactive agents such as caffeine and other stimulants.
• Specifically, the acute toxicity for theacrine ingestion in mice has been previously reported [4] to be an LD50 of 810.6 mg/kg, which would equate to roughly 4.0 g for an individual weighing 76 kg.
Warszawski D, Gorodischer R, Kaplanski J. Comparative toxicity of caffeine and aminophylline (theophylline ethylenediamine) in young and adult rats. Biology of the Neonate. 1978, 34 (1-2): 68–71. PMID 698326. doi:10.1159/000241107. In adult rats, the LD50 of caffeine and aminophylline was the same after 24 h and after 1 week of observation: caffeine 265 mg/kg