Lam L K, Sparnins V L, Wattenberg L W
Cancer Res. 1982 Apr;42(4):1193-8.
Glutathione (GSH) S-transferase is a major detoxification enzyme system that catalyzes the binding of a variety of electrophiles, including reactive forms of chemical carcinogens, to GSH. Green coffee beans fed in the diet induced increased GSH S-transferase activity in the mucosa of the small intestine and in the liver of mice. A potent compound that induces increased GSH S-transferase activity was isolated from green coffee beans and identified as kahweol palmitate. The corresponding free alcohol, kahweol, and its synthetic monoacetate are also potent inducers of the activity of GSH S-transferase. A similar diterpene ester, cafestol palmitate, isolated from green coffee beans was active but less so than was kahweol palmitate. Likewise, the corresponding alcohol, cafestol, and its monoacetate showed moderate potency as inducers of increased GSH S-transferase activity. Kahweol palmitate and cafestol palmitate were extracted from green coffee beans into petroleum ether. The petroleum ether extract was fractionated by preparative normal-phase and reverse-phase liquid chromatographies successively. Final purification with silver nitrate-impregnated thin-layer chromatography yielded the pure palmitates of cafestol and kahweol. The structures were determined by examination of the spectroscopic data of the esters and their parent alcohols and by derivative comparison.
谷胱甘肽（GSH）S-转移酶是一种主要的解毒酶系统，可催化包括化学致癌物的活性形式在内的多种亲电试剂与GSH结合。饮食中摄入的生咖啡豆可诱导小鼠小肠黏膜和肝脏中GSH S-转移酶活性增加。从生咖啡豆中分离出一种能诱导GSH S-转移酶活性增加的强效化合物，并鉴定为棕榈酸咖啡豆醇酯。相应的游离醇咖啡豆醇及其合成单乙酸酯也是GSH S-转移酶活性的强效诱导剂。从生咖啡豆中分离出的一种类似的二萜酯，棕榈酸咖啡醇酯具有活性，但活性低于棕榈酸咖啡豆醇酯。同样，相应的醇咖啡醇及其单乙酸酯作为GSH S-转移酶活性增加的诱导剂显示出中等效力。将棕榈酸咖啡豆醇酯和棕榈酸咖啡醇酯从生咖啡豆中提取到石油醚中。石油醚提取物先后通过制备型正相和反相液相色谱进行分离。用硝酸银浸渍的薄层色谱进行最终纯化，得到咖啡醇和咖啡豆醇的纯棕榈酸酯。通过检查酯及其母体醇的光谱数据以及进行衍生物比较来确定结构。
