Han L K, Takaku T, Li J, Kimura Y, Okuda H
2nd Department of Medical Biochemistry, School of Medicine, Ehime University, Japan.
Int J Obes Relat Metab Disord. 1999 Jan;23(1):98-105. doi: 10.1038/sj.ijo.0800766.
Oolong tea is traditionally reported to have anti-obesity and hypolipidaemic effects. The present study was performed to clarify whether oolong tea prevented obesity induced in mice by the oral administration of a high-fat diet for 10 weeks.
High-fat diet-induced obese mice were treated with oolong tea for 10 weeks. The effects of various active fractions isolated from oolong tea on noradrenaline-induced lipolysis were examined with isolated fat cells and a cell-free system consisting of lipid droplets and hormone-sensitive lipase (HSL).
The mean food consumption was not significantly different between high-fat diet-treated mice and high-fat plus oolong tea diet-treated mice. Oolong tea prevented the obesity and fatty liver induced by a high-fat diet. A water extract of oolong tea enhanced noradrenaline-induced lipolysis, and the active substance was identified as caffeine. Caffeine enhanced noradrenaline-induced lipolysis in fat cells without a concomitant increase in HSL activity and also accelerated the hormone-induced lipolysis in a cell-free system consisting of lipid droplets and HSL, but not in the cell-free system with sonicated lipid droplets and HSL. Oolong tea extract inhibited pancreatic lipase activity.
It was demonstrated that the anti-obesity effects of oolong tea in high-fat diet-treated mice might be due partly to the enhancing effect of caffeine isolated from oolong tea on noradrenaline-induced lipolysis in adipose tissue, and to the inhibitory action of some other substance in oolong tea on pancreatic lipase activity. Caffeine was found to enhance lipolysis through acting on lipid droplets but not on HSL. The results suggest that oolong tea may be an effective crude drug for the treatment of obesity and fatty liver caused by a high-fat diet.
传统上报道乌龙茶具有抗肥胖和降血脂作用。本研究旨在阐明乌龙茶是否能预防通过口服高脂饮食10周诱导的小鼠肥胖。
用乌龙茶对高脂饮食诱导的肥胖小鼠进行10周治疗。用分离的脂肪细胞和由脂滴及激素敏感脂肪酶（HSL）组成的无细胞系统检测从乌龙茶中分离的各种活性成分对去甲肾上腺素诱导的脂肪分解的影响。
高脂饮食处理的小鼠与高脂加乌龙茶饮食处理的小鼠之间的平均食物消耗量无显著差异。乌龙茶预防了高脂饮食诱导的肥胖和脂肪肝。乌龙茶的水提取物增强了去甲肾上腺素诱导的脂肪分解，活性物质鉴定为咖啡因。咖啡因增强了脂肪细胞中去甲肾上腺素诱导的脂肪分解，且HSL活性无相应增加，还加速了由脂滴和HSL组成的无细胞系统中激素诱导的脂肪分解，但在由超声处理的脂滴和HSL组成的无细胞系统中未加速。乌龙茶提取物抑制胰脂肪酶活性。
证明乌龙茶对高脂饮食处理的小鼠的抗肥胖作用可能部分归因于从乌龙茶中分离出的咖啡因对脂肪组织中去甲肾上腺素诱导的脂肪分解的增强作用，以及乌龙茶中其他某种物质对胰脂肪酶活性的抑制作用。发现咖啡因通过作用于脂滴而非HSL来增强脂肪分解。结果表明乌龙茶可能是治疗高脂饮食引起的肥胖和脂肪肝的有效天然药物。
