The rhizome of ginger has been used in the Kampo medicine for several hundred years. In the Japanese Pharmacopoeia (17th ed.), two crude drugs derived from the rhizome of Zingiber officinale are listed as “Ginger” and “Processed Ginger”. The latter is dried after being passed through hot water or being steamed and is known to have stronger thermogenic actions. We established the mice model to evaluate the thermogenic effects of crude drugs and the thermogenic effects of Ginger extract and Processed Ginger extract were evalutated. When normal mice were forced to swim in water at 25 °C for 15 min, their core body temperature dropped by ca. 6 °C, and then quickly recovered to normal temperature after the mice were transferred to a dry cage at room temperature (25 °C). A 1-h immobilization before swimming caused the core body temperature to drop by ca. 11 °C (5 °C lower than normal mice), and the recovery time of core body temperature doubled. We considered this delay in recovery from hypothermia to be a sign of stress-induced cold hypersensitivity [1]. In this study, we showed that recovery from the stress-induced hypothermia were remarkably faster in mice administered Processed Ginger extract than those administered Ginger extract. The contents of two major thermogenic compounds, 6-shogaol and 6-gingerol [2], were also quantified and their contribution in thermogenic actions were discussed.
[1] Kobayashi Y, Narita K, Chiba K, Takemoto H, Morita M, and Morishita K. Pharmacognosy Res. 2014; 6:297-302; [2] Yoshitomi T, Oshima N, Goto Y, Nakamori S, Wakana D, Anjiki N, Sugimura K, Kawano N, Fuchino H, Iida O, Kagawa T, Jinno H, Kawahara N, Kobayashi Y, Maruyama T. J Agric Food Chem. 2017; 65: 3581-3588.