Analgesic Effects and Side Effects of Ephedra Herb Extract and Ephedrine Alkaloids-free Ephedra Herb Extract

Ephedra Herb is classified "pungent, slightly bitter, and warm" in tastes and natures, and is used to provide warmth to the body, dispel coldness, remove dampness, and reduce pain. Similar herbs are "pungent and hot" chili peppers, "pungent and hot" evodia fruit," "pungent and warm" ginger, "pungent and hot" processed ginger, "pungent and hot" Zanthoxylum fruit, etc. These herbs are prescribed to provide heat to the outer or inner body. Some pungent components such as capsaicin, evodiamine, gingerol, and shogaol are known to be activators of transient receptor potential vanilloid 1 (TRPV1). TRPV1, a pain receptor, is activated in response to irritant chemicals such as capsaicin and high heat (>43℃) and strongly acidic conditions (pH<6). The typical TRPV1 activator capsaicin has various effects such as improvement of peripheral circulation, enhancement of thermogenesis, and pain relief. These effects are commonly observed for the "pungent and hot/warm" herbs, suggesting that TRPV1 stimulation plays an important part in their pharmacological action. In this study, we demonstrated that Ephedra Herb extract (EHE) shows strong TRPV1 activation, although ephedrine didn't show such effects. Both EHE and ephedrine alkaloids-free EHE (EFE) expressed similar analgesic action following oral administration, suggesting the presence of active components other than ephedrine alkaloids. Furthermore, EFE did not show side effects such as loss of sleep and irregular heartbeat in mice. Caution needs to be exercised while prescribing Ephedra Herb because it contains ephedrine. The application of EFE in Kampo medicine might be a better alternative in some cases.