Comparison of the contents of kampo decoctions containing ephedra herb when prepared simply or by re-boiling according to the traditional theory

Herbal formulas containing ephedra herb (mao-zai) are among the most important medicinal prescriptions in Japanese traditional kampo medicine to treat cold symptoms, bronchial asthma, arthralgia, and rheumatism. Shokan-zatsubyo-ron (Shanghan zabing lun in Chinese), a classical textbook of kampo medicine published in 220 A.D., describes that when herbal formulas containing ephedra herb (stem of Ephedra sinica) such as maoto (mahuang-tang) and kakkonto (gegen-tang) are prepared, ephedra herb is first boiled alone, the scum is removed, and then other crude drugs are added and decocted. In the present study, we evaluated evidence for the benefit of boiling ephedra herb prior to other crude drugs by analyzing the contents of the extract and four ephedrine alkaloids (ephedrine, methylephedrine, pseudoephedrine, and norephedrine), which are considered the main active ingredients in ephedra herb. We prepared two different decoctions of maoto and kakkonto: one decoction was prepared by boiling all the crude drugs at the same time and the other decoction was prepared according to the classical textbook. In both decoctions of maoto and kakkonto, neither alkaloid contents in the extract nor extracting ratio of four ephedrine alkaloids exhibited significant difference. As far as the ephedrine alkaloid content goes, there is no evidence for the benefit of the boiling method for ephedra herb described in the classical textbook of kampo medicine.