Interest in the study and application of traditional herbal medicine is currently growing. As opposed to modern drugs, in which chemical ingredients are definite, herbal formulas have some unknown ingredients and require extraction processes to enable the delivery of their active compounds. Although many studies try to select one small compound with a well-known structure as a representative of the whole herb or herbal formula, neither the pharmacological efficacies nor mechanisms can be considered equivalent1,2. While fingerprinting enables the analysis of the constituents of complex herbal formulas, some constituents are still not clearly analyzed, leading to a challenge when combining all extracts for study3. The interactions of numerous constituents/extracts mediate the therapeutic effects of herbal medicines. To retain this advantage, the traditional extract form—decoction—is still widely used in the clinic. Since the extract procedure has a great impact on the therapeutic efficacy, a standard protocol of traditional water decoction is necessary, especially for in vivo studies4,5.
On the other hand, when exploring pharmacological mechanisms, the administration of herbal decoctions during in vitro or ex vivo studies is also a challenge. The concept of a drug-containing serum was first proposed by Tashino in 19886. Since then, increasing numbers of researchers have applied it to herbal medicine7,8,9. Although the method of drug-containing serum has some limitations, such as the influence of certain components of the serum, it is still considered to be a method that closely mimics physiological conditions.
The er-xian decoction was developed in the early 1950s to relieve menopausal symptoms10,11,12,13. It has also been applied to the treatment of aplastic anemia14, menopausal osteoporosis15,16,17, premature ovarian failure18, breast cancer19, ovarian cancer20, and delayed puberty21. Here, we present detailed protocols for the preparation of both the er-xian decoction (EXD) and its drug-containing serum. In addition, we describe the application of EXD and EXD-containing serum to murine menopausal osteoporotic models.
An EXD is composed of 9 g each of Curculigo orchioides Gaertn, Herbaa Epimedii, Radix Morindae Officinalis, and Radix Angelicae Sinensis and 6 g each of Cortex Phellodendri and Rhizoma Anemarrhenae per adult patient per day. The equivalent dose for a mouse is 0.1418 EXD/kg/day based on the following equation22: dB = dA * RB / RA * (WA / WB) 1/3. dA and dB refer to the dose per bodyweight (mg/kg) of the human and mouse, respectively. The dose, in mg/kg, is replaced by the number of EXD/kg. RA and RB represent the human body factor and mouse body factor, respectively, which are proportional to the (body surface area (m2) / body weight (kg))2/3 (See Table 1). WA and WB indicate the bodyweight (kg) of the human and mouse, respectively.