The crucial component(s) of Guizhi Fuling Wan in inhibiting endometriosis development.

Ethnopharmacological relevance: Endometriosis is a common gynecological disorder that manifests as chronic pelvic pain and subfertility. Guizhi Fuling Wan (GFW), which contains five herbs, was first described in Chinese canonical medicine to treat qi stagnation and circulation. Although the inhibition of endometriosis by GFW has been previously demonstrated, its efficacy could potentially be improved by adjusting the dose of each component.

Aim: This study aimed to examine the relative importance of herbs in endometriosis treatment.

Materials and methods: Endometriosis was induced in C57BL/6NCrlBltw mice, followed by treatment with H₂O, GFW, all individual herbs of GFW, and GFW with sequential deletion of a single herb for 28 days. Immunohistochemistry and western blotting were performed to examine the expression of inflammatory and apoptotic markers.

Results: The endometriosis-inhibiting effect of GFW was reduced by deletion of either Guizhi or Fuling. Guizhi, Fuling, or Taoren alone also inhibit the development of endometriosis. The reduction in intercellular adhesion molecule 1 (ICAM-1) by GFW was attenuated by deletion of Guizhi, Fuling, or Taoren, whereas either Guizhi or Fuling alone decreased ICAM-1 expression. The deletion of either Guizhi or Fuling diminished the enhancement of caspase-3 by GFW, whereas caspase-3 expression was elevated by either Guizhi or Fuling alone.

Conclusion: Deletion of either Guizhi or Fuling attenuated the inhibition of endometriosis development, while either Guizhi or Fuling alone maintained the endometriosis-inhibiting effect of GFW. Consistent with the description in the canonical literature of traditional Chinese medicine, this study revealed that Guizhi and Fuling are the most crucial components of GFW in treating endometriosis, as they are the emperor drugs of this formula, whereas Taoren is a minister drug.