Objective: To analyze the relaxant effect of Curcuma comosa (Wan chak motluk) and explore its mechanism and its major compound, diarylheptanoid, on human myometrium with adenomyosis.

Materials and Methods: An in vitro experimental study was performed in the Gynecologic Endocrinology Unit, Department of Obstetrics and Gynecology in Ramathibodi Hospital. Subjects were myometrial strips with histologically confirmed adenomyosis and collected from seventeen non-pregnant premenopausal women undergone hysterectomy. They were incubated in an organ bath system. Spontaneous activities and responses of myometrium to Curcuma comosa and diarylheptanoid were recorded under isometric conditions.

Results: Log of the concentration required to achieve 50% of the maximal response (log IC50) for Curcuma comosa and diarylheptanoid were 1.504±1.797 and 1.487±5.334 μg/ml, respectively. Diarylheptanoid significantly decreased myometrial contraction in adenomyosis in a dose-dependent manner (p = 0.04). Pre-incubation with ICI (estrogen receptor antagonist), L-NAME (nitric oxide synthase inhibitor), or ODQ (guanylase cyclase inhibitor) did not exert significant changes in signal comparing to control (without pre-incubation).

Conclusion: Diarylheptanoid provided relaxant effects on human myometrium with adenomyosis. However, these relaxant effects did not contribute through non-genomic estrogen receptor [ER], nitric oxide [NO] dependent guanylase cyclase pathway. Further study focusing on the molecular mechanism behind Curcuma comosa and diarylheptanoid is still needed. A major compound extracted from the Wan chak motluk could be an alternative treatment for dysmenorrhea and pelvic pain caused from adenomyosis.

Keywords: Curcuma comosa, Diarylheptanoid, Adenomyosis, Myometrium