Prunella stica inhibits the proliferation but not the prostaglandin production of Ishikawa cells

Chinese herbs have been used to relieve dysmenorrhea associated with endometriosis. Active components in the herbs and their mechanisms of action remain unknown. Prunella stica, a Chinese herb commonly used to treat dysmenorrhea, was chosen for the present studies. Its effects were investigated on Ishikawa cells, an epithelial cell line derived from human endometrium. Cell proliferation and inhibition of interleukin 1β (IL-1β) induced prostaglandin (PG) production were examined. To learn more about the active components, 120 fractions were collected from the crude extract and each fraction was tested individually. To further characterize the active components, aliquots of fractions with activity were subject to mass spectrometry analysis. Crude extract of P. stica inhibited the proliferation of Ishikawa cells but not the IL-1β induced PG production. Active components of P. stica clustered around fractions 64 and 92; they increased cell doubling time from 18.6 to 26.2 and 29.4 h, respectively. Mass spectrometry analysis showed fractions 64 and 92 consisted of three components whose molecular weights were 337, 348 and 430 Daltons. The therapeutic effects of P. stica reside, in part, in inhibiting the proliferation of the epithelial cells derived from human endometrium. The active components are small molecules.