Effect of Sairei-to and its ingredients on prostaglandin E2 production by mouse macrophage-like cells.

Sairei-to and its twelve ingredients were investigated for their activity to stimulate prostaglandin E2 (PGE2) production by unstimulated and lipopolysaccharide (LPS)-stimulated mouse macrophage-like RAW 264.7 cells. LPS significantly stimulated the production and extracellular secretion of PGE2 by RAW 264.7 cells. Sairei-to concentration-dependently modified the LPS-stimulated PGE2 production. Among Sairei-to ingredients, Scutellariae radix inhibited the LPS-stimulated PGE2 production to the greatest extent, followed by Zingiberis rhizoma, Glycyrrhizae radix, Atractylodis lanceae rhizoma and Pinelliae tuber. On the other hand, Bulpeuri radix, Alismatis rhizoma, Zizyphi fructus, Polyporus, Hoelen, ginseng radix and Cinnamomi cortex further enhanced the LPS-stimulated PGE2 production. Western blot analysis demonstrated that Sairei-to unexpectedly enhanced the expression of cyclooxygenase-2 (COX-2) protein level, but did not significantly affect phospholipase A2 protein level. The present study suggests that the modification of the enzyme activity of COX-2 may be involved in the concentration-dependent effect of Sairei-to on PGE2 production by macrophages.