Effects of certain herbal medicines on the biotransformation of arachidonic acid: a new pharmacological testing method using serum.

Two in vitro experimental systems were compared to evaluate the pharmacological effects of some herbal medicines on the biotransformation of arachidonic acid (AA) using the microsomal fraction of sheep vesicular glands as an enzyme source. The first system involved the addition of serum obtained from rats treated orally with the herbal medicines, while the second system involved the direct addition of herbal medicine extracts to the enzyme medium. Both systems were performed in parallel. Indomethacin, used as a reference drug, inhibited AA biotransformation in a dose-dependent manner in both experimental systems. The serum of rats orally pretreated for 1 h with Coptis japonica rhizome and Paeonia lactiflora root also inhibited AA biotransformation. Direct addition of hot water extracts of Rheum officinale rhizome, Scutellaria baicalensis root, Paeonia moutan bark and Zingiber officinale rhizome also inhibited AA biotransformation, while the extracts of Coptis japonica rhizome and Paeonia lactiflora root showed no effects.