Inhibition of 15-Hydroxyprostaglandin Dehydrogenase Activity in Rabbit Gastric Antral Mucosa by Panaxynol Isolated from Oriental Medicines

Panaxynol is a polyacetylene compound with anti‐inflammatory and anti‐platelet‐aggregatory effects isolated from commonly used oriental medicines. The effects of panaxynol on the activity of prostaglandin‐synthesizing and catabolizing enzymes in the rabbit gastric antral mucosa have been examined. At concentrations ranging from 25 to 200 μM panaxynol had no effect on the synthesis of prostaglandins E2, F2α and D2 from exogenous arachidonic acid in the microsomal fraction of the gastric mucosa whereas at 25–200 μM it dose‐dependently inhibited the activity of 15‐hydroxyprostaglandin dehydrogenase (PGDH), which catalyses the initial step of prostaglandin catabolism, in the cytosolic fraction. The concentration required for 50% inhibition (IC50) was approximately 25 μM. Inhibition of PGDH by panaxynol was non‐competitive with regard to NAD+ and prostaglandin E2. These results suggest that panaxynol has the potential to inhibit PGDH activity in gastric mucosa, possibly as a result of pharmacological activity.