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 mu M panaxynol had no effect on the synthesis of prostaglandins E-2, F-2 alpha and D-2 from exogenous arachidonic acid in the microsomal fraction of the gastric mucosa whereas at 25-200 mu M 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 mu M. Inhibition of PGDH by panaxynol was noncompetitive with regard to NAD(+) and prostaglandin E-2. These results suggest that panaxynol has the potential to inhibit PGDH activity in gastric mucosa, possibly as a result of pharmacological activity.