Study of the pharmacological effect of the bile salt, sodium scymnol sulfate, from Rhizoprionodon acutus. IV. Effects of naturally occurring bile alcohols, bile acids and their conjugates on lesion development and vascular endothelial cell injury in a rat peripheral arterial occlusion model.

A series of naturally occurring bile alcohols, bile acids and their conjugates has been investigated as part of our studies to develop unique anticoagulants with a potent prophylactic effect against vascular endothelial cell injury induced by lactic acidosis in vivo and in vitro. In an in vivo rat peripheral arterial occlusion model induced by lactic acid injection, oral administration of a single dose of 3 mg/kg scymnol significantly inhibited edematous swelling and development of lower limb lesions, including gangrene, and reduced changes in clotting system functions and serum lactate dehydrogenase activity. It had no effect on clotting system functions in sham-operated rats. The structure-activity relationship suggests that the [24R-(+)-5beta-cholestane-3alpha,7alpha,24,26-pento l] or [3alpha,7alpha-dihydroxy-5beta-cholanic acid] structure is important for a potent prophylactic effect following oral administration. Intravenous administration of a single dose of 0.3 mg/kg sodium (25S)-scymnol sulfate or scymnol prevented lesion progression as effectively as oral administration of scymnol. Sodium (25S)-scymnol sulfate and ursodeoxycholic acid showed clear protective effects against cultured vascular endothelial cell damage due to lactic acidosis which were dose-dependent. The above results suggest that bile steroids such as scymnol, sodium (25S)-scymnol sulfate, ursodeoxycholic acid, and chenodeoxycholic acid may play a role in protecting endothelial cells against injury caused by lactic acidosis. These compounds are candidates for novel anti-ischemic drugs that act by specifically protecting vascular endothelial cells.