Stability of authentic PGI2 during routine extraction. Clarification of the nature and sequence of products formed by the rat stomach including the origin of the ozonolysis products reported in 1971.

Authentic PGI2 and PGI2 formed by rat stomach homogenates were carried through a simple extraction and purification procedure to explore the feasibility of isolation of this biologically active bicyclic ether product of arachidonic acid. The integrity of PGI2 was followed throughout by bioassay on the rat blood pressure. In this system we recently reported that PGI2 has very potent hypotensive actions which are easily distinguishable from those observed for PGE2 (14). Our results indicate that PGI2 survives the initial extraction steps (i.e. ethanol extraction, diethyl ether - HCl extraction and methylation) up to the step involving thin layer chromatography with an acidic developing solvent system. This latter procedure converts PGI2 entirely into a stable derivative, 6-keto-PGF1alpha (3,8--10). Oxidative ozonolysis of the methyl ester acetate derivative of authentic 6-keto PGF1alpha reveals products identical to those reported by Pace-Asciak and Wolfe in 1971 (1) which are also produced from authentic PGI2. This data sheds new light into 1) the nature of the biological product formed by stomach homogenates, 2) its transformation into 6-keto PGF1alpha during purification and 3) the origin of the ozonolysis products in the experiments reported in 1971.