The identification of two novel prostaglandins and a thromboxane

6,15-Dioxo-PGF1alpha, 6,15-dioxo-13,14-dihydro-PGF1alpha and 15-oxo-thromboxane B2 have been identified in incubates of ram seminal vesicle homogenates with added arachidonic acid or in the perfusate from sensitised challenged guinea pig lungs. These compounds are probably related to 6-oxo-PGF1alpha and thromboxane B2. The structures have been determined by gas chromatography mass spectrometry, following suitable chemical derivatisation.