The acetone soluble compounds of the latex of Euphorbia ingens can be separated by combination of adsorption chromatography and Craig-distribution. Besides irritant and tumor promoting derivatives of the diterpene ingenol, an additional compound 1 has been isolated, which is the 3,7,12-triacetate-8-nicotinate of a new polyfunctional diterpene ingol 2. Structural elucidation via spectral analysis (high resolution mass spectrometry, NMR, 13C NMR, IR, UV) and chemical reactions (transesterification, acetylation, reduction, oxidation) revealed that ingol 2 exhibits the same tricyclic carbon skeleton as lathyrole and its derivatives, and berthyadionol, and may be biogenetically formed from geranylgeranyl-pyrophosphate via casbene. In the mouse ear assay system, neither compound 1 nor any other derivative of ingol 2 shows irritant activity in doses up to 100 μM/ear. A chromatographically uniform mixture of further tetraesters of ingol 2 was isolated from non-irritant fractions, and their molecular formulae were identified by mass spectrometric analysis.