Polycyclic organic compounds

thumb|right|alt=Complex chemical diagram|class=skin-invert-image|Structure of 24-ethyl-lanostane, a prototypical steroid with 32 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with [[IUPAC-approved ring lettering and atom numbering.]]A steroid is an organic compound with four fused rings (designated A, B, C, and D) arranged in a specific molecular configuration.

chemical compound having more than one ring

Luteoskyrin is a carcinogenic mycotoxin with the molecular formula which is produced by the mold Penicillium islandicum. Luteoskyrin has strong cytotoxic effects. Luteoskyrin can cause the yellow rice disease.