Nitro-phenanthrenes occurring in Aristolochiaceae and other Plants. They derive from stephanine (Aporphines) by oxidative ring cleavage. The nitro group is a reactive alkylator (Alkylating Agents) that binds to biological macromolecules. Ingestion by Humans is associated with nephropathy (Nephritis). There is no relationship to the similar named aristolochene (SESQUITERPENES).