The invention provides naphthofuran compounds, polymorphs of naphthofuran compounds, naphthofuran com- pounds in particle form, purified compositions that contain one or more naphthofuran compounds, purified compositions that contain one or more naphthofuran compounds in particle form, methods of producing these naphthofuran compounds, polymorphs, purified compositions and/or particle forms, and methods of using these naphthofuran compounds, polymorphs, purified compositions and/or particle forms to treat subjects in need thereof.