Hoechst 33258 nucleic acid stain is a popular nuclear counterstain that emits blue fluorescence when bound to dsDNA. Its uses are similar to Hoechst 33342 for counterstaining, apoptosis and cell cycle studies, but Hoechst 33258 is reportedly less cell-permeant.

Molecular formula:C25H37Cl3N6O6
Molecular weight:623.96
CAS name/number: Phenol, 4-[5-(4-methyl-1-piperazinyl)[2,5'-bi-1H-benzimidazol]-2'-yl]-, trihydrochloride 23491-45-4