Hoechst 33342 trihydrochloride

Hoechst 33342 trihydrochloride is an A:T-specific DNA minor groove ligand that is a widely used fluorochrome for visualizing cellular DNA. Excitation of the dye occurs around 350 nm with an emission maxima around 461 nm. Hoechst-33342, unlike other Hoechst dyes, is more lipophillic due to an additional ethyl group. The compound has been observed to displace several known DNA intercalators. Adriamycin has been shown to disrupt the DNA dye update.

The compound can be used in sorting living cells based on DNA content by FACS, in the visualization of chromatin distribution in living cells, to detect BrdU incorporation into cells, the visualization of fixed cells by microscopy, and to study the initial stages of apoptosis and cell-cycle distribution. In addition to Hoechst-33342's fluorescent capability, the chemical has also had varying effects on differing cell types. The stain has been shown to induce cell differentiation, bind reversibly to Friend erythroleukemia cells, inhibit Topo I (topoisomerase I), induce apoptosis in HL-60 cells, and in junctional sarcoplasmic reticulum cells regulate Ca²⁺ efflux and affect cell differentiation.