3,8-diamino-6-ethyl-5-phenylphenathridium bromide, or more commonly known as ethidium bromide. Ethidium bromide is an aromatic compound with the a chemical formula C21H20BrN3. It is a strong mutagen and is thought to be a carcinogen or teragenic agent. Ethidium bromide can cause frameshift mutations in the DNA. This means that the mutated DNA is not read correctly in your body, possibly causing lethal problems. A carcinogen can cause cancer in your body. A teragenic agent could cause birth defects.

Ethidium bromide was made in the 1950s as a trypanocidal agent. A trypanocidal agent was made to kill trypanosomes. A trypanosome is a small parasite that cause illnesses, such as trypanosomiasis. Trypanosomiasis is most common in Africa, which is why it is called the African Sleeping Sickness. It was quickly accepted because it was 10-50 times more effective against trypanosome then earlier treatments that was used before. It also was not toxic to mice or inducing photosensitivity in cattle. One use of this compound is to treat cattle of trypanomiasis in cattle.

Another use of this compound is Ethidium bromide is to detect nucleic acids in the lab. This is usually done by adding it to an agarose gel for gel electrophoresis, before DNA is added. Then ultraviolet light is used to detect the DNA. Ultraviolet light is harmful to humans, so a protective barrier is needed or the use of a camera. The camera detects fluorescence of the DNA.

Ethidium bromide has a high level of fluorescence to ultraviolet light, because of the hydrophobic area. The hydrophobic area makes the ethidium cation remove all water that comes into contract with it. Since water is fluorescent quencher, this allows the ethidium to light up under ultraviolet light.