• ENU
  • Ethylnitrosourea
  • 1-ethyl- 1 -nitrosourea


300 mg · kg -1 ( LD50, rat, oral)

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N -ethyl-N -nitrosourea, also often referred to as ethylnitrosourea and usually as ENU ( = ethyl nitroso urea ) abbreviated, is a compound from the group of nitrosoureas. It is a potent carcinogen and highly potent mutagen.


ENU is a highly reactive compound which is sensitive to moisture and light. The storage is usually carried out at temperatures below -10 ° C. The compound is soluble in water to about 1.3%. The octanol - water partition coefficient (log Kow ) is 0.23.

The stability of aqueous solutions of pH dependent. At room temperature and pH 4.0 the half-life of 190 hours in water. At pH 6.0 only 31 hours at pH 7.0 for 1.5 hours at pH 8.0 and six minutes at pH 9.0 three minutes. In alkaline solutions, ENU decomposed to diazoethane. During the thermal decomposition, oxides of nitrogen. Ethylnitrosourea is an alkylating agent, the ethyl group on its nucleic - mostly thymine - which DNA can transfer in the nucleus. This feature makes this connection to a to a strong carcinogen (a substance that can cause cancer ), on the other hand can with ethylnitrosourea in animal experiments produced ENU, depending on the type of application to application and place tumors in various organs. Thus for example the subcutaneous injection in rats for liver cancer, hepatocellular carcinoma, adenocarcinoma of the lung, lymphoma, and tumors of the peripheral nervous system, spinal cord and brain. The oral administration leads in particular tumors of the nervous system. Intraperitoneal injections induce malignant tumors, among others, in the liver, kidneys, ovaries, lungs and stomach. Intravenous arise leukemias, gliomas, and tumors of the uterus and vagina.

ENU alkylated and the spermatogonial, the stem cell population in the germinal epithelium of the testes


For ethylnitrosourea there is no technical use because of the instability and the high toxicity. It is produced on a laboratory scale in small quantities. The first synthesis was 1919.

In biochemical research ENU is used for the induction of mutations since the early 1970s. In this application, it is also referred to as " Supermutagen ". The transfer of the ethyl group on the nucleobase is irreversible. This alkylation can lead to mismatches in the complementary strand of DNA during replication. The mismatches cause primarily point mutations (adenine → thymine ). Spermatogonial by point mutations can be made in the germline ( germline mutation ).

The mutation rate is about 1 per 1,000 base pairs.