Pharmacology · Class
Antitumour antibiotics !
Cancer drugs first found in Streptomyces bacteria: anthracyclines, bleomycin, dactinomycin and mitomycin. They damage DNA in different ways.
Updated 2026-11-01
What they are
Natural products (and their derivatives) with no use against infection. Anthracyclines (doxorubicin, daunorubicin, epirubicin, idarubicin) intercalate in DNA and poison topoisomerase II; bleomycin cuts DNA with oxygen radicals; dactinomycin blocks RNA synthesis; mitomycin cross-links DNA.
Mechanism of action
Anthracyclines slip between DNA base pairs and trap topoisomerase II after it has cut both strands, so the breaks are never resealed; their quinone ring also makes free radicals, which explains the heart damage. Bleomycin binds iron and oxygen and breaks DNA strands. Dactinomycin intercalates between guanine–cytosine pairs and stops RNA polymerase. Mitomycin is activated inside the cell into an alkylating agent that cross-links DNA.
Target: DNA and topoisomerase II
Drugs in this class
- DoxorubicinA red anthracycline that wedges into DNA and traps topoisomerase II. Used in breast cancer, lymphomas and sarcomas; it…Topoisomerase IIα (and DNA, by intercalation)
- BleomycinA Streptomyces glycopeptide that uses iron and oxygen to cut DNA. Used in testicular cancer and Hodgkin lymphoma; it…DNA (oxidative strand cleavage)
- DactinomycinActinomycin D: wedges into DNA and stops RNA synthesis. Used for childhood solid tumours such as Wilms tumour and for…DNA (guanine–cytosine steps); blocks RNA polymerase
- DaunorubicinThe first anthracycline, used to induce remission in acute leukaemias. Like doxorubicin it is red, a vesicant and…Topoisomerase IIα (and DNA, by intercalation)
- EpirubicinAn anthracycline closely related to doxorubicin, used in adjuvant chemotherapy for breast cancer. Same cautions…Topoisomerase IIα (and DNA, by intercalation)
- IdarubicinA more fat-soluble anthracycline that enters cells quickly. Used with cytarabine to treat acute myeloid leukaemia in…Topoisomerase IIα (and DNA, by intercalation)
- MitomycinA Streptomyces drug that, once activated in the cell, cross-links DNA. Used for anal, gastric and pancreatic cancers…DNA (cross-links at guanine and adenine)
Others in the class
- mitoxantrone
- pixantrone
- valrubicin
- plicamycin
Test yourself
Think of the answer, then tap the question to see it.
Which two mechanisms explain how anthracyclines kill tumour cells?
DNA intercalation with trapping of topoisomerase II (unrepaired double-strand breaks) and production of free radicals.
Why does bleomycin damage the lungs and skin more than other organs?
Those tissues have little bleomycin hydrolase, the enzyme that inactivates the drug.
Which antitumour antibiotic mainly blocks RNA synthesis?
Dactinomycin (actinomycin D).
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - DOXORUBICIN HYDROCHLORIDE injection, solution (DailyMed (U.S. National Library of Medicine), 2025); DailyMed - BLEOMYCIN- bleomycin sulfate powder, for solution (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - DACTINOMYCIN injection, powder, lyophilized, for solution (DailyMed (U.S. National Library of Medicine), 2024); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 70 (McGraw Hill, 2023).
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Representative model, for educational purposes only.