What is the main mechanism of action for cytotoxic antibiotics?

The main mechanism of action for cytotoxic antibiotics is indeed disrupting DNA and damaging the cell membrane. These agents, which include well-known drugs such as doxorubicin and bleomycin, work primarily by intercalating into DNA strands, preventing the normal replication and transcription processes necessary for cell survival and division. This interference leads to structural damage to the DNA, which ultimately triggers cellular mechanisms that can result in cell death.

Additionally, specific cytotoxic antibiotics can produce free radicals that further damage cellular components, including the cell membrane. This combination not only inhibits the cell's ability to replicate but can also cause direct lysis of cancer cells. Therefore, the effectiveness of these drugs in oncology is largely due to their dual action on both the genetic material and the overall integrity of the cell, making option B the correct choice.

The other choices involve mechanisms that may apply to different classes of drugs or processes but do not accurately reflect the primary action of cytotoxic antibiotics. For example, inhibiting protein synthesis and blocking cell division might relate more closely to certain chemotherapeutic agents that function as anti-metabolites or target specific protein synthesis pathways. Inducing apoptosis may be a consequence of the effects of cytotoxic agents, but it is not their specified mechanism of