Action of Anticancer Drugs (Oxford AQA International A Level Chemistry)

Action of Anticancer Drugs

• In the 1960s, the drug cis-platin was discovered

• This drug has been extremely effective in treating a number of different types of cancer such as testicular, ovarian, cervical, breast, lung and brain cancer

  • Cancer cells grow and replicate much faster than normal cells

• Cis-platin is a square planar molecule that has a geometric isomer with the side groups in different positions

The structures of cis-platin and trans-platin

How cisplatin prevents DNA replication

• Cis-platin works by binding to the nitrogen atoms on the bases in DNA

• Cis-platin passes through the cell membrane and undergoes ligand exchange where the chlorines are replaced by water molecules

• The nitrogen in DNA molecules is a better ligand than water and forms dative covalent bonds with the modified cis-platin

• Cis-platin distorts the shape of the DNA and prevents the DNA from replicating

How cis-platin binds to DNA to prevent replication

Adverse Effects

• Cis-platin binds to healthy cells as well as cancerous cells

  • But, it affects cancer cells more as they are replicating faster

• Unfortunately, this means that other healthy cells which replicate quickly, such as hair follicles, are also affected by cis-platin

  • This is why hair loss is a side-effect of people undergoing cancer treatment

• Despite this drawback, cisplatin is a highly effective drug and society needs to find a balance between the adverse effects of drugs and their therapeutic value

• New therapeutic pathways are constantly under development that aim to deliver drugs that target cancer cells while leaving healthy cells untouched