Which of the following is used as cancer anti-tumour agent?

cis-\([Pt(NH_3)_2Cl_2]\)

The correct answer is option 2. cis-\([Pt(NH_3)_2Cl_2]\).

Let us go into more detail about why cis-[Pt(NH3)2Cl2] (cisplatin) is used as an anti-tumor agent and why the other compounds listed are not.

Mechanism of Action:

DNA Binding: Cis-platin functions by binding to DNA in cancer cells. Specifically, it forms platinum-DNA adducts. The most common form of these adducts involves the binding of cisplatin to two adjacent guanine bases on the same strand of DNA.

DNA Crosslinking: This binding causes crosslinking of the DNA strands, which inhibits DNA replication and transcription, ultimately leading to apoptosis (programmed cell death) of the cancer cells.

Effectiveness: The spatial arrangement of the cis isomer is crucial for its ability to bind effectively to DNA. The two chloride ligands are in a cis position, allowing the platinum atom to form two covalent bonds with the nitrogen atoms of the guanine bases on the same DNA strand.

Clinical Use:

Cancer Treatment: Cis-platin is used to treat a variety of cancers, including testicular, ovarian, bladder, and lung cancers. It is particularly effective against testicular cancer, where it has dramatically improved survival rates.

Why the Other Compounds are Not Used as Anti-Tumor Agents:

1. \([RhCl(PPh_3)_3]\) (Wilkinson's Catalyst):

This compound is primarily used as a catalyst for hydrogenation reactions in organic synthesis. It does not have the ability to bind to DNA in the same way that cisplatin does, and thus, it does not have the same anti-cancer properties.

3. trans-\([Pt(NH_3)_2Cl_2]\):

The trans isomer of \([Pt(NH_3)_2Cl_2]\) places the two chloride ligands opposite each other. This spatial arrangement makes it much less effective at forming the same kind of crosslinks in DNA that the cis isomer does. Therefore, it does not have the same ability to inhibit DNA replication and kill cancer cells.

4. Ziese’s Salt \([K[PtCl_3(C_2H_4)]⋅H_2O]\):

Ziese’s salt is primarily of interest in the field of organometallic chemistry due to its structure and reactivity, particularly with ethylene. It does not interact with DNA in the same way as cisplatin and thus does not have anti-tumor properties.

Summary:

cis-\([Pt(NH_3)_2Cl_2]\) (cisplatin) is specifically effective as an anti-tumor agent due to its ability to form DNA crosslinks, which disrupts the replication and transcription processes necessary for cancer cell survival.

Other Compounds: The other compounds listed do not possess the same structural characteristics or mechanisms of action that would allow them to be effective in cancer treatment.