Camptothecin (CPT) is a naturally occurring alkaloid isolated from the bark of the Chinese tree Camptotheca acuminata and the Asian tree Nothapodytes nimmoniana. It has garnered significant attention due to its potent anti-cancer properties. Camptothecin has a pentacyclic ring structure, which is crucial for its biological activity. The key feature of its structure is the lactone ring, which is essential for its binding to the target enzyme.
Alfa Chemistry offers high-quality camptothecin for research and development purposes.
Product Detail
| Product Name | Camptothecin |
| CAS No. | 7689-03-4 |
| Catalog | ALKS7689034 |
| Molecular Weight | 348.35 |
| Molecular Formula | C20H16N2O4 |
| Purity | ≥ 98% |
| Density | 1.3112 (rough estimate) |
| Boiling point | 482.73 °C (rough estimate) |
| Solubility | Insoluble in water |
| Storage | Refrigerate at 2-8 °C |
Mechanism of Action
Camptothecin exerts its anti-cancer effects primarily through the inhibition of DNA topoisomerase I, an enzyme involved in the unwinding of DNA during replication and transcription.
Topoisomerase I Inhibition
Topoisomerase I creates transient single-strand breaks in the DNA to alleviate torsional strain during replication and transcription. Camptothecin stabilizes the topoisomerase I-DNA complex after the enzyme has cleaved the DNA strand, preventing the re-ligation (rejoining) of the DNA strand. This results in the accumulation of DNA breaks.
DNA Damage and Apoptosis
The accumulation of single-strand breaks leads to replication fork collapse and the formation of double-strand breaks, which are more difficult for the cell to repair. This extensive DNA damage triggers apoptotic pathways, leading to cell death. Cancer cells, which divide more rapidly than normal cells, are particularly susceptible to this mechanism.
Applications of Camptothecin
Anti-Cancer Therapy
Camptothecin itself is not widely used clinically due to its poor solubility and severe side effects. However, several derivatives have been developed to improve its therapeutic index. The two most notable derivatives are:

- Irinotecan (CPT-11): Used primarily for the treatment of colorectal cancer. It is a prodrug that is converted into its active form, SN-38, which exerts the cytotoxic effects.
- Topotecan: Used to treat ovarian cancer, small cell lung cancer, and cervical cancer. It is more water-soluble than camptothecin, improving its usability in clinical settings.
Research and Experimental Uses
- Experimental Therapies: Camptothecin and its derivatives are being investigated for potential use in other types of cancer and combination therapies.
- Biological Research: They are used as tools in molecular biology to study DNA replication, transcription, and the mechanisms of DNA damage and repair.
Pharmacokinetics and Delivery Challenges
The clinical use of camptothecin is limited by its poor water solubility and instability of the lactone ring at physiological pH, which can lead to toxicity and reduced efficacy. Efforts to overcome these challenges include:
- Development of Prodrugs: As seen with irinotecan, which is activated in the body to produce the more active SN-38.
- Nanoparticle Delivery Systems: Encapsulating camptothecin or its derivatives in nanoparticles to improve solubility, stability, and targeted delivery to tumors.
- Polymeric Conjugates: Linking camptothecin to polymers to enhance its solubility and circulation time in the bloodstream.
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