Camptothecin (Quinoline Alkaloid · Topoisomerase I Inhibitor · Irinotecan Lead · Informational)
| Compound | Camptothecin (CPT) |
| Chemical class | Alkaloid — Quinoline (Pentacyclic quinoline alkaloid with β-hydroxy lactone) |
| CAS | 7689-03-4 |
| Primary source | Camptotheca acuminata (Happy tree / Chinese tree of joy, bark and fruit), Nothapodytes foetida |
| Key applications | Topoisomerase I inhibitor; pharmaceutical anticancer lead (irinotecan, topotecan); informational reference |
| Claim strength | High (pharmaceutical derivatives); Informational only (camptothecin itself) |
| Typical form | Pharmaceutical anticancer drugs (irinotecan, topotecan); camptothecin is not a supplement ingredient |
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Name origin: From Camptotheca acuminata (the “happy tree” of China). Camptothecin is a pentacyclic alkaloid with a unique β-hydroxy lactone ring — this lactone is essential for biological activity and was the key structural feature elucidated in the landmark Monroe Wall and Mansukh Wani 1966 isolation from Camptotheca acuminata at the USDA Research Triangle Institute. Discovery and pharmaceutical development: The 1966 discovery of camptothecin’s remarkable anticancer activity initiated one of the most important pharmaceutical development programmes in oncology. Camptothecin itself was too toxic and insoluble for clinical use. Thirty years of medicinal chemistry produced water-soluble analogues: irinotecan (CPT-11, approved 1994 for colorectal cancer) and topotecan (approved 1996 for ovarian and small cell lung cancer). These are now on the WHO Essential Medicines List for cancer chemotherapy. More recently, antibody-drug conjugates (ADCs) using camptothecin analogues (deruxtecan, SN-38) have revolutionised targeted cancer treatment in breast, lung, and gastric cancers. Mechanism — Topoisomerase I inhibition: Camptothecin stabilises the covalent DNA-Topoisomerase I complex (“cleavable complex”), preventing DNA re-ligation after single-strand cleavage. This traps the replication fork and causes double-strand breaks during S-phase, selectively killing rapidly dividing cells. Supplement status: Camptothecin and its sources are pharmaceutical oncology territory only. Not a supplement ingredient.
Camptothecin — Oncological and Scientific Context
Topoisomerase I inhibition — mechanism: Topoisomerases are essential enzymes that manage DNA topology during replication and transcription. Topoisomerase I cuts one DNA strand to relieve torsional stress, then re-ligates. Camptothecin intercalates at the enzyme-DNA interface, stabilising the cleavable complex and converting Topo I from a DNA repair enzyme into a DNA-damaging agent. The colliding replication fork converts single-strand cuts to irreversible double-strand breaks, triggering apoptosis. Cancer cells with higher replication rates are preferentially killed. Pharmaceutical mechanism: High evidence.
Irinotecan — colorectal cancer standard of care: Irinotecan (a camptothecin prodrug converted to active SN-38 by carboxylesterases) is a standard component of FOLFIRI and FOLFOX-FOLFIRI chemotherapy regimens for metastatic colorectal cancer. The UGT1A1 pharmacogenetic polymorphism (Gilbert’s syndrome allele) affects SN-38 metabolism and toxicity — patients with UGT1A1*28 homozygosity have 40–50% reduced SN-38 glucuronidation and higher toxicity risk. Pharmaceutical evidence: High.
Antibody-drug conjugates — current oncology frontier: Camptothecin analogues are increasingly used as ADC payloads. Trastuzumab deruxtecan (T-DXd, Enhertu) — containing a camptothecin analogue — has produced dramatic response rates in HER2-positive and HER2-low breast cancer (DESTINY-Breast04 trial, 2022). This represents the current pharmaceutical frontier for camptothecin-class compounds. Pharmaceutical evidence: High (ADC trials).
This compound is documented for research and formulator education purposes. For commercially available botanical ingredients, explore the HerbIQ Compound Index →
Frequently Asked Questions — Camptothecin
Can any botanical preparation provide meaningful camptothecin exposure?
Botanical preparations from Camptotheca acuminata or Nothapodytes foetida could theoretically provide camptothecin, but: (1) the concentration needed for anticancer effect requires pharmaceutical formulation — botanical preparations would provide sub-therapeutic and highly variable exposures; (2) camptothecin’s pH-sensitive lactone ring equilibrium (closed ring = active; open ring = inactive) requires precise pH control for efficacy; (3) the toxicity profile at any meaningful dose makes uncontrolled botanical supplementation dangerous. This is strictly pharmaceutical territory.
What is the UGT1A1 pharmacogenetic consideration for irinotecan?
UGT1A1*28 (Gilbert’s syndrome allele, TA repeat in the UGT1A1 promoter, approximately 10–15% prevalence of homozygosity in European populations) reduces SN-38 (active irinotecan metabolite) glucuronidation by ~40–50%. Patients homozygous for UGT1A1*28 have higher SN-38 plasma levels and greater risk of severe neutropaenia and diarrhoea. FDA recommends UGT1A1 genotyping before irinotecan in patients with higher risk profiles. This is one of the better-established pharmacogenetic dose-adjustment recommendations in oncology.
Why is camptothecin itself not used in cancer treatment?
Camptothecin has multiple pharmaceutical liabilities: (1) very poor aqueous solubility; (2) the active closed lactone form is in equilibrium with the inactive open hydroxy acid form at physiological pH (equilibrium favours open form at pH 7.4); (3) severe systemic toxicity (haemorrhagic cystitis in early trials); (4) no selectivity-enhancing functional groups for optimisation. The pharmaceutical development strategy of creating water-soluble analogues (irinotecan, topotecan) solved these problems, making camptothecin itself obsolete as a clinical agent.
Is Camptotheca acuminata commercially available?
Camptotheca acuminata (Chinese happy tree) is cultivated in China for camptothecin supply to pharmaceutical manufacturers producing irinotecan and topotecan. Commercial camptothecin is extracted from the bark, wood, and fruit and is a pharmaceutical raw material rather than a supplement ingredient. The tree itself is a landscape tree in subtropical regions and is not restricted as a plant, but its alkaloid content places it firmly in the pharmaceutical sourcing chain rather than supplement supply.
Related compounds: Quinine, Taxol, Colchicine, Vinblastine
Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.
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