The Primary Source: Autumn Crocus (Colchicum autumnale)
Autumn crocus, scientifically known as Colchicum autumnale, is the most renowned source of the alkaloid colchicine. This plant belongs to the lily family (Colchicaceae) and is native to Europe, though it can be found across the Northern Hemisphere. Despite its common name, it is distinct from the true saffron crocus (Crocus sativus), which is not poisonous. The autumn crocus is sometimes called "meadow saffron" or "naked lady" because its vibrant, pinkish-purple flowers emerge from the ground in the fall long before its leaves appear.
All parts of the autumn crocus are highly toxic, with the most concentrated levels of colchicine found in its seeds and bulbs (corms). The concentration of colchicine in the seeds can be as high as 1%. The potent toxicity is due to colchicine's ability to interfere with cell mitosis by binding to tubulin, a protein essential for cell division. This antimitotic effect makes it toxic to all rapidly dividing cells in the body. Historically, the plant's extract was used for medicinal purposes as far back as 1500 BCE, as mentioned in ancient Egyptian texts. However, due to its narrow therapeutic window, ingestion is extremely dangerous and can be lethal.
The Flame Lily: Another Source of Colchicine
While less common as a commercial source than autumn crocus, the flame lily (Gloriosa superba) is another plant known to contain significant amounts of colchicine. This climbing plant, native to tropical regions of Asia and Africa, is prized for its exotic flowers but is also highly toxic. All parts of the flame lily, particularly the tubers, contain potent alkaloids, including colchicine. In India, the flame lily is cultivated as a cash crop for the extraction of colchicine for pharmaceutical and industrial use. The exploitation of this plant for its valuable compounds, coupled with its illegal harvesting, has caused it to be classified as a threatened species in some regions.
Parts of the plant where colchicine is found
Colchicine is distributed throughout the plants in varying concentrations. For both Colchicum autumnale and Gloriosa superba, the most concentrated parts of the plant tend to be the underground storage organs and seeds.
- Seeds: The seeds of the autumn crocus have the highest concentration of colchicine, exceeding 1%. The seeds of the flame lily also contain high amounts, ranging from 0.7% to 0.9%.
- Bulbs/Corms: The corms of the autumn crocus are rich in colchicine, with concentrations around 0.6%. The tubers of the flame lily also contain significant levels.
- Leaves: The fresh leaves of the autumn crocus contain a lower but still toxic concentration of colchicine, between 0.15% and 0.4%.
- Flowers: The flowers of both plants are also toxic and contain colchicine, though in different concentrations depending on the species and season.
Toxicity and Handling Precautions
Given the extreme toxicity of colchicine, it is critically important to understand the risks associated with these plants. Accidental poisoning has occurred when the leaves of the autumn crocus were mistaken for wild garlic or onions. The effects of poisoning can be severe, progressing through distinct phases involving gastrointestinal distress, multiorgan failure, and, for survivors, hair loss. Medical intervention is required immediately upon suspected ingestion, as there is no specific antidote.
For those involved in botanical studies or plant breeding, handling these species requires significant care and attention to safety protocols. It is not recommended to use these plants for any self-medication purposes. Prescription colchicine, which is a standardized and regulated form of the drug, is the only safe way to use this medication under medical supervision.
Medicinal and Other Applications
Despite its toxicity, the alkaloid colchicine has valuable medicinal uses when administered in controlled, low doses. It has a long history of use for treating gout and has been used to treat Familial Mediterranean Fever (FMF) for decades. In recent years, it has also been approved for use in patients with coronary artery disease to reduce the risk of heart attacks and strokes.
Beyond medicine, colchicine is a potent tool for plant breeders. By disrupting cell division, it can be used to induce polyploidy, a state where a plant's number of chromosomes is doubled. This process is used to create new and improved plant varieties that are often larger, hardier, and faster-growing than their diploid counterparts. This is a fundamental technique in modern agricultural and horticultural development, even being used to create seedless fruits like watermelon.
Comparison of Colchicine Sources
| Feature | Autumn Crocus (Colchicum autumnale) | Flame Lily (Gloriosa superba) |
|---|---|---|
| Appearance | Autumn-flowering, pink/purple flowers, appears before leaves | Tropical, climbing lily with exotic red and yellow flowers |
| Family | Colchicaceae | Colchicaceae |
| Native Range | Europe and Northern Hemisphere | Tropical Asia and Africa |
| Colchicine Content | Highest concentration in seeds and corms | High concentration in seeds and tubers |
| Traditional Use | Historical remedy for gout since antiquity | Traditional use in Ayurveda for rheumatism and cancer |
| Status | Can be mistaken for edible plants like wild garlic | Can be over-harvested, considered threatened in some regions |
Conclusion
The primary plant source of the alkaloid colchicine is the autumn crocus, also known as meadow saffron or Colchicum autumnale. While this is the most common answer to the question, it is also important to recognize the flame lily (Gloriosa superba) as another significant botanical source. Both plants are highly poisonous, and it is crucial to handle them with extreme caution. The potent nature of colchicine is a dual-edged sword, providing a valuable medicinal agent for treating conditions like gout while also serving as a crucial tool for plant breeding. Regardless of its application, the extreme toxicity of these plants means that colchicine should only be used under strict medical or scientific guidance. For more information on the history and modern uses of this ancient drug, refer to scholarly resources such as the article from the National Institutes of Health.
Further Reading
For more detailed information on colchicine's medicinal properties and history, see the PubMed article: Isolating Colchicine in 19th Century: An Old Drug Revisited.
