Colchicine is a water-soluble alkaloid found in the autumn crocus; it has been used as an anticancer drug. It blocks or suppresses cell division by inhibiting mitosis, the division of a cell's nucleus. Specifically, it inhibits the development of spindles as the nuclei are dividing. Normally, the cell would use its spindle fibers to line up its chromosomes, make a copy of them, and divide into two new cells with each daughter cell having a single set of chromosomes. With colchicine present, the spindle fibers don't form, and so the cell can't move its chromosomes around. The cell may end up copying some or all of the chromosomes anyway, but can't parcel them out into new cells, and so it never divides.

Because cancer cells divide much more rapidly than normal cells, cancers are more susceptible to being poisoned by mitotic inhibitors such as colchicine, paclitaxel, and the Vinca alkaloids.

However, colchicine has proven to have a fairly narrow range of effectiveness as a chemotherapy agent, so its only FDA-approved use is to treat gout (it is one of the active ingredients of ColBenemid, anti-gout tablets marketed by Merck & Co.), though it is also occasionally used in veterinary medicine to treat cancers in some animals. It is also used as an antimitotic agent in cancer research involving cell cultures.

Researchers aren't sure exactly how colchicine works against gout, but it does seem to reduce the frequency of severe attacks and relieves residual pain.

As far as side effects go, colchicine can cause a temporary reduction in the number of leukocytes (white blood cells) in the bloodstream; afterward, the leukocyte count can rebound to abnormally high levels. Colchicine also causes teratogenic birth defects in lab animals, and so pregnant women with gout should not use colchicine-containing drugs.

Colchicine poisoning resembles arsenic poisoning; the symptoms (which, because it is a mitotic poison, occur 2 to 5 hours after the toxic dose has been ingested) include burning in the mouth and throat, diarrhea, stomach pain, vomiting, and kidney failure. Death from respiratory failure often follows. A specific antidote doesn't exist, so treatment typically involves giving the victim activated charcoal or pumping the stomach.

Colchicine is also used as a mutagen in horticulture, often of cannabis but also orchids, tulips and other flowering plants.

Applied in 0.25% solution as a soak for seeds or directly to the primary meristem (growing tip), it inhibits chromosome segregation to daughter cells and cell wall formation, resulting in larger-than-average daughter cells with multiple chromosome sets: (polyploidy). This results in taller, bushier plants, more leaf mass, and bigger flowers.

Perhaps future genetic microbotanists will find a way to lock that condition and give us strawberries like grapefruit, but for now polyploidy, even when induced in seeds, does not "take" permanently, so after a very few generations the plants revert to a normal diploid state.

As noted above, Colchicine is very toxic so no part of a plant to which it has been applied should ever be consumed; either soak the seeds or use second-generation offspring of the treated plants.

Col"chi*cine (? ∨ ?), n. [Cf. F. colchicine.] Chem.

A powerful vegetable alkaloid, C17H19NO5, extracted from the Colchicum autumnale, or meadow saffron, as a white or yellowish amorphous powder, with a harsh, bitter taste; -- called also colchicia.


© Webster 1913.

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