Demecolcine, also known as colcemid, is a drug used in chemotherapy

Chemotherapy

Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

.It is closely related to the natural alkaloid

Alkaloid

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

 colchicine

Colchicine

Colchicine is a medication used for gout. It is a toxic natural product and secondary metabolite, originally extracted from plants of the genus Colchicum...

 with the replacement of the acetyl

Acetyl

In organic chemistry, acetyl is a functional group, the acyl with chemical formula COCH3. It is sometimes represented by the symbol Ac . The acetyl group contains a methyl group single-bonded to a carbonyl...

 group on the amino moiety with methyl, but it is less toxic. It depolymerises

Depolymerization

Depolymerization is the process of converting a polymer into a monomer or a mixture of monomers.Thioglycolysis, thiolysis and phloroglucinolysis are reactions used to study condensed tannins by means of their depolymerisation. Thioglycolysis is also used to study lignin....

 microtubules and limits microtubule formation (inactivates spindle fibre formation), thus arresting cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

s in metaphase

Metaphase

Metaphase, from the ancient Greek μετά and φάσις , is a stage of mitosis in the eukaryotic cell cycle in which condensed & highly coiled chromosomes, carrying genetic information, align in the middle of the cell before being separated into each of the two daughter cells...

 and allowing cell harvest and karyotyping to be performed.

During cell division Demecolcine inhibits mitosis at metaphase by inhibiting spindle formation. Medically Demecolcine has been used to improve the results of cancer radiotherapy by synchronising tumour cells at metaphase, the radiosensitive stage of the cell cycle.

In animal cloning procedures Demecolcine makes an ovum eject its nucleus, creating space for insertion of a new nucleus.

Mechanism of Action

Demecolcine is a microtubule-depolymerizing drug like vinblastine

Vinblastine

Vinblastine is an antimicrotubule drug used to treat certain kinds of cancer, including Hodgkin's lymphoma, non-small cell lung cancer, breast cancer, head and neck cancer, and testicular cancer. It is also used to treat Langerhan cell histiocytosis....

. It acts by two distinct mechanisms. At very low concentration it binds to microtubule plus end to suppress microtubule dynamics. Recent study has found at higher concentration colcemid can promote microtubule detachment from microtubule organizing center. Detached microtubules with unprotected minus end depolymerizes with time. Cytotoxicity of the cells seems to correlate better with microtubule

Microtubule

Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...

detachment. Lower concentration affects microtubule dynamics and cell migration.