Demecolcine (

INN Inns are generally establishments or buildings where travelers can seek lodging, and usually, food and drink. Inns are typically located in the country or along a highway; before the advent of motorized transportation they also provided accommo ...

; also known as colcemid) is a drug used in

chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...

. It is closely related to the natural

alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

colchicine Colchicine is a medication used to treat gout and Behçet's disease. In gout, it is less preferred to NSAIDs or steroids. Other uses for colchicine include the management of pericarditis and familial Mediterranean fever. Colchicine is taken ...

with the replacement of the

acetyl In organic chemistry, acetyl is a functional group with the chemical formula and the structure . It is sometimes represented by the symbol Ac (not to be confused with the element actinium). In IUPAC nomenclature, acetyl is called ethanoyl, ...

group on the

amino In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent s ...

moiety with

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...

, but it is less toxic. It depolymerises

microtubules Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...

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

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...

s in

metaphase Metaphase ( and ) is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase). These chromosomes, carrying genetic information, align ...

and allowing cell harvest and

karyotyping A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...

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 (VBL), sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. This includes Hodgkin's lymphoma, non-small cell lung cancer, bladder ca ...

. 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 demecolcine can promote microtubule detachment from microtubule organizing center. Detached microtubules with unprotected minus end depolymerize with time. Cytotoxicity of the cells seems to correlate better with

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...

detachment. Lower concentration affects microtubule dynamics and cell migration.

Research use

Demecolcine is used for scientific research in cells. It is used in a variety of ways, however, until recently, was used mostly for the study of

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...

in cells. For example, microtubules are necessary for the splitting of cells. More importantly, the movement of chromosomes during the M phase. Demecolcine inhibition of microtubules causes

aneuploidy Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any ...

in mitotic cells where the microtubules fall apart or are suppressed before they can complete their function of pulling chromosomes into the daughter cell, also known as nondisjunction of chromosomes. Demecolcine, depending on dose, has also been found to cause

DNA fragmentation DNA fragmentation is the separation or breaking of DNA strands into pieces. It can be done intentionally by laboratory personnel or by cells, or can occur spontaneously. Spontaneous or accidental DNA fragmentation is fragmentation that gradually a ...

of chromosomes in

micronuclei Micronucleus is the name given to the small nucleus that forms whenever a chromosome or a fragment of a chromosome is not incorporated into one of the daughter nuclei during cell division. It usually is a sign of genotoxic events and chromosomal i ...

when nondisjunction occurs.

References

{{Xenobiotic-sensing receptor modulators Pyrogallol ethers Microtubule inhibitors Heptalenes Tropolones Amines