Mimosine or leucenol is an 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...

, β-3-hydroxy-4 pyridone amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

. It is a toxic

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

 non-protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 free amino acid otherwise chemically similar to tyrosine

Tyrosine

Tyrosine or 4-hydroxyphenylalanine, is one of the 22 amino acids that are used by cells to synthesize proteins. Its codons are UAC and UAU. It is a non-essential amino acid with a polar side group...

, and was first isolated from Mimosa pudica

Mimosa pudica

Mimosa pudica , is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, re-opening minutes later...

. It occurs in a few other Mimosa

Mimosa

Mimosa is a genus of about 400 species of herbs and shrubs, in the subfamily Mimosoideae of the legume family Fabaceae. The generic name is derived from the Greek word μιμος , meaning "mimic."...

spp.

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 and all members of the closely related genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Leucaena

Leucaena

Leucaena is a genus of flowering plants in the subfamily Mimosoideae of the legume family Fabaceae. It contains about 24 species of trees and shrubs, which are commonly known as Leadtrees. They are native to the Americas, ranging from Texas in the United States south to Peru...

.

This compound, also known as leucenol, was first isolated from the seeds of Leucaena glauca Benth., and was later investigated by Adams and coworkers.

Properties

Mimosine melts with decomposition. The hydrochloride

Hydrochloride

In chemistry, hydrochlorides are salts resulting, or regarded as resulting, from the reaction of hydrochloric acid with an organic base . This is also known as muriate, derived from hydrochloric acid's other name: muriatic acid....

 salt melts at 174.5-175.0 °C with decomposition; the hydrobromide decomposes at 179.5 °C, and the hydroiodide decomposes at 183.0-183.5 °C. Mimosine only forms monobasic acids, but the methyl ester forms a dihydrochloride, C₇H₉O₂N₂(COOMe)•2 HCl•½ H₂O, mp. 175-6 °C.

Biological effects

Mimosine arrests dividing cells in the late G1 phase by inhibiting DNA replication initiation. In ruminant

Ruminant

A ruminant is a mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first compartment of the stomach, principally through bacterial actions, then regurgitating the semi-digested mass, now known as cud, and chewing it again...

s, mimosine is degraded to 3,4- and 2,3-dihydroxypyridone (3,4- and 2,3-DHP).

Although toxicosis has occurred in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, Papua New Guinea

Papua New Guinea

Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...

, Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

 and Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, it has not been recorded in any other tropical and subtropical regions. Goat

Goat

The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...

s in Burma lost hair

Alopecia

Alopecia means loss of hair from the head or body. Alopecia can mean baldness, a term generally reserved for pattern alopecia or androgenic alopecia. Compulsive pulling of hair can also produce hair loss. Hairstyling routines such as tight ponytails or braids may induce Traction alopecia. Both...

 when fed to diet containing 50 % of Leucaena

Leucaena

Leucaena is a genus of flowering plants in the subfamily Mimosoideae of the legume family Fabaceae. It contains about 24 species of trees and shrubs, which are commonly known as Leadtrees. They are native to the Americas, ranging from Texas in the United States south to Peru...

. Goats and cattle

Cattle

Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...

 in Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 are able to degrade the 3,4-DHP ruminally

Rumen

The rumen, also known as a paunch, forms the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. It serves as the primary site for microbial fermentation of ingested feed...

. Tolerance might be related to the presence or absence of microbes tolerant to mimosine and 3,4-DHP. It is known that at least Australian goats do not share the abilities of their Hawaiian counterparts.

Bickel and Wibaut found in feeding experiments with rats and mice that leucenol is probably the toxic constituent of Leucaena glauca seeds, but they did not observe with these animals the loss of hair which seems to occur when these seeds are fed to cattle. Aung from Myanmar isolated the new subspecies of K. pneumonae that can degrade mimosine.