Rhamnose (Rha, Rham) is a naturally occurring deoxy sugar. It can be classified as either a methyl- pentose or a 6-deoxy- hexose. Rhamnose predominantly occurs in nature in its L-form as L-rhamnose (6-deoxy-L- mannose). This is unusual, since most of the naturally occurring sugars are in D-form. Exceptions are the methyl pentoses L- fucose and L-rhamnose and the pentose L- arabinose. However, examples of naturally-occurring D-rhamnose are found in some species of bacteria, such as '' Pseudomonas aeruginosa'' and '' Helicobacter pylori''. Rhamnose can be isolated from buckthorn (''Rhamnus''), poison sumac, and plants in the genus ''

Uncaria ''Uncaria'' is a genus of flowering plants in the Family (biology), family Rubiaceae. It has about 40 species.''Uncaria'' At: World Checklist of Rubiaceae At: Kew Gardens Website. (see ''External links'' below). Their Range (biology), distribut ...

''. Rhamnose is also produced by microalgae belonging to class Bacillariophyceae (diatoms). Rhamnose is commonly bound to other sugars in nature. It is a common glycone component of

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...

s from many plants. Rhamnose is also a component of the outer cell membrane of acid-fast bacteria in the ''

Mycobacterium ''Mycobacterium'' is a genus of over 190 species in the phylum Actinomycetota, assigned its own family, Mycobacteriaceae. This genus includes pathogens known to cause serious diseases in mammals, including tuberculosis (''Mycobacterium tuberculo ...

'' genus, which includes the organism that causes

tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

. Natural antibodies against L-rhamnose are present in human serum, and the majority of people seem to possess IgM, IgG or both of these types of immunoglobulins capable of binding this

glycan The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate ...

. An interesting particularity of rhamnose is the presence of formaldehyde production when reacted with periodates in the vicinal diol cleavage reaction, that makes it very useful to remove excess periodate in

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

or other vicinal diol analysis, that would otherwise give colored blank issues.

See also

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Further reading