MOLECULE

Rhamnose

Rhamnose (Rham) is a naturally occurring deoxy sugar that is structurally derived from mannose. It can be classified as either a methyl-pentose or a 6-deoxy-hexose. It is a member of the class of compounds known as hexoses. Hexoses are monosaccharides in which the sugar unit is a is a six-carbon containing moiety. Rhamnose 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. Rhamnose exists in two anomeric forms, alpha-L-rhamnose and beta-L- Rhamnose. Rhamnose is often bound to other sugars in nature. It is a common glycone component of many glycosides (such as phenolic glycosides) from many plants. In particular, rhamnose can be isolated from a number of plants including Buckthorn (Rhamnus), poison sumac, and various plants in the genus Uncaria. Rhamnose is moderately sweet, having a sweetness rating of about 33% of sucrose. Sweetness is detected through the binding of sugars to the T1R3 and T1R2 proteins, to form a G-protein coupled receptor that is the sweetness receptor in mammals. In addition to being found in plants, rhamnose is also a component of the outer cell membrane (especially of the lipopolysaccharides) of certain gram-negative bacteria including Klebsiella and Pseudomonas (https://link.springer.com/article/10.1007/BF00369505) as well as certain strains of Mycobacteria. L-rhamnose is metabolized to L-lactaldehyde, which is a branching point in the metabolic pathway of L-fucose and L-rhamnose utilization. Rhamnose is also one of many sugars that are found in cannabis plants (PMID: 6991645).