{ "id": "epnavkh7hb", "slug": "rhamnose", "title": "Rhamnose", "updated": "2026-10-15", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.organic", "label": "Organic substances", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.organic" }, { "id": "physical.chemistry.organic.alcohols_ethers_and_organooxygen", "label": "Alcohols, ethers, and organooxygen groups", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.organic.alcohols_ethers_and_organooxygen" }, { "id": "physical.chemistry.organic.alcohols_ethers_and_organooxygen.alcohols_polyols", "label": "Alcohols and polyols", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.organic.alcohols_ethers_and_organooxygen.alcohols_polyols" } ], "geo": [ { "id": "geo.nongeo.nodate.physical.chemistry.organic.alcohols_ethers_and_organooxygen", "label": "Non-geographic · Not dated: Alcohols, ethers, and organooxygen groups", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.physical.chemistry.organic.alcohols_ethers_and_organooxygen", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.nodate", "label": "Non-geographic · Not dated", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate" }, { "id": "geo.nongeo.nodate.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.physical" }, { "id": "geo.nongeo.nodate.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.physical.chemistry" }, { "id": "geo.nongeo.nodate.physical.chemistry.organic", "label": "Organic substances", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.physical.chemistry.organic" }, { "id": "geo.nongeo.nodate.physical.chemistry.organic.alcohols_ethers_and_organooxygen", "label": "Alcohols, ethers, and organooxygen groups", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.physical.chemistry.organic.alcohols_ethers_and_organooxygen" } ] } ], "excerpt": "Rhamnose is a 6-deoxy hexose sugar, 6-deoxy-L-mannose with formula C6H12O5, found in plant cell wall pectins and gram-negative bacterial lipopolysaccharides; because animals lack it, its bacterial enzymes are studied as antibacterial targets.", "snippet": "Rhamnose is a 6-deoxy hexose sugar, 6-deoxy-L-mannose with formula C6H12O5, found in plant cell wall pectins and gram-negative bacterial lipopolysaccharides; because animals lack it, its bacterial enzymes are studied as antibacterial targets.", "node": "physical.chemistry.organic.alcohols_ethers_and_organooxygen.alcohols_polyols", "markdown": "# Rhamnose\n\n**Rhamnose** is a 6-deoxy hexose sugar, specifically 6-deoxy-L-mannose, a methylpentose with the molecular formula C₆H₁₂O₅ whose L-isomer occurs naturally in many plant glycosides and in some gram-negative bacterial lipopolysaccharides.[1](https://www.ncbi.nlm.nih.gov/mesh/68012210) It is widely distributed in bacteria and plants but rare in animals, a distribution that underlies both its role as a building block of plant cell walls and its value as a target in antibacterial research.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934) • [3](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/)\n\n| Key fact | Detail |\n|---|---|\n| Identity | 6-Deoxy-L-mannose (methylpentose); IUPAC name 6-deoxy-L-manno-hexopyranose; PubChem CID 25310[4](https://pubchem.ncbi.nlm.nih.gov/compound/L-Rhamnose) |\n| Formula and mass | C₆H₁₂O₅; molecular weight 164.16 g/mol; melting point 122 °C; CAS Registry Number 3615-41-6[4](https://pubchem.ncbi.nlm.nih.gov/compound/L-Rhamnose) • [5](https://webbook.nist.gov/cgi/cbook.cgi?ID=C3615416) |\n| Natural occurrence | Plant glycosides, gram-negative bacterial lipopolysaccharides, plant cell wall pectins, and bacterial capsular polysaccharides[1](https://www.ncbi.nlm.nih.gov/mesh/68012210) • [6](https://www.preprints.org/manuscript/202603.1063/v1/download) |\n| Activated donor forms | dTDP-Rha and GDP-Rha in bacteria and fungi; UDP-Rha in plants[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/) |\n| Bacterial catabolism | Many bacteria, including Enterobacteriaceae and Rhizobiaceae, use L-rhamnose as a carbon source; E. coli imports it through the RhaT permease[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870299/) |\n| Industrial relevance | Sugar moiety of rhamnolipid biosurfactants; removed by naringinase to debitter citrus juices and increase flavonoid bioavailability[8](https://www.sciencedirect.com/science/article/pii/S0308814626027640) • [9](https://www.mdpi.com/1420-3049/30/11/2376) |\n\n## Chemical identity\n\nRhamnose is a hexose that lacks the hydroxyl group at carbon 6, which is replaced by a hydrogen and makes it a 6-deoxy sugar; the methyl group at that position is why it is also classed as a methylpentose.[1](https://www.ncbi.nlm.nih.gov/mesh/68012210) In its common cyclic form it is L-rhamnopyranose, the enantiomer of D-rhamnopyranose.[4](https://pubchem.ncbi.nlm.nih.gov/compound/L-Rhamnose) NIST lists synonyms including isodulcit, isodulcitol, locaose, and L-mannomethylose.[5](https://webbook.nist.gov/cgi/cbook.cgi?ID=C3615416) Computed properties reflect a small, highly hydrophilic molecule: XLogP of −2.1, four hydrogen bond donors, five acceptors, and no rotatable bonds.[4](https://pubchem.ncbi.nlm.nih.gov/compound/L-Rhamnose)\n\n## Occurrence in plants\n\n**Cell wall polysaccharides** hold most of the rhamnose in plants. In [Arabidopsis](https://www.edgepedia.org/arabidopsis) leaves, about 682 μg per gram fresh weight, roughly 90 percent of the total rhamnose, is incorporated into cell wall matrix polysaccharides, with smaller amounts in soluble specialized metabolites and water-soluble polymers such as arabinogalactan proteins.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934) The principal destination is the pectin domain rhamnogalacturonan I (RG-I), whose backbone is the repeating disaccharide (1,4)-α-GalA-(1,2)-α-Rha, alternating galacturonic acid and rhamnose residues that anchor arabinan, galactan, and arabinogalactan side chains.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934) • [10](https://doi.org/10.1146/annurev-arplant-081519-035846) Rhamnose also appears in rhamnogalacturonan II, a highly conserved pectic domain containing more than 20 linkages on 12 different sugars.[11](https://onlinelibrary.wiley.com/doi/10.1111/jipb.13055)\n\nThe distribution differs by plant lineage: rhamnose accumulation in the cell walls of grasses (commelinid monocotyledons) is significantly smaller than in dicotyledonous plants, consistent with the lower pectin content of grass walls.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934) • [12](https://www.sciencedirect.com/science/article/pii/S0008621509002006) Rhamnose is also conjugated to specialized metabolites, including flavonoids such as the C-glycosylflavone violanthin, in which the sugar is attached through a carbon-carbon bond that is more stable and resistant to acid hydrolysis than the usual ether linkage.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934)\n\n## Biosynthesis\n\nCells attach rhamnose to acceptor molecules through rhamnosyltransferases that use nucleotide-sugar donors. Three donors are known: deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), guanosine diphosphate rhamnose (GDP-Rha), and uridine diphosphate-rhamnose (UDP-Rha). dTDP-Rha and GDP-Rha occur in bacteria and fungi, whereas UDP-Rha is found only in plants.[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/)\n\n**The bacterial dTDP-Rha pathway** is the most studied. Four enzymes convert D-glucose-1-phosphate to dTDP-L-rhamnose: glucose-1-phosphate thymidylyltransferase (RmlA), dTDP-D-glucose 4,6-dehydratase (RmlB), dTDP-4-keto-6-deoxy-D-glucose 3,5-epimerase (RmlC), and dTDP-4-keto-L-Rha reductase (RmlD).[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/) In *Pseudomonas aeruginosa*, this pathway supplies the hydrophilic moiety of rhamnolipids, and coexpression of the rmlBDAC operon is used to raise rhamnolipid titers in engineered production strains.[8](https://www.sciencedirect.com/science/article/pii/S0308814626027640) • [13](https://pmc.ncbi.nlm.nih.gov/articles/PMC7642724/)\n\n**The plant UDP-Rha pathway** starts from [UDP-glucose](https://www.edgepedia.org/udp-glucose) and is catalyzed by multifunctional rhamnose synthases (RHM). The RHM enzyme carries an N-terminal UDP-Glc 4,6-dehydratase domain that forms the intermediate UDP-4-keto-6-deoxy-D-glucose, and a C-terminal domain with dual 3,5-epimerase and 4-keto-reductase activities that complete the conversion to UDP-Rha.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934) Rhamnosyltransferases then transfer the rhamnose residue from UDP-Rha onto a large variety of substrates in primary and specialized metabolism.[2](https://www.sciencedirect.com/science/article/pii/S0168945220302934)\n\n## Catabolism in microorganisms\n\nMany microorganisms can degrade rhamnose-containing polymers and use the released sugar. Plant-pathogenic *Erwinia* species and saprophytes such as *Bacillus subtilis* break down rhamnogalacturonans with extracellular enzymes including rhamnogalacturonate lyases and α-L-rhamnosidases; the liberated L-rhamnose then enters the cell through specific transporters such as the RhaT permease of [Enterobacteriaceae](https://www.edgepedia.org/enterobacteriaceae).[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870299/) A comparative genomics survey across six bacterial phyla reconstructed the catabolic pathways and found substantial variation in the transcriptional regulators controlling them, including a novel bifunctional aldolase-dehydrogenase enzyme in [Chloroflexi](https://www.edgepedia.org/chloroflexi), Bacilli, and [Alphaproteobacteria](https://www.edgepedia.org/alphaproteobacteria).[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870299/) An alternative nonphosphorylated pathway, converting L-rhamnose to pyruvate and L-lactaldehyde in four steps, has been identified in fungi and in the bacteria *Azotobacter vinelandii* and *Sphingomonas* sp.[7](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870299/)\n\n## Industrial and medical relevance\n\n**Rhamnolipids** are bacterial biosurfactants in which one rhamnose ring (mono-rhamnolipids) or two (di-rhamnolipids) form the polar head, linked to β-hydroxy fatty acid chains. They are valued for surface activity, rapid biodegradability, and antimicrobial and antitumor bioactivities, with applications explored in oil recovery, cosmetics, food science, agriculture, and drug delivery; low yield and high production cost currently limit industrial use.[8](https://www.sciencedirect.com/science/article/pii/S0308814626027640) • [14](https://www.sciencedirect.com/science/article/pii/S135902942300105X) Rhamnolipids themselves serve as a source of L-rhamnose, which can be released by enzymatic hydrolysis as a raw material for flavor compounds.[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC5544971/)\n\n**Food processing** exploits enzymes that cleave rhamnosidic bonds. Naringinase, a complex of α-L-rhamnosidase and β-D-glucosidase, removes the rhamnose moiety from bitter flavonoid glycosides such as naringin in citrus juice; when rhamnose is removed from such glycosides the bitter taste is lost, and the resulting products show increased water solubility and bioavailability.[9](https://www.mdpi.com/1420-3049/30/11/2376) • [16](https://revistas.elpoli.edu.co/index.php/pol/article/download/2408/2384/15935) α-L-Rhamnosidases are also applied to enhance the aroma of wine and fruit juices.[17](https://www.sciencedirect.com/topics/chemistry/l-rhamnose)\n\n**Medicine** takes advantage of the taxonomic distribution of the sugar. Because rhamnose-containing molecules are present in bacteria but not mammals, their biosynthetic enzymes are studied as potential antibacterial targets, and rhamnose-associated compounds are also being investigated for tumor immunotherapy.[3](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/) In bacterial cell walls and capsular polysaccharides, rhamnose contributes to structural integrity and to immunological properties by influencing host-pathogen interactions.[6](https://www.preprints.org/manuscript/202603.1063/v1/download)\n\n## Commercial production\n\nCommercial L-rhamnose was historically extracted from plant glycosides such as those of oak bark and citrus fruits. Current production relies on extraction from rhamnose-rich starting materials, including purified glycosides such as rutin and naringin, crude citrus material from unripe fruit or peel waste, gum arabic, and microbial rhamnolipids or rhamnopolysaccharides such as polyrhamnose.[18](https://wellkr.com/how-is-rhamnose-produced-commercially) • [19](https://patents.google.com/patent/US5077206) Citrus peel, generated in large quantities by the juice industry, is a particularly practical feedstock because its flavonoid glycosides carry rhamnose in a terminal position that hydrolysis releases.[19](https://patents.google.com/patent/US5077206)\n\n## References\n\n1. [Rhamnose, Medical Subject Headings, NCBI](https://www.ncbi.nlm.nih.gov/mesh/68012210)\n2. [Jiang, N. et al. (2021). Rhamnose in plants – from biosynthesis to diverse functions. Plant Science 302, 110687.](https://www.sciencedirect.com/science/article/pii/S0168945220302934)\n3. [Rhamnose-Containing Compounds: Biosynthesis and Applications (2022), PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC9415975/)\n4. [L-Rhamnose, CID 25310, PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/L-Rhamnose)\n5. [Rhamnose, NIST Chemistry WebBook, SRD 69](https://webbook.nist.gov/cgi/cbook.cgi?ID=C3615416)\n6. [Rhamnose (preprint section), Preprints.org](https://www.preprints.org/manuscript/202603.1063/v1/download)\n7. [Comparative genomics and functional analysis of rhamnose catabolic pathways and regulons in bacteria, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC3870299/)\n8. [Pang, A.-P. et al. (2026). Rhamnolipids: from biosynthesis to applications. Food Chemistry 525.](https://www.sciencedirect.com/science/article/pii/S0308814626027640)\n9. [Use of Naringinase to Modify the Sensory Quality of Foods and Increase the Bioavailability of Flavonoids: A Systematic Review, Molecules](https://www.mdpi.com/1420-3049/30/11/2376)\n10. [Dynamic Construction, Perception, and Remodeling of Plant Cell Walls, Annual Review of Plant Biology](https://doi.org/10.1146/annurev-arplant-081519-035846)\n11. [Zhang, B. et al. (2021). The plant cell wall: Biosynthesis, construction, and functions. Journal of Integrative Plant Biology.](https://onlinelibrary.wiley.com/doi/10.1111/jipb.13055)\n12. [Atmodjo, M. A. et al. (2009). The structure, function, and biosynthesis of plant cell wall pectic polysaccharides.](https://www.sciencedirect.com/science/article/pii/S0008621509002006)\n13. [Heterologous Rhamnolipid Biosynthesis: Advantages, Challenges, and Opportunities, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC7642724/)\n14. [Guzman, E., Ortega, F., Rubio, R. G. (2024). Exploring the world of rhamnolipids. Current Opinion in Colloid & Interface Science 69, 101780.](https://www.sciencedirect.com/science/article/pii/S135902942300105X)\n15. [Microbial production of rhamnolipids: opportunities, challenges and strategies, PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC5544971/)\n16. [Revista Politécnica 21(41), 47–77 (2025)](https://revistas.elpoli.edu.co/index.php/pol/article/download/2408/2384/15935)\n17. [L-Rhamnose overview, ScienceDirect Topics](https://www.sciencedirect.com/topics/chemistry/l-rhamnose)\n18. [How is Rhamnose Produced Commercially? Extraction & Biotech, Wellkr](https://wellkr.com/how-is-rhamnose-produced-commercially)\n19. [US5077206A – Process for preparing L-rhamnose, Google Patents](https://patents.google.com/patent/US5077206)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Alcohols, ethers, and organooxygen groups › Alcohols and polyols*\n\n*Initially written Oct 15, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/rhamnose", "markdown_url": "https://www.edgepedia.org/rhamnose.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"Rhamnose\", Edgepedia (EdgeChat), https://www.edgepedia.org/rhamnose. Edgepedia Community License 1.0.", "credit_md": "\"[Rhamnose](https://www.edgepedia.org/rhamnose)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/rhamnose](https://www.edgepedia.org/rhamnose). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"Rhamnose\", Edgepedia (EdgeChat), https://www.edgepedia.org/rhamnose. Edgepedia Community License 1.0.", "speakable": "Rhamnose is a 6-deoxy hexose sugar, 6-deoxy-L-mannose with formula C6H12O5, found in plant cell wall pectins and gram-negative bacterial lipopolysaccharides; because animals lack it, its bacterial enzymes are studied as antibacterial targets." }