Fructose Chemical Structure

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1. Identification

Summary

Fructose is a ketohexose monosaccharide (C₆H₁₂O₆). It exists predominantly as furanose/pyranose hemiketals in solution and serves as a dietary sugar and endogenous metabolite in human carbohydrate metabolism.

Brand Names

Not applicable.

Name

Fructose (D-fructose)

Background

Naturally present in fruits, honey, and sucrose (as the fructosyl moiety). Principal intestinal transporter GLUT5; hepatic entry into glycolytic/gluconeogenic pathways via ketohexokinase (fructokinase).

Modality

Small molecule (monosaccharide)

Groups

Nutrient; endogenous metabolite; food ingredient

Structure

Weight

~180.16 g/mol

Chemical Formula

C₆H₁₂O₆

Synonyms

D-Fructose; Levulose; β-D-fructofuranose; α/β-D-fructopyranose

External IDs

CAS: 57-48-7; PubChem CID: 5984; UNII: 6YSS42VSEV

2. Pharmacology

Indication

Not a therapeutic drug. Nutrient/sweetener; metabolic substrate.

Associated Conditions

Dietary carbohydrate metabolism; hereditary disorders include essential fructosuria (KHK deficiency) and hereditary fructose intolerance (ALDOB deficiency).

Associated Therapies

None (nutrient context).

Contraindications & Blackbox Warnings

None applicable (not a drug). Clinical cautions derive from specific inborn errors of metabolism and dietary management.

Pharmacodynamics

Enters intermediary metabolism after phosphorylation → fructose-1-phosphate (KHK) or fructose-6-phosphate (hexokinase, minor in most tissues) → glycolysis/gluconeogenesis.

Mechanism of action

Biochemical substrate: intestinal GLUT5 uptake → portal circulation (GLUT2) → hepatic KHK phosphorylation → aldolase B cleavage to dihydroxyacetone phosphate and glyceraldehyde.

Absorption

Predominantly via GLUT5 (SLC2A5) in enterocytes; facilitated diffusion.

Volume of distribution

Distributes in total body water; rapid hepatic extraction.

Protein binding

Negligible.

Metabolism

Hepatic phosphorylation (KHK) and cleavage (ALDOB) to triose phosphates; interconversion with glucose via gluconeogenesis/glycolysis.

Route of elimination

Metabolized to CO₂ and water; carbon shunted to glycogen, lipids, or glucose depending on nutritional state.

Half-life

Short (minutes) in circulation post-absorption due to rapid hepatic uptake.

Clearance

High hepatic clearance (first-pass).

Adverse Effects

Nutrient-level effects depend on dose and context; clinical toxicity pertains to inherited enzyme deficiencies.

Toxicity

In hereditary fructose intolerance, fructose/ sucrose/ sorbitol ingestion causes F-1-P accumulation with hypoglycemia and hepatic/renal injury.

Pathways

Intestinal GLUT5 → GLUT2 export; hepatic KHK (F-1-P) → ALDOB → triose phosphates.

Pharmacogenomic Effects/ADRs

Pathogenic variants in KHK (essential fructosuria) and ALDOB (HFI) alter handling/tolerance.

3. Interactions

Drug Interactions

None specific at therapeutic-drug level; co-ingested nutrients/hormonal milieu modulate downstream metabolic routing.

Food Interactions

Occurs within mixed meals; absorption enhanced with co-ingested glucose (shared transport/export).

4. Categories

ATC Codes

None.

Drug Categories

Monosaccharide; Nutrient; Carbohydrate

Chemical Taxonomy

Ketohexose; predominantly furanose/pyranose cyclic hemiketals in aqueous solution.

Affected organisms

Humans (nutrient/metabolite)

5. Chemical Identifiers

UNII

6YSS42VSEV

CAS number

57-48-7

InChI Key

BJHIKXHVCXFQLS-FUTKDDECSA-N

InChI

InChI=1S/C6H12O6/c7-2-6(11)5(10)4(9)3(8)1-12-6/h3-5,7-11H,1-2H2

IUPAC Name

(3S,4R,5R)-1,3,4,5,6-pentahydroxyhexan-2-one

SMILES

C(C(C(C(C(=O)CO)O)O)O)O

6. References

PubChem Compound Summary — D-(−)-Fructose (CID 5984); formula C₆H₁₂O₆, MW ~180.16, synonyms and identifiers. PubChem
NIST Chemistry WebBook — CAS 57-48-7; InChIKey BJHIKXHVCXFQLS-FUTKDDECSA-N; cyclic/linear form note. webbook.nist.gov+1
FDA GSRS/UNII — Fructose UNII 6YSS42VSEV registry entry. gsrs.ncats.nih.gov
StatPearls — Fructose metabolism overview: GLUT5 absorption; ketohexokinase (fructokinase) pathway; hepatic handling. NCBI
Peer-review/Annual Reviews — regulatory updates in glucose/fructose metabolism. annualreviews.org
Supplier/Nomenclature refs — linear SMILES and IUPAC name for D-fructose. Fisher Scientific

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