Carbohydrates

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The non-sugar compound remaining after replacement of the glycosyl group from a glycoside by a hydrogen atom. (The alternative spelling aglycone is discouraged because it suggests a ketonic structure, but in other languages it may be used, according to custom.) 2-Carb-33.1.

aldaric acids:*

Polyhydroxy dicarboxylic acids having the general formula HOC(=O)[CH(OH)]_nC(=O)OH, formally derived from an aldose by oxidation of both terminal carbon atoms to carboxyl groups. 2-Carb-1.12.

alditols:*

Acyclic polyols having the general formula HOCH₂[CH(OH)] _nCH₂OH (formally derivable from an aldose by reduction of the carbonyl group). 2-Carb-1.8.

aldoketoses:*

A now less preferred synonym for ketoaldoses. 2-Carb-1.5.

aldonic acids:*

Polyhydroxy acids having the general formula HOCH₂[CH(OH)]_nC(=O)OH and therefore derived from an aldose by oxidation of the aldehyde function. 2-Carb-1.9. E.g. D-gluconic acid

aldoses:*

Aldehydic parent sugars (polyhydroxyaldehydes H[CH(OH)]_nC(=O)H, n greater than 1) and their intramolecular hemiacetals. 2-Carb-1.2. See also monosaccharides. E.g. D-glucose

amino sugars:*

Monosaccharides having one alcoholic hydroxy group (commonly but not necessarily in position 2) replaced by an amino group; systematically known as x-amino-x-deoxymonosaccharides. (Glycosylamines are excluded.) 2-Carb-1.7, 2-Carb-14.

D-glucosamine or 2-amino-2-deoxy-D-glucopyranose

carbohydrates:

Originally, compounds such as aldoses and ketoses, having the stoichiometric formula C_n(H₂O)_n, hence "hydrates of carbon". The generic term carbohydrate includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups to carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom, an amino group, thiol group or similar groups. It also includes derivatives of these compounds. 2-Carb-1.1.

cyclitols:*

Hydroxylated cycloalkanes containing at least three hydroxy groups, each attached to a different ring carbon atom. BNRD, Nomenclature of Cyclitols (p. 149).

cyclodextrins:

Cyclic oligoglucosides containing 5 to ca. 10 glucose residues in which an enclosed tubular space allows reception of a guest molecule to form a clathrate. The synonymous term Schardinger dextrins is not recommended. (-Cyclodextrin has 6 glucose residues; -cyclodextrin has 7.) Semi-systematically -cyclodextrin is called cyclomaltohexaose. 2-Carb-37.4.1. See also dextrins.

dextrans:

Branched poly--D-glucosides of microbial origin having glycosidic bonds predominantly C-1 C-6. Cf. glycosides.

dextrins:

Poly--D-glucosides of intermediate chain length derived from starch components (amylopectins) by the action of amylases (starch hydrolysing enzymes). See also cyclodextrins, dextrans.

disaccharides:*

Compounds in which two monosaccharides are joined by a glycosidic bond. 2-Carb-36.1. See saccharides, glycosides.

enoses:*

Monosaccharides having a carbon-carbon double bond anywhere in the backbone chain. Glycals (term not recommended) designates the enoses that are generated by formal elimination of the hemiacetal hydroxy group and an adjacent hydrogen atom. Thus glycals are cyclic enol ethers. 2-Carb-17. Unsaturated hexoses, for example, are called hexenoses. E.g. (the hex-1-enopyranose derived from D-glucopyranose)

furanoses:*

Cyclic hemiacetal forms of monosaccharides in which the ring is five-membered (i.e. a tetrahydrofuran skeleton). 2-Carb-5.1.

glycals: See under enoses.

glycans:*

Synonymous with polysaccharides. Glycans composed of a single type of monosaccharide residue (homopolysaccharide, synonym homoglycan) are named by replacing the ending '-ose' of the sugar by '-an'. E.g. mannans, fructans, xylans, arabinans. 2-Carb-39.1. Dextrans and dextrins belong to the class glucans

glycaric acids: An obsolescent synonym for aldaric acids.

glycitols: An obsolescent synonym for alditols.

glyconic acids: An obsolescent synonym for aldonic acids.

glycopeptides/glycoproteins:*

Compounds in which a carbohydrate component is linked to a peptide/protein component. BNRD, Nomenclature of Glycoproteins, Glycopeptides, and Peptidoglycans, (p. 84).

glycoproteins: See glycopeptides.

glycosamines:

A term synonymous with amino sugars; now restricted to some trivial names. 2-Carb-14.

glycoses: A less frequently used term for monosaccharides.

glycosides:*

Originally mixed acetals resulting from the attachment of a glycosyl group to a non-acyl group RO- (which itself may be derived from a saccharide) and chalcogen replacements thereof (RS-, RSe-). The bond between the glycosyl group and the OR group is called a glycosidic bond. 2-Carb-33.1. Also called osides. By extension, the terms N-glycosides and C-glycosides are used as class names for glycosylamines and for compounds having a glycosyl group attached to a hydrocarbyl group respectively. These terms are misnomers and should not be used. The preferred terms are glycosylamines and C-glycosyl compounds, respectively. 2-Carb-33.1. 2-Carb-33.5, 2-Carb-33.7. Cf. glycosylamines.

m and n may be 0, 1, 2, etc.; and x usually 2 or 3.
4--D-glucopyranosylbenzoic acid a C-glycosyl compound

The structure obtained by removing the hydroxy group from the hemiacetal function of a monosaccharide (2-Carb-31.1) and, by extension, of a lower oligosaccharide.

glycosylamines:

Compounds having a glycosyl group attached to an amino group, -NR₂; less elegantly called N-glycosides. Cf. glycosides. 2-Carb-33.1, 2-Carb-33.5 E.g. N,N-dimethyl--D-glucopyranosylamine

glycuronic acids: An obsolescent synonym for uronic acids. BNRD, Polysaccharide Nomenclature 5 (p.174).

inositols:*

Cyclohexane-1,2,3,4,5,6-hexols. BNRD Rule I-1.1 (p. 151).

ketoaldonic acids:*

Monosaccharides in which a structure containing a keto group and a carboxylic acid group is in equilibrium with a hemiacetal structure. 2-Carb-1.10. Specific compounds are named using the -ulosonic acid suffix. 2-Carb-22.1. See also oxo compounds. E.g. D-arabino-hexulosonic acid

ketoaldoses:*

Monosaccharides which contain both an aldehydic and a ketonic carbonyl group in equilibrium with intramolecular hemiacetal forms. 2-Carb-1.5. See also oxo compounds.

ketoses:*

Ketonic parent sugars (polyhydroxy ketones H-[CHOH]_n-C(=O)[CHOH]_m-H with three or more carbon atoms) and their intramolecular hemiacetals. 2-Carb-1.2. The oxo group is usually at C-2. See also monosaccharides . E.g. D-fructose

lipopolysaccharides:

Natural compounds consisting of a trisaccharide repeating unit (two heptose units and octulosonic acid) with oligosaccharide side chains and 3-hydroxytetradecanoic acid units (they are a major constituent of the cell walls of Gram-negative bacteria).

monosaccharides:*

A term which includes aldoses, ketoses and a wide variety of derivatives. Derivation includes oxidation, deoxygenation, introduction of other substituents, alkylation and acylation of hydroxy groups, and chain branching. 2-Carb-1.2. Cf glycosides. See saccharides. E.g.

Subgroups of monosaccharides mentioned in this glossary are aldoketoses, uronic acids and amino sugars.

mucopolysaccharides:

Polysaccharides composed of alternating units from uronic acids and glycosamines, and commonly partially esterified with sulfuric acid. BNRD Nomenclature of glycoproteins, glycopeptides and peptidoglycans (p.86).

oligosaccharides:* See oligo and saccharides. 2-Carb-1.14.

osazones:

1,2-Bis(arylhydrazones) of ketoaldoses (aldoketoses) formed from aldoses and 2-ketoses by reaction with excess arylhydrazine. 2-Carb-16.5.

R = rest of monosaccharide chain

osides: See glycosides.

osones: An obsolescent and non-recommended term for 1,2-ketoaldoses, usually derived by hydrolysis of osazones. BNRD Rule 2-Carb-12 (p. 132).

osotriazoles:

The 1,2,3-triazoles formed on oxidising osazones.

R = rest of monosaccharide chain

pectins:

Polyuronic acids mostly derived from D-galacturonic acid (abundant in some fruits). See also uronic acids.

polysaccharides:*

Compounds consisting of a large number of monosaccharides linked glycosidically. This term is commonly used only for those containing more than ten monosaccharide residues. Also called glycans. See also 2-Carb-1.15.

pyranoses:*

Cyclic hemiacetal forms of monosaccharides in which the ring is six-membered (a tetrahydropyran). Cf. furanoses. 2-Carb-5.1.

reductones:

Compounds containing an enediol structure stabilized by conjugation and hydrogen bonding with an adjacent carbonyl group, RC(OH)=C(OH)C(=O)R. They are strong reducing agents, fairly strong acids and commonly derived from saccharides by oxidation at the carbon atom alpha to the carbonyl function. E.g. ascorbic acid.

saccharides:

The monosaccharides and di-, oligo-, and polysaccharides, which are made up of n monosaccharide units linked to each other by a glycosidic bond. Considered by some to be synonymous with carbohydrates.

sugars:

A loose term applied to monosaccharides and lower oligosaccharides. 2-Carb-1.1.

ulosonic acids: See ketoaldonic acids.

uronic acids:*

Monocarboxylic acids formally derived by oxidation to a carboxy group of the terminal -CH₂OH group of aldoses. 2-Carb-1.11 (p. 188). E.g. D-glucuronic acid