OIA2007 CARBOHYDRATES

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen (CH₂O)n, functioning as structural materials, energy sources, and storage molecules.

Biological roles of carbohydrates

Provide calories, form structural frameworks (cellulose), act as water-retaining agents (e.g., mucilage), and serve in signaling or storage (e.g., starch, inulin).

Photosynthesis product

Glucose is the primary carbohydrate produced during photosynthesis.

Monosaccharides

Simple sugars like glucose, fructose, galactose; classified by carbon number and functional group (aldose/ketose).

Disaccharides

Composed of two monosaccharides; e.g., sucrose (glucose + fructose), lactose (galactose + glucose), maltose (glucose + glucose).

Oligosaccharides

Contain 3–10 monosaccharide units; examples include raffinose and chitosan.

Polysaccharides

Long chains of monosaccharides; structural (e.g., cellulose) or storage (e.g., starch, glycogen).

Furanoses and Pyranoses

5-membered (furanose) and 6-membered (pyranose) ring forms; e.g., β-D-ribofuranose, α-D-glucopyranose.

Anomeric carbon

Carbon that forms new chiral center during cyclization; gives rise to α and β forms.

Epimers

Isomers differing at only one carbon (e.g., glucose and galactose).

Anomers

α and β forms differing in orientation of OH at the anomeric carbon (e.g., α-D-glucose vs β-D-glucose).

Enantiomers

Non-superimposable mirror images; D- and L-forms of sugars differ in configuration at the chiral center farthest from the carbonyl group.

Sucrose

Formed by α1→β2 linkage between glucose and fructose; non-reducing sugar.

Lactose

Galactose and glucose joined by β1→4 linkage; used as a filler in tablets.

Maltose

Two glucose units joined by α1→4 linkage; product of starch hydrolysis.

Chitosan

Derived from chitin (shells of shrimp, crabs); linear β1→4-linked polymer of glucosamine; used in bandages, drug delivery, and biotechnology.

Raffinose

Trisaccharide found in legumes; difficult to digest, leading to fermentation in large intestine.

Starch

Plant storage polysaccharide composed of amylose (linear α1→4) and amylopectin (branched α1→4 and α1→6).

Glycogen

Animal starch; more branched than amylopectin; used for rapid glucose mobilization.

Cellulose

Linear β1→4-linked D-glucose units; major structural component of plant cell walls; indigestible to humans.

Starch hydrolysis products

Yields glucose, maltose, and dextrins depending on enzyme and degree of hydrolysis (DE value).

High-fructose corn syrup

Enzymatically treated corn syrup to convert glucose into fructose; used as a sweetener.

DE (Dextrose Equivalent) value

Indicates extent of starch hydrolysis; DE 100 = pure glucose.

α-Glucosidases

Enzymes hydrolyzing α1→4 bonds; used industrially for starch breakdown.

Methylcellulose

Used as suspending agent, bulk laxative, emulsifier, and binder.

Cellulose acetate/phthalate

Used for enteric tablet coatings; resists stomach acid.

Hydroxycellulose

Used in ophthalmic solutions and as excipient.

Carboxycellulose

Used as thickener/stabilizer in creams and dairy pharmaceuticals.

Acacia gum

From Acacia senegal; water-soluble exudate gum; demulcent, emulsifier, and suspending agent.

Tragacanth gum

From Astragalus species; contains tragacanthin and bassorin; used as thickener and tablet binder.

Psyllium seed mucilage

From Plantago ovata; bulk-forming laxative and demulcent.

Guar gum

Galactomannan from Cyamopsis; used as thickener and cholesterol-lowering agent.

Locust bean gum

From Ceratonia siliqua; contains galactose and mannose; used in tablets and food products.

Agar

From red algae (Gelidium, Gracilaria); gel-forming polysaccharide used in culture media and food industry.

Agarose & agaropectin

Agarose = β-D-galactose + 3,6-anhydro-α-L-galactose; agaropectin contains sulfated galactose and uronic acids.

Inulin

Fructose polymer (β1→2 linkages); used as GFR marker and in diabetic diets; found in chicory and dandelion.

Lichenin

Cellulose-like polysaccharide in lichens; contains β1→3 and β1→4 glucosidic bonds.

Sugar alcohols

Hydrogenated sugars like sorbitol, xylitol, erythritol; used in sugar-free products with fewer calories.

Amino sugars

Hydroxyl group replaced by amino group (e.g., glucosamine); used in joint supplements.

Uronic acids

Oxidized sugars with carboxylic acid group (e.g., glucuronic acid); part of detoxification pathways and polysaccharides.