OIA2007 W6 CARBS

Major class biological molecules (plant): sugar, fatty acids, amino acids, nucleotides

Carbo (C, H & O)

Glucose: 1st product in photosynthesis

Large proportion of plant biomass as cellulose (rigid cellular frame)

Sugar: glucosides & glycosides

Oxidation to Uronic Acid (from Polysaccharides)

Sugar formation: glucose-6-phosphate & fructose-6-phosphate

Hydrolysed to glucose/ fructose -> starch or conserved energy

Form sugar nucleotides with UTP (Uridine triphoshate)/ ATP

Fx: starch (energy store in green plants) & cellulose (biomass)

Class of Sugar

Monosaccharides - pentose & hexose

Few amount available in free form

Example: glucose/ dextrose, fructose, galactose, mannose, rhamnose

Glucose/ dextrose - dextrose-a-glucopyranose (pyranose form)

Hydrolysis of starch in HCl + heat 30 minutes

Monosaccharides have 4, 5 or 6-carbon forms, 5 or 6-carbon form have 1 O atom in ring

Triose, tetrose

5-sided ring (furanose): ribose, ...

6-sided ring (pyranose): glucose, ...

Simple: glucose; Complex: combine of simple sugar (ring or open chain form)

Disaccharides - combine 2 simple sugars

Glucose + fructose -> sucrose by 1,4-glycosidic linkage

Glucose + galactose -> lactose

Glucose + glucose -> maltose

Oligosaccharides (3-10 units)

Chitosan: linear Polysaccharides with randomly distributed B-(1,4)-linked D-glucosamine (deacetylated) & N-acetyl-D-glucosamine (acetylated)

- treat chitin shells of crustaceans w alkaline substance (e.g., NaOH)

*Any more than 3 units considered Polysaccharides

Trisaccharides/ Oligosaccharides: rafflose & melitose in beans, cabbage, bcrocoli & etc.

Polysaccharides (>10 units)

Building blocks

Hexoses: D-glucose, D-mannose, D-fructose, D-galactose, D-rhamnose

Pentoses: D-xylose, L-arabinose

Modified sugar: D-glucosamine, D-glucuronic acid, D-mannuronic acid, D-galacturonic acid, L-fructose, L-rhamnose

Dextrins & Dextrans

White dextrins: prepare in acid & heat w less adhesive properties

Yellow dextrins: smaller & partially breakdown by acid

Use: adhesive dressing, food products

Dextrans: 1,6- linkage of glucose units

Form by microbes

Commercially used Leuconostic mesenteriodes (sucrose -> a-1,6-glucose dextrans

Use: blood plasma expanders

**Cellulose Derv.

Pyroxylin (partially nitrate cellulose) - make colloidon, plastics & nail polish; OH groups replaced

Cellulose acetate - acetate replace ~2/3 OH group

Combine for tablet coatings

Methyl cellulose - suspending agent, produce viscous suspension

Good emulsifier

Hydroxyl cellulose - excipients & topical ophthalmic protectant & lubricant

Carboxyl cellulose - thickener & stabiliser for pharmaceutical & dairy products, cream & coatings

Cellulose nitrate - nitration of polymer-guncotton

Skin coatings over abrasion

Inulin - reserved carbs abundant in Compositae

Linear chains up to 50 B-1,2-linked fructofuranose units terminated by single glucose unit

E.g., chicory (Cichorium intybus) & dandelion (Taraxacum official)

Use: sweetener, determine glomerular filtration rate (GFR)

Hemicellulose (xylans, mannans & galactans)

Occur in cell wall w cellulose & pectic

Not cellulose components

Mainly hexose & pentose units

Lichenin or Lichen starch - resemble cellulose

Contain 25% B-1,3-glucosidic linkages

Chitin: polymer of N-acetyl glucosamine (unbranded polymer)

2nd C replaced w acetamido (NHCOCH3) group

Polysaccharides w Uronic Acid: Pectin

In middle lamellae of cell wall

Abundant in fruits & roots

Protopectin (insoluble) easy convert by restricted hydrolysis -> pectininc acids (pectins)

D-galacturonic acid residues w a-1,4-glycosidic linkages & interspersed w rhamnose units

High MW polymer, coagultae w Cu & Al, ions of aqueous-viscous solutions, gel, diarrhea preparation, hemostatic-substitute plasma therapy

Gums - mixture of various sugars/ combinations - different physicochemical properties

Exudate gums: acacia, tragacanth, sterculia

Seed gums: psyllium seeds, carob gum, guar gum

Seaween gums: alginic acid & agar

Acacia gum - no odor/ taste in aqueous

Constituent: D-galactose + D-glucose (Glucuronic acid) contain L-arabinose + L-Rhammose w 16-linkage + 1,3-linkage

Water soluble, low viscosity solution

Easy digestion + absorption

Non toxic

Uses

Emulsion stabilisers, treat cough, diarrhea, throat (demulcent properties)

Tragacanth gum (astragalus gummifier & leguminosae)

More acidic than acacia

Constituent: D-glucuronic acid, tragacanth (acidic group + hydrophilic ), bassorin (no acid groups + hydrophobic)

Suspending agent, thickening agent, tableting

Seed gum (Psyllium seed) - epidermis of testa

Neutral polymer (mucilage) of seed coat

Not purified

D-galacturonic acid + L-arabinose, D-xylose, L-mannose

Uses

Demulcent, chronic constipation

Carob gum (Leguminosae) - endosperm separate from seeds

Constituent: mannose & galactose

Shorter/ less branched

Neutral

Uses

Mild suspending agent, thickening agent, tableting

Food: thickener

Guar gum (Cyamopsis tetragonobulus)

Constituent: galactomannan

Uses

Food: thickening agent (5-6X > starch)

Oral hypoglycemiic drug: change gastric emptying & gastric transit

Reduce cholesterol levels (bind bile salts in gut)

Polysaccharides w sulphuric acid ester: agar (Gellidium sp. & Gracilaria sp.)

Agarose = B-D-galacturose & 3,6-anhydro-a-L-galactose

Agaropectin: D-galactose, D-glucuronic acid, L-galactose w sulfate esters

Series of polymers at low conc. very viscous & stable (stable gel)

Uses: agar plates, thickener, emulsifiers

Sugar Alcohols (glucitol, sorbitol, erythritol, xylitol)

Hydrogenated form of aldolses/ ketose: sorbitol has same linear structure of chain form but aldehyde replaced w CH2OH, include other monosaccharides erythritol/ xylitol

Have 1/2 of calories of sugars

Amino sugar - OH replaced w NH2

E.g., glucosamine treat cartilage a damage & reduce arthritis pain

Uronic acids - have COOH on C that not part of ring

Chemical structures differ only in orientation of OH

Slight structural diff. -> diff. biochemical properties, organoleptic properties (taste), physical properties & specific rotation

Aldose & ketose

Chain-form monosaccharides having C=O at terminal C -> form aldehyde (aldoses)

Chain-form monosaccharides having C=O at n inner atom -> form ketone (ketoses)

Acyclic form: anomeric center important for reactivity (ring opening occurs) where C-OH -> C=O

Anomeric center/ anomeric C: attach to 2 O atoms by single bonds

Cyclic form: anomeric center depend on substituents (if aldose)

Epimer: structure having opposite config. of OH at only one position (e.g., glucose, mannose)

Anomer: rearrangement produce a-D-glucose (OH opposite of CH2OH) or B-D-glucose (OH same of CH2OH)

Enantiomers - compounds w mirror image or each other but not identical comparable

Different config.: different chemical & biological properties

D-form (Dextro-) or L-form (Levo-): identify by compare stereochemistry at chirality center beside -CH2OH group