Are natural plants hydrocolloids containing more than one kind of monosaccharide units.
I. Gums Natural products that yield with hydrolysis more than one type of monosaccharide units or their salts or their acids. Salts: Mg, Ca, K salts. Acids: called uronic acids. Uronic acids: Glucose glucuronic acid Galactose galacturonic acid Arabinose Arabic acid
Definition of Gums: Translucent, amorphous substances which formed on the stems or branches ( higher plants parts ) after injury. Gums forms: 1. exudates gums: formed in barks of the stems and branches- –to prevent dehydration –to heal the cavities 2. seeds gum: formed in seeds embryo- to reserve food 3. marine gum: component of the cell wall or intracellular region - to reserve food
The dried gummy exudations obtained by incision from the stems and branches of the Tragacanth trees. Physicochemical properties: 1.Translucent. 2.Amorphous. 3.Solid substance. 4.White or pale yellow colour. 5.Odourless. 6.Mucilaginous taste. 7.Partly soluble in water: 30% water soluble. 8.Insoluble in organic solvents. 9.Has resistance to the hydrolysis by acids
Constituents 1.Bassorin 70%: water insoluble portion. Bassorin ---Hydrolysis--- galactose+ Arabinose 2. Tragacanthin 30%: water soluble portion. Tragacanthin yields with hydrolysis demethoxylated bassorin. 3. Starch. 4. Proteins
Purity tests: 1. Aqueous gum solution + lead acetate precipitation ( due the presence of protein ) 2. Aqueous gum solution + I 2 deep blue colour in some places ( presence of starch ) 3. Aqueous gum solution + FeCl3 no deep blue or deep green colour ( absence of tannins ) 4. Aqueous gum solution + resorcinol + HCl no red or pink colour ( absence of ketoses )
Identification tests: 1.30% soluble in water. 2.Aqueous gum solution + NaOH yellow or brown colour 3.Gives positive reaction with Molisch’s and Fehling’s solution test.
Uses 1.Demulcent. 2.Emollient. 3.Laxative ( bulk laxative ). 4.Pharmaceutical uses: 1.Suspending agent. 2.Emulsifying agent. 3.Stabilizer. 4.Thickener. 5.Cosmetics: hand creams and body lotions ( emollient and emulsifying agent )
Arabic gum The dried gummy exudations obtained by incision from the stems and branches of Arabic gum trees (Acacia trees)
Physicochemical properties 1.Translucent. 2.Amorphous. 3.White or pale yellow colour. 4.Odourless. 5.Mucilaginous taste. 6.Soluble in water. 7.Insoluble in organic solvents.
Constituents 1.Arabin: a mixture of Ca, Mg, K salts for 1.Arabic acid. 2.Glucuronic acid. 3.Galacturonic acid. 4.Rhamnurnic acid. Arabin (hydrolysis) Arabinose +Rhamnose + Glucose+ Galactose 2.Enzymes: Oxidase enzyme. Peroxidase enzyme. Pectinase enzyme.
Purity tests 1. Aqueous gum solution + lead acetate no precipitation. 2. Aqueous gum solution + I 2 no deep blue colour. 3. Aqueous gum solution + FeCl 3 no deep blue or deep green. 4. Aqueous gum solution + resorcinol + HC l no red or pink colour
Identification tests: 1.Aqueous gum solution pH slightly acidic with time more acidic 2.Aqueous gum solution + Borax ( Na 2 B 4 O 7 ) translucent mass 3.Aqueous gum solution + Benzedene + H 2 O 2 blue colour 4. Aqueous gum solution + alcohol + acetic acid white precipitate 5. Gives positive reactions with Molisch’s and Fehling’s solution tests.
Uses: 1.Demulcent: ( more than the other gums ) : required in the following preparations: Anti-tussives. Anti-diarrheal preparations ( suspending, demulcent ). Throat problems. 2. Emollient. 3. Laxative ( bulk laxative ). 4. Pharmaceutical uses: 1.Suspending agent. 2.Emulsifying agent. 3.Tablet binder.
C-Guar gum: Guar gum is the powdered endosperm (embryo) of guar seeds. Physicochemical properties: 1.Translucent. 2.Amorphous. 3.Pale yellow. 4.Solid substance. 5.Odourless. 6.Mucilaginous taste. 7.Freely soluble in water (both cold and hot water). 8.Insoluble in organic solvents.
Identification 1.Aqueous gum solution + Borax translucent mass ( gel ) 2.Gives positive reactions with Molisch’s and Fehling’s solution tests.
Uses: 1. Pharmaceutical uses: a)Thickener. b)Tablet binder. c)Stabilizer. d)Emulsifying. 2. Cosmetics: lotions and creams. 3. Laxative. 4. Food industry: a. Ice creams. b. Cheese. c. Soup.
D- Locust bean gum: Carob gum : The powdered endosperm obtained from carob seeds. Physicochemical properties: 1.Translucent. 2.Amorphous. 3.Pale yellow. 4.Solid substance. 5.Odourless. 6.Mucilaginous taste. 7.Freely soluble in water ( both cold and hot water ). 8.Insoluble in organic solvents.
Identification tests: Aqueous gum solution + Borax translucent mass ( gel ) Gives positive reactions with Molisch’s and Fehling’s solution tests
Uses: 1.pharmaceutical uses: for external preparations as a)Thickener. b)Stabilizer. 2.Cosmetics. 3.Has laxative effect (but not used as laxative)
E- Karaya gum: Indian gum: Sterculia gum: The dried gummy exudations obtained by incision from the stems and branches of Sterculia trees.
Physicochemical properties: Colourless time yellow(10 days), pink ( weeks), brown (months) colour. Characteristic odour and taste ( acetic acid ). Slightly soluble in water. Insoluble in the organic solvents.
F- Xanthan Gum is a polysaccharide with a β-D-glucose backbone like cellulose, but every second glucose unit is attached to a tri-saccharide consisting of mannose, glucuronic acid, and mannose. The mannose closest to the backbone has an acetic acid ester on carbon 6, and the mannose at the end of the trisaccharide is linked through carbons 6 and 4 to the second carbon of pyruvic acid. Xanthan Gum is produced by the bacterium Xanthomonas campestris, which is found on cruciferous vegetables such as cabbage and cauliflower. The negatively charged carboxyl groups on the side chains cause the molecules to form very viscous fluids when mixed with water.
The repeating unit of Xanthan Gum Alpha-D-mannose beta-D-mannose Beta-D- glucuronic aid
uses Xanthan gum is used as a thickener for sauces, to prevent ice crystal formation in ice cream, and as a low-calorie substitute for fat. Xanthan gum is frequently mixed with guar gum because the viscosity of the combination is greater than when either one is used alone.
G- Glucomannan Glucomannan is a dietary fiber obtained from tubers of Amorphophallus konjac (Devil's Tongue) cultivated in Asia. Glucomannan is used as a hunger suppressant because it produces a feeling of fullness by creating very viscous solutions that retard absorption of the nutrients in food. One gram of this soluble polysaccharide can absorb up to 200 ml of water, so it is also used for absorbent articles such as disposable diapers and sanitary napkins.
The polysaccharide consists of glucose (G) and mannose (M) in a proportion of 5:8 joined by β1→4 linkages. The basic polymeric repeating unit has the pattern: GGMMGMMMMMGGM. Short side chains of 11-16 monosaccharides occur at intervals of 50-60 units of the main chain attached by β1→3 linkages. Also, acetate groups on carbon 6 occur at every 9-19 units of the main chain. Hydrolysis of the acetate groups favors the formation of intermolecular hydrogen bonds that are responsible for the gelling action.
portion (GGMM) of the glucomannan repeating unit. The second glucose has an acetate group.
Definition: Natural plants product, heteroglycan complex polysaccharide. Mucilage give with hydrolysis : a.monosaccharide units. b.Ca, Mg, K, Na salts of monosaccharides. c.Monosaccharide acids. d.Ca, Mg, K, Na salts of monosaccharide acids. They founded in some plants part as food reservoir or and as water reservoir ( hydrophilic substances).
Examples for plants parts containing mucilage : 1.Leaves: Buchu. 2.Roots and rhizomes: Cinnamon and Marshmallow. 3.Seeds: Lin (flax), Mustard, Fenugreek. 4.Weeds: Marine plants ( Laminaria, Red Algae ).
Agar is Natural product. Dry powder. Hydrophilic substance. Obtained from: 1.Red Algae. 2.Gracilaria. 3.Golidium.
Extraction of mucilage: ( Isolation of Agar ) : 1.Fresh weeds washed with running water for 24 hours. 2.Extracted with diluted HCl Filtration. 3.Washed with diluted NaOH, then with water ( for about 30 hours ). 4.Extract ( Agar+ water ) congealed in ice. 5.Water separated as ice. 6.Extract dried with hot air.
Physicochemical properties: 1.Yellowish white powder. 2.Odourless or with slight odour. 3.Mucilaginous taste. 4.Slowly soluble in water viscous mass 5.insoluble in the organic solvents.
Agar contains 1.Proteins. 2.Mixture of : a)L-galactose. b)D-galactose. c)Galacturonic acid. d)Sulphate ions.
Agarobiose is the repeating disaccharide unit in agar Agar is a polymer of agarobiose, a disaccharide composed of D-galactose and 3,6-anhydro-L-galactose
Purity tests: Aqueous Agar solution + lead acetate precipitate Aqueous Agar solution + I 2 negative Aqueous Agar solution + FeCl 3 negative Aqueous Agar solution + resorcinol + HCl negative
Identification chemical tests: 1.Positive reaction with Molisch’s and Fehling’s solution test. 2.Aqueous agar solution + HCl conc. SO 4 +Bacl 2 BaSO 4 ( white precipitate ). 3.Aqueous agar solution + HCl conc. SO 4 + KCl K 2 SO 4 ( yellow precipitate ). 4.Aqueous agar solution + water Δ then cooling gel.
Agar main uses: 1.pharmaceutical uses: a)Suspending. b)Emulsifying. c)Gelating agent for suppositories. 2.Laxative ( bulk laxative ). 3.Food industry. 4. Highly refined agar is used as a medium for culturing bacteria, cellular tissues, and for DNA fingerprinting.
Carrageenan Carrageenan is a generic term for several polysaccharides extracted from seaweed. Carrageenan compounds differ from agar in that they have sulfate groups (-OSO3-) in place of some hydroxyl groups. Carrageenan is also used for thickening, suspending, and gelling food products.
Psyllium seeds: Plantago seeds : Plantain seeds: 1.Small seeds. 2.Have grey or brown colour. 3.Mucilaginous taste and slightly bitter. 4.Odourless.
The structure of the Plantago seeds includes a remarkable glycoside of the monoterpene class (iridoid) called Aucubin. This glycoside has been studied and numerous scientific papers have been written about this particular member of the monoterpene family.
The general characteristics of the iridoid monoterpene aucubin are as follows: 1.Sedative 2.Anesthetic 3.Analeptic 4.Anaseptic (Anti-viral) 5.Anti-toxic 6.Anti-Histaminic 7.Anti-Inflammatory 8.Anti-Rheumatic 9.Anti-Tumor (Anti-Blastic, Anti-Cancer, Anti- Carcinogenic) 10.Diuretic 11.Expectorant 12.Hypotensive 13.Organoleptic (Odor, Taste)
The anti-toxic, anti-inflammatory and expectorant characteristics suggest why the plant is useful in lung disorders, and as inferences as to the effect of the Plantago on smokers.
Uses: 1.Laxative (f.o + mucilage) lubricant and bulk laxative. 2.Diuretic. 3.Demulcent. 4.Anti-inflammatory activity specially for GIT and mouth mucus membrane inflammations.
Physicochemical properties: 1.White cream powder. 2.Odourless. 3.Mucilaginous taste except alginic acid ( slightly acidic ). 4.soluble in water. 5.Insoluble in the organic solvents. Note: Alginic acid + water doesn’t form viscous mass. Na-alginate + water form viscous mass
IngredientsDosage form ProducerTrade Name Al(OH) 3 Mannitol Alginic acid Sodium bicarbonate Al(OH) 3 CaCO 3 Sodium alginate Sodium bicarbonate Powder. Chewing tablet Liquid FerringGaviscon This drug- used for treatment of Gastro esophageal Reflux Disease (GERD)
Note: Alginic acid + sodium bicarbonate saliva, water sodium alginate water viscous mass.
III. Pectin Heteroglycan complex polysaccharide, present in the cell wall of plants tissues which function as intercellular cementing agent, obtained from: Citrus fruits. Apple pomace. Protopectin 90°C + HCl (pH=3.4-4), organic solvent pectin Note: Protopectin: water insoluble. Pectin: water soluble. Organic solvent used to precipitate pectin.
Pectin Pectin is a polysaccharide that acts as a cementing material in the cell walls of all plant tissues. The white portion of the rind of lemons and oranges contains approximately 30% pectin. Pectin is an important ingredient of fruit preserves, jellies, and jams.
Physicochemical properties: 1.Yellowish white powder. 2.Odourless. 3.Mucilaginous taste. 4.Soluble in water ( 1:20 ). 5.Insoluble in the organic solvents
Constituents: A mixture of : 1.Galactose. (alpha-D-galacturonic acid- methoxylated)alpha1,4-bond galacturonan 2.Fructose. (traces) 3.Arabinose. ok 4.Xylose. traces
α-1,4 -linkage 1.Pectin is a polymer of α-Galacturonic acid with a variable number of methyl ester groups 2.The structure shown here has three methyl ester forms (-COOCH 3 ) for every two carboxyl groups (-COOH ) Pectin
Purity tests: Aqueous pectin solution + lead acetate negative Aqueous pectin solution + I 2 negative Aqueous pectin solution + FeCl 3 negative Aqueous pectin solution + resorcinol + HCl red to pink colour
Identification tests: Positive reaction with Molisch’s and Fehling’s solution tests. Positive reaction with Selivanoff’s test.
Uses: 1. Treatment of diarrhea: absorbent anti-diarrheal agent. Absorption of: oFluids. oBacteria. oToxins. oGases. 2. Haemostatic. 3. Emulsifying and gelling agent in the pharmaceutics and cosmetics. 4. Thickening agent in food industry.
Note: Pectin usually comes with kaolin. Kaolin: Absorbent anti-diarrheal agent obtained from: Sand stones. Rocks. Clay. All contain Al 2 O 3 + SiO 2 Uses: Treatment of diarrhea (the same way as pectin). Coat for irritated intestinal mucosa caused by diarrhea.
There is 2 types of anti-diarrheal agents according to their mechanism of action: 1. Absorbent anti-diarrheal agents : –Pectin. –Kaolin. 2. Anti-peristaltic agents: Loperamide: from opiate alkaloids, decrease intestinal hyper motility. Furazolidine: decrease intestinal hyper motility.
References 1.Gonzáles Canga, A., et al., Glucomannan: Properties and Therapeutic Applications, Nutr. Hosp., 19(1) 45-50, 2004. 2.J. P. Roubroeks, R. Andersson, D. I. Mastromauro, B. E. Christensen and P. Åman, Molecular weight, structure and shape of oat (1→3),(1→4)-b-D-glucan fractions obtained by enzymatic degradation with (1→4)-b-D-glucan 4-glucanohydrolase from Trichoderma reesei, Carbohydr. Polym. 46 (2006) 275-285.