Plant and Marine Gums

• Gums and Mucilages are being discussed as part of Pharmacognosy and Plant Chemistry study.
• Students should be able to classify, characterize, and enumerate the uses and sources of gums and mucilages, including Philippine medicinal plants.
• The primary reading material is "Trease and Evans Pharmacognosy" by William Charles Evans, 16th edition.
• The outline includes difference between gums and mucilage, uses, sources, and examples of gums.

Gums

• Natural plant hydrocolloids
• Anionic or non-ionic polysaccharides
• Translucent, amorphous substances
• Readily dissolve in water.
• Pathologic products, meaning they are produced as a result of injury or stress to the plant.

Mucilage

• Form slimy masses.
• Physiologic products, being naturally produced by the plant.

Uses of Gums and Mucilage

• Ingredients in dental and other adhesives.
• Ingredients bulk laxatives.
• Tablet binders.
• Emulsifiers.
• Gelating agents.
• Suspending agents.
• Stabilizers.
• Thickeners.

Sources of Gums

• Shrub or tree exudate
• Marine gums
• Seed gums
• Plant extracts
• Microbial gums

Tree or Shrub Exudates

• These gums are obtained from the sap or resin that exudes from trees or shrubs, often in response to injury or stress.

Tragacanth

• Obtained from Astragalus gummifer (Fam. Leguminosae).
• Commonly known as gum tragacanth.
• The nature of the incision governs the shape of the final product.
• tragacanth is derived from Greek words: tragos (goat) and akantha (horn), likely referencing the drug's curved shape.
• astragalus means milkbone which refers to the exuding and subsequent hardening of the drug.
• gummifer is Latin for gumbearing.

Types of Tragacanth

• Vermiform tragacanth: wormlike and twisted into coils.
• Tragacanth sorts: shaped like irregular tears and are yellowish or brownish in color.
• Ribbon gum and flake gum: Better grade comes from transverse incisions made with a knife in the main stem and older branches.

Components of Tragacanth

• Bassorin: Makes up 60-70% of tragacanth, a complex of polymethoxylated acids; swells in water but does not dissolve.
  • A product of Bassorin hydrolysis: galactose+ Arabinose
• Demethoxylated bassorin (tragacanthin): Composes about 30% of the gum and is the more water-soluble component.

Commercial Grades and Uses of Tragacanth

• No. 1: Almost colorless and nearly translucent.
• No. 2 and No. 3: Have more color and opacity.
• Uses: Suspending agent, emulsifying agent for oils and resins, adhesive.
• Most resistant hydrocolloid to acid hydrolysis.
• Preferred for use in highly acidic conditions.
• Demulcent and emollient, found in hand lotions.

Acacia

• Derived from the stems and branches of Acacia senegal (Fam. Leguminosae).
• Commonly known as gum arabic.

Components of Acacia

• Arabin: a mixture of Ca, Mg, K salts, Arabic acid, Glucuronic acid, Galacturonic acid, and Rhamnurnic acid.
• Contains 12 to 15% of water.
• Contains enzymes like Oxidases, peroxidases, and Pectinases.
• The enzymes present can cause problems in some formulations.
• Remains in solution at alcohol concentrations below 60%.
• Solutions have low viscosity and good stability over the pH range of 2 to 10.
• Excellent emulsifying agent.

Ghatti Gum (Indian Gum)

• Sometimes used as a substitute for acacia.
• Derived from Anogeissus latifolia (Fam. Combretaceae).
• Color changes from colorless, to yellow (10 days), pink (weeks), then brown (months).
• Has a characteristic odor and taste (acetic acid).
• It readily forms a dispersion in cold water.
• The resulting dispersions are viscous than those of acacia.
• Contains: Galactose, Galacturonic acid, Rhamnose, and Acetic acid.

Karaya Gum (Sterculia Gum)

• Sources: Fam. Sterculiaceae (Sterculia urens, S. villosa, S. tragacantha) and Fam. Bixaceae (Cochlospermum gossypium, Cochlospermum Kunth).
• Sterculia derives from Latin, referencing the deity of manuring, related to the trees' fetid odor.
• Contains D-galacturonic acid and D-glucoronic acid residues.
• Forms a discontinuous type of mucilage.
• Used as a bulk laxative.

Uses for Karaya Gum (Sterculia Gum)

• An agent for forming emulsions and suspensions, a dental abrasive, extensively in wave set solutions and skin lotions.
• Utilized in the textile and printing industries.
• Used in the preparation of food products and composite building materials.

Marine Gums

• Marine gums are considered mucilages and not gums.
• They are physiologic products and create slimy masses with water.

Algin

• Algin = (sodium alginate + alginic acid)
• Extracted from brown seaweeds by using diluted alkali.
• Chief source: Macrocystis pyrifera (Fam. Lessoniaceae).
• Other sources: Class Phaeophyceae, Ascophyllum, Ecklonia, Laminaria, and Nereocystis.
• It is major component of Mannuronic acid.
• Components: L-glucuronic acid and D-mannuronic acid.
• Sodium alginate: a mixture of: beta-D- and Sodium salts of glucuronic acid ( Na-glucuronate ).
• It is a suspending agent.
• Used in the food industry (ice cream, chocolate milk, salad dressing, icings, confectionery).
• Utilized for cosmetic preparations, as a sizing, and for other industrial purposes.
• Is metabolized by the body.
• Has a caloric value of approximately 1.4 calories per gram.

Alginic Acid

• Relatively insoluble in water
• Used as a tablet binder and thickening agent.
• Useful gel-forming properties are associated with salts of various polyvalent cations and alginic acid.
• Calcium alginate is used in gelation purposes, including the formation of a firm gel for preparing dental impressions.
• The propylene glycol ester of algin is useful because formulations require greater acid stability than that of the hydrocolloid.
• Ex: In treatment for Gastro esophageal Reflux Disease (GERD); Gaviscon contains alginic acid and sodium alginate.

Agar (Japanese Isinglas)

• Dried, hydrophilic, colloidal substance extracted from: Gelidium cartilagineum (Fam. Gelidiaceae) and Gracilaria confervoides (Fam. Sphaerococcaceae).
• It is related red algae(Class Rhodophyceae).
• Properties: weak yellowish orange, yellowish to pale yellow or colorless, tough when damp, brittle when dry, odorless or slightly odorous plus has mucilaginous taste.
• Major fractions: agarose and agaropectin.
• Agarobiose: is the repeating disaccharide unit in agar and is a polymer of agarobiose made of D-galactose and 3,6-anhydro-L-galactose.
• Agar is used as a laxative, suspending agent/emulsifier, gelating agent for suppositories/surgical lubricants, tablet excipient/disintegrant, and extensively in bacteriologic culture media.

Agarose

• It is used as a matrix for immunodiffusion
• Used for electrophoresis
• Used for chromatography.

Carrageenan

• Obtained from various red algae or seaweeds.
• Major sources: Chondrus crispus (Linne) Stackhouse and Gigartina mamillosa (Goodenough and Woodward) J. Agardh (Fam. Gigartinaceae).
• Chondrus crispus, or Irish Moss, with cartilage-like dry thallus.
• Gigartina mamillosa has elevated tubercles in the thallus that appear as fruit bodies.
• Components: к-carrageenan (Kappa), ì-carrageenan (lota), and λ-carrageenan (Lambda) which is a thickener and Phlogistic agent.
• USES: Widely used to form gels, give stability to emulsions and suspensions, firm texture and good rinsability for toothpastes, demulcent, and bulk laxative.
• Used in many food preparations.

Furcellaran

• AKA: Danish agar
• A red algae from Furcellaria fastigiata (Furcellariaceae).
• Similar hydrocolloid to K-carrageenan, used especially in Europe as a gelating and suspending agent.

Seed Gums

• Plantago seed synonyms: psyllium seed and plantain seed.
• SOURCES: Clean and dried, ripe seed of Plantago psyllium; P. indica Linne , P. arenaria (Spanish or French psyllium seed), P. ovata Forskal (blonde psyllium or Indian plantago seed (Fam. Plantaginaceae).
• Commercially, the husk of P. ovata seed is the most important plantago product.
• Solutions of the purified gum are thixotropic; viscosity decreases as shear rate increases which is of potential value.
• Contain 10 to 30% hydrocolloid, located in the outerside seed coat.

Components of Plantago seed

• Hydrocolloid material can be separated into acidic and neutral polysaccharide fractions. Upon hydrolysis, L- arabinose, D-galactose, D- galacturonic acid, L- rhamnose, and D- xylose are obtained.

Cydonium or Quince Seed

• From the ripe seed of Cydonia vulgaris (Fam. Rosaceae).
• Components: cellulose suspended in a more soluble polysaccharide that yields L- arabinose plus a mixture of aldobiouronic acids.
• The hydrocolloid forms viscous solutions with thixotropic properties, and used as an ingredient in wave setting lotions.

Guar Gum or Guaran

• From the powdered endosperm of Cyamopsis tetragonolobus seed (Fam. Leguminosae), it hydrates and stabilizes in cold water.
• The hydrocolloid is a galactomannan (Guaran galactomannan): a-D-galactose + B-D-mannose
• Used as a bulk-forming laxative and thickening agent and a tablet binder/disintegrant. The food processing and paper industries are large users of this gum.
• 1.Guaran (galactomannan ): a-D-galactose + B-D-mannose

Locust Bean Gum

• Ceratonia siliqua Linne (Fam. Leguminosae).
• Slow-growing tree: approximately 15 years for initial seed production.
• Also called "carob" pulp or St. John's bread.
• It is a galactomannan and used as a thickener and a stabilizer.

Microbial Gums

• Xanthan Gum: A high-molecular-weight microbial gum, prepared by the action of Xanthomonas campestris on suitable carbohydrates which when fermented creates Exocellular gum and can be recovered by precipitation with isopropyl alcohol, and sold as sodium, potassium, or calcium salt.
• Acetic acid, mannose, and Glucuronic acid are the xanthan gum encircled components.
• Xanthan gum used for its excellent emulsifying and suspending properties + Pseudoplastic properties.
• Toothpastes and ointments use it to hold its shape and spread readily.

Plant Extracts

• Pectin: 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 around 30% pectin, an important ingredient of fruit preserves, jellies, and jams.
• A purified carbohydrate obtained from the dilute acid extract of inner rind of citrus fruits or from apple pomace- Greek origin and means curdled/congealed with an MW: ranges from 100,000 to 250,000
• The gelling power and viscosity of pectins depend on the number of galacturonic acid units in the molecule.

Components of Pectin

• The chief component is methoxylated polygalacturonic acids + Linear: 1, 4- linked D- galacturonan where Pectin yields no less than 74% of galacturonic acid.
• Found as commercial pectin, pharmaceutic pectin or Propectin.
• Commercial pectin contains sugars or organic acids.
• Pharmaceutic pectin: pure pectin with nothing added.
• Propectin: when in fruit and in insoluble form converts to soluble form by heating fruit with dilute acid.
• USES: Classified as protectant and suspending agent when in colloidal solution as it can conjugate toxins thus enhancing digestive tract functions due to given physical and chemical properties

Questions about plant and marine gums such as tragacanth, ghatti, karaya, and acacia. Covers their chemical composition and characteristics. Includes discussion of their uses in thickening, pharmaceutical formulations and as tablet binders.