Carbohydrates - Polysaccharides Flashcards
What are Polysaccharides?
Polysaccharides are polymers of monosaccharide units bound by
glycosidic linkages.
Starch has alpha-glycosidic bonds and
cellulose has beta-glycosidic bonds. Beta are not digestible by humans, so we can digest starch but not cellulose.
**Beta-glucans polymers (beta linkage):
have some immomodulating properties
(immunomodulating polysaccharides). **They are found in grains such as oats, but mostly in mushrooms; shiitake, Reishi
What are heteropolysaccharides (or heteroglycans)?
Heteropolysaccharides (or heteroglycans) are as follows:
* hetero: they have more than one kind of
monosaccharide monomers
* include gums, pectins or mucilages
* included in immunomodulating polysaccharides if it has immunomodulating activity.
What are gums?
Gums are:
* Branched heteropolysaccharides, highly
polar, and soak up water like a sponge.
* Released by the plant in response to injury.
* Gums and soluble dietary fibre can lower
serum cholesterol and LDL, and reduce the risk of coronary artery disease and diabetes.
* Also a laxative and reduce risk of colon cancer.
* An example is acacia gum (Acacia arabica): this is a demulcent, soothes mucous membranes, skin healing, antitussive. Gel reduces gingivitis and plaque.
What are pectins?
“Pectins
* Heteropolysaccharides usually found in plant cell walls. They bind to other molecules or ions, including iron (so can enhance iron absorption)
* Digestion: they are prebiotic, and adheres to mucous membranes, so can support dogestion and protect the gut lining as a physical barrier
* Delays gastric emptying
* Apple pectin has a bacteriostatic action
* Can also reduce serum glucose and cholesterol
* Some have immunomodulating effects, antitumour in vivo and in vitro.
What are Immunomodulating polysaccharides?
Immunomodulating polysaccharides
* Immunomodulating is a functional rather than a phytochemical classification.
* Astragalus membranaceus, Panax ginseng, Echinacea, and the medicinal mushrooms all contain them.
* However they are insoluble in ethanolic tinctures of 50% or more.
* Large water-soluble molecules, polysaccharides have low bioavailability.
* Whether herb or mushroom, high doses of water extract are needed in order for any to reach the body. Most clinical trials have been in vitro or in vivo (injections).
What polysaccharides do we get from mushrooms?
Polysaccharides from mushrooms
* Are beta linked, so not broken down by
our digestive enzymes
* **Affect immuno-active tissue (GALT or
tonsils) **
* Colon microflora metabolise many of
the polysaccharides.
* There are surface receptors on immune cells specific for fungal polysaccharides which increase cytotoxic immune response - perhaps this is because we have developed to react to some mushrooms?
What do Shitake and Turkey Tail contain?
Shiitake and Turkey Tail
* PSK (Polysaccharide Kurcha) is an isolate from turkey tail (Coriolus versicolor). Approved as an adjunctive cancer treatment in Japan
** Shiitake mushroom benefits patients with prostate cancer**
What do Reishi mushrooms contain?
Reishi mushrooms
* Ganoderma lucidum (reishi); prostate cancer (clinical evidence).
* Tested in multiple cancer models.
* Effective against androgendependent and independent prostate cancer cells
What does Astragalus contain?
“Astragalus (in vivo, in vitro, clinical trials)
* Polysaccharides and saponins
* Improves immune responses
* mononuclear cell phagocytosis
* responses of lymphocytes*
* natural killer cell activity*
* interleukin-2 production*
* Increased serum IgM, IgE, immunoglobulin,
cAMP, enhances induction of interferon
* More IgA and IgG in nasal secretions
Protects against immuno-suppression
induced by anti-tumour agents”*
What does Aloe Vera contain?
Aloe vera
* Polysaccharides: acemannan - found in leaf skin.
* Osteogenic (stimulates bone
tissue formation), antiinflammatory, healing.
* Antiviral and antibacterial.
What polysaccharides exist in adaptogenic herbs?
Polysaccharides in adaptogenic herbs
* antioxidant
* immunomodulatory
* anti-inflammatory
Though there are other
constituents, too…
Other plants with immune-enhancing
polysaccharides. Various heteropolysaccharides (arabinogalactans):
* Plantago
* Calendula
* Echinacea
* Baptisia
BUT to access needs to be bioavailable, so not in high alcohol tinctures, but powders or water infusions.
