Glycosides Flashcards
What molecular features define the phytochemical class of glycosides?
Characterised by a sugar moiety (portion) attached by a particular bond to a non-sugar portion (aglycone)
Pharmacokinetics of glycosides
Inert until hydrolysed in large intestine by bacteria, which yield the aglycone
Class of phytochemical known for stimulating laxative action Any similar sounding class also laxative?
Anthraquinone glycoside
Anthraquinone aglycone, no laxative action
Herbs commonly used in WHM known to have phototoxic potential
Hypericum perforatum
Angelica archangelica
Arnica montana
Apium graveolens
Most common mechanism of action of Hypericum perforatum, and constituent responsible for herb-drug interactions
Hyperforin demonstrates neuro chemical modulation,
Also induces P-gp and CYP3A4 pathways, which is responsible for numerous herb-drug interactions by inhibiting their absorption
What part of the plant can glycosides be found in
Roots, shoots, flowers, leaves, seeds
Cautions and contraindications of Hypericum perforatum
Serious depression, patients with psychotic episodes or suicide ideation
Pregnancy and lactation
Drugs - warfarin, digoxin, cyclosporine, theophylline, aniretroviral, reverse transcriptase inhibitors, anticonvulsants, antineoplastics.
Subclasses of cardiac glycosides
Cardenolide - 4 carbons in lactone ring
Bufadienolide - 5 carbons in lactone ring
What plant family would you find glucosinolates and isothiocyanates
Brassicaceae
Cautions and contraindications for use of isothiocyanates
Hypothyroidism; may depress thyroid function
Pharmacokinetics of cyanogenic glycosides and any toxicity concerns
Release cyanide upon metabolism
Detoxified by enzyme rhodanese in liver
Excreted rapidly through lungs and kidneys as thiocyanates
>3.5mg/kg needed for toxic effects
Toxicity symptoms include inactivation of respiratory enzymes, causing dizziness and high facial colour
Plants known to produce cyanogenic glycosides
Prunus serotina
Sambucus nigra
Prunus spp.
Linum usitatissimum
Bambusoideae subfamily
Subclasses of glycosides known for being bitter, herb examples
Iridoid glycosides
Physiological responses bitter substances cause, and how
Priming effect on upper GIT function due to vagal nerve reflex from bitter tastebuds which triggers release of gastric.
This leads to producing HCl and digestive enzymes in stomach and small intestine, pancreatic juices in pancreas, bile production and release in liver and gallbladder.
Chemical class of emodin, aloe-8-O-glycoside, hypericin
Emodin - anthraquinone glycoside
Aloe-8-O-glycoside - anthraquinone glycoside
Hypericin - naphthodianthrone
