Slide 1 : Diosgenin from clover, Meliotus
Cardiac glycosides : Cardiac glycosides They are distinguished from other steroid glycosides by the presence of a lactone ring.
In over 200 species representing 55 genera and 12 families.
Perhaps the best known is "digitalis," a mixture of cardenolides extracted from the seeds, leaves, and roots of purple foxglove, Digitalis purpurea.
The two principal cardenolides in digitalis are digitoxin and its close analog digoxin
Digitalis purpurea = foxglove : Digitalis purpurea = foxglove The extreme toxicity of cardenolides has long been exploited by African hunters, who coated their arrows and spears with cardenolide-rich extracts from plants without ill effect.
Slide 4 : Increase strength of heart contractions
Balance the heartbeat rate
Remedy of coronary insufficiency
Cyanogenic glycosides : Cyanogenic glycosides Appear to be derived from four amino acids phenylalanine, tyrosine, valine and isoleucine) or from nicotinic acid.
Cyanogenic glycosides are not themselves toxic, but when the plant is damaged by an herbivore, the glycoside undergoes an enzymatic breakdown and cyanide is released.
Cassava from Manihot esculenta is rich in such compounds.
Slide 7 : Deterrent to Herbivores
GLUCOSINOLATES : GLUCOSINOLATES Primarily in the mustard family, Brassicaceae
Gives the pungent taste to condiments
It is due to myrosin compound and myrosinase enzyme.
Also good as insect fumigants.
Slide 9 : Phytoalexins
PHENOLICS = Flavonoid compounds : PHENOLICS = Flavonoid compounds The family of secondary metabolites derived from the aromatic amino acids are known generally as phenolics, polyphenols.
Examples:
Tannins and lignin
Pisatin is a pea phytoalexin: inhibits fungal infections.
Slide 11 : Warfarin
COUMARINS : COUMARINS Widespread group of lactones
Gives new-mown hay its characteristic pleasantly sweet odor
While coumarin itself is not toxic, it can be converted by fungi to a toxic product, dicoumarol, that is typically found in moldy hay.
Slide 13 : The discovery of dicoumarol in the 1940s led to the development of a coumarin derivative, warfarin, as a rat poison.