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Glycosides.
Cyanoglycosides, heart glycosides, anthraquinone glycosides, hydroquinone glycosides ...
Let's get this straight first: Glycosides are not glucosides.
But, of course, glucosides are glycosides.
Glycosides are constituents bound to a sugar, and in a glucoside the sugar is glucose. In a fructoside the sugar is fructose, in a galactoside the sugar is galactose (dunno how you'd get milk sugar into a plant, though), and so on.
Because of that sugar glycosides usually start working in the gut, after the sugar has been stripped away.
Glycosides are water- and alcohol-soluble.
The cyanoglycosides are found in most if not all rose family plants. You get cyanide from cyanoglycosides; they'll stop you breathing if you ingest large enough amounts of them.
You'll find heart glycosides in foxglove (Digitalis spp.) and a lot of other plants which act on the heart. The glycosides digitoxin, digitalein, digitonin, digitalin and so on are cumulative and toxic; they work in doses rather too close to the deadly dose, and they will kill people who regularly take them -- if these folks suddenly get much weaker. The thing is, though, that without these toxic glycosides, the same folks would have died years earlier.
Foxglove with its toxic glycosides is trotted out every time doctors want to discourage the use of herbs: "Digitalis is a herb, too, and it's deadly!". Problem is, herbalists don't use foxglove. Doctors do ... and prescribe it rather a lot, to those with heart trouble.
The various anthraquinone glycosides are contact laxatives. You'll find them in senna, rhubarb root, and in the barks of Frangula and Rhamnus species. A lot of these glycosides are rapidly addictive: use them to kick your colon into gear regularly for two weeks or more, and your colon won't be able to get into gear at all anymore without them.
Which is why bulk laxatives are a better idea: they don't kick, they tone.
I know of just one hydroquinone glycoside, and that's arbutin, which is found in the leaf of uva ursi (Arctostaphylos spp.) and various Vaccinium species. Because of the arbutin, these leaves work for some urinary tract (and prostata) inflammations. Also because of the arbutin, you'll get gut upset if you drink your uva ursi leaf tea for too long. 10 days is the usual maximum - but it's better to check if symptoms have subsided at all after three days on the tea, and, if they haven't, to take something else instead.
Saponins, coming up. Any I've missed?
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Other entries: Rose family astringents - Constituents
Comments
Katja asked, "how toxic is
Katja asked, "how toxic is rose water?".
You'll find cyanoglycosides in the seeds of roses. Some people like the taste of bitter almonds; I don't. You'll find that taste in apple seeds, plum seeds, cherry seeds, peach seeds etc., and it's all the taste of cyanoglycosides. Toxic, sure, if you eat enough; apples, plums, cherries and peaches are still food. And rose water is completely and utterly nontoxic.
ah, great! well, while that
ah, great!
well, while that doesn't bode well for all those apple seeds i ate as a kid, i am fortunately long and away past that habit! funny: i grew up knowing that cherry pits and peach pits were toxic, but not apple seeds. i might have extrapolated that plum pits were too, from the shape...
Poison is a matter of
Poison is a matter of quantity... things can be healthy in small and deadly in large doses. Some people indeed claim amygdalin to be healthy (especially for cancer patients) because it may act as an highly selective antioxidant. Anyway, if your liver is doing well you can eat up to 5 apricot kernels each hour without any symptoms of poisoning (I wouldn't recommend that however). Eat 50, however, and you're as dead as a dodo.