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C60H60O22(?) , which hydrolyses to rhamnose and hesperetin, C16H14O6, the phloroglucin ester of meta-oxy-para-methoxycinnamic acid or isoferulic acid, C,oHioO4. We may here include various coumarin and benzo-y-pyrone derivatives. Aesculin, C16H16O9, occurring in horse -chestnut , and daphnin, occurring in Daphne alpine, are isomeric; the former hydrolyses to glucose and aesculetin (4.5-dioxycoumarin), the latter to glucose and daphnetin (3.4-dioxycoumarin). Fraxin, C,EH,80,o, occurring in Fraxinus excelsior, and with aesculin in horse -chestnut , hydrolyses to glucose and fraxetin, the mono-methyl ester of a trioxycoumarin. Flavone or benzo-7-pyrone derivatives are very numerous; in many cases they (or the non-sugar part of the molecule) are vegetable dyestuffs. Quercitrin, C21H22O12, is a yellow dyestuff found in Quercus tinctoria; it hydrolyses to rhamnose and quercetin, a dioxy-/3-phenyl-trioxybenzoy-pyrone. Rhamnetin, a splitting product of the glucosides of Rhamnus, is monomethyl quercetin; fisetin, from Rhus cotinus, is monoxyquercetin; chrysin is phenyl-dioxybenzo-y-pyrone. Saponarin, a glucoside found.in Saponaria officinalis, is a related compound. Strophanthin is the name given to three different compounds, two obtained from Strophanthus Kombe and one from S. hispidus.
4. Anthracene Derivatives.These are generally substituted anthraquinones; many have medicinal applications, being used as purgatives, while one, ruberythric acid, yields the valuable dye-stuff madder , the base of which is alizarin (q.v.). Chrysophanic acid, a dioxymethylanthraquinone, occurs in rhubarb, which also contains emodin, a trioxymethylanthraquinone; this substance occurs in combination with rhamnose in frangula bark.
The most important cyanogenetic glucoside is amygdalin, which occurs in bitter almonds. The enzyme maltase decomposes it into glucose and mandelic nitrile glucoside; the latter is broken down by emulsin into glucose, benzaldehyde and prussic acid. Emulsin also decomposes amygdalin directly into these compounds without the intermediate formation of mandelic nitrile glucoside. Several other glucosides of this nature have been isolated. The saponins are a group of substances characterized by forming a lather with water; they occur in soap-bark (q.v.). Mention may also be made of indican, the glucoside of the indigo plant; this is hydrolysed by the indigo ferment, indimulsin, to indoxyl and indiglucin.
End of Article: C60H60O22(?)
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