Taraxastanes and Ursanes

To date, about 25 taraxastanes have been isolated, predominantly from Asteraeeae Representatives inelude (+)-20-Taraxasten-3p-ol (v /-taraxasterol) and (+)-20(30)-taraxasten-3p,16p-diol (amidenediol) from lion s tooth Taraxacum officinale and Arnica montana as well as 20-taraxasten-3p,16p-diol (faradiol) from Arnica mon-tana, Tussilago farfara, Senecio alpinus and gold-bloom Calendula officinalis (all Asteraeeae). 

More than 150 ursanes of plant origin are documented (+)-3p-Hydroxyursan-28-oic acid, for example, represents a saturated triterpene found in the leaves of oleander Nerium oleander (Apocynaceae). (-l-)-3p-Hydroxy-12-ursen-28-oic acid is the most prominent derivative this was first isolated from the leaves and berries of bearberry Arctostaphylos uva-ursi, and therefore is commonly known as ursolic acid. It is also found in Rhododendron species, in cranberries Vaccinum macrocar-pon (Ericaceae), and in the protective wax coating of apples, pears, prunes, and other fruits. Ursolic acid is reported to have antileukemic and cytotoxic activities it is also used as an emulsifier in pharmaceuticals and foods, and is similar to (-1-)-3p,19a-dihydroxy-12-ursen-28-oic acid (known as pomolic acid) extracted from the wax coats of apples. 

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