出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/06/22 04:33 UTC 版)
Betulin (lup-20(29)-ene-3β,28-diol) is an abundant naturally occurring triterpene. It is commonly isolated from the bark of birch trees and forms up to 30% of the dry weight of the extractive . The purpose of the compound in the bark is not known. It can be converted to betulinic acid (the alcohol group replaced by a carboxylic acid group), which is biologically more active than betulin itself.