Betulin (BT)

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. Chemically, betulin is a triterpenoid of lupane structure. It has a pentacyclic ring structure, and hydroxyl groups in positions C3 and C28. Recent clinical studies have verified that red alder (Alnus rubra) contains betulin and lupeol, compounds shown to be effective against a variety of tumors. Native Americans used red alder bark to treat poison oak, insect bites, and skin irritations. Blackfeet Indians used an infusion made from the bark of red alder to treat lymphatic disorders and tuberculosis.