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Betulin
IUPAC name	Lup-20(29)-ene-3β,28-diol
Identifiers
CAS number	473-98-3 Y
PubChem	72326
EC-number	207-475-5
SMILES	O[C@H]5CC[C@@]4([C@@H]3[C@@]([C@]2([C@@H]([C@@H]1[C@](CO)(CC[C@H]1C(=C)\C)CC2)CC3)C)(C)CC[C@H]4C5(C)C)C
InChI	1/C30H50O2/c1-19(2)20-10-15-30(18-31)17-16-28(6)21(25(20)30)8-9-23-27(5)13-12-24(32)26(3,4)22(27)11-14-29(23,28)7/h20-25,31-32H,1,8-18H2,2-7H3/t20-,21+,22-,23+,24-,25+,27-,28+,29+,30+/m0/s1
InChI key	FVWJYYTZTCVBKE-ROUWMTJPBQ
ChemSpider ID	65272
Properties
Molecular formula	C30H50O2
Molar mass	442.72 g mol−1
Melting point	256–257 °C
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 ^[1]. 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.

Chemistry

Chemically, betulin is a triterpenoid of lupane structure. It has a pentacyclic ring structure, and hydroxyl groups in positions C3 and C28.

Biological activities

Betulinic acid and its synthetic analogues exhibit anti-malarial, anti-inflamatory and anti-HIV activity as well as showing cytotoxicity towards a number of tumour cell lines. Even though betulin derivatives are most widely studied for their anticancer activity, also the anti-HIV effect is quite well characterized and it has been demonstrated that betulins can inhibit HIV entry to T cells by binding to the gp41, an HIV protein needed for the invasion of the virus into the cell.

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. ^[2]

References