[Epimerization of hydroxyl group in the lupan series of triterpenes].
Two methods of obtaining of 3 alpha-betulinic acid and related compounds from their 3 beta-epimers were studied: the reaction of bimolecular substitution and the stereoselective reduction of 3-ketoderivatives. The substitution of acyloxy by formyloxy group in 3-O-tosyllupeol or of the betulin hydroxyl by benzoyloxy group resulted only in delta 2, 3-elimination products, with none of the expected products of bimolecular substitution being found. The catalytic hydrogenation of betulonic acid over Raney nickel resulted only in reduction of the isopropenyl double bond, whereas the use of 5% Ru/C gave a 60:40 mixture of epimers of dihydrobetulinic acid. Practically the same mixture of betulinic acid epimers was obtained when reducing betulonic acid with L-Selectride. The cytotoxic activity of 3 alpha-betulinic acid increased toward melanoma Bro cells and decreased toward melanoma MS cells.
Symon
A V
AV
Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 119571 Russia.
Kaplun
A P
AP
Vlasenkova
N K
NK
Gerasimova
G K
GK
Shon
Le Bang
le B
Litvin
E F
EF
Kozlova
L M
LM
Surkova
E L
EL
Shvets
V I
VI
D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D001671:Biochemistry / Q000379:methods*; D002277:Carcinoma / Q000188:drug therapy; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D008545:Melanoma / Q000188:drug therapy; D010051:Ovarian Neoplasms / Q000188:drug therapy; D053978:Pentacyclic Triterpenes; D013237:Stereoisomerism; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D000094062:Betulinic Acid
D000970:Antineoplastic Agents; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D000094062:Betulinic Acid
Epimerizatsiia gidroksil'noĭ gruppy v triterpenakh lupanovogo riada.