E. F. Khusnutdinova

Synthesis and cytotoxicity of allobetulin derivatives

A variety of oxygen-, nitrogen-, sulfur-, and platinum-containing allobetulin derivatives, including those with different positions of double bonds in rings A and B, the penta- and hexacyclic ring A, and the 21-acetyl-20,28-epoxy-18α,19βH-ursanoisomeric cycle E, have been synthesized, and the screening of their antineoplastic activity in vitro (cytotoxicity) has been carried out. A significant cytotoxic activity was exhibited by (3R,5R)-19β,28-epoxy-4,5-seco-18α-olean-3(5)-ozonide toward MeWo melanoma cells and by 2,3-indolo-21β-acetyl-20β,28-epoxy-18α,19βH-ursane toward SR leukosis cells. The 3S,5S-diastereoisomer of the former compound showed no cytotoxicity.

Oxidation of ursolic acid by ozone

Oxidation of methyl esters of ursolic and 3-acetoxyursolic acids by ozone formed products with a 12-oxo11S,13R-oxetane moiety on ring C.

EFFECTIVE SYNTHESIS OF 2,3-seco-2,3-DICARBOXYPLATANIC ACID

An effective method for preparing triterpene 2,3-seco-2,3-diacids by ozonolysis of 2-exomethylene-substituted derivatives of betulonic acid and 28-oxoallobetulone was proposed.

Synthesis of new olean-18(19)-ene derivatives from allobetulin

New olean-18(19)-ene triterpenoids were effectively synthesized by the interaction of allobetulin or its acetate with phosphorous oxychloride in refluxing pyridine. The structures of the synthesized 17-chloromethyloleane-18(19)-enes were confirmed by NMR spectroscopy and X-ray analysis.

Molecular structure of 1,2,6,6,10,16,17-heptamethyl-20-(acetoxymethyl)pentacyclo [12.8.0.02.11.05.10.015.20]docos-17-en-7-yl acetate

The molecular structure of 3β,28-diacetoxy-18αH,19βH-ursan-20-en is determined. Compound C34H54O4 II crystallizes in the P212121 chiral space group: a = 8.2721(6) Å, b = 11.2728(8) Å, c = 32.559(2) Å.

Synthesis and evaluation of 2,3-indolotriterpenoids as new α-glucosidase inhibitors

A series of ring-A fused heterocycles of lupane, oleanane, ursane and dammarane triterpenoids were synthesized and evaluated for their inhibitory activity against α-glucosidase. An influence of the different types of triterpenoids with indole and pyrazine cycles on the activity was revealed. Among them, 2,3-indolo-lup-20(29)-en-28-oic acid with an IC50 of 1.8 µM was the most active compound being 221-fold more active than the market drug acarbose. In the most cases, the replacement of the indole by the pyrazine fragment provided the decreasing of activity (except dammarane type pyrazine derivative).Graphical Abstract

Synthesis and molecular structure of 1α,10α: 9β,1β: 19β,28-triepoxy-A-neo-5β-methyl-25-nor-18α-oleane

Ozonolysis of 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-ene gave 23% of 1α,10α: 9β,11β: 19β,28-triepoxy-A-neo-5β-methyl-25-nor-18α-oleane whose structure was determined by X-ray analysis.

Synthesis of new cyanoethyl derivatives from 3-oxotriterpenoids

Reaction of 3-oxotriterpenoids and steroids with acrylonitrile in the presence of BnEt3NCl and 30% KOH in dioxane proceeds with the formation of 2,2-biscyanoethyl derivatives substituted in the α-position to 3-oxo group. In the presence of several α-hydrogen atoms at the 3-oxo group the reaction of cyanoethylation involved the positions C4 and C5, leading to 2,2,5-tricyanoethyl and 2,4-dicyanoethyl derivatives. The cyanoethylation of tetracyclic compounds occurred with the formation of monocyanoethyl derivatives with an overall increase in the yield.

Stereospecific epoxidation of an olean-18(19)-ene-type triterpenoid

An effective method for stereospecific epoxidation of olean-18(19)-ene-type triterpenoids with ozone is proposed using 3S-acetoxy-17-chloromethylolean-18(19)-ene as an example.

Allylic oxidation of 19β,28-epoxy-a-neo-5β-methyl-25-nor-18α-olean-9-ene

Allylic oxidation of 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-ene by ozone produced 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-en-1-one.