Synthesis of conjugates of lupane triterpenoids with chromane antioxidants and <Emphasis Type="Italic">in vitro</Emphasis> study of their influence on the production of nitrogen monoxide and on the arginase activity in activated macrophages

Conjugates of lupane triterpenoids (betulin and betulonic and betulinic acids) with synthetic analogs of α-tocopherol were obtained via ester bond formation and tested in vitro. Showing low cytotoxicity, some of them suppress nitrogen monoxide production without affecting the activity of arginase, which suggests their antiinflammatory and immunomodulating properties.     

X-ray Diffraction Analysis and Electron Microscopy of the Carbon Fiber Structure

Crystallography Reports - A technique for studying the carbon-fiber structure using X-ray diffraction and electron microscopy has been developed. Average crystal-structure parameters are determined...     

Novel lupane triterpenoids containing allyl substituents in ring A: synthesis and in vitro study of antiinflammatory and cytotoxic properties

Selective methods for the synthesis of C(2)-monoallyl and C(2)-diallyl derivatives of lupane terpenoids were developed. The methods involve reactions of allyl halides with potassium enolates or potassium enoxy(triethyl)borates generated in situ from 3-oxolupanes (betulonic acid, 3-oxo betulin) under the action of KN(SiMe₃)₂, KH, or Bu^tOK with subsequent addition of Et₃B. The use of the reagent KN(SiMe₃)₂-Et3B in 1,2-dimethoxyethane ensured the kinetically controlled generation of enolate anions, which yielded 2??-propenyl lupane terpenoids with high stereoselectivity. Reactions of 3-oxolupanes with excesses of Bu^tOK and allyl halide (2.5 equiv.) gave 2,2-bisallylation products. In vitro studies revealed that one of the latter efficiently suppresses the NO production by activated macrophages and has an antitumor effect on Ehrlich carcinoma and P-815 mastocytoma cell lines.