The synthesis and hepatoprotective activity of esters of the lupane group triterpenoids

Флехтер, О. Б.; Karachurina, L. T.; Poroikov, Vladimir; Nigmatullina, L. P.; Балтина, Л. А.; Zarudii, F. S.; Davydova, V. A.; Спирихин, Л. В.; Байкова, И. П.; Галин, Ф. З.; Толстиков, Г. А.

doi:10.1007/bf02786345

Cited by 34 publications

(17 citation statements)

References 12 publications

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“…In continuation of our studies on the synthesis of new triterpene derivatives with valuable pharmacological activity [1][2][3][4][5], we synthesized betulin 29-norlup-20-ketones and their hydroxyimino derivatives and studied the antiviral and immunotropic activties of several compounds.…”

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Synthesis and Pharmacological Activity of 20-Keto-29-norlupane Derivatives

et al. 2005

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“…Ozonation of 3β,28-di-O-acetylbetulin (1) and its 30-bromo derivative (2) produced the corresponding 20-ketones 3 and 4 in yields of 73 and 65%, respectively. The structures of the compounds were established using NMR spectroscopy.…”

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Synthesis and Pharmacological Activity of 20-Keto-29-norlupane Derivatives

et al. 2005

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“…The crude product was a yellowish powder with mp 230-257°C. It was recrystallized twice from ethanol to obtain a loose white powder with mp 251-252°C; published data [5]: mp 256-258°C. According to the 1 H NMR data, the product contained ≥95% of the main substance.…”

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Betulin 3,28-Bis-O-trifluoroacetate: Synthesis and Molecular Structure

et al. 2010

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The reaction of betulin with excess trifluoroacetic anhydride gave the corresponding 3,28-bis-Otrifluoroacetate whose molecular structure as a slightly bent "stairway" was determined by X-ray analysis.Betulin (I) is a lupane triterpenoid possessing high biological activity (antiphlogistic, choleretic, antiviral, antitumor, immune modulating, etc.) [1]. The main natural source of betulin is birch bark, where its concentration ranges from 10 to 35%. The ease of isolation and purification of betulin determines sharply increased interest in the synthesis of various its derivatives. Esterification of betulin whose molecule possesses two hydroxy groups gave a number of O-acyl derivatives, some of which were found to be promising as anti-HIV agents [1].In the present work we synthesized betulin 3,28-bis-O-trifluoroacetate (II), taking into account that perfluorocarboxylic acid esters are known to exhibit stronger and more diverse biological activity than their fluorine-free analogs. Compound II was obtained in 89% yield by reaction of betulin with excess trifluoroacetic anhydride (1 : 16) in carbon tetrachloride at 0 to 10°C (Scheme 1). Bis-trifluoroacetate II was isolated previously [2] as a mixture with 28-O-trifluoroacetate in the oxidation of betulin with dimethyl sulfoxide activated by trifluoroacetic anhydride.Diester II is an almost colorless crystalline substance, which is readily soluble in chloroform, methylene chloride, and acetone, poorly soluble in ethyl acetate, and even more poorly soluble in alcohol. The structure of compound II was confirmed by the IR and 1 H and 19 F NMR spectra and X-ray analysis. The IR spectrum of II lacked absorption at about 3446 cm -1 , which is typical of initial diol I, but contained a strong ester carbonyl absorption band (1792 cm -1 ); also, absorption bands due to stretching vibrations of C=C (1640 cm -1 ) and C-F bonds (1220 cm -1 ) were observed. Compound II displayed in the 19 F NMR spectrum two signals with equal intensities at δ F -76.08 and -76.49 ppm, which confirmed the presence of two trifluoroacetoxy groups on C 3 and C 28 . In the 1 H NMR spectrum of II protons in the CH 2 O group resonated as

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“…The structures of the esters were elucidated using IR and NMR spectra and comparison of them with those of analogous compounds [5,9,10]. 13 C NMR spectra of synthesized 2-8 exhibited resonances for the betulin part of the molecule and the corresponding number of C resonances for the acyl components (Table 1).…”

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“…Esters 2-8 were prepared by reaction of 1 with the acid chlorides in Py (1:1.2 mole ratio) in the presence of dimethylaminopyridine (1.2 equivalents). The 28-O-monosubstituted betulin derivatives were isolated in 56-69% yields.The structures of the esters were elucidated using IR and NMR spectra and comparison of them with those of analogous compounds [5,9,10]. 13 C NMR spectra of synthesized 2-8 exhibited resonances for the betulin part of the molecule and the corresponding number of C resonances for the acyl components (Table 1).…”

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Synthesis and antibacterial activity of betulin esters

2011

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547.597+547.918Betulin isonicotinate, 6-chloronicotinate, 2-chlorocinnamate, and benzoates were synthesized by the reaction of betulin and the acid chlorides. It was shown that the 3,4-difluorobenzoate exhibited antibacterial activity against Ochrobactrum anthropi, Stenotrophomonas maltophilia, and S. nitritireducens whereas the 3,5-dinitrobenzoate was active against the last two microorganisms.The outer part of the bark of several white birch species is a rich source of pentacyclic lupane triterpenoids [1]. The most famous of these is betulin [2]. The high content, simple isolation methods, and presence of reactive functional groups make it an available and convenient starting material for synthesizing new biologically active compounds [3][4][5]. Compounds with anti-inflammatory, antioxidant, antibacterial, hepatoprotective, antiviral, antitumor, and immunostimulant properties were found among synthesized betulin derivatives [6,7]. The increasing number of publications in this area indicates that active research is continuing.Herein we present results from the synthesis of betulin esters and data on their antibacterial activity. Betulin (1) was obtained by extraction of birch (Betula platyphylla) bark collected in Chungbuk Province (South Korea). The structure of 1 was confirmed by comparison of its PMR and 13 C NMR spectra with those published [8]. Esters 2-8 were prepared by reaction of 1 with the acid chlorides in Py (1:1.2 mole ratio) in the presence of dimethylaminopyridine (1.2 equivalents). The 28-O-monosubstituted betulin derivatives were isolated in 56-69% yields.The structures of the esters were elucidated using IR and NMR spectra and comparison of them with those of analogous compounds [5,9,10]. 13 C NMR spectra of synthesized 2-8 exhibited resonances for the betulin part of the molecule and the corresponding number of C resonances for the acyl components (Table 1). A weak-field shift of the C-28 resonances and the appearance of resonances at 163.1-167.9 ppm indicated that the ester bonds had formed. This was also confirmed by the appearance of absorption bands at ~1700 cm -1 in the IR spectra of these compounds.Synthesized 2-8 were checked for antibacterial activity that was assessed using the diameter of the colony growth inhibition zone around paper disks with the applied compound (values are given below after the name of the bacteria). Betulin 3,4-difluorobenzoate (8) exhibited activity against Ochrobactrum anthropi (12 mm), Stenotrophomonas nitritireducens (13 mm), and S. maltophilia (11 mm) whereas the 3,5-dinitrobenzoate (5) inhibited growth of the last two test cultures (11 and 10 mm, respectively).

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The synthesis and hepatoprotective activity of esters of the lupane group triterpenoids

Cited by 34 publications

References 12 publications

Synthesis and Pharmacological Activity of 20-Keto-29-norlupane Derivatives

Synthesis and Pharmacological Activity of 20-Keto-29-norlupane Derivatives

Betulin 3,28-Bis-O-trifluoroacetate: Synthesis and Molecular Structure

Synthesis and antibacterial activity of betulin esters

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