RESUMO
In addition to fatty acids, a mixture of sterols (beta-sitosterol, stigmasterol, campesterol and stigmastanol), lupeol, arctigenin methylether, sesamin, vanillic acid (1), 2,6-dimethoxy-1,4-benzoquinone (2), betulinic acid and two pentacyclic triterpene acetates were isolated from Fagara tessmannii Engl. They were identified as 3beta-acetoxy-16beta-hydroxybetulinic acid (3a) and 3beta,16beta-diacetoxybetulinic acid (3b), and their structures were established using 1 and 2D NMR spectra and by comparison with published data. Two derivatives of the compounds were prepared. Some isolated compounds were evaluated for their antifungal and antibacterial activities. Compounds 1 and 3a showed significant inhibition of alpha-glucosidase.
Assuntos
Inibidores Enzimáticos/isolamento & purificação , Caules de Planta/química , Rutaceae/química , Triterpenos/isolamento & purificação , alfa-Glucosidases/isolamento & purificação , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Fitosteróis/química , Fitosteróis/isolamento & purificação , Triterpenos/química , Triterpenos/farmacologiaRESUMO
The butenolide ring is the main common characteristic of all cardenolides. Its formation is supposed to be initiated by the transfer of a malonyl moiety from malonyl-coenzyme A to an appropriate 21-hydroxypregnane. A new, reliable, fast and sensitive method to determine malonyl-coenzyme A: 21-hydroxypregnane 21-O-malonyltransferase activity had to be developed since previous attempts employing HPLC, TLC or GC did not prove successful. A surrogate substrate was synthesized containing a side chain resembling the sugar side chain attached to C-3 of putative cardenolide precursors and containing a chromophor allowing UV detection. 3beta-benzoyloxy-5beta-pregnane-14beta,21-dihydroxy-20-one and its 21-O-malonylated derivative were synthesized, the latter being the expected product of the enzyme reaction. The new substrate was well accepted by the enzyme. An HPLC method has been established to detect and quantify 3beta-benzoyloxy-5beta-pregnane-14beta,21-dihydroxy-20-one and its 21-O-malonylated derivative, 3beta-benzoyloxy-5beta-pregnane-14beta-hydroxy-20-one 21-O-malonylhemiester. The method was validated.
Assuntos
Aciltransferases/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Gasosa , Cromatografia em Camada Fina , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta , Especificidade por SubstratoRESUMO
In addition to lupeol (1a), three long-chain alkanoic acid esters of lupeol, in which two were new, were isolated from the hexane and ethyl acetate twigs extract of Dorstenia harmsiana Engl. (Moraceae). The structures of the new compounds were elucidated on the basis of 1D and 2D NMR experiments. Some isolated compounds were evaluated for their antimicrobial activities. The lupeol and its three long-chain alkanoic acid esters showed antifungal and antibacterial activities.