- Auxiliary-directed oxidation of ursolic acid by 'Ru'-porphyrins: Chemical modulation of cytotoxicity against tumor cell lines
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Derivatization of ursolic acid, one of the natural ursene-type pentacyclic triterpenes, was investigated by the oxidation with dioxoruthenium(VI) tetraphenylporphyrins. Oxidation selectivity on the terpene structure was modulated by the auxiliaries introd
- Tanaka, Katsunori,Mazumder, Kishor,Siwu, Eric R.O.,Nozaki, Satoshi,Watanabe, Yasuyoshi,Fukase, Koichi
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supporting information; experimental part
p. 1756 - 1759
(2012/05/04)
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- Biotransformation of ursolic acid by an endophytic fungus from medicinal plant Huperzia serrata
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Endophytic fungi were used not only for their producing bioactive products but also for their ability to transform natural compounds. An endophytic fungus, isolated from medicinal plant Huperzia serrata, was identified as Umbelopsis isabellina based on the internal transcribed spacer of ribosomal DNA (rDNA-ITS) region. It was used to transform ursolic acid (1), a pentacyclic triterpene. Incubation of ursolic acid with U. isabellina afforded three products, 3β-hydroxy-urs-11-en-28,13-lactone (2), 3β,7β-dihydroxy-urs-11- en-28,13-lactone (3), 1β,3β-dihydroxy-urs-11-en-28,13-lactone (4). Although product 2 was a known compound, it was first obtained by microbial transformation. Products 3 and 4 were new compounds. The structural elucidation of the three compounds was achieved mainly by the 1D- and 2D-NMR, MS, IR data. The endophytic fungus U. isabellina can hydroxyate the C12-C13 double bond at position 13 of ursolic acid 1 and form a five-member lactone effectively. In the meantime, this fungus can also introduce the hydroxyl group at C-1 or C-7 of ursolic acid 1.
- Fu, Shao-Bin,Yang, Jun-Shan,Cui, Jin-Long,Feng, Xu,Sun, Di-An
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experimental part
p. 1180 - 1182
(2011/10/11)
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- A new triterpenic acid from Eucalyptus robusta
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A new triterpene "Robustanic acid" I has been isolated from the leaves of Eucalyptus robusta along with, ursolic acid lactone 2, sideroxylin 5, 2α 3β-dihydroxy-urs- 12-ene-28-oic acid 6. ursolic acid 7, β-sitosterol-β-D-glucoside 8 and gallic acid 9. On the other hand, stem results in the isolation and characterization of β-sitosterol 10 and an isomeric mixture of oleanolic acid 11 and ursolic acid 7. The structure of new triterpenic acid has been deduced as 3β-hydroxy, 11α-methoxy-urs-12-ene-28-oic acid on the basis of spectroscopic data and chemical correlation with compounds of established structure. Presence of compounds 6, 7, 8, 9 and 11 in E. robusta is being reported for the first time.
- Khare, Monika,Srivastava,Singh
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p. 440 - 445
(2007/10/03)
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