- Carbon-13 Resonance Assignments of some Friedelanes and Taraxasteranes
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Carbon-13 signal assignments of taraxasteryl acetate, taraxasteryl palmitate, taraxasterol and epi-friedenyl acetate are reported.Some signal assignments of the friedelanones, reported recently by others, are inconsistent and require revision.
- Patra, Amarendra,Mukhopadhyay, Apurba K.,Mitra, Alok K.
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- Antispasmodic and spasmogenic effects of Scolymus hispanicus and taraxasteryl acetate on isolated ileum preparations
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Taraxasteryl acetate (1) was identified as the major triterpenoid of the ethanolic extract of the root bark of Scolymus hispanicus L. Antispasmodic and spasmogenic effects of the ethanolic extract, its fractions, taraxasteryl acetate, and a fluid extract of this plant were tested on isolated rat ileum preparations. The strong biphasic responses observed suggested a possible lithuretic activity of the compounds and the fractions tested.
- Kirimer, Nes'E,Tunalier, Zeynep,Baser, K. Huesnue Can,Cingi, Ipek
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- Terpenoids in four Inula species from Bulgaria
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Phytochemical study of the chloroform extract of the aerial parts of Inula germanica L., I. ensifolia L., I. conyza (Griess.) DC. and I. salicina L. led to the identification of 33 terpenoids. β- and α-amyrin, lupeol, taraxasterol, ψ-taraxasterol and their 3-O-acetates and 3-O-palmitates were identified by GC/MS. In addition, the structures of 3-O-palmitates of mainaladiol, arnidiol, faradiol and 16-hydroxylupeol were confirmed by NMR. ent-Kaur-16-en-19- -oic acid and its 15α-(3-methylpentanoyloxy) and 15α-(3-methylbutanoyloxy) derivatives were isolated from I. conyza. Ten closely related sesquiterpene lactones (germacranolides and melampolides) were found in I. germanica and their structural identification was performed by spectral analyses. I. ensifolia and I. salicina were free of sesquiterpene lactones and diterpenoids. All triterpenoids and diterpenoids, grazielia acid, desacetylovatifolin and 8-(2-methylbutanoyloxy)- 1(10),4,11(13)-germacrutrien-6,12-olide-14-oic acid are described for the first time in the studied species. The principal component analysis was used to find a relationship between the investigated up to now Inula species, growing in Bulgaria.
- Aneva, Ina,Ivanova, Victoria,Staleva, Plamena,Todorova, Milka,Trendafilova, Antoaneta
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p. 1229 - 1240
(2022/02/16)
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- A short enantioselective total synthesis of the fundamental pentacyclic triterpene lupeol
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(Chemical Equation Presented) The first enantioselective synthesis of lupeol has been developed by applying two carefully crafted cation-π cyclization stages to generate the pentacyclic structure with complete stereocontrol. The synthesis (Scheme 1) is no
- Surendra, Karavadhi,Corey
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supporting information; experimental part
p. 13928 - 13929
(2009/12/25)
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- Arabidopsis thaliana LUP1 converts oxidosqualene to multiple triterpene alcohols and a triterpene diol
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lupeol lupeol, germanicol, synthase β-amyrin, taxasterol, oxidosqualene → ψ-taraxasterol, and 3,20-dihydroxylupane The Arabidopsis thaliana LUP1 gene encodes an enzyme that converts oxidosqualene to pentacyclic triterpenes. Lupeol and β-amyrin were previously reported as LUP1 products. Further investigation described here uncovered the additional products germanicol, taraxasterol, ψ-taraxasterol, and 3,20-dihydroxylupane. These results suggest that the 80 known C30H50O compounds that are structurally consistent with being oxidosqualene cyclase products may be derived from fewer than 80 enzymes and that some C30H52O2 compounds may be direct cyclization products of oxidosqualene.
- Segura, Michael J. R.,Meyer, Michelle M.,Matsuda, Seiichi P. T.
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p. 2257 - 2259
(2007/10/03)
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- Preventive effect of taraxasteryl acetate from Inula britannica subsp. japonica on experimental hepatitis in vivo
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The survival rate for acute hepatic failure induced by Propionibacterium acnes and lipopolysaccharide (LPS) was increased when a hot water extract from the flowers of Inula britannica h. subsp. japonica Kitam. was injected into the experimental hepatitis mice, and anti-hepatitis substances could be extracted with CHCl3. The CHCl3 extract from I. britannica was fractionated and anti-hepatitis fractions IB-3-2 and IB3-3 were obtained. IB-3-3 had the most potent antihepatitis activity among the fractions but further purification of the active compound was not achieved because of the low yield. IB-3-2 contained only one substance which was identified to be taraxasteryl acetate by 1H- and 13C-NMR and MS. Taraxasteryl acetate showed potent preventive activity against acute hepatic failure induced by P. acnes and LPS in a dose-dependent manner, however deacetylation and modification of the olefinic bonds significantly decreased the anti-hepatitis activity of taraxasteryl acetate. Taraxasteryl acetate also inhibited the increment of plasma transaminase on acute hepatic failure induced by carbon tetrachloride (CCl4) or D-galactosamine. From a histological study it appeared that degeneration and necrosis, which were observed in the liver from CCl4 mice, were not found in the liver cells from taraxasteryl acetate treated mice. These results indicates that taraxasteryl acetate shows preventive effects on experimental hepatitis caused by either immunologically induced injuries or hepatotoxic chemicals.
- Iijima,Kiyohara,Tanaka,Matsumoto,Cyong,Yamada
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- Steric Effects on Oxymercuration: Oxymercuration-Demercuration of Taraxasteryl, Pseudo-Taraxasteryl, and 19-Epi-Taraxasteryl Acetates
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Contrary to usual expectation, taraxasteryl acetate (1b) and pseudo-taraxasteryl acetate (2b) were found to be totally intensive to normal oxymercuration.This has been rationalised as being due to the steric effects of the 19-and 17 methyl groups on the formation of intermediate mercurium ions, and on the nucleophile attacking these species.Conformational analysis of 1b shows that its ring E is not a normal chair, but assumes a twisted conformation due to severe nonbonded interaction between the 12-methylene and the 19-methyl group.Both 1b and 2b, however, underwent oxymercuration-demercuration with allylic rearrangement to give the same compound 2c, when heated with Hg(OAC)2 in glacial HOAc.A partial synthesis of 19-epi-taraxasteryl acetate (1d) has been achieved by Wittig reaction on the 19-epi-norketone (4b) formed by base-catalysed epimerization of 4a which in turn was derived from 1b.The steric effects providing the driving force for this unconventional epimerisation of 4a to 4b have been explained and supported by comparative 13C nmr spectral analysis of 4a and 4b.Unlike 1b and 2b, 19-epi-taraxasteryl acetate (1d) undervent normal oxymercuration.The stereochemical aspect of this reaction has been discussed.
- Majumder, P. L.,Laha, S.
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p. 548 - 554
(2007/10/02)
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