Circular dichroism of sesquiterpene lactones

Waddell, Thomas G.; Stöcklin, W.; Geissman, T. A.

doi:10.1016/s0040-4039(01)87872-2

Cited by 35 publications

(9 citation statements)

References 21 publications

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“…The absolute configuration at C-7 was determined to be R by the negative Cotton effects at 225 and 268 nm observed in its CD spectrum. This is consistent with previous studies demonstrating that sesquiterpene lactones with a C-7, C-6 trans-fused α-methylene-γ-lactone moiety display negative Cotton effects in the range of 216–225 and 252–271 nm in their CD spectra, arising from the π→π * and n→π* transitions of the lactone ring, respectively[9]. Compound 1 was thus assigned as (5 S ,6 S ,7 R ,8 S ,10 R )-1-oxo-3,10-epoxy-5-methoxy-8-(2-methylacryloxy)germacra-2,4(15),11(13)-trien-6,12-olide[10], or 5- O -methyl-5-epiisogoyazensolide.…”

supporting

confidence: 93%

Antiproliferative and Antimalarial Sesquiterpene Lactones from Piptocoma antillana from Puerto Rico [1]

et al. 2014

Natural Product Communications

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Bioassay-directed fractionation of an antiproliferative ethanol extract of the leaves and twigs of Piptocoma antillana (Asteraceae) afforded two new goyazensolide-type sesquiterpene lactones named 5-O-methyl-5-epiisogoyazensolide (1) and 15-O-methylgoyazensolide (2), together with the known compounds 1-oxo-3,10-epoxy-8-(2-methylacryloxy)-15-acetoxygermacra-2,4,11(13)-trien-6(12)-olide (3) and 5-epiisogoyazensolide (4). The structure elucidation of all compounds was carried out based on NMR and mass spectroscopic data analyses. The relative and absolute configurations of all the isolated compounds were determined from their CD and NOESY NMR spectra. Compounds 1–4 showed moderately potent antiproliferative activities against A2780 ovarian cancer cells, with IC50 values of 1.5±0.5, 0.6±0.3, 1.62±0.05, and 1.56±0.04 µM, respectively. They also displayed antimalarial activity against Plasmodium falciparum, with IC50 values of 6.2 ± 0.5, 2.2 ± 0.5, 8.0 ±0.4, and 9.0±0.6 µM, respectively.

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supporting

confidence: 93%

Antiproliferative and Antimalarial Sesquiterpene Lactones from Piptocoma antillana from Puerto Rico [1]

et al. 2014

Natural Product Communications

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“…(O.llyo solution in CH,OH) @%: = -2801", @255 = O", @g2x = f9018"; CD. (the same solution) 0 : : = -4545".These data compare favorably with the trans-fused a-methylene-y-butyrolactone moiety characteristic of many naturally occurring sesquiterpenes [3].The trans-configuration of the lactone was also evident from NMR. spectrum [CDCl,, 220 MHz, (CH,),Si, &values]: 2.72 for allylic C(7)-proton, a doublet of quartets, with J,,*/ = 12 Hz (axial-axial), J,,8a = 3 Hz (axial-equatorial), J,,la = 3 Hz CH I 3 I f 1 (perpendicular allylic, confirmed by decoupling) ; 5.44 and 6.14 for C(l3)-methylene protons, two doublets each with J,,13 = 3 Hz.…”

supporting

confidence: 57%

“…These data compare favorably with the trans-fused a-methylene-y-butyrolactone moiety characteristic of many naturally occurring sesquiterpenes [3].…”

mentioning

confidence: 63%

The Structure and Absolute Configuration of Arteannuin B

Uskoković

Williams

Blount

1974

Helvetica Chimica Acta

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The recent publication of StefunoviC et al. [I] describing the structure of arteannuin B prompted us to disclose our results, which also produced a structure of this compound. A generous sample of arteannuin B, isolated from Artemisia annua L. [l], was received from Prof. StefanoviC for a collaborative effort in structural investigation. After recrystallization from ether, the sample (m. p. 152-152.5') exhibited a rotation of [a]g = -72.2" (c = 1.025, CH,OH)l). The high resolution mass spectrum (mle 248.1418, M+) and elemental analysis (C 72.35, H 8.09%) indicated that the molecular formula was C,,H,,O,. Spectral evidence including an X-ray analysis and consideration of the biogenetic scheme proposed by Andersen [Z] led to the structure and absolute configuration 1 [4 a, 5 a-epoxyd whydroxy-10 a-cadin-1 1 (13) -en-lZ-oic acid lactone] for this natural product.The IR. spectrum in chloroform exhibited absorptions for a y-lactone at 1775, an epoxide at 950-1200, and a double bond at 1665 cm-'. The last functionality was also indicated to be part of a conjugated lactone grouping by an UV. These data compare favorably with the trans-fused a-methylene-y-butyrolactone moiety characteristic of many naturally occurring sesquiterpenes [3].The trans-configuration of the lactone was also evident from NMR. spectrum [CDCl,, 220 MHz, (CH,),Si, &values]: 2.72 for allylic C(7)-proton, a doublet of quartets, with J,,*/ = 12 Hz (axial-axial), J,,8a = 3 Hz (axial-equatorial), J,,la = 3 Hz CH I 3 I f 1 (perpendicular allylic, confirmed by decoupling) ; 5.44 and 6.14 for C(l3)-methylene protons, two doublets each with J,,13 = 3 Hz. Since no NMR. signal for a proton on a carbon bearing the ether oxygen of the lactone was observed, the carbon atom C(6) had to be tertiary. l) 2,Reported [l] : [a]g = -6" (no solvent indicated).

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“…The structures and absolute configuration of compounds 75 – 88 were determined by analysis of their NMR and ECD spectroscopic and single-crystal X-ray diffraction data and comparison of the values with those of (−)-goyazensolide ( 74 ). Investigation of the structures and ECD spectra of these compounds has confirmed that the early conclusions on the ECD spectra and the resultant configurations of SQLs are informative . The negative Cotton effects around 220 and 260 nm in the ECD spectra and the UV absorption maxima around 215 nm indicate a 7 R absolute configuration for both goyazensolide-type SQLs and germacranolides, while the positive Cotton effects around 210 and 310 nm in the ECD spectra and the UV absorption maxima around 260 nm indicate a 10 R configuration for goyazensolide-type SQLs only …”

Section: Sesquiterpene Lactonesmentioning

confidence: 99%

Potential Anticancer Agents Characterized from Selected Tropical Plants

et al. 2019

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Higher plants are well known for their value in affording clinically useful anticancer agents, with such compounds acting against cancer cells by a range of mechanisms of action. There remains a strong interest in the discovery and development of plant secondary metabolites as additional cancer chemotherapeutic lead compounds. In the present review, progress on the discovery of plant-derived compounds of the biflavonoid, lignan, sesquiterpene, steroid, and xanthone structural types is presented. Several potential anticancer leads of these types have been characterized from tropical plants collected in three countries as part of our ongoing collaborative multi-institutional project. Preliminary structure-activity relationships and work on in vivo testing and cellular mechanisms of action are also discussed. In addition, the relevant work reported by other groups on the same compound classes is included herein.

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Circular dichroism of sesquiterpene lactones

Cited by 35 publications

References 21 publications

Antiproliferative and Antimalarial Sesquiterpene Lactones from Piptocoma antillana from Puerto Rico [1]

Antiproliferative and Antimalarial Sesquiterpene Lactones from Piptocoma antillana from Puerto Rico [1]

The Structure and Absolute Configuration of Arteannuin B

Potential Anticancer Agents Characterized from Selected Tropical Plants

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