scholarly journals Alkaloids from the Tuber of Stephania cf. rotunda

2016 ◽  
Vol 11 (7) ◽  
pp. 1934578X1601100
Author(s):  
Duy Hoang Le ◽  
Katsumi Nishimura ◽  
Takao Tanahashi
Keyword(s):  
Absolute Configuration ◽  
Chemical Investigation ◽  
Chemical Methods ◽  
H Nmr ◽  
Chemical Structures ◽  
Cd Spectrum ◽  
Nmr Data ◽  
The Absolute ◽  
First Time

Chemical investigation of the tuber of Stephania cf. rotunda collected in Vietnam led to the isolation of a new stephaoxocane-type alkaloid, stepharotudine (1), twenty-eight known alkaloids, and two known amides. The chemical structures of the isolated compounds were determined by spectroscopic and chemical methods. The absolute configuration of the new compound was determined from its CD spectrum and by 1H NMR analyses of its MPA esters. For the known alkaloids (-)-crebanine-β- N-oxide (2), uthongine (3), and palmatrubine (4), fully assigned NMR data are also reported for the first time.

Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

1986 ◽  
Vol 51 (4) ◽  
pp. 903-929 ◽  
Author(s):  
Miroslav Holub ◽  
Miloš Buděšínský ◽  
Zdenka Smítalová ◽  
David Šaman ◽  
Urszula Rychłewska
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Chemical Correlation ◽  
The Absolute

On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.

Difference CD spectrum : the absolute configuration of methyl sarcophytoate

1991 ◽  
Vol 32 (45) ◽  
pp. 6595-6596 ◽  
Author(s):  
Midori O. Ishitsuka ◽  
Takenori Kusumi ◽  
Hiroshi Kakisawa
Keyword(s):  
Absolute Configuration ◽  
Cd Spectrum ◽  
The Absolute

scholarly journals Absolute Configuration of Cembrane Diterpenoids from Bursera multijuga

2014 ◽  
Vol 9 (9) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Juan D. Hernández-Hernández ◽  
Hugo A. García-Gutiérrez ◽  
Luisa U. Román-Marín ◽  
Yunuen I. Torres-Blanco ◽  
Carlos M. Cerda-García-Rojas ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Absolute Configuration ◽  
2D Nmr ◽  
Vibrational Circular Dichroism ◽  
Conformational Preference ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
First Time ◽  
Good Agreement

The stems of Bursera multijuga afforded (-)-(1 S,3 E,7 R,8 R,11 E)-7,8-epoxycembra-3,11-dien-1-ol (1) and its acetate 2, together with cembrene A (3), nephthenol (4), and cembrenol (5). The structures of 1 and 2 were elucidated by 1D and 2D NMR, HRESIMS, and X-ray diffraction. The conformational preference of flexible 1 was studied by molecular modeling at the DFT B3LYP/DGDZVP level of theory. Good agreement between calculated and experimental vibrational circular dichroism curves established the absolute configuration of 1. This is the first time that cembrane derivatives have been isolated from the genus Bursera.

scholarly journals A New Bisabolene from Stevia tomentosa

2011 ◽  
Vol 6 (9) ◽  
pp. 1934578X1100600
Author(s):  
Alejandro Valdez-Calderón ◽  
J. Martín Torres-Valencia ◽  
J. Jesús Manríquez-Torres ◽  
René Velázquez-Jiménez ◽  
Mario A. Gómez-Hurtado ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Coupling Constants ◽  
Spectral Studies ◽  
Dihedral Angles ◽  
Model Compounds ◽  
H Nmr ◽  
Aerial Parts ◽  
The Absolute

The new sesquiterpene (1 R,2 R,3 R,6 R,7 S)-1-acetoxy-2,3-dmydroxy-2,3-dihydrobisabolene (3) together with ten known terpenes and three known flavonoids were isolated from the aerial parts and from the roots of Stevia tomentosa. The structure of 3 follows from spectral studies, the relative chirality at C-3 follows from 1H NMR coupling constants comparison with the corresponding calculated values obtained by applying a generalized Karplus-type relationship to the dihedral angles of model compounds, and the absolute configuration is assumed in analogy to known (2 R,3 R,6 R,7 S)-2,3-epoxy-2,3-dihydrobisabolen-1-one (2).

scholarly journals Three New Biflavonoids from Chinese Dragon's Blood, Dracaena cochinchinensis

2012 ◽  
Vol 7 (5) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Jing Guan ◽  
Shun-Xing Guo
Keyword(s):  
Quantum Chemical Calculation ◽  
Quantum Chemical ◽  
Chemical Calculation ◽  
Dragon’S Blood ◽  
Esi Ms ◽  
H Nmr ◽  
Cd Spectrum ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
C Nmr

Three new biflavonoids, named (2 Rγ S)-3′-methoxy-8-methylsocotrin-4′-ol (1), (2 Sγ R)-3′-methoxy-8-methylsocotrin-4′-ol (2), and (2 Rγ R)-8-methylsocotrin-4′-ol (3), were isolated from Chinese Dragon's blood [Dracaena cochinchinensis (Lour.) S. C. Chen], together with two known ones. The structures of these new biflavonoids were elucidated by a combination of HR-ESI-MS, 1H NMR, 13C NMR, HMQC, and HMBC spectra. The absolute configurations of compounds 1-4 were determined by quantum chemical calculation of the circular dichroism spectrum and comparison with the experimental CD spectrum.

Prenylated Flavonoids and Phenolic Compounds from the Rhizomes of Marine Phanerogam Cymodocea nodosa

Planta Medica ◽  
2017 ◽  
Vol 84 (09/10) ◽  
pp. 704-709
Author(s):  
Abla Smadi ◽  
Maria Ciavatta ◽  
Fatma Bitam ◽  
Marianna Carbone ◽  
Guido Villani ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Phenolic Compounds ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Chemical Investigation ◽  
Nuclear Magnetic Resonance Analysis ◽  
Cymodocea Nodosa ◽  
Prenylated Flavonoids ◽  
Resonance Analysis ◽  
The Absolute

AbstractChemical investigation of the rhizomes of the marine phanerogam Cymodocea nodosa resulted in the isolation of two new prenylated flavon-di-O-glycosides, cymodioside A (1) and B (2), along with known phenolic compounds 3–7, some of which never reported from seagrasses to date. The structures of compounds 1 and 2 were established by extensive nuclear magnetic resonance analysis. In addition, the absolute configuration of 4-(2,5-dihydroxyhexyl) benzene-1,2-diol (7), which was not previously reported in the literature, has been now determined.

The assignment of the configuration for α-hydroxy acid esters using a CEC strategy

2016 ◽  
Vol 14 (23) ◽  
pp. 5258-5262 ◽  
Author(s):  
Ruixue Peng ◽  
Lili Lin ◽  
Yuheng Zhang ◽  
Wangbin Wu ◽  
Yan Lu ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Hydroxy Acid ◽  
H Nmr ◽  
Nmr Method ◽  
The Absolute ◽  
Acid Esters

A simple and efficient 1H NMR method for determining the absolute configuration of chiral α-hydroxy acid esters using a CEC strategy with a chiral N,N′-dioxide-scandium(iii) complex was developed.

Sesquiterpenic lactones of Inula aschersoniana JANKA var. aschersoniana species

1990 ◽  
Vol 55 (6) ◽  
pp. 1562-1567 ◽  
Author(s):  
Ełżbieta Błoszyk ◽  
Miloš Buděšínský ◽  
Włodzimierz M. Daniewski ◽  
Eva Pešková ◽  
Bohdan Drożdż ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
H Nmr ◽  
Aerial Parts ◽  
The Absolute

Aerial parts of species Inula aschersoniana JANKA var. aschersoniana have been shown to contain parthenolide (I), costunolide diepoxide (III) and the hitherto undescribed inusoniolide (IV) whose structure, including the absolute configuration, was determined using 1H NMR and CD spectroscopy.

scholarly journals A Novel Acylated Anthocyanin with a Linear Trisaccharide from Flowers of Convolvulus althaeoides

2015 ◽  
Vol 10 (11) ◽  
pp. 1934578X1501001 ◽  
Author(s):  
Luis Cabrita
Keyword(s):  
Absolute Configuration ◽  
Complete Characterization ◽  
H Nmr ◽  
Chromatographic Techniques ◽  
Maldi Tof ◽  
The Absolute

An acylated anthocyanin trioside was isolated from pink flowers of Convolvulus althaeoides using a combination of chromatographic techniques. On the basis of MS (MALDI-TOF) and NMR (1H NMR, 1H-1H COSY, 1D TOCSY, HSQC, HMBC, 13C CAPT) its structure was determined as cyanidin 3- O-[6- O-(4- O-(6- O-( E-caffeoyl)-β-D-glucopyranosyl)-α-L-rhamnopyranosyl)-β-D-glucopyranoside]-5- O-β-D-glucopyranoside. The absolute configuration of the aldose enantiomer moieties was determined from the separation of the corresponding thiazolidine diastereoisomer derivatives by HPLC-DAD. This is a novel trisaccharide within the flavonoids, and the first complete characterization of a linear glucosyl-rhamnosyl-glucoside (4′-glucosylrutinoside) within the anthocyanins. Whilst acylation of rhamnose moieties in position 4 is quite common, the occurrence in anthocyanins of a glycosylated rhamnose is a unique trait. Although many complex anthocyanins have been found amongst the Convolvulaceae, the genus Convolvulus had not yet been surveyed for anthocyanins and thus this account could be of significance within the current chemotaxonomy of this family.

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