scholarly journals Immunosuppressive Isopimarane Diterpenes From Cultures of the Endophytic Fungus Ilyonectria robusta

2022 ◽  
Vol 12 ◽  
Author(s):  
Ke Ye ◽  
Xiao Lv ◽  
Xian Zhang ◽  
Pan-Pan Wei ◽  
Zheng-Hui Li ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Lymphocytes ◽  
Absolute Configuration ◽  
Endophytic Fungus ◽  
Structure Elucidation ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
Bletilla Striata ◽  
X Ray ◽  
C Nmr

Five new isopimarane diterpenes, robustaditerpene A-E (1–5), which include 19-nor-isopimarane skeleton and isopimarane skeleton, were isolated from the liquid fermentation of the endophytic fungus Ilyonectria robusta collected from Bletilla striata. The structure elucidation and relative configuration assignments of all compounds were accomplished by interpretation of NMR and HRESIMS spectrometric analyses and 13C NMR calculation. And the absolute configuration of 1-5 were identified by single-crystal X-ray diffraction and ECD calculation. Compound 3 inhibited lipopolysaccharide-induced B lymphocytes cell proliferation with an IC50 value at 17.42 ± 1.57 μM while compound 5 inhibited concanavalin A-induced T lymphocytes cell proliferation with an IC50 value at 75.22 ± 6.10 μM. These data suggested that compounds 3 and 5 may possess potential immunosuppressive prospect.

Coordination Chemistry of N-(2-Hydroxybenzyl)-(S)-amino Acids. Absolute Configuration of LAMBDA-mer-R,R-[Co(ohb-(S)-Ala)2]- Anion

1997 ◽  
Vol 62 (8) ◽  
pp. 1205-1213 ◽  
Author(s):  
Svetlana Pakhomova ◽  
Jan Ondráček ◽  
František Jursík
Keyword(s):  
Absolute Configuration ◽  
Diffraction Method ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
Molecular Mechanics Calculations ◽  
X Ray ◽  
Bond Network ◽  
Twist Boat ◽  
C Nmr

The crystal and molecular structure of the Ag[Co(ohb-(S)-Ala)2] . 5 H2O have been determined by X-ray diffraction method. The crystals are hexagonal with a = b = 9.039(0.002) Å, c = 24.896(0.006) Å, space group P3221, and Z = 3. Each Ag+ counterion coordinated by one water molecule which is a part of hydrogen bond network, is bonded to aromatic rings. The anion adopts LAMBDA-mer absolute configuration. Mer geometry is in accord with the molecular mechanics calculations. Since CD spectroscopy does not reflect configurational chirality, the absolute configuration has been determined by the X-ray structure analysis and assigned using chirality descriptors. The arrangements at the chiral centers are R for both N atoms. The two five-membered rings each assume envelope conformation with C1 and C2 atoms exceptionally deviated (0.378(7) and 1.210(7) Å) from the N-Co-O plane. Both six-membered rings have delta twist boat conformations. The complex described has been also characterized by the electronic and 13C NMR spectroscopies.

(1S,7S)-7-Methyl-6,9-diazatricyclo[6,3,0,01,6]tridecane-5,10-dione, a tricyclic spirodilactam containing non-planar amide groups: Synthesis, NMR, crystal structure, absolute configuration, electronic and vibrational circular dichroism

1988 ◽  
Vol 53 (11) ◽  
pp. 2447-2472 ◽  
Author(s):  
Petr Maloň ◽  
C. L. Barness ◽  
Miloš Buděšínský ◽  
Rina K. Dukor ◽  
Dick Van der Helm ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optically Active ◽  
Vibrational Circular Dichroism ◽  
X Ray Diffraction ◽  
X Ray ◽  
Circular Dichroïsm ◽  
C Nmr ◽  
Active Precursor

The title spirocyclic dilactam (1S,7S)-7-methyl-6,9-diazatricyclo[6,3,0,01,6]tridecan-5,10-dione (I), a molecule designed to contain non-planar amide groups, has been synthesized from an optically active precursor of known absolute configuration. The relative and absolute configuration have been determined by X-ray diffraction. The conformation of the compound has been investigated by X-ray, 1H and 13C NMR, electronic and vibrational circular dichroism. The compound possesses moderately non-planar amide groups in the two rings of nonequal geometry. The electronic CD is dominated by inherent chirality of the amide chromophores. The dilactams I and II ((1S,6S)-6-methyl-5,8-diazatricyclo[6,3,0,01,5]undecan-4,9-dione – having five-membered rings) exhibit monosignate amide I VCD and strong VCD bands in the mid-ir region.

Stereoisomeric chiral 2,9-diazabicyclo[4.4.0.]decane-3,10-diones as models of dipeptide grouping: Synthesis, X-ray, IR, NMR and cd studies

1984 ◽  
Vol 49 (3) ◽  
pp. 712-742 ◽  
Author(s):  
Karel Bláha ◽  
Ahmed M. Farag ◽  
Dick VAN DER Helm ◽  
M. Bilayet Hossain ◽  
Miloš Buděšínský ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Stereospecific Synthesis ◽  
Cd Spectra ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
H Nmr ◽  
Chemical Correlation ◽  
Cd Studies ◽  
C Nmr

Synthesis of the title optically active bicyclic dilactams I and II with cis- and trans-annelation of rings is described. The stereospecific synthesis started from (2R)-2-benzamido-2-(4-oxocyclohexyl)acetic acid ((-)-VI) whose absolute configuration was determined by chemical correlation with the known (2R)-2-amino-(4-hydroxyphenyl)acetic acid ((-)-IIIb). Relative configuration at the bridgehead atoms in I and II was assigned by 1H and 13C NMR spectroscopy and confirmed by X-ray diffraction analysis which showed the detailed conformation in crystal. According to the 1H NMR spectra in solution the trans-isomer II has the same configuration as in crystal whereas the cis-isomer I exists in two forms one of which is identical with that in crystal. This conformational analysis agrees also with the IR spectra, detecting an intramolecularly hydrogen-bonded conformation for IIbut no hydrogen bond for I. The CD spectra of both lactams were successfully interpreted using the exciton theory in the π-π region where it reflects the differences in the angles Φ and ψ (for I Φ = 110°, ψ = -143°; forII Φ = -145°, ψ = 162°). In the n-π transition region the interpretation was based on the quadrant rule and also inherent non-planarity of one of the amide groups in II.

Crystal structure of aristoserratine

1983 ◽  
Vol 36 (5) ◽  
pp. 1037 ◽  
Author(s):  
IRC Bick ◽  
MA Hai ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Circular Dichroism Spectrum ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The crystal structure of the alkaloid aristoserratine,* C20H24N2O, has been determined by single-crystal X-ray diffraction methods at 295 K, the structure being refined to a residual of 0.034 for 1107 independent 'observed' reflections. Crystals are monoclinic, P21, a 14.836(5), b 8.568(3), c 6.633(3) �, β 98.05(3)�, Z 2. The relative configuration is established and, by inference, by comparison of the circular dichroism spectrum with that of aristoteline, the absolute configuration is assigned.

Sesquiterpenic lactones of the Inula caspica BLUME species

1990 ◽  
Vol 55 (6) ◽  
pp. 1568-1579 ◽  
Author(s):  
Sergazy M. Adekenov ◽  
Miloš Buděšínský ◽  
Metram A. Abdikalikov ◽  
Coblandy M. Turdybekov ◽  
David Šaman ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray

From Inula caspica BLUME (Compositae) were isolated 3β-hydroxy-2α-senecioyloxyisoalantolactone (I), whose structure was confirmed by X-ray diffraction and completed by determination of its absolute configuration, and britannin (II) whose relative configuration was determined by X-ray diffraction and absolute configuration by CD spectroscopy.

scholarly journals Difficulties to Determine the Absolute Configuration of Guaiaretic Acid

2018 ◽  
Vol 13 (8) ◽  
pp. 1934578X1801300
Author(s):  
Alfredo R. Ortega ◽  
Eleuterio Burgueño-Tapia ◽  
Pedro Joseph-Nathan
Keyword(s):  
Symmetric Space ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Structure Elucidation ◽  
Carbon Chain ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
The Absolute ◽  
Stereogenic Center

An account of the difficulties to determine the absolute configuration (AC) of guaiaretic acid (1a), using contemporary methodology, is described in commemoration of the century of its structure elucidation. In fact, the herein studied molecule was the derived diacetate 1b, since the natural lignan slowly decomposes upon manipulation. Single crystal X-ray diffraction of 1b demonstrated the structure, but calculation of Flack and Hooft parameters to know the AC was unsuccessful since the crystals were triclinic, P-1, which is a centro-symmetric space group. In turn, manual band to band comparison of experimental and DFT B3LYP/DGDZVP calculated VCD spectra of 1b allowed ascertaining its AC, although automatic comparison using the Compare VOA software was not very successful. This behavior is associated to the fact that the studied molecule has a sole stereogenic center located on the acyclic portion of a carbon chain possessing two quite similar substituents. The behavior is discussed in relation to cases where the molecular flexibility also generates a very large number of conformers.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

scholarly journals New Haloterpenes from the Marine Red Alga Laurencia papillosa: Structure Elucidation and Biological Activity

Marine Drugs ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 35
Author(s):  
Mohamed Shaaban ◽  
Ghada S. E. Abou-El-Wafa ◽  
Christopher Golz ◽  
Hartmut Laatsch
Keyword(s):  
Biological Activity ◽  
Crude Extract ◽  
Structure Elucidation ◽  
Antimicrobial Activities ◽  
Red Alga ◽  
Spectroscopic Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Structures ◽  
Terpene Derivatives

Analysis of the air-dried marine red alga Laurencia papillosa, collected near Ras-Bakr at the Suez gulf (Red Sea) in Egypt delivered five new halogenated terpene derivatives: aplysiolic acid (1), 7-acetyl-aplysiol (2), aplysiol-7-one (3), 11,14-dihydroaplysia-5,11,14,15-tetrol (5a), and a new maneonene derivative 6, named 5-epi-maneolactone. The chemical structures of these metabolites were characterized employing spectroscopic methods, and the relative and absolute configurations were determined by comparison of experimental and ab initio-calculated NMR, NOE, ECD, and ORD data, and by X-ray diffraction of 2 and 6. The antimicrobial activities of the crude extract and compounds 1–3, 5a and 6 were studied.

Darstellung, 11B-, 13C-, 29Si-NMR- und Schwingungsspektren von Trimethylsilylmethyl-hexahydro-closo-hexaborat, [B6H6(CH2Si(CH3)3)]- sowie Kristallstruktur von [P(C6H5)4][B6H6(CH2Si(CH3)3)] / Preparation, 11B, 13C, 29Si NMR and Vibrational Spectra of Trimethylsilylmethyl-hexahydro-clo-hexaborate, [B6H6(CH2Si(CH 3)3)]-and the Crystal Structure of [P(C6H5)4] [B6H6(CH2Si(CH3)3)]

1995 ◽  
Vol 50 (7) ◽  
pp. 1025-1029 ◽  
Author(s):  
J. Baurmeister ◽  
A. Franken ◽  
W. Preetz
Keyword(s):  
Crystal Structure ◽  
Monoclinic Space Group ◽  
29Si Nmr ◽  
X Ray Diffraction ◽  
Nmr Spectrum ◽  
X Ray ◽  
Quadrupole Coupling ◽  
Stretching Vibration ◽  
Ir And Raman ◽  
C Nmr

By reaction of [N(C4H9 )4]2 [B6H6] with iodomethyl-trimethylsilane in acetonitrile a solution with trimethylsilylm ethyl-closo-hexaborate(1-)anions, [B6H6 (CH2Si(CH3)3)]-, is formed. The crystal structure of [P(C6H5 )4][B6H6(CH2Si(CH3)3)] has been determined by single crystal X-ray diffraction analysis; monoclinic, space group P21/n with a = 16.140(2), b = 11.646(8), c = 16.731(3) Å, β 109.664(11)°. The 11B NMR spectrum reveals features of a mono hetero substituted octahedral B6 cage. The 13C NMR spectrum exhibits a quartet at +0.18 ppm with 1J(C,H) = 118 Hz for the three methyl groups and a weak multiplet at -0.65 ppm for the methylene bridge due to quadrupole coupling with the boron atoms. In the 29Si NMR spectrum a decet at +2.25 ppm with 2J(C,H ) = 6.9 Hz is observed. The B -C stretching vibration is observed at 1155 cm-1 in the IR and Raman spectrum.

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