Stereochemistry of spongosoritins: beyond optical rotation

2019 ◽  
Vol 17 (45) ◽  
pp. 9772-9777
Author(s):  
Andrea N. L. Batista ◽  
Fernando M. dos Santos ◽  
Alessandra L. Valverde ◽  
Joao M. Batista
Keyword(s):  
Optical Rotation ◽  
Structural Features ◽  
Spectroscopic Methods ◽  
Chiroptical Properties

A combination of spectroscopic methods reveals the dependence of the chiroptical properties of spongosoritins on achiral structural features.

scholarly journals Cytotoxic and Anti-HIV Phenanthroindolizidine Alkaloids from Cryptocarya chinensis†

2012 ◽  
Vol 7 (6) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Tian-Shung Wu ◽  
Chung-Ren Su ◽  
Kuo-Hsiung Lee
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Cancer Cell ◽  
Optical Rotation ◽  
Ethanol Extract ◽  
Cancer Cell Lines ◽  
Spectroscopic Methods ◽  
Bioassay Guided Fractionation ◽  
Phenanthroindolizidine Alkaloids ◽  
Anti Hiv

Bioassay-guided fractionation of the cytotoxic ethanol extract of Cryptocarya chinensis has led to the isolation of 11 compounds, including two phenanthroindolizidine alkaloids [(-)-antofine (1) and dehydroantofine (2)], five pavine alkaloids (3-7), and four proaporphine alkaloids (8-11). The structures of the isolated compounds were determined by means of NMR spectroscopic methods, and supported by HRMS and optical rotation data. Compounds 1 and 2 showed cytotoxic activity against four cancer cell lines, L1210, P388, A549, and HCT-8, with 1 being the most potent against A549 and HCT-8 with EC50 values of 0.002 and 0.001 μg/mL, respectively. In addition, 2 is first reported to exhibit significant anti-HIV activity.

scholarly journals A New Neolignan from Panicum turgidum

2016 ◽  
Vol 11 (7) ◽  
pp. 1934578X1601100
Author(s):  
Ahmed A. Zaki ◽  
Zulfiqar Ali ◽  
Yasser A. El-Amier ◽  
Ikhlas A. Khan
Keyword(s):  
Circular Dichroism ◽  
Optical Rotation ◽  
2D Nmr ◽  
Circular Dichroism Spectroscopy ◽  
Spectroscopic Methods ◽  
Relative Configuration ◽  
Esi Ms ◽  
Spectroscopy Optical ◽  
Circular Dichroïsm

A new neolignan, paniculignan (1), and a known lignan, tetracentronside B (2), were isolated from Panicum turgidum. The structure of 1 was elucidated by extensive spectroscopic methods including 1D and 2D NMR and HR-ESI-MS. The relative configuration of 1 was determined on the basis of circular dichroism spectroscopy, optical rotation, and NOESY correlations.

scholarly journals New Ophiobolin Derivatives from the Marine Fungus Aspergillus flocculosus and Their Cytotoxicities against Cancer Cells

Marine Drugs ◽  
2019 ◽  
Vol 17 (6) ◽  
pp. 346 ◽  
Author(s):  
Byeoung-Kyu Choi ◽  
Phan Thi Hoai Trinh ◽  
Hwa-Sun Lee ◽  
Byeong-Woo Choi ◽  
Jong Soon Kang ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Chemical Shifts ◽  
Optical Rotation ◽  
2D Nmr ◽  
Cancer Cell Lines ◽  
Marine Fungus ◽  
Side Chain ◽  
Spectroscopic Methods

Five new sesterterpenes, 14,15-dehydro-6-epi-ophiobolin K (1), 14,15-dehydro- ophiobolin K (2), 14,15-dehydro-6-epi-ophiobolin G (3), 14,15-dehydro-ophiobolin G (4) and 14,15-dehydro-(Z)-14-ophiobolin G (5), together with four known ophiobolins (6–9) were isolated from the marine fungus Aspergillus flocculosus derived from the seaweed Padina sp. collected in Vietnam. The five new ophiobolins were first isolated as ophiobolin derivatives consisting of a fully unsaturated side chain. Their structures were elucidated via spectroscopic methods including 1D, 2D NMR and HR-ESIMS. The absolute configurations were determined by the comparison of chemical shifts and optical rotation values with those of known ophiobolins. All compounds (1–9) were then evaluated for their cytotoxicity against six cancer cell lines, HCT-15, NUGC-3, NCI-H23, ACHN, PC-3 and MDA-MB-231. All the compounds showed potent cytotoxicity with GI50 values ranging from 0.14 to 2.01 μM.

1-Alkyl-3-Methylpyridinium Halide Structural Features Studied by Vibrational Spectroscopic Methods

2015 ◽  
Vol 47 (3) ◽  
pp. 171-176 ◽  
Author(s):  
E. S. Sashina ◽  
D. A. Kashirskii ◽  
T. V. Artamonova ◽  
L. V. Myznikov
Keyword(s):  
Structural Features ◽  
Spectroscopic Methods

Unravelling chlorophyll catabolism in higher plants

2002 ◽  
Vol 30 (4) ◽  
pp. 625-630 ◽  
Author(s):  
B. Kräutler
Keyword(s):  
Higher Plants ◽  
Structural Features ◽  
Spectroscopic Methods ◽  
Chlorophyll Metabolism ◽  
Chlorophyll Breakdown ◽  
Chlorophyll Catabolites

Chlorophyll metabolism is probably the most visible manifestation of life. In spite of this, chlorophyll catabolism has remained something of a mystery until about 10 years ago. At that time, the first non-green tetrapyrrolic chlorophyll breakdown products from higher plants were discovered, and the structure of the first one of them was elucidated by modern spectroscopic methods. In the meantime, the essential structural features of chlorophyll catabolites and some of the biochemistry of chlorophyll breakdown in higher plants have been uncovered, as outlined in this article.

scholarly journals Design of a single protein that spans the entire 2-V range of physiological redox potentials

2015 ◽  
Vol 113 (2) ◽  
pp. 262-267 ◽  
Author(s):  
Parisa Hosseinzadeh ◽  
Nicholas M. Marshall ◽  
Kelly N. Chacón ◽  
Yang Yu ◽  
Mark J. Nilges ◽  
...  
Keyword(s):  
Entire Range ◽  
Critical Parameter ◽  
Reduction Potential ◽  
Structural Features ◽  
Water Soluble ◽  
Spectroscopic Methods ◽  
Redox Potentials ◽  
Hydrogen Electrode ◽  
Single Protein ◽  
Redox Agents

The reduction potential (E°′) is a critical parameter in determining the efficiency of most biological and chemical reactions. Biology employs three classes of metalloproteins to cover the majority of the 2-V range of physiological E°′s. An ultimate test of our understanding of E°′ is to find out the minimal number of proteins and their variants that can cover this entire range and the structural features responsible for the extreme E°′. We report herein the design of the protein azurin to cover a range from +970 mV to −954 mV vs. standard hydrogen electrode (SHE) by mutating only five residues and using two metal ions. Spectroscopic methods have revealed geometric parameters important for the high E°′. The knowledge gained and the resulting water-soluble redox agents with predictable E°′s, in the same scaffold with the same surface properties, will find wide applications in chemical, biochemical, biophysical, and biotechnological fields.

Gamma Irradiation of Uridine and Uridylic Acid in Aerated A queous Solutions: Identification of the Major Product

1974 ◽  
Vol 29 (9-10) ◽  
pp. 643-644 ◽  
Author(s):  
R Ducolomb ◽  
J Cadet ◽  
R Teoule
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Thin Layer ◽  
Gamma Irradiation ◽  
Optical Rotation ◽  
Hydrolytic Degradation ◽  
Major Product ◽  
Gel Chromatography ◽  
Spectroscopic Methods ◽  
Silica Gel Chromatography

Abstract The major product of uridine gamma irradiation in aerated aqueous solution (10-3 ᴍ, pH ~6) has been identified: N-(β-ᴅ-ribofuranosyl) -formamide. Thin-layer silica gel chromatography and spectroscopic methods (mass spectrometry. NMR, IR, optical rotation) enabled us to isolate and characterize this product. It may be assumed that this substance resulted from the hydrolytic degradation of unstable hydroxy-hydroperoxides. It was also prepared by uridine oxydation with pertrifluoracetic acid. A similar major compound in the radiolysis of uridylic acid has been found

scholarly journals Nuclear Spin Induced Optical Rotation of Functional Groups in Hydrocarbons

2020 ◽  
Author(s):  
Petr Štěpánek
Keyword(s):  
Molecular Structure ◽  
Nuclear Spin ◽  
Density Functional ◽  
Optical Rotation ◽  
Magnetic Moments ◽  
Spectroscopic Method ◽  
Density Functional Theory Calculations ◽  
Carbon Chain ◽  
Structural Features ◽  
Experimental Development

Nuclear spin-induced optical rotation (NSOR) is a nuclear magneto-optic effect manifesting as a change of polarization of light induced by nuclear magnetic moments within a molecule. NSOR probes molecular optical properties through localized nuclear interactions and has a potential to be developed into a new spectroscopic tool. However, so far the connection between the molecular structure and NSOR response has not been systematically investigated. To obtain insight into this relation and to assess its viability as a foundation for a new spectroscopic method, NSOR of a set of hydrocarbon molecules with various structural motifs is theoretically investigated using density functional theory calculations. The results reveal that NSOR intensities are correlated with several structural features of the molecules, such as the position of the nucleus in the carbon chain, isomerism and presence of nearby unsaturated groups. Specific patterns connecting NSOR to the local chemical environment of the nucleus can be observed. It is also shown that this effect can be to a good approximation modelled as a sum of individual contributions from nearby chemical groups, allowing for a rapid estimation of its values. The demonstrated systematic dependence of NSOR signal on the molecular structure is a desirable feature for theoretical and experimental development of new spectroscopic methods based on this phenomenon.

scholarly journals Nuclear Spin Induced Optical Rotation of Functional Groups in Hydrocarbons

2020 ◽  
Author(s):  
Petr Štěpánek
Keyword(s):  
Molecular Structure ◽  
Nuclear Spin ◽  
Density Functional ◽  
Optical Rotation ◽  
Magnetic Moments ◽  
Spectroscopic Method ◽  
Density Functional Theory Calculations ◽  
Carbon Chain ◽  
Structural Features ◽  
Experimental Development

Nuclear spin-induced optical rotation (NSOR) is a nuclear magneto-optic effect manifesting as a change of polarization of light induced by nuclear magnetic moments within a molecule. NSOR probes molecular optical properties through localized nuclear interactions and has a potential to be developed into a new spectroscopic tool. However, so far the connection between the molecular structure and NSOR response has not been systematically investigated. To obtain insight into this relation and to assess its viability as a foundation for a new spectroscopic method, NSOR of a set of hydrocarbon molecules with various structural motifs is theoretically investigated using density functional theory calculations. The results reveal that NSOR intensities are correlated with several structural features of the molecules, such as the position of the nucleus in the carbon chain, isomerism and presence of nearby unsaturated groups. Specific patterns connecting NSOR to the local chemical environment of the nucleus can be observed. It is also shown that this effect can be to a good approximation modelled as a sum of individual contributions from nearby chemical groups, allowing for a rapid estimation of its values. The demonstrated systematic dependence of NSOR signal on the molecular structure is a desirable feature for theoretical and experimental development of new spectroscopic methods based on this phenomenon.

Stereochemistry and chiroptical properties of 1,3-dialkylaziridinones (α-lactams). Chiral rules for the nonplanar amide chromophore

1994 ◽  
Vol 72 (2) ◽  
pp. 279-286 ◽  
Author(s):  
G. V. Shustov ◽  
A. V. Kachanov ◽  
I. I. Chervin ◽  
R. G. Kostyanovsky ◽  
A. Rauk
Keyword(s):  
Rydberg State ◽  
Singlet State ◽  
Structural Features ◽  
Molecular Orbital Calculations ◽  
Cd Spectra ◽  
Trans Isomers ◽  
Excited Singlet ◽  
Chiroptical Properties ◽  
Tert Butyl ◽  
Cotton Effects

Structural features, configurational stability, and chiroptical properties of the nonplanar amide group in α-lactams were investigated by means of ab initio (6-31 + G*) molecular orbital calculations on (1R)-aziridinone 1, (1R)-1-methylaziridinone 2, (1R,3R)-3-methylaziridinone 3, (1R,3R)-1,3-dimethylaziridinone 4a, its cis diastereomer (1S,3R)-1,3-dimethylaziridinone 4b, and (1R,3R)-3-tert-butyl-1-methylaziridinone 5, and by experimental CD spectra of 1-tert-butyl- and 1-(1′-adamantyl)-substituted 3(R)-3-tert-butylaziridinones 6 and 7. The nitrogen inversion barriers of 4a and 4b are 2.8 and 1.6 kcal mol−1, respectively. The lowest excited singlet state of all of the aziridinones is a valence state (the nO–πCO* transition); the second is a Rydberg state (the nN–3s transition). The signs of the first and second Cotton effects in the CD spectra of the compounds 6 and 7 coincide with the calculated ones for 1 and 2 and the trans isomers 3, 4a, and 5. According to the calculated and experimental data for aziridinones 1–7 as well as to the well-known data for other nonplanar amides, the sign of the first Cotton effects is determined by the intrinsic chirality of the nonplanar amide chromophore and obeys a spiral rule. For cases where the chromophore has the conformation around the N—C(O) bond, which is close to the antiperiplanar, a reverse octant rule is proposed.

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