scholarly journals Crystal Structures and Cytotoxicity of ent-Kaurane-Type Diterpenoids from Two Aspilia Species

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3199 ◽  
Author(s):  
Souaibou Yaouba ◽  
Arto Valkonen ◽  
Paolo Coghi ◽  
Jiaying Gao ◽  
Eric M. Guantai ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Nuclear Magnetic Resonance ◽  
Nmr Assignments ◽  
A549 Cells ◽  
Mass Spectrometric ◽  
X Ray Diffraction ◽  
Hep G2 ◽  
X Ray ◽  
Aerial Parts ◽  
Phytochemical Investigation

A phytochemical investigation of the roots of Aspilia plurisetaled to the isolation of ent-kaurane-type diterpenoids and additional phytochemicals (1–23). The structures of the isolated compounds were elucidated based on Nuclear Magnetic Resonance (NMR) spectroscopic and mass spectrometric analyses. The absolute configurations of seven of the ent-kaurane-type diterpenoids (3–6, 6b, 7 and 8) were determined by single crystal X-ray diffraction studies. Eleven of the compounds were also isolated from the roots and the aerial parts of Aspilia mossambicensis. The literature NMR assignments for compounds 1 and 5 were revised. In a cytotoxicity assay, 12α-methoxy-ent-kaur-9(11),16-dien-19-oic acid (1) (IC50 = 27.3 ± 1.9 µM) and 9β-hydroxy-15α-angeloyloxy-ent-kaur-16-en-19-oic acid (3) (IC50 = 24.7 ± 2.8 µM) were the most cytotoxic against the hepatocellular carcinoma (Hep-G2) cell line, while 15α-angeloyloxy-16β,17-epoxy-ent-kauran-19-oic acid (5) (IC50 = 30.7 ± 1.7 µM) was the most cytotoxic against adenocarcinomic human alveolar basal epithelial (A549) cells.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

scholarly journals Improving Linear Range Limitation of Non-Enzymatic Glucose Sensor by OH− Concentration

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 186
Author(s):  
Lory Wenjuan Yang ◽  
Elton Enchong Liu ◽  
Alex Fan Xu ◽  
Jason Yuanzhe Chen ◽  
Ryan Taoran Wang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Glucose Oxidation ◽  
Glucose Sensor ◽  
Linear Range ◽  
Diabetic Patients ◽  
Current Response ◽  
Effective Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naoh Solution

The linear range of the non-enzymatic glucose sensor is usually much smaller than the glucose level of diabetic patients, calling for an effective solution. Despite many previous attempts, none have solved the problem. Such a challenge has now been conquered by raising the NaOH concentration in the electrolyte, where amperometry, X-ray diffraction, Fourier-transform infrared spectroscopy, and Nuclear magnetic resonance measurements have been conducted. The linear range has been successfully enhanced to 40 mM in 1000 mM NaOH solution, and it was also found that NaOH affected the degree of glucose oxidation, which influenced the current response during sensing. It was expected that the alkaline concentration must be 25 times higher than the glucose concentration to enhance the linear range, much contrary to prior understanding.

Tautomerism of bis(2-benzothiazolyl)methanes

1988 ◽  
Vol 66 (6) ◽  
pp. 1467-1473 ◽  
Author(s):  
Carmen Avendaño ◽  
María Teresa Ramos ◽  
José Elguero ◽  
María Luisa Jimeno ◽  
Juana Bellanato ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Infrared Spectroscopy ◽  
Magnetic Resonance ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
Methyl Derivative ◽  
Model Compounds ◽  
X Ray ◽  
Nuclear Magnetic

Tautomerism of dibenzothiazolylmethane (1) and its C-methyl derivative (2) has been studied by 1H nuclear magnetic resonance, ultraviolet, and infrared spectroscopy using C,C-dimethyl (3) and N-methyl (4) derivatives as model compounds of the "CH" and "NH" forms, respectively. X-ray diffraction analysis of the "fixed" N-methyl derivative 4 shows that it corresponds to the Z-sE isomer 4b2. The CH tautomers are unstable in solution and they slowly isomerize into a mixture of NH tautomers that depends on the solvent and on the C-substituent (H or CH3).

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