scholarly journals Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

2015 ◽  
Vol 11 ◽  
pp. 1950-1959 ◽  
Author(s):  
Redouane Beniazza ◽  
Natalia Bayo ◽  
Florian Molton ◽  
Carole Duboc ◽  
Stéphane Massip ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Copper Catalysts ◽  
Water Soluble ◽  
Sodium Ascorbate ◽  
X Ray Diffraction ◽  
Click Reactions ◽  
Ethylenediamine Complex ◽  
Layer Chromatography ◽  
Full Conversion ◽  
Uva Radiation

The search for copper catalysts able to perform effectively click reactions in water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II)–EDA (EDA = ethylenediamine) complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer, has been synthesized and characterized by different techniques including single crystal X-ray diffraction. Highly efficient photoreduction was demonstrated when solutions of 1 in hydrogen atom donating solvents, such as THF or MeOH, were exposed to UVA radiation (350–400 nm) provided by a low pressure mercury lamp (type TLC = thin-layer chromatography, 365 nm), or by a 23 W fluorescent bulb, or by ambient/sunlight. In water, a much poorer hydrogen atom donating solvent, the photoreduction of 1 proved inefficient. Interestingly, EPR studies revealed that complex 1 could nonetheless be effectively photoreduced in water when alkynes were present in solution. The catalytic activity of 1 for click reactions involving a range of water-soluble alkynes and azides, in particular saccharides, was tested under various illumination conditions. Complex 1 was found to exhibit a photolatent character, the photogenerated copper(I) being very reactive. On irradiating aqueous reaction mixtures containing 1 mol % of 1 at 365 nm (TLC lamp) for 1 h, click reactions were shown to proceed to full conversion.

scholarly journals Structure Analysis and Antioxidant Activity of a Novel Polysaccharide from Katan Seeds

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Imen Trabelsi ◽  
Sirine Ben Slima ◽  
Naourez Ktari ◽  
Mohamed Bouaziz ◽  
Riadh Ben Salah
Keyword(s):  
High Performance ◽  
Antioxidant Properties ◽  
Water Soluble ◽  
Uv Absorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
1H Nuclear Magnetic Resonance ◽  
Soluble Polysaccharide ◽  
Promising Source ◽  
Layer Chromatography

In the present work, a novel water-soluble polysaccharide (LWSP) was purified from Katan seeds. Polysaccharide was structurally characterized by NMR spectroscopic analysis, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD), and UV absorption. TLC and HPLC showed that LWSP was a polysaccharide consisted mainly of glucose, mannose, xylose, and arabinose. The FTIR spectrum and UV absorption proved polysaccharide characteristic of LWSP. According to XRD, LWSP presented a semicrystalline behavior. The molecular weight was estimated as 64.56 kDa. Results obtained through 13C and 1H nuclear magnetic resonance (NMR) indicated that LWSP is consisted of four monosaccharide residues with α and β anomers. Physicochemical and antioxidant properties of LWSP were also investigated. Results revealed that LWSP exhibited interesting 1,1-diphenyl-2-picrylhydrazyl (DPPH) ( I C 50 = 4.48  mg/ml) and chelating activity ( I C 50 = 4.79  mg/ml), and it displayed moderate reductive capacities. Overall, the findings suggested that LWSP is a promising source of natural additives in various industries fields.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Water soluble biguanide salts and their 1,3,5-triazine derivatives as inhibitors of acetylcholinesterase and α-glucosidase

2020 ◽  
Vol 235 (10) ◽  
pp. 465-475
Author(s):  
Ozge Gungor ◽  
Seda Nur Kertmen Kurtar ◽  
Muhammet Kose
Keyword(s):  
Spectroscopic Method ◽  
Substitute Aniline ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
Nucleophilic Reaction ◽  
X Ray ◽  
Triazine Derivatives ◽  
Acidic Conditions ◽  
Approved Drugs ◽  
Solid State Structures

AbstractSeven biguanide derivatives were prepared by the nucleophilic reaction between dicyandiamide and p-substitute aniline derivatives or memantine or adamantine under acidic conditions. The cyclization of the biguanide compounds were also conducted via acetone to give 1,3,5-triazine derivatives. The structures of the synthesized compounds were characterized by analytical methods. The solid state structures of [HL5]Cl, [H2L7]Cl2, [HL1a]Cl and [HL5a]Cl were investigated by X-ray diffraction study. The acetylcholinesterase and α-glucosidase inhibitor properties of the compounds were then evaluated by the spectroscopic method. The compounds were found to show considerable acetylcholinesterase and α-glucosidase inhibitory activities compared to the approved drugs. The cyclization of biguanide derivatives with acetone did not affect inhibition of acetylcholinesterase, yet increased the α-glucosidase inhibition.

scholarly journals Enhanced Water Solubility and Oral Bioavailability of Paclitaxel Crystal Powders through an Innovative Antisolvent Precipitation Process: Antisolvent Crystallization Using Ionic Liquids as Solvent

Pharmaceutics ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1008 ◽  
Author(s):  
Qilei Yang ◽  
Chang Zu ◽  
Wengang Li ◽  
Weiwei Wu ◽  
Yunlong Ge ◽  
...  
Keyword(s):  
Oral Bioavailability ◽  
High Performance ◽  
Water Solubility ◽  
Water Soluble ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Antisolvent Precipitation ◽  
Antisolvent Crystallization ◽  
Artificial Gastric Juice

Paclitaxel (PTX) is a poor water-soluble antineoplastic drug with significant antitumor activity. However, its low bioavailability is a major obstacle for its biomedical applications. Thus, this experiment is designed to prepare PTX crystal powders through an antisolvent precipitation process using 1-hexyl-3-methylimidazolium bromide (HMImBr) as solvent and water as an antisolvent. The factors influencing saturation solubility of PTX crystal powders in water in water were optimized using a single-factor design. The optimum conditions for the antisolvent precipitation process were as follows: 50 mg/mL concentration of the PTX solution, 25 °C temperature, and 1:7 solvent-to-antisolvent ratio. The PTX crystal powders were characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, high-performance liquid chromatography–mass spectrometry, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Raman spectroscopy, solid-state nuclear magnetic resonance, and dissolution and oral bioavailability studies. Results showed that the chemical structure of PTX crystal powders were unchanged; however, precipitation of the crystalline structure changed. The dissolution test showed that the dissolution rate and solubility of PTX crystal powders were nearly 3.21-folds higher compared to raw PTX in water, and 1.27 times higher in artificial gastric juice. Meanwhile, the bioavailability of PTX crystal increased 10.88 times than raw PTX. These results suggested that PTX crystal powders might have potential value to become a new oral PTX formulation with high bioavailability.

scholarly journals Enhancement of solubility and dissolution rate of poorly water soluble raloxifene using microwave induced fusion method

2013 ◽  
Vol 49 (3) ◽  
pp. 571-578 ◽  
Author(s):  
Payal Hasmukhlal Patil ◽  
Veena Sailendra Belgamwar ◽  
Pratibha Ramratan Patil ◽  
Sanjay Javerilal Surana
Keyword(s):  
Dissolution Rate ◽  
Hydroxypropyl Methylcellulose ◽  
Microwave Treatment ◽  
Water Soluble ◽  
Fusion Method ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Wetting Properties ◽  
Poorly Soluble ◽  
Poorly Water Soluble

The objective of the present work was to enhance the solubility and dissolution rate of the drug raloxifene HCl (RLX), which is poorly soluble in water. The solubility of RLX was observed to increase with increasing concentration of hydroxypropyl methylcellulose (HPMC E5 LV). The optimized ratio for preparing a solid dispersion (SD) of RLX with HPMC E5 LV using the microwave-induced fusion method was 1:5 w/w. Microwave energy was used to prepare SDs. HPMC E5 LV was used as a hydrophilic carrier to enhance the solubility and dissolution rate of RLX. After microwave treatment, the drug and hydrophilic polymer are fused together, and the drug is converted from the crystalline form into an amorphous form. This was confirmed through scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies. These results suggested that the microwave method is a simple and efficient method of preparing SDs. The solubility and dissolution rate of the SDs were increased significantly compared with pure RLX due to the surfactant and wetting properties of HPMC E5 LV and the formation of molecular dispersions of the drug in HPMC E5 LV. It was concluded that the solubility and dissolution rate of RLX are increased significantly when an SD of the drug is prepared using the microwave-induced fusion method.

scholarly journals Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound

2017 ◽  
Vol 13 ◽  
pp. 2138-2145 ◽  
Author(s):  
Joana M Pais ◽  
Maria João Barroca ◽  
Maria Paula M Marques ◽  
Filipe A Almeida Paz ◽  
Susana S Braga
Keyword(s):  
Inclusion Compound ◽  
Antioxidant Properties ◽  
Physicochemical Analysis ◽  
Water Soluble ◽  
Solid Inclusion ◽  
Human Consumption ◽  
X Ray Diffraction ◽  
Wide Range ◽  
Soluble Solid ◽  
Cp Mas Nmr

Fisetin is a natural antioxidant with a wide range of nutraceutical properties, including antidiabetic, neuroprotecting, and suppression or prevention of tumors. The present work describes the preparation of a water-soluble, solid inclusion compound of fisetin with gamma-cyclodextrin (γ-CD), a cyclic oligosaccharide approved for human consumption. A detailed physicochemical analysis of the product is carried out using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13C{1H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host–guest units. The antioxidant activity of the γ-CD·fisetin inclusion compound is evaluated by the DPPH assay.

scholarly journals SYNTHESIS OF AN AZIDE–THIOL LINKER FOR HETEROGENEOUS POLYMER FUNCTIONALIZATION VIA THE “CLICK” REACTION

2018 ◽  
Vol 55 (1B) ◽  
pp. 152
Author(s):  
Thuy Thu Truong
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Click Reaction ◽  
Proton Nuclear Magnetic Resonance ◽  
Reaction Yield ◽  
Reaction Conditions ◽  
Click Reactions ◽  
Heterogeneous Polymer ◽  
Ft Ir ◽  
First Time ◽  
Layer Chromatography

In this study, the synthesis of a telechelic linker bearing both azide and thiol functional groups was described. The reaction conditions were investigated to optimize the reaction yield. The product was analyzed using thin layer chromatography (TLC) and proton nuclear magnetic resonance (1H NMR). The employment of the obtained azide–thiol linker in heterogeneous polymer “click” functionalization was demonstrated for the first time, which was monitored by an online FT–IR method. The obtained telechelic azide–thiol linker is envisioned to be useful chemical tools to link macromolecular chains via orthogonal click reactions.

scholarly journals Engineering cocrystals of Paliperidone with enhanced solubility and dissolution characteristics

2021 ◽  
Vol 71 (5) ◽  
pp. 393-409
Author(s):  
Earle Radha-Rani ◽  
Gadela Venkata-Radha
Keyword(s):  
Benzoic Acid ◽  
Aqueous Solubility ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
X Ray ◽  
Water Soluble Drug ◽  
Novel Approach ◽  
Enhanced Solubility ◽  
Poorly Water Soluble ◽  
Poorly Water Soluble Drug

In the present study, co-crystals (CCs) of Paliperidone (PPD) with coformers like benzoic acid (BA) and P-amino benzoic acid (PABA) were synthesized and characterized to improve the physicochemical properties and dissolution rate. CCs were prepared by the solvent evaporation (SE) technique and were compared with the products formed by neat grinding (NG) and liquid assisted grinding (LAG) in their enhancement of solubility. The formation of CCs was confirmed by the IR spectroscopy, powder X-ray diffraction and thermal analysis methods. The saturation solubility studies indicate that the aqueous solubility of PPD-BA and PPD-PABA CCs was significantly improved to 1.343±0.162mg/ml and 1.964±0.452mg/ml, respectively, in comparison with the PPD solubility of 0.473mg/ml. This increase in solubility is 2.83-and 3.09-fold, respectively. PPD exhibited a poor dissolution of 37.8% in 60min, while the dissolution of the CCs improved tremendously to 96.07% and 89.65% in 60min. CCs of PPD with BA and PABA present a novel approach to overcome the solubility challenges of poorly water-soluble drug PPD.

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