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Methods of Phyto-Constituent Detection
Published in Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf, Fingerprinting Analysis and Quality Control Methods of Herbal Medicines, 2018
Ravindra Kumar Pandey, Shiv Shankar Shukla, Amber Vyas, Vishal Jain, Parag Jain, Shailendra Saraf
Salkowski test: When shaken with concentrated sulfuric acid, the lower layer of a chloroform solution of the test drug will turn yellow on standing.Lieberman–Burchard test: A chloroform solution of the test drug with a few drops of acetic acid and one mL of concentrated sulfuric acid produces a deep red at the junction of the 2 layers.Tschugajen test: A chloroform solution of the test drug with an excess of acetyl chloride and a pinch of zinc chloride, when warmed in a water bath, produces an Eosin red color.
Innovative industrial technology starts with iodine
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
Later, BP Chemicals Ltd. developed a Cativa catalyst (see the diagram) combining iodine and iridium. Under the Cativa method, acetic acid is produced by combining methanol and carbon monoxide. Methyl iodide (CH3I), acetyl chloride (CH3COCl), hydrogen iodide (HI), and iridium complex are formed as intermediates and have high reactivity, and efficiently produce acetic acid. The Cativa method, in comparison to the Monsanto method, requires less water in the reaction mixture, produces less acid, and uses simplified production facilities. Presently, most industrial acetic acid is produced using this method [33a,b].
Manual Methods for Protein/Peptide Sequence Analysis
Published in Ajit S. Bhown, Protein/Peptide Sequence Analysis: Current Methodologies, 1988
HPLC grade solvent is fine for most purposes: triethylamine (TEA) and dimethylformam-ide (DMF) from Aldrich, HFo from Baker, heptane and acetonitrile (MeCN) from Burdick and Jackson. Sequencing grade ethyl acetate (EA), TFA, and PITC are necessary for sequencing (Pierce and B & J, or repurify these reagents yourself). Good DMF and tert-amines can be made from yellowed stocks by redistillation (in vacuo if the bp is high) from a little succinic anhydride. Distill 100% ethanol (EtOH, Aaper Chemical) from NaOH. Good water can be purchased, but slow redistillation of house-distilled water from NaOH/KMnO4 (2 g each per 4.5 ϵ water, collect between 300 and 3500 mℓ) makes a product at least as free of interfering materials as commercial water. The buffer used in the partition method (see below) is made from 15 μℓ hexafluoroacetone trihydrate (HFA) and 22 μℓ 25% aqueous trimethylamine (TMA, both from Aldrich) per 5 mℓ of solvent, but the latter is rather variable in actual concentration, so the ratio required for dilute aqueous pH 7.2 should be empirically determined. Polybrene (Aldrich), used as a carrier in the film method, is purified by Edman cycling 10 to 20 mg in a 13 × 100 mm tube and precipitation from methanol with acetone, or by dialysis against dilute aqueous TFA using Spectrapor 3500 MW cutoff. About half the polymer is lost by either process, and the oligomer-free product, now the TFA salt, should be completely soluble in methanol. Anhydrous HCl/MeOH is made by dropwise addition sans stirring of redistilled acetyl chloride to MeOH at 0°C in a vertical 13 × 100 mm tube. Use a ratio of 0.3:3.9 for 1 N and 0.6:3.6 for 2 N; store at 0°C. The conversion reagent, concentrated HCl, and EA should be protected from development of oxidizing agents by addition of about 0.02% ethanethiol. Working stocks of all reagents and solvents should be small and replenished periodically from main reserves. TEA and PITC should be kept cold and removed under N2 barrier, and all reserves should be stored at 0°C.
Quantification of serum homoarginine, methylated arginine and inhibin-A levels in a high-risk pregnancy
Published in Journal of Obstetrics and Gynaecology, 2022
Hatice Banu Keskinkaya, Sedat Abuşoğlu, Ali Ünlü, Mehmet Nuri Atalar, Setenay Arzu Yilmaz
Serums stored in Eppendorf tubes at −80°C were kept at room temperature for thawing and then subjected to vortex for 3–5 s to obtain homogeneity. After, the stable-isotope labelled internal standard (d7-ADMA) dissolved in 100 μL methanol was added to 200 μL serum sample, settled proteins were removed by 10 min of centrifuge at 13,000 rpm. Then, the sample was taken in a supernatant another tube and evaporated at 60°C under nitrogen gas. 200 μL %5 (v v−1) butanol/acetyl chloride solution prepared fresh for derivatization was added in hot-water bath and maintained for incubation 60°C’ for 20 min. Then, the solvent was evaporated at 60 C under nitrogen gas. Dissolving process was done by 100 μL water–methanol (90:10, v v−1) containing 0.1% (v v−1) formic acid. 40 μL was injected into the analytic column.
Design and synthesis of naphthalimide group-bearing thioglycosides as novel β-N-acetylhexosaminidases inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Shengqiang Shen, Wei Chen, Lili Dong, Qing Yang, Huizhe Lu, Jianjun Zhang
As shown in Scheme 1, the key intermediate thiol 10 was obtained from N-acetyl-d-glucosamine as the starting material. In the procedure, acetyl chloride was first used for acetylation and chlorination. Thiourea was then used in substitution prior to removing carbamimidoyl by Na2S2O5 in DCM and H2O. These three steps can conveniently be carried out without chromatographic purification and has made large-scale preparation of compound 10 possible. Then, compound 10 was reacted with α,ω-dibromoalkane in the presence of potassium carbonate in acetone and H2O to obtain mono-bromide precursors 11a–11d. Meanwhile, 1,8-naphthalic anhydride 12 was refluxed with α,ω-diaminoalkane in ethanol to yield 13a–13c. Subsequently, the preparations of acetyl-protected compounds 14a–14l were completed by the reactions of bromides 11a–11d with excess naphthalimide derivatives 13a–13c under the condition of potassium carbonate and acetonitrile with 65–72% yield. Finally, deacetylation of hydroxyl groups by methanol-ammonia catalysis resulted in the target compounds 15a–15l.
Synthesis and pharmacological evaluation of novel isoquinoline N-sulphonylhydrazones designed as ROCK inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Ramon Guerra de Oliveira, Fabiana Sélos Guerra, Cláudia dos Santos Mermelstein, Patrícia Dias Fernandes, Isadora Tairinne de Sena Bastos, Fanny Nascimento Costa, Regina Cely Rodrigues Barroso, Fabio Furlan Ferreira, Carlos Alberto Manssour Fraga
In a 50 ml round bottom flask, 300 mg of 6 (0.7 mmol) was dissolved in 15 ml of dry ethanol. Then, 1.570 mg of acetyl chloride (14 mmol) was added drop wise to a stirred solution of the N-(tert-butoxycarbonyl)-protected sulphonylhydrazone (6) at room temperature. The mixture was stirred overnight and evaporated in vacuum to give the title compound as a pale yellow solid, which was recrystallized in methanol (156 mg, 63% yield); mp: 186 °C.1 H NMR (400 MHz, DMSO-d6) δ (ppm): 12.07 (s, 1H); 9.92 (s, 1H); 8.95 (d, J = 6 Hz, 1H); 8.88 (d, J = 6 Hz, 1H); 8.75 (d, J = 8 Hz, 1H); 8.65 (d, J = 8 Hz, 1H); 8.10 (t, J = 8 Hz, 1H); 7.30 (d, J = 4 Hz, 1H); 3.05–3.07 (m, 2H); 2.74–2.81 (m, 2H); 2.34–2.40 (m, 1H); 1.69–1.72 (m, 2H); 1.39–1.47 (m, 2H). 13C NMR (50 MHz, DMSO-d6) δ (ppm): 153.2; 152.6; 149.9; 136.8; 136.0; 134.5; 132.9; 128.9; 128.2; 121.0; 42.2; 35.5; 25.0. IR (ATR, cm−1): 2949; 2695; 1327; 1179. HRMS (ESI, m/z): calculated for [M + H]+ C15H18N4O2SH+, 319.1223, found 319.1223.