Preparation and optimization of water-soluble cationic sago starch with a high degree of substitution using response surface methodology

Modification and characterizations of cationic sago starch with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) prepared via etherification reaction was reported in this study. The optimization of cationic sago starch modification was performed by utilizing the combination of response surface methodology and central composite design (RSM/CCD). The effect of each variable and the interaction between the three variables, the concentration of CHPTAC, concentration of the catalyst NaOH, and the reaction times on the degree of substitution (DS) of the product were investigated and modeled. Moderate conditions were employed and a water-soluble cationic sago starch with high DS value was obtained. Based on RSM, the highest DS = 1.195 was obtained at optimum conditions: 0.615 mol of CHPTAC concentration (CHPTAC/SS = 5), 30% w/v NaOH, and 5 h reaction time, at 60 °C reaction temperature. Furthermore, the cationic sago starch was characterized using Fourier transform infrared spectroscopy, FTIR, X-ray diffraction, XRD, and field emission scanning electron microscopy, FESEM

Synthesis and in vitro bioactivity evaluation of new glucose and xylitol ester derivatives of 5- aminosalicylic acid

New glucose and xylitol esters of 5-amino salicylic acid (5-ASA) were synthesized followed by evaluation of their in vitro antimicrobial, anti-cancer and anti-inflammatory activities. The results of the antimicrobial activity assessment revealed that the new final esters were more effective against Gram-negative as well as Gram-positive bacteria than the original drug. Furthermore, the new final products were confirmed by a cytotoxicity assay over HT-29 and 3T3 cell lines to be less toxic for normal cells compared to the initial drug. On the other hand, however, their suppressive effect against cancerous cells was somewhat lower. Meanwhile, the anti-inflammatory activity assay over a RAW264.7 macrophage cell line demonstrated that the NO inhibition activity of the conjugated drug to the previously mentioned saccharides, especially to glucose, has slightly improved compared to the non-conjugated drug. Finally, in silico screening was also performed in order to predict the potential interactions and binding energy of the novel products against cyclooxygenase (COX-1/COX-2) and lipoxygenase (5-LOX) proteins. Findings indicated that the new products had greater hydrogen bonds and binding affinities with the active sites of proteins towards 5-ASA

Exploring the Potential of a Highly Scalable Metal-Organic Framework CALF-20 for Selective Gas Adsorption at Low Pressure

In this study, the ability of the highly scalable metal-organic framework (MOF) CALF-20 to adsorb polar and non-polar gases at low pressure was investigated using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The results from the simulated adsorption isotherms revealed that the highest loading was achieved for SO2 and Cl2, while the lowest loading was found for F2 molecules. The analysis of interaction energies indicated that SO2 molecules were able to form the strongest adsorbent-adsorbate interactions and had a tight molecular packing due to their polarity and angular structure. Additionally, Cl2 gas was found to be highly adsorbed due to its large van der Waals surface and strong chemical affinity in CALF-20 pores. MD simulations showed that SO2 and Cl2 had the lowest mobility inside CALF-20 pores. The values of the Henry coefficient and isosteric heat of adsorption confirmed that CALF-20 could selectively adsorb SO2 and Cl2. Based on the results, it was concluded that CALF-20 is a suitable adsorbent for SO2 and Cl2 but not for F2. This research emphasizes the importance of molecular size, geometry, and polarity in determining the suitability of a porous material as an adsorbent for specific adsorbates

Elucidating the aromatic properties of covalent organic frameworks surface for enhanced polar solvent adsorption

Covalent organic frameworks (COFs) have a distinguished surface as they are mostly made by boron, carbon, nitrogen and oxygen. Many applications of COFs rely on polarity, size, charge, stability and hydrophobicity/hydrophilicity of their surface. In this study, two frequently used COFs sheets, COF-1 and covalent triazine-based frameworks (CTF-1), are studied. In addition, a theoretical porous graphene (TPG) was included for comparison purposes. The three solid sheets were investigated for aromaticity and stability using quantum mechanics calculations and their ability for water and ethanol adsorption using molecular dynamics simulations. COF-1 demonstrated the poorest aromatic character due to the highest energy delocalization interaction between B–O bonding orbital of sigma type and unfilled valence-shell nonbonding of boron. CTF-1 was identified as the least kinetically stable and the most chemically reactive. Both COF-1 and CTF-1 showed good surface properties for selective adsorption of water via hydrogen bonding and electrostatic interactions. Among the three sheets, TPG’s surface was mostly affected by aromatic currents and localized π electrons on the phenyl rings which in turn made it the best platform for selective adsorption of ethanol via van der Waals interactions. These results can serve as guidelines for future studies on solvent adsorption for COFs materials

Efficacy of Afatinib in the treatment of patients with non-small cell lung cancer and head and neck squamous cell carcinoma: a systematic review and meta-analysis

Several randomized controlled trials (RCTs) evaluated the afatinib efficacy in patients with advanced non-small cell lung cancer (NSCLC) and recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). This review systemically outlined and meta-analyzed the afatinib efficacy in NSCLC and R/M HNSCC in terms of overall survival (OS) and progression-free survival (PFS) endpoints. Records were retrieved from PubMed, Web of Science, and ScienceDirect from 2011 to 2020. Eight afatinib RCTs were included and assessed for the risk of bias. In meta-analysis, overall pooled effect size (ES) of OS in afatinib group (AG) significantly improved in all RCTs and NSCLC-RCTs [hazard ratios (HRs): 0.89 (95% CI: 0.81–0.98, p = 0.02); I2 = 0%, p = 0.71/ 0.86 (95% CI: 0.76–0.97; p = 0.02); I2 = 0%, p = 0.50, respectively]. ES of PFS in AG significantly improved in all RCTs, NSCLC-RCTs, and HNSCC-RCTs [HRs: 0.75 (95% CI: 0.68–0.83; p < 0.00001); I2 = 26%, p = 0.24; 0.75 (95% CI: 0.66–0.84; p < 0.00001); I2 = 47%, p = 0.15/0.76 (95% CI: 0.65–88; p = 0.0004); I2 = 34%, p = 0.0004, respectively]. From a clinical viewpoint of severity, interstitial lung disease, dyspnea, pneumonia, acute renal failure, and renal injury were rarely incident adverse events in the afatinib group. In conclusion, first- and second-line afatinib monotherapy improved the survival of patients with NSCLC, while second-line afatinib monotherapy could be promising for R/M HNSCC. The prospective protocol is in PROSPERO (ID = CRD42020204547)

Synthesis of Nagstatin and its Analogues

Nagstatin is a naturally occurring carbohydrate mimic with glycosidase inhibiting properties. It was isolated from the fermentation broth of Streptomyces amakuensis and was shown to be specific inhibitor of N-acetyl-~-D-glucosaminidase.1 The aims of the described study were to establish an efficient and versatile approach towards the synthesis of nagstatin that would be applicable for a rapid synthesis ofa library of nagstatin analogues. In the initial approach, a key lactam intermediate was generated via ring-closing metathesis of an amide, which was derived from both enantiomers of methionine. An Nisoxazolylmethyl group served the dual purpose of protecting group and as a direct precursor of the imidazole unit. Unfortunately, suitable conditions for the transformation of the resulting ~-ketonitrile into the desired fused piperidine-imidazole were not found. In the next approach, a protected, optically active, vinylglycinol derivative was prepared in 6 steps from L-methionine via sulfi1imine elimination and converted into an unsaturated lactam intermediate via ring-closing metathesis. Elaboration into the fullyfunctionalized lactam ofnagstatin was envisaged but not performed. A gluco-analogue of the fully-functionalized lactam was later synthesized in 6 steps from sorbyl alcohol via tethered aminohydroxylation, cross metathesis, dihydroxylation and base-induced cyclization. Finally, a key unsaturated lactam intermediate was accessed via Pd-catalyzed decarboxylative carbonylation of 5-vinyloxazolidinone at low pressure on N-tosyl protection. Directed epoxidation attempted on a homoallylic alcohol with mCPBA later resulted in the almost exclusive formation of the trans-epoxy alcohol. Directed dihydroxylation attempted on the resulting allylic alcohol failed and the diol was recovered as a lactone on hydrolysis or thiolysis ofthe osmate ester.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A Focused Review of Synthetic Applications of Lawesson’s Reagent in Organic Synthesis

Lawesson’s reagent (LR) is a well-known classic example of a compound with unique construction and unusual chemical behavior, with a wide range of applications in synthetic organic chemistry. Its main functions were rounded for the thionation of various carbonyl groups in the early days, with exemplary results. However, the role of Lawesson’s reagent in synthesis has changed drastically, and now its use can help the chemistry community to understand innovative ideas. These include constructing biologically valuable heterocycles, coupling reactions, and the thionation of natural compounds. The ease of availability and the convenient usage of LR as a thionating agent made us compile a review on the new diverse applications on some common functional groups, such as ketones, esters, amides, alcohols, and carboxylic acids, with biological applications. Since the applications of LR are now diverse, we have also included some new classes of heterocycles such as thiazepines, phosphine sulfides, thiophenes, and organothiophosphorus compounds. Thionation of some biologically essential steroids and terpenoids has also been compiled. This review discusses the recent insights into and synthetic applications of this famous reagent from 2009 to January 2021

A focused review of synthetic applications of Lawesson’s reagent in organic synthesis

Lawesson’s reagent (LR) is a well-known classic example of a compound with unique construction and unusual chemical behavior, with a wide range of applications in synthetic organic chemistry. Its main functions were rounded for the thionation of various carbonyl groups in the early days, with exemplary results. However, the role of Lawesson’s reagent in synthesis has changed drastically, and now its use can help the chemistry community to understand innovative ideas. These include constructing biologically valuable heterocycles, coupling reactions, and the thionation of natural compounds. The ease of availability and the convenient usage of LR as a thionating agent made us compile a review on the new diverse applications on some common functional groups, such as ketones, esters, amides, alcohols, and carboxylic acids, with biological applications. Since the applications of LR are now diverse, we have also included some new classes of heterocycles such as thiazepines, phosphine sulfides, thiophenes, and organothiophosphorus compounds. Thionation of some biologically essential steroids and terpenoids has also been compiled. This review discusses the recent insights into and synthetic applications of this famous reagent from 2009 to January 2021

Anticancer activity and high content screening of New 6 substituted-5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazoline derivatives

Pursuing our interest in bioactive heterocyclic compound, two benzoimidazoquinazoline derivatives were synthesised using both microwave-assisted and classical heating methods. Structures of the compounds were confirmed by standard spectroscopic methods and elemental analysis. The target scaffolds were incidentally found to emit blue light when exposed to ultraviolet light. Consequently, a photoluminescence characterization was carried out as a part of characterization protocol. The anticancer activities of the benzimidazoquinazoline compounds were investigated using both methylthiazol tetrazolium (MTT) and the high content screen (HCS) assays against liver hepatocellular cells. The results showed a significant reduction in the inhibitory concentration of the cancer cells by 1 and 2.6 fold when exposed to compounds (3a) and (3b), respectively. The high content screen (HCS) was conducted for compound (3b) and the results showed high toxicity towards the cancer cells

Tetrabutylammonium Bromide (TBABr)-Based Deep Eutectic Solvents (DESs) and Their Physical Properties

Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES