Combined computational and experimental study on the inclusion complexes of β-cyclodextrin with selected food phenolic compounds

Phenolic compounds, such as caffeic acid, trans-ferulic, acid and p-coumaric acid that are commonly found in food products, are beneficial for human health. Cyclodextrins can form inclusion complexes with various organic compounds in which the physiochemical properties of the included organic molecules are changed. In this study, inclusion complexes of three phenolic compounds with β-cyclodextrin were investigated. The complexes were characterized by various analytical methods, including nuclear magnetic resonance (NMR) spectroscopy, Fourier IR (FT-IR) spectroscopy, mass spectrometry, differential scanning calorimetry, and scanning electron microscopy. Results showed that the phenolic compounds used in this study were able to form inclusion complexes in the hydrophobic cavity of β-cyclodextrin by non-covalent bonds. Their physicochemical properties were changed due to the complex formation. In addition, a computational study was performed to find factors that were responsible for binding forces between flavors and β-cyclodextrin. The quantum-mechanical calculations supported the results obtained from experimental studies. Thus, ΔH_f for the complex of p-coumaric acid and β-cyclodextrin has been found as ??11.72 kcal/mol, which was about 3 kcal/mol more stable than for inclusion complexes of other flavors. Energies of frontier orbitals (higher occupied molecular orbital (HOMO) and lower unoccupied molecular orbital (LUMO)) were analyzed, and it was found that H-L gap for the complex of p-coumaric acid and β-cyclodextrin had the largest value (8.19 eV) in comparison to other complexes, which confirmed the experimental findings of the most stabile complex.

     

Novel Method for the High-Yielding Synthesis of Steroidal Hydroxamic acid Derivatives

Steroidal 17-hydroxamic acid derivatives were synthesized in high yields in palladium-catalysed carbonylation reaction of 17-iodo-androst-16-ene derivatives under mild reaction conditions.     

Photoresponsive poly(methyl methacrylate)2–(polystyrene)2 miktoarm star copolymer containing an azobenzene moiety at the core

We prepared a novel miktoarm star copolymer with an azobenzene unit at the core via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated free radical polymerization (NMP) routes. For this purpose, first, mikto‐functional initiator, 3 , with tertiary bromide (for ATRP) and 2,2,6,6‐tetramethylpiperidin‐1‐yloxy (TEMPO) (for NMP) functionalities and an azobenzene moiety at the core was synthesized. The initiator 3 thus obtained was used in the subsequent living radical polymerization routes such as ATRP of MMA and NMP of St, respectively, to give A₂B₂ type miktoarm star copolymer, (PMMA)₂‐(PSt)₂ with an azobenzene unit at the core with controlled molecular weight and low polydispersity (M_w/M_n < 1.15). The photoresponsive properties of 3 and (PMMA)₂‐(PSt)₂ miktoarm star copolymer were investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1396–1403, 2006     

Structural,Morphological and Optical Properties of Well-Ordered CdO Nanostructures Synthesized by Easy-Economical Chemical Bath Deposition Technique

In this Study, Cadmium Oxide (CdO) nanostructures were synthesized by using Chemical Bath Deposition Technique. The synthesized process was carried out at room temperature. The structural and optical properties of nanostructures was characterized by XRD, SEM and UV-Vis techniques. As a result, the CdO nanostructures are oriented along (111) plane of cubic crystal structure. The morphology of CdO nanostructures showed interconnected prism-like and cauliflower-type cluster nanostructure. The UV results of this structures with high absorbtion coefficient are observed to be in accordance with the CdO nanoparticles.     

Synthesis and characterization of new cyclotriphosphazene compounds

In the present study, spiro (1a), dispiro (1b, 2, 3), per-substituted spermine-bridged (6–9) and dispiroansa spermine (10) derivatives of cyclotriphosphazene have been synthesized. The structures of the novel compounds (1b, 6–10) have been characterized by elemental analysis, FTIR, mass spectrometry, ¹H and ³¹P NMR spectroscopy. The molecular structures of 1b, 2, 8, and 10 were determined by single crystal X-ray crystallography. In order to investigate the anti-tumour properties of the newly synthesized cyclotriphosphazene derivatives, in vitro cytotoxic activity test (MTT assay) has been performed using HT-29 (human colon adenocarcinoma) and Hep2 (human epidermoid larynx carcinoma) cell lines. The result of the MTT assay showed that while compound 1a has cytotoxic effect on both Hep2 and HT-29 cell lines, compound 3 has only cytotoxic effect towards the Hep 2 cells.     

Ring opening metathesis polymerization (ROMP) of five- to eight-membered cyclic olefins: Computational,thermodynamic, and experimental approach

Ring opening metathesis polymerization (ROMP) of a series of low-strain cyclic olefins and their hydroxyl derivatives using second generation Hoveyda–Grubbs catalyst has been investigated. Additionally, density functional theory (DFT) calculations were performed to evaluate the ring strain energies of the cyclic olefins and their hydroxyl derivatives, coupled with kinetic studies for the ROMP reactions. It was found that among different ring size monomers, Cy8 having a relatively moderate ring strain energy in comparison with the other cyclic olefins, exhibited the highest monomer conversion. The effect of temperature (0, 10, 15, and 25 °C) and monomer concentration (1 M; 2.5 M and 5 M for Cy5 ; and 1 M and 5 M for Cy7 ) for the cyclic olefins Cy5 and Cy7 were investigated. In general, the experimental results for the kinetic ROMP studies obtained using complex HG2 correlate really well with the DFT calculations determined for the ring strain energies of the cyclic olefins. For comparison, DFT calculations predicted the following trend for the ring strain energies Cy8 > Cy5 > Cy7 > Cy6 , and the polymerizations carried out experimentally followed the same trend in terms of monomer conversion, with the exception of Cy5 and Cy7 at lower concentrations, which followed this trend Cy8 > Cy7 > Cy5 > Cy6 . © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3137–3145     

Comparative Metabolite Fingerprinting of Four Different Cinnamon Species Analyzed via UPLC–MS and GC–MS and Chemometric Tools

The present study aimed to assess metabolites heterogeneity among four major Cinnamomum species, including true cinnamon (Cinnamomum verum) and less explored species (C. cassia, C. iners, and C. tamala). UPLC-MS led to the annotation of 74 secondary metabolites belonging to different classes, including phenolic acids, tannins, flavonoids, and lignans. A new proanthocyanidin was identified for the first time in C. tamala, along with several glycosylated flavonoid and dicarboxylic fatty acids reported for the first time in cinnamon. Multivariate data analyses revealed, for cinnamates, an abundance in C. verum versus procyandins, dihydro-coumaroylglycosides, and coumarin in C. cassia. A total of 51 primary metabolites were detected using GC-MS analysis encompassing different classes, viz. sugars, fatty acids, and sugar alcohols, with true cinnamon from Malaysia suggested as a good sugar source for diabetic patients. Glycerol in C. tamala, erythritol in C. iners, and glucose and fructose in C. verum from Malaysia were major metabolites contributing to the discrimination among species.     

Synthesis and characterization of magnetic nanocomposite for in vitro evaluation of irinotecan using human cell lines

In this study, magnetic O-carboxymethyl chitosan (MOCC) nanocomposite was synthesized and characterized as a drug delivery system for loading the anticancer drug irinotecan (CPT-11). To increase the drug loading capacity, MOCC was synthesized by linking the carboxyl group functionally to chitosan. Also, several critical factors such as concentration, the dose of MOCC, and contact time for optimum drug loading condition were investigated. The loading capacity of CPT-11 onto MOCC was calculated as 5.6 mg/g, and the loaded drug concentration was calculated as 0.04787 mM at pH value of 5. Besides, the cytotoxic properties of MOCC, CPT- 11 loaded MOCC (MOCC-CPT-11), and free CPT-11 were studied on glioblastoma multiforme cell lines, including U87 and U373. According to the results, the MOCC-CPT-11 showed at least as toxic effect as free CPT-11 even at very low concentrations, while the MOCC showed slight toxicity (cell viability of 96% to 78%) on U373 cell lines at all concentrations and for 24 h and 48 h incubation times. Moreover, the results showed that the MOCC indicated significant toxicity in increasing concentrations and incubation times, and the MOCC-CPT-11 is as toxic as free CPT-11 on U87 cells at all concentrations and incubation times.     

Electrocatalytic Reduction of Oxygen at Glassy Carbon Electrodes Coated with Diazonium‐derived Porphyrin/Metalloporphyrin Films

In this study, the influence of the film structure was investigated on the electrocatalytic oxygen reduction at GC electrodes covered with porphyrin and metalloporphyrin rings via the diazonium modification method. For that purpose, primarily, tetraphenylporphyrin (TPP) films on GC electrode surfaces were prepared by electroreduction of in situ generated diazonium salts of 5‐(4‐aminophenyl)‐10,15,20‐triphenylporphyrin (APP) and 5,10,15,20‐tetrakis(4‐aminophenyl)porphyrin (TAPP) molecules. Next, the formation of metalloporphyrin films on the modified surfaces was accomplished through the complexation reactions of surface porphyrin rings with metal ions in the salt solutions containing Mn(II), Fe(III) and Co(II) ions. The resulting porphyrin and metalloporphyrin layers were identified with XPS and ICP‐MS. The electrochemical barrier properties of the films on GC surfaces were examined by cyclic voltammetry in K₃Fe(CN)₆ aqueous solution. The electrocatalytic abilities of the resulting films were also investigated for the oxygen electrochemical reduction by employing cyclic voltammetry in PBS solutions saturated with oxygen. The results showed that the oxygen reduction potentials on modified GC electrodes were shifted to less negative potentials compared to that of bare GC electrode. Also, it was obtained that the oxygen reduction reaction was more effective on the GC electrodes modified with TPP rings by using TAPP molecules than those prepared by using APP molecules.     

Effects of Lipid-Based Encapsulation on the Bioaccessibility and Bioavailability of Phenolic Compounds

Phenolic compounds (quercetin, rutin, cyanidin, tangeretin, hesperetin, curcumin, resveratrol, etc.) are known to have health-promoting effects and they are accepted as one of the main proposed nutraceutical group. However, their application is limited owing to the problems related with their stability and water solubility as well as their low bioaccessibility and bioavailability. These limitations can be overcome by encapsulating phenolic compounds by physical, physicochemical and chemical encapsulation techniques. This review focuses on the effects of encapsulation, especially lipid-based techniques (emulsion/nanoemulsion, solid lipid nanoparticles, liposomes/nanoliposomes, etc.), on the digestibility characteristics of phenolic compounds in terms of bioaccessibility and bioavailability.