Search results for "Lode"

Mononuclear rearrangements of heterocycles in water/β-CD: information on the real site of reaction from structural modifications of substrates and fr…

2007

Abstract The effect of β-cyclodextrin (β-CD) on the reactivity in the base-catalyzed pathway for the rearrangement in water of some ( Z )-hydrazones of 3-benzoyl-1,2,4-oxadiazoles ( 1b – f ) into the relevant triazoles ( 2b – f ) was investigated, finding different behavior as a function of the proton concentration. ESIMS and 1 H NMR data evidence the formation of host – guest complexes. The whole of the experimental and calculated (MM2) data enabled us to draw some intriguing conclusions concerning the influence of the structures of the substrates and the nature of the formed host – guest complexes on the real site of the reaction.

Spectrophotometric study on the thermodynamics of binding of α- and β-cyclodextrin towards some p-nitrobenzene derivatives

2003

Binding properties of native alpha- and beta-cyclodextrin towards some nitrobenzene derivatives have been studied by means of UV-vis spectrophotometry. The former host is able to form complexes having 1 : 1 and 1 : 2 stoichiometric ratios with these guests, while only 1 : 1 complexes are detected with the latter host. A careful analysis of the thermodynamic parameters for complexation equilibria, under the perspective of the enthalpy-entropy compensation effect, reveals that binding abilities of the two different hosts are subject to different features.

Cyclodextrins: heterocyclic molecules able to perform chiral recognition (Part II)

2006

The present paper collects the most significant advances appeared since late 1998 up to June 2005 in the field of applications of natural and modified cyclodextrins as chiral selectors, with particular regard for pharmaceuticals and natural products.

Binding porperties of hetpakis-(2,6-di-O-methyl)-beta-cyclodextrin and mono-(3,6-anydro)-beta-cyclodextrin

Tworzenie kompleksów inkluzyjnych pomiędzy 5-fluorouracylem a β-cyklodekstrynami

2017

Celem przedstawionego opracowania jest omówienie najważniejszych zagadnień dotyczących chemioterapii z użyciem 5-fluorouracylu, jego metabolizmu oraz zagrożenia wynikające z leczenia tym chemioterapeutykiem. Poruszona została również kwestia możliwości ograniczenia toksyczności 5FU, przez zainkludowaniu go we wnętrzu molekuły β-cyklodekstryny. Przedstawiono również najważniejsze wyniki badań teoretycznych w których przedstawiono geometrię kompleksu inkluzyjnego 5FU⎼βCD. Struktura została zoptymalizowana na poziomie teorii funkcjonału gęstości (DFT) z użyciem metody B3LYP/6-31G. Wykazano istnienie przynajmniej jednego wiązania wodorowego pomiędzy grupą aminową 5FU, a grupą hydroksylową powie…

Structural Features of β-Cyclodextrin Solvation in the Deep Eutectic Solvent, Reline

2020

The inherently amphiphilic nature of native cyclodextrins (CDs) determines their peculiar molecular encapsulation features, enabling applications such as targeted drug nanodelivery, aroma protection, etc. On the contrary, it may also lead to poor solubility in water and other organic solvents and to potentially detrimental flocking in these media, thus posing limitations to more extensive usage. Here we use small angle X-ray scattering to show that deep eutectic solvent reline (1:2 choline chloride:urea) succeeds in dissolving large amounts of beta-CD (at least 800 mg/mL, compared with the solubility in water of 18 mg/mL), without aggregation phenomena occurring. At the microscopic level, m…

CCDC 1022517: Experimental Crystal Structure Determination

2015

Related Article: Khaleel I. Assaf, Merve S. Ural, Fangfang Pan, Tony Georgiev, Svetlana Simova, Kari Rissanen, Detlef Gabel, Werner M. Nau|2015|Angew.Chem.,Int.Ed.|54|6852|doi:10.1002/anie.201412485

Preparation and physico-chemical study of inclusion complexes between idebenone and modified beta-cyclodextrins

1996

The inclusion properties of modifiedβ-cyclodextrins (trimethyl-β-cyclodextrin, dimethyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin) towards idebenone were compared with naturalβ-cyclodextrin. The inclusion complexes were prepared by different methods (coprecipitation, kneading, and freeze-drying) and characterized by differential scanning calorimetry, X-ray diffractometry, UV, CD and NMR spectroscopy. The results obtained by CD and NMR spectroscopy indicate a different orientation of idebenone in dimethyl-β-cyclodextrin with respect to other cyclodextrins. Stability constants of the complexes were determined in water at various temperatures and consequently thermodynamic parameters wer…

Sūnu kārpvardes Theloderma corticale mazuļu dzimuma attiecību atšķirības

2017

Rīgas Nacionālajā Zooloģiskajā dārzā (turpmāk - RNZD) tiek pavairotas vairākas aizsargājamas abinieku sugas, tai skaitā sūnu kārpvarde (turpmāk - T. corticale). Laika posmā no 1998. gadam līdz 2001. gadam RNZD metamorfozi bija izgājušas 245 sūnu kārpvardes. Tikai viena no šīm vardēm bija mātīte. Tiek uzskatīts, ka varžu dzimumu nosaka gēni, taču vairāki pētījumi ir pierādījuši, ka ir vairākas varžu sugas, kuru dzimuma veidošanos ietekmē ārējie apstākļi, piemēram, kā temperatūra. Sūnu kārpvardes kurkuļi, pēc izšķilšanās, tika sadalīti vairākās plastmasas bļodās, kur tiem tika mainīti ārējie apstākļi kā temperatūra, pH un barība. Iegūtie rezultāti tika apkopoti un salīdzināti viens ar otru, l…

Special Issue: Improvements for Resveratrol Efficacy

2017

International audience; Resveratrol is a well-known phenolic stilbene because of its presence in several edible plants and its proposed properties that are beneficial to human health [...].