The application of biopolymers in tissue engineering is of a great interest due to of their inherent properties such as cell adhesion, biodegradation, bioavailability, and viscoelasticity. In this study, we synthesized cryogels based on biopolymers of gelatin, chitosan, and chondroitin sulfate by cryopolymerization and studied the effect of chondroitin sulfate on changing the physicochemical properties of cryogels such as pore size, pore volume, density, gel fraction, and biodegradation. A macroporous surface of the synthesized polymers has been investigated by SEM. The glass transition temperatures of the crosslinked cryogels, determined by the DSC method, were higher compared to that of the non-crosslinked cryogel used as a reference. The results of the MTT test showed that aqueous extracts of the prepared cryogels had no toxic effect on rat adipose-derived mesenchymal stem cells. The research in this area is of great importance and provides new insights into novel, effective methods for obtaining biopolymers that can be used as carriers of cells.
Glycosylthiourea derivatives were synthesized from the alkaloids cytisine and anabasine and 1-deoxy-2,3,4,6-tetra-O-acetyl-E-D-glucopyranosylisothiocyanate. The structures of the synthesized compounds were proved using PMR spectroscopy, mass spectrometry, and an x-ray crystal structure analysis.Most thiourea derivatives are known to exhibit valuable pharmacological properties and are used as antituberculosis, antimicrobial, anti-ulcer, and other therapeutically active agents [1,2]. Thiourea derivatives containing natural biologically active compounds in their structure are especially interesting.In continuation of our research on the synthesis of various polyfunctional thiourea derivatives based on the alkaloids cytisine and anabasine [3][4][5][6], the preparation of glycosyl-containing thiourea derivatives of these alkaloids was planned because it is known that introducing biologically active compounds into the structure reduces sharply their toxicity, increases the water solubility, and prolongs the action of the drugs [7]. One of the oldest methods for synthesizing N-glycosylthioureas is the Fischer isothiocyanate method [8] based on the reaction of acetyl-substituted glycosylisothiocyanates with amines. A convenient preparative method for synthesizing the starting glycosylisothiocyanates, in addition to the method developed at the start of the last century by Fischer (from the corresponding glycosylbromides and silver thiocyanate), involves nucleophilic substitution of glycosylhalides by potassium thiocyanate under phase-transfer catalysis conditions in the presence of quaternary ammonium salts as proposed by Tashpulatov et al. [9]. Because the starting silver thiocyanate was expensive, the cheaper and more available lead thiocyanate was used to synthesize glycosylisothiocyanates [10]. Also, glycosylisothiocyanates were prepared in a melt of the starting glycosylbromides and potassium thiocyanate [11].We synthesized tetra-O-acetyl-D-D-glucopyranosylbromide (acetobromoglucose, ABG) by a simplified method developed by us that differed markedly from that described before [12] in order to prepare glycosylthiourea derivatives of several alkaloids. The method is classical for its simplicity and higher yields and purities. The resulting ABG (1) underwent a substitution reaction with a 1.5-fold excess of lead thiocyanate.
Three-component condensation of fullerene C 60 with sarcosine and 4-(4-bromo-3,5-dimethyl-1H-pyrazol-1-yl)benzaldehyde under the conditions of the Prato reaction has afforded new fulleropyrrolidine; the product structure has been confirmed by IR and NMR spectroscopy as well as mass spectrometry.
In recent years the functionalization of the fullerene moiety based on Prato reaction [1, 2] is a widely used approach to the synthesis of fullerene derivatives for obtaining new materials and bioactive compounds. Availability of aldehydes allows to synthesize a number of dyad and triad donor-acceptor dyes and to investigate their biochemical and photophysical properties [3,4].In this work we synthesized two new 4-aminosubstituted aromatic aldehydes and performed their condensation with fullerene C 60 . 4-Amino-substituted aromatic aldehydes I and II were obtained by reacting morpholine and piperidine with fluorobenzaldehyde under microwave irradiation in the presence of a specially prepared catalyst supported on Silpearl silica activated with potassium carbonate as described in [5] (Scheme 1).Reaction of C 60 with N-methylglycine (sarcosine) and 4-N-aminobenzaldehydes I and II in refluxing toluene under an argon atmosphere for 4 h resulted in the formation of N-methyl-1-(4-aminophenyl)fullero-C 60 [1,9]pyrrolidines III and IV in the yield of 88 and 62%, respectively (Scheme 2).The target compounds III and IV were isolated by column chromatography on SiO 2 , eluting sucsessively with toluene and pyridine. The structure of III and IV was confirmed by 1 H and 13 C NMR spectroscopy and mass spectrometry.The obtained new fulleropyrrolidines are of interest as potential bioactive compounds.N-Methyl-1-(4-morpholinophenyl)fullero-C 60 -[1,9]pyrrolidine (III). To a solution of 40 mg (0.0555 mmol) of fullerene С 60 in 40 mL of toluene was added 5.3 mg (0.0277 mmol) of 4-morpholyl-
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