Crystalline arrays of side chain modified bile acids derivatives. Two novel self-assemblies based on π-π and belly-to-belly interactions

Self-Assembly of an Amphiphilic Bile Acid Dimer: A Combined Experimental and Theoretical Study of Its Medium-Responsive Fluorescence

This work describes the synthesis and aggregation behavior of a dimeric bile acid derivative in which two steroid cores are bridged by a p-di(phenylethynyl)phenylene fluorophore. The studied compound contains three key characteristics: (a) restricted conformational equilibrium in solution, (b) efficient fluorescence conferred by the bridge, and (c) medium responsiveness encoded in the steroid fragments. The incorporation of the three components afforded a compound that generates nano- and micrometric spherical particles with aggregation-responsive fluorescence emission. The observed self-assembly process of the featured molecule was induced by the gradual addition of water to the tetrahydrofuran (THF) solution. This aggregation led to significant changes in fluorescence that went from two bands at λ_em values of 370 and 390 nm in pure THF to a new spectrum with two maxima at λ_em values of 395 and 418 nm at high water contents, without a decrease in emission. The observed changes can be ascribed to weakly coupled aggregation, a hypothesis supported by multiscale molecular modeling, which sheds light on the mechanism of the self-assembly of this unconventional amphiphile.

A straightforward one-pot two-step conversion of bile acids into dehomologated alcohols

Irradiation of dichloroethane solutions of different bile acids with diacetoxy(iodobenzene) and iodine followed by treatment of the resulting raw mixture with MCPBA led to the 41-50% yields of the corresponding dehomologated alcohols in an uncomplicated one-pot protocol that can be completed in less than one day of work.

Application of palladium-catalyzed cross-coupling between bile acids and 2-furanylboronic acid to the synthesis of 24-(2'-furanyl)-24-oxo steroids

Palladium-catalyzed cross-coupling of bile acids with 2-furanylboronic acid produced steroid furanyl ketones in low yields. Unambiguous assignments of the NMR signals were made with the aid of combined 1D and 2D NMR techniques.

Fabrication of deoxycholic acid tethered α-cyanostilbenes as smart low molecular weight gelators and AIEE probes for bio-imaging

Four novel deoxycholic acid tethered α-cyanostilbenes were designed, synthesized and characterized using detailed spectroscopic analysis. The synthesized deoxycholic acid tethered α-cyanostilbene derivatives formed stable gels with a variety of solvents, such as xylene, toluene, mesitylene, decane, dodecane etc. The stable gels showed lamellar sheet type structures stacked over each other, consisting of entangled fibres as evident from SEM, TEM and Fluorescence Microscopy images; The synthesized compounds exhibited AIEE behaviour in H₂O/THF mixture, with the maximum emission observed in 70% H₂O/THF fraction along with a bathochromic shift. A solvent thickening experiment was perform to establish the mechanism of AIEE and the AIEE property was explored for bacterial bio-imaging. The synthesized derivatized steroids proved their potential as multifunctional organic materials.

Haemolytic activity of formyl- and acetyl-derivatives of bile acids and their gramine salts

Bile acids (lithocholic: LCA, deoxycholic: DCA and cholic: CA) and their formyl- and acetyl-derivatives can be used as starting material in chemical synthesis of compounds with different biological activity strongly depended on their chemical structures. Our previous studies showed that biological activity of bile acids salts with gramine toward human erythrocytes was significantly different from the activity of bile acids alone. Moreover, gramine effectively modified the membrane perturbing activity of other steroids. As a continuation of our work, the haemolytic activity of formyl- and acetyl-substituet bile acids as well as their gramine salts was studied in vitro. The structures of new compounds were confirmed by spectral (NMR, FT-IR) analysis, mass spectrometry (ESI-MS) as well as PM5 semiempirical methods. The results shown that the haemolytic activity of formyl- and acetyl-LCA and DCA was significantly higher in comparison with their native forms at the whole concentration range. At high concentration, formyl derivative of CA was as effective as LCA and DCA derivatives whereas at lower concentration its haemolytic activity was at the level of original acid. The acetyl-CA was not active as membrane perturbing agents. Furthermore, gramine significantly decreased the membrane-perturbing activity of hydrophobic bile acids derivatives. The results obtained with the cellular system are in line with physicochemical calculation.