Transformations of Griseofulvin in Strong Acidic Conditions – Crystal Structures of 2′-Demethylgriseofulvin and Dimerized Griseofulvin

The structure of griseofulvic acid, C16H15ClO6, at 100 K has orthorhombic (P21212) symmetry. It is of interest with respect to biological activity. The structure displays intermolecular O–H···O, C–H···O hydrogen bonding as well as week C–H···π and π ···π interactions. In strong acidic conditions the griseofulvin undergoes dimerization. The structure of dimerized griseofulvin, C34H32Cl2O12·C2H6O·H2O, at 100 K has monoclinic (P21) symmetry. The molecule crystallized as a solvate with one ethanol and one water molecule. The dimeric molecules form intermolecular O–H···O hydrogen bonds to solvents molecules only but they interact via week C–H···O, C–H···π, C–Cl···π and π···π interactions with other dimerized molecules.

Biochemistry of anionic calix[n]arenes

This review treats the biological properties of the various anionic calix[n]arenes, both as soluble forms and in the colloidal state. The complexation of these molecules with amino-acids, peptides and proteins is discussed, as is their interaction with model membranes. The complexations with various Active Pharmaceutical Ingredients as complexes, for tamoxifen as solid state and colloidal structures, are treated in depth. Two sections deal with the direct biological action of the calix[n]arenes and their use as biosensors. A final section deals with the toxicity, in reality the lack of toxicity of the calix[n]arenes.

Paraquat detoxification with p-sulfonatocalix-[4]arene by a pharmacokinetic study

The p-sulfonatocalix[n]arenes are supposed to show potential application in the clinical treatment of viologen poisoning. In the present study, p-sulfonatocalix[4]arene (C4AS), the most common derivative of p-sulfonatocalix[n]arenes, is used to study the antidotic mechanism for paraquat (PQ) by pharmacokinetics in vivo. A high-performance liquid chromatography (HPLC) method was established to determine the concentration of PQ in rat plasma. The results showed that the peak plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC(0-t)) were significantly lower after C4AS intervention than in the PQ intoxication group. It was considered that C4AS has great effective detoxication to PQ poisoning, and the results of in vitro intestinal absorption studies showed that C4AS can inhibit the absorption of PQ via oral administration by forming a stable inclusion constant.

Multistimuli responsive supramolecular vesicles based on the recognition of p-Sulfonatocalixarene and its controllable release of doxorubicin

We report the novel construction of nanosupramolecular binary vesicles based on host-guest complex formation between p-sulfonatocalix[4]arene and asymmetric viologen, which was identified by UV-vis and fluorescence spectroscopy, dynamic laser scattering, transmission electron microscopy, scanning electron microscopy, and surface tension experiments. The critical aggregation concentration of asymmetric viologen decreases pronouncedly by a factor of ca. 1000 owing to the complexation of p-sulfonatocalix[4]arene. Furthermore, we have demonstrated that the resulting vesicles can respond to multiple external stimuli, including temperature, host-guest inclusion, and redox. Methods of warming and inclusion of cyclodextrins were then employed to disrupt the vesicle architecture to release hydrophilic doxorubicin from the interior of the vesicle. Finally, cell experiments were performed to evaluate the cellular toxicity of the supramolecular binary vesicle and the anticancer efficiency of doxorubicin-loaded vesicle.

Use of Electrospray Mass Spectromtery to Study the Interactions between Para-Sulphonato-Calix[4]Arene and a Series of Serum Albumin Proteins

The binding of para-Sulphonato-calix[4]arene to a series of Serum Albumin Proteins has been studied using Electrospray Mass Spectrometry, each protein shows different capacities to interact with para-Sulphonato-calix[4]arene, including the number of ligands bound, the Association Constants observed, and the stoichiometries at which the onset of each binding event is observed.

Solid-state interactions of calixarenes with biorelevant molecules

Among all crystalline complexes of calix-type calix[n]arenes those with organic molecules which are biologically relevant are especially of interest due to their potential medical and pharmaceutical applications. The co-crystallization of drugs with water-soluble calixarenes offers the opportunity to modify chemical and physical properties of APIs (active pharmaceutical ingredients) and to control drug conformation. Such co-crystallization can improve solubility, bioavailability and stability of pharmaceutically active molecules and/or eliminate polymorphism. In this article the solid-state interactions between calixarene hosts and biologically relevant guest molecules are summarized for the currently available structures solved by single-crystal X-ray crystallography.