Study of molecular complexation of glycyrrhizic acid with chloramphenicol by electrospray ionization mass spectrometry.

CONTEXT: Glycyrrhizic acid (GA) is a triterpene glycoside representing the main active component of licorice root extract obtained from plants of the Glycyrrhiza glabra L. and widely used as a complex-forming agent for the synthesis of new transport forms of the well-known drugs. AIMS: For the first time, the complexation of GA with chloramphenicol antibiotic (ChlA) was investigated by electrospray ionization mass spectrometry (ESI MS). SUBJECTS AND METHODS: ESI MS was utilized in order to determine the composition and evaluate the stability of complexes of the GA and ChlA. The validation of the complex formation was confirmed by ultraviolet/visible and infrared (IR) spectroscopy. RESULTS: MS data confirmed the noncovalent interactions between chloramphenicol and GA. Formation of the host: guest complexes of GA and chloramphenicol with the ratio 1:1 and 2:1 were registered in the negative ion mode. Binding of GA and ChlA was accompanied by changes in absorbance and IR spectrum of ChlA indicating the complex formation of these compounds. CONCLUSIONS: The research results confirmed the considerable potential of ESI MS as a technique for simple and fast detection of formation of the complexes of GA and the well-known drugs.

Study of an Acid-Free Technique for the Preparation of Glycyrrhetinic Acid from Ammonium Glycyrrhizinate in Subcritical Water.

The aim of this work was to study an application of a previously developed expedient acid-free technique for the preparation of glycyrrhetinic acid from ammonium glycyrrhizinate that requires no use of acids and toxic organic solvents. Subcritical water that serves as a reactant and a solvent was used in order to obtain glycyrrhetinic acid in good yields starting from ammonium glycyrrhizinate. It has been shown that variation of only one parameter of the process (temperature) allows alteration to thecomposition of the hydrolysis products. A new method was used for the synthesis of glycyrrhetinic acid (glycyrrhizic acid aglycone) and its monoglycoside. HPLC combined with mass spectrometry and NMR spectroscopy were used to determine the quantitative and qualitative compositions of the obtained products. The method developed for the production of glycyrrhetinic acid in subcritical water is environmentally friendly and faster than conventional hydrolysis methods that use acids and-expensive and toxic organic solvents. The proposed technique has a potential for the future development of inexpensive and environmentally friendly technologies for production of new pharmaceutical plant-based substances.

N-[2-[(3,5-di-tert-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)amino]phenyl]-N-(5,7-dinitroquinolin-8-yl)-1-phenylmethanesulfonamide: the nature of intramolecular shortened contacts.

The title compound, C(36)H(35)N(5)O(7)S, is found to exist in a non-spirocyclic (ring-opened) form in the crystal, although equilibrium of ring-opened and ring-closed forms (or so-called ring-chain isomerization) is possible in solution. The 4-oxocyclohexa-2,5-diene ring has a flattened sofa conformation. The N.C intramolecular separation of the atoms which would be directly bonded in a ring-closed form is quite short [2.813 (5) A]. Topological analysis of charge density based on density-functional-theory calculations was used for consideration of shortened intramolecular contacts and indicates a strong attractive bonding interaction between these N and C atoms in the crystal structure.