Study of fluorescence characteristics of the charge-transfer reaction of quinolone agents with bromanil.

A spectrofluorimetric method was discussed for the determination of three antibacterial quinolone derivatives, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CIP) through charge-transfer complexation (CTC) with 2,3,5,6-tetrabromo-1,4-benzoquinone (bromanil, TBBQ). The method was based on the reaction of these drugs as n-electron donors with the pi-acceptor TBBQ. TBBQ was found to react with these drugs to produce a kind of yellow complexes and the fluorescence intensities of the complexes were enhanced by 29-36 times more than those of the corresponding monomers. UV-vis, (1)H NMR and XPS techniques were used to study the complexes formed. The various experimental parameters affecting the fluorescence intensity were studied and optimized. Under optimal reaction conditions, the rectilinear calibration graphs were obtained in the concentration range of 0.021-2.42 microg mL(-1), 0.017-2.63 microg mL(-1) and 0.019-2.14 microg mL(-1) for OFL, NOR and CIP, respectively. The methods developed were applied successfully to the determination of the subject drugs in their pharmaceutical dosage forms with good precision and accuracy compared to official and reported methods as revealed by t- and F-tests.

[Study of cefadroxil and cephradine charge transfer process by fluorescence quenching method].

A simple and sensitive fluorescence quenching method was developed for the examination of cefadroxil and cephradine. The method is based on the reaction of fluorescein with cefadroxil or cephradine, resulting in the formation of complexes with weak fluorescence, i.e. quenching the fluorescence intensity of the system. By the use of absorption spectroscopy, infrared spectroscopy and quantum chemistry calculation the reaction process of the cephalosporins and the bonding of reaction mechanism were basically analyzed. Based on this, the fluorescence spectrometry method for the determination of the contents of cefadroxil and cephradine was developed: The maximum excitation and emission wavelength was at 483 nm, and 517 nm and 519 nm respectively. The linear calibration curves were obtained over the cefadroxil and cephradine concentration ranges of 0.3-13.5 mg x L(-1) and 0.1-1.2 mg x L(-1) respectively. The proposed method has been successfully applied to the examination of the subject drugs in its pharmaceutical dosage with good precision and accuracy. The recoveries are 99.63%-99.91% and 99.71%-100.08% respectively.

[Studies on chemical structure of complexes compounds formed by acid and alkaline components of pair medicines in decoction].

OBJECTIVE: To study the chemical structures of macromolecular complexes formed by aconitine and glycyrrhizic acid, aconitine and rhein, berberine and rhein, ephedrine and glycyrrhizic acid in decoctions. METHOD: The binding energy of reactants and products was determined by X-ray spectrography, the ground level charge distribution of products was caculated by density function theory of quantum chemistry. RESULT: The binding energy of aconitine and glycyrrhizic acid, aconitine and rhein, berberine and rhein were changed after reaction. The characteristic atoms in the molecular structures of acid components have higher positive electric charge, while the ones in alkaline components have higher negative charge. CONCLUSION: Aconitine and glycyrrhizic acid, aconitine and rhein, berberine and rhein can form macromolecular complexes, ephedrine and glycyrrhizic acid can not.

[Research on compatibility chemistry of acid-alkaline pair medicines in formulas of traditional Chinese medicine].

Compatibility chemistry of acid-alkaline pair medicines in formulas of traditional Chinese medicine (TCM) is an important research field which should merit to pay attention. The ideas and methods in prescription compatibility research on formulas containing alkaline-acid pair medicines were summarized from the aspect of chemical groups of alkaline and acid ingredients; the research results were introduced and analyzed; the research meaning was elaborated; and the expectation of the field was viewed.