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17. The flavin dimers I. The application of absorption in anti-stokes excitation region to investigate the flavin dimer formation

Author

Drabent, Regina and Grajek, Hanna

Abstract

The dimer formation process of the flavin in aqueous solution has been studied. The difference absorption spectra with the change of concentration in Stokes and anti-Stokes excitation region of the flavomononucleotide and riboflavin were measured. The highest temperature in which the dimers still appear is discussed. It is suggested that this temperature Tdcan be treated as one of the empirical parameters which describe the dimer formation process of the dyes in solutions. The aqueous solution of flavins with the concentration c⩽5·10−5M at room temperature can be treated as a flavin monomers solution. For higher concentrations the flavin monomers and dimers exist in a solution at room temperature.

Published
1983
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20. Instability of chlorophyll in yellow lupin seedlings grown in soil contaminated with ciprofloxacin and tetracycline.

Author

Piotrowicz-Cieślak, Agnieszka I., Michalczyk, Dariusz J., Rydzyński, Dariusz, and Grajek, Hanna

Subjects
*CHLOROPHYLL, *LUPINES, *SOIL composition, *ANTIBIOTICS, *TETRACYCLINE
Abstract

With increasing soil concentrations of ciprofloxacin and tetracycline a decrease of leaf chlorophyll content was observed. Tetracycline was more detrimental than ciprofloxacin. The chlorophyll content in plants growing for ten days on a tetracycline containing soil decreased by 68%. The decrease of chlorophyll concentration was even sharper in new leaves that formed after application of the antibiotic (up to 81% drop). The comparison of absorption spectra of commercial, reagent grade chlorophyll, alone and incubated with antibiotics, has shown that ciprofloxacin and tetracycline can react directly with chlorophyll and decrease its concentration by 47.7% and 48.5%, respectively. The changes in fluorescence spectra confirmed the formation of chlorophyll degradation product. The chlorophyll decay was a second order reaction and depended on antibiotic concentration and duration of exposure. Reaction rate constants differed with antibiotics and their soil concentrations. With increasing contents of antibiotics in soil the constant of chlorophyll degradation rate in lupin plants increased from k = 870 M −1 day −1 for 3 mg ciprofloxacin to k = 2490 M −1 day −1 for 90 mg ciprofloxacin, and in the case of tetracycline the reaction rate constant increased from k = 1330 M −1 day −1 to k = 2910 M −1 day −1 . The sensitivity of chlorophyll to ciprofloxacin and tetracycline was confirmed by determining EC and TU indices. [ABSTRACT FROM AUTHOR]

Published
2017
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