<abstract xmlns="http://www.w3.org/1999/xhtml">The levels of tryptophan (TRP) and its main metabolite kynurenic acid (KYNA) were measured in rat livers treated with raloxifene – a selective estrogen receptor modulator. The research was conducted by applying high-performance liquid chromatography on a 5 μm Zorbax Eclipse XDB-C18 column. Selective fluorescence detection (FL) was performed at an excitation of 219 nm and emission of 360 nm for TRP and KYNA. The assays showed good linearity (R2 >0.95) within the tested ranges of 0.045-0.20 µg mL−1, 0.025-0.32 µg mL−1, respectively, for KYNA and TRP. The limits of the detection were found to be 0.1480 ng mL−1 for KYNA and 0.0332 ng mL-1 for TRP. The deproteinization of the liver homogenate samples was accomplished by 80% methanol addition combined with boiling precipitation. The average recovery values were between 94.84% and 99.54% with RSDs no more than 5.5%. The work revealed that raloxifene decreased the mean value of tryptophan, as compared with the control group, while simultaneously leaving kynurenic acid at the same level. For the first time the research suggests that, in the case of raloxifene therapy, tryptophan is not metabolized via the kynurenine pathway.</abstract>

The levels of tryptophan (TRP) and its main metabolite kynurenic acid (KYNA) were measured in rat livers treated with raloxifene – a selective estrogen receptor modulator. The research was conducted by applying high-performance liquid chromatography on a 5 μm Zorbax Eclipse XDB-C18 column. Selective fluorescence detection (FL) was performed at an excitation of 219 nm and emission of 360 nm for TRP and KYNA. The assays showed good linearity (R2 >0.95) within the tested ranges of 0.045-0.20 µg mL−1, 0.025-0.32 µg mL−1, respectively, for KYNA and TRP. The limits of the detection were found to be 0.1480 ng mL−1 for KYNA and 0.0332 ng mL-1 for TRP. The deproteinization of the liver homogenate samples was accomplished by 80% methanol addition combined with boiling precipitation. The average recovery values were between 94.84% and 99.54% with RSDs no more than 5.5%. The work revealed that raloxifene decreased the mean value of tryptophan, as compared with the control group, while simultaneously leaving kynurenic acid at the same level. For the first time the research suggests that, in the case of raloxifene therapy, tryptophan is not metabolized via the kynurenine pathway.

The effect of a selective estrogen receptor modulator – raloxifene – on the levels of tryptophan and kynurenic acid in the livers of rats as studied via RP-HPLC-FL

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The levels of tryptophan (TRP) and its main metabolite kynurenic acid (KYNA) were measured in rat livers treated with raloxifene – a selective estrogen...

The effect of a selective estrogen receptor modulator – raloxifene – on the levels of tryptophan and kynurenic acid in the livers of rats as studied via RP-HPLC-FL

Published Online: Sep 13, 2020

Page range: 162 - 167

Received: Feb 03, 2020

Accepted: Jul 06, 2020

DOI: https://doi.org/10.2478/cipms-2020-0029

Keywords
ryptophan, kynurenic acid, liquid chromatography, raloxifene therapy

© 2020 Jolanta Flieger et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

The effect of a selective estrogen receptor modulator – raloxifene – on the levels of tryptophan and kynurenic acid in the livers of rats as studied via RP-HPLC-FL

Published Online: Sep 13, 2020

Page range: 162 - 167

Received: Feb 03, 2020

Accepted: Jul 06, 2020

DOI: https://doi.org/10.2478/cipms-2020-0029

Keywordsryptophan, kynurenic acid, liquid chromatography, raloxifene therapy

© 2020 Jolanta Flieger et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
ryptophan, kynurenic acid, liquid chromatography, raloxifene therapy