TY  - JOUR
A1  - Kotthoff, Lisa
A1  - O'Callaghan, Sarah-Louise
A1  - Lisec, Jan
A1  - Schwerdtle, Tanja
A1  - Koch, Matthias
T1  - Structural annotation of electro- and photochemically generated transformation products of moxidectin using high-resolution mass spectrometry
JF  - Analytical and bioanalytical chemistry : a merger of Fresenius' journal of analytical chemistry, Analusis and Quimica analitica
N2  - Moxidectin (MOX) is a widely used anthelmintic drug for the treatment of internal and external parasites in food-producing and companion animals. Transformation products (TPs) of MOX, formed through metabolic degradation or acid hydrolysis, may pose a potential environmental risk, but only few were identified so far. In this study, we therefore systematically characterized electro- and photochemically generated MOX TPs using high-resolution mass spectrometry (HRMS). Oxidative electrochemical (EC) TPs were generated in an electrochemical reactor and photochemical (PC) TPs by irradiation with UV-C light. Subsequent HRMS measurements were performed to identify accurate masses and deduce occurring modification reactions of derived TPs in a suspected target analysis. In total, 26 EC TPs and 59 PC TPs were found. The main modification reactions were hydroxylation, (de-)hydration, and derivative formation with methanol for EC experiments and isomeric changes, (de-)hydration, and changes at the methoxime moiety for PC experiments. In addition, several combinations of different modification reactions were identified. For 17 TPs, we could predict chemical structures through interpretation of acquired MS/MS data. Most modifications could be linked to two specific regions of MOX. Some previously described metabolic reactions like hydroxylation or O-demethylation were confirmed in our EC and PC experiments as reaction type, but the corresponding TPs were not identical to known metabolites or degradation products. The obtained knowledge regarding novel TPs and reactions will aid to elucidate the degradation pathway of MOX which is currently unknown.
KW  - veterinary drug
KW  - moxidectin
KW  - transformation products
KW  - electrochemistry
KW  - photochemistry
KW  - LC
KW  - HRMS
Y1  - 2020
U6  - https://doi.org/10.1007/s00216-020-02572-1
SN  - 1618-2642
SN  - 1618-2650
VL  - 412
IS  - 13
SP  - 3141
EP  - 3152
PB  - Springer
CY  - Heidelberg
ER  -