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Trimethylamine (TMA) and trimethylamine-N-oxide (TMAO) play a crucial role in many biochemical processes within diverse organisms including animals, plants, fungi and bacteria. Studies have linked these metabolites with cardiovascular and kidney diseases; however, emerging evidence demonstrates their protective properties. Owing to these controversies and co-existence of these metabolites in biological samples, it is crucial to accurately quantify these metabolites to associate their concentrations with various physiological and pathophysiological conditions to elucidate their potential roles. We reported interferences on TMA quantification without derivatizing the analyte. A combined sample preparation method, including sample derivatization with ethyl bromoacetate and use of ion pairing reagent (sodium heptanesulfonate), minimized these interferences and provided improved accuracy and precision for simultaneous quantification of TMA and TMAO. The linearity for TMAO ranged from 0.01 µM to 300 µM and 0.1 µM - 300 µM for TMA. With the application of this method, we reported that the circulating concentrations of TMA was 4 times higher in male mice (33.1 ± 5.9 µmol/L) compared to females (8.3 ± 1.39 µmol/L), whereas TMAO levels were 6 times lower in male (7.2 ± 0.4 µmol/L) than female mice (42.1 ± 4.5 µmol/L). In contrast, concentrations of TMA and TMAO in the colonic tissue did not differ significantly between males and females. The robust analytical method for simultaneously quantifying TMA and TMAO presents a significant value in facilitating investigations on TMA and TMAO biology., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jia Li reports financial support was provided by Imperial College London. Jia Li reports a relationship with Cardiff University that includes: consulting or advisory. Jia Li reports a relationship with Khon Kaen University that includes: travel reimbursement. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The antioxidant activity of two synthesized coumarins namely, N-(4,7-dioxo-2- phenyl-1,3-oxazepin-3(2H,4H,7H)-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 5 and N-(4-oxo-2-phenylthiazolidin-3-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 6 were studied with the DPPH, hydrogen peroxide and nitric oxide radical methods and compared with the known antioxidant ascorbic acid. Compounds 5 and 6 were synthesized in a good yield from the addition reaction of maleic anhydride or mercaptoacetic acid to compound 4, namely N'-benzylidene-2-(2-oxo-2H-chromen-4-yloxy)acetohydrazide. Compound 4 was synthesized by the condensation of compound 3, namely 2-(2-oxo-2H-chromen-4-yloxy) acetohydrazide, with benzaldehyde. Compound 3, however, was synthesized from the addition of hydrazine to compound 2, namely ethyl 2-(2-oxo-2H-chromen-4-yloxy)acetate, which was synthesized from the reaction of ethyl bromoacetate with 4-hydroxycoumarin 1. Structures for the synthesized coumarins 2-6 are proposed on the basis of spectroscopic evidence.