Solar-mediated degradation of linezolid and tedizolid under simulated environmental conditions: Kinetics, transformation and toxicity

Linezolid (LIN) and Tedizolid (TED) are representatives of oxazolidinone antibiotics of last resort with a strong efficacy against gram-positive bacteria. This study focused on their solar-mediated degradation to understand better their fate in aquatic environment, for the realistic concentrations in the range of 1 μg/L. Results showed that both antibiotics (ABs) are degradable by simulated sunlight (1 kW/m²), with half-lives of 32 and 93 h in ultrapure water, for LIN and TED, respectively. LIN showed similar photolytic behaviour in pure solution and in surface water, whereas sunlight enhanced the degradation of LIN in pure solutions, but not in surface water. Structure elucidation by liquid chromatography coupled to high resolution mass spectrometry provided information about seven transformation products for LIN and five for TED. The morpholinyl-ring was identified as the target site for most transformation reactions of LIN. TED was prone to oxidation and cleavage of the oxazolidinone ring. Results of a growth inhibition test on Bacillus subtilis exposed to UV light showed antibacterial efficacy of transformation products of LIN and no significant efficacy of degradation products of TED for the concentration range of 100 μg/L-10 mg/L of parent compounds. Photolytically treated solutions of the ABs maintained their inhibitory effect on the bioluminescence of Aliivibrio fischeri.

Detection and identification of the new potential synthetic cannabinoids 1-pentyl-3-(2-iodobenzoyl)indole and 1-pentyl-3-(1-adamantoyl)indole in seized bulk powders in Hungary

3-Naphthoyl- and 3-phenylacetylindoles represent a group of substances of cannabimimetic activity with affinities - strongly influenced by their functional groups - to cannabinoid receptors CB1 and CB2. Some of them have been described as ingredients of herbal blends also known as "smart products" by several research groups. Recently further cannabimimetic substances possessing new chemical structures like benzoylindoles and adamantoylindoles have emerged. In Hungary, two powder samples were seized by the authorities and identified as 1-pentyl-3-(2-iodobenzoyl)indole (AM-679) and 1-pentyl-3-(1-adamantoyl)indole. Structure elucidation was carried out by LC-UV-MS/MS, LC-TOF-MS, GC-MS and NMR. The benzoylindole AM-679 is a known agonist of cannabinoid receptors while the adamantoylindole derivative also carries chemical features typical for cannabimimetics. It is thus assumed that both substances might be detected in "smart products" in the future.

Identification and characterization of the new designer drug 4'-methylethcathinone (4-MEC) and elaboration of a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening method for seven different methcathinone analogs

A fast and simple LC-MS/MS method was developed for screening mephedrone, butylone, methylenedioxypyrovalerone (MDPV), flephedrone, methylone and methedrone in bulk powder samples. Samples were separated on a reverse phase column using gradient elution with mixtures of water, acetonitrile and formic acid. After optimization a limit of detection of about 2ngmL(-1) was achieved using multiple reaction monitoring (MRM) mode. Total run time was less than 8min. Typical fragmentation characteristics of the studied compounds are discussed. The method was successfully applied to several unknown bulk powder samples seized by the Hungarian Customs and Finance Guard. One of the samples contained the new designer drug 4'-methylethcathinone (4-MEC), which was identified and characterized by LC-MS/MS, NMR, FT-IR and LC-TOF-MS techniques. The method is also deemed to be applicable for the screening of simple dosage forms such as tablets and capsules.

Detection and characterization of twenty-eight isomers of fumonisin B1 (FB1) mycotoxin in a solid rice culture infected with Fusarium verticillioides by reversed-phase high-performance liquid chromatography/electrospray ionization time-of-flight and ion trap mass spectrometry

Fumonisin mycotoxins which are hazardous to humans and animals were produced in a Fusarium verticillioides-infected solid rice culture. To decrease the possibility of the formation of artifacts, the fumonisins were analysed by reversed-phase high-performance liquid chromatography/electrospray ionization time-of-flight (RP-HPLC/ESI-TOFMS) and ion trap mass spectrometry (RP-HPLC/ESI-ITMS) immediately after the extraction of the culture material, without any further sample clean-up. The fumonisin isomers were separated by using a flat gradient on a special, high-coverage C(18), narrow-bore HPLC column (YMC-Pack J'sphere ODS H80) suggested for the separation of structural isomers by the manufacturer. Exact mass measurements (TOFMS) of the protonated molecules and extraction of the ion chromatogram corresponding to the empirical formula (C(34)H(59)NO(15)) of FB(1) toxins led to the identification of 29 peaks and shoulders, including those of FB(1). The FB(1) toxin and 28 of its isomers were also detected by ITMS after separation with RP-HPLC. The characteristic m/z values of the product ions, including the backbones obtained by ITMS(2), undoubtedly indicated the structures of the FB(1) isomers for 28 peaks and shoulders. In the MS(2) spectra of the protonated molecules of the FB(1) isomers, with some exceptions, 15 characteristic product ions including the hydrocarbon backbone at m/z 299 were observed. The abundance ratio of the cation at m/z 299 ranged up to 5.8%. The relative quantities of the isomers found in the sample extract were expressed as percentages of the FB(1) content (0.001-0.579%). The total amount of the 28 FB(1) isomers was 2.803% of the quantity of FB(1) that is important from the aspect of food and feed safety.