title: Stereoselective biodegradation of amphetamine and methamphetamine in river microcosms.
abstract: Here presented for the first time is the enantioselective biodegradation of amphetamine and methamphetamine in river microcosm bioreactors. The aim of this investigation was to test the hypothesis that mechanisms governing the fate of amphetamine and methamphetamine in the environment are mostly stereoselective and biological in nature. Several bioreactors were studied over the duration of 15 days (i) in both biotic and abiotic conditions, (ii) in the dark or exposed to light and (iii) in the presence or absence of suspended particulate matter. Bioreactor samples were analysed using SPE-chiral-LC-(QTOF)MS methodology. This investigation has elucidated the fundamental mechanism for degradation of amphetamine and methamphetamine as being predominantly biological in origin. Furthermore, stereoselectivity and changes in enantiomeric fraction (EF) were only observed under biotic conditions. Neither amphetamine nor methamphetamine appeared to demonstrate adsorption to suspended particulate matter. Our experiments also demonstrated that amphetamine and methamphetamine were photo-stable. Illicit drugs are present in the environment at low concentrations but due to their pseudo-persistence and non-racemic behaviour, with two enantiomers revealing significantly different potency (and potentially different toxicity towards aquatic organisms) the risk posed by illicit drugs in the environment should not be under- or over-estimated. The above results demonstrate the need for re-evaluation of the procedures utilised in environmental risk assessment, which currently do not recognise the importance of the phenomenon of chirality in pharmacologically active compounds.
authors.affiliation: University of Bath, Department of Chemistry, Faculty of Science, Bath BA2 7AY, UK.
authors.forename: John
authors.initials: J
authors.lastname: Bagnall
authors.forename: Louis
authors.initials: L
authors.lastname: Malia
authors.forename: Anneke
authors.initials: A
authors.lastname: Lubben
authors.forename: Barbara
authors.initials: B
authors.lastname: Kasprzyk-Hordern
mesh_terms: D000661:Amphetamine / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D008694:Methamphetamine / Q000737:chemistry / Q000378:metabolism*; D045483:Rivers / Q000382:microbiology*; D013237:Stereoisomerism
chemical_list: D008694:Methamphetamine; D000661:Amphetamine
keywords: Biodegradation; Chiral drugs; Enantiomeric profiling; Environment; Pharmaceuticals; River microcosms; Sorption