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- Pharmaceuticals biodegradation by activated sludge and pure culturesPublication . Bessa, Vânia S.; Moreira, Irina S.; Maia, Alexandra S.; Tiritan, Maria E.; Castro, Paula M. L.The occurrence of pharmaceuticals in the environment have been a topic of increasing concern. Most of the pharmaceuticals are not completely mineralized in the human body and are released on the sewage systems as the pharmaceutical itself and as their “biologically active” metabolites through excretion, as well as by improper elimination and disposal. Once current wastewater treatment plants (WWTPs) are not designed to remove these emerging pollutant, they are easily released into the environment.The effects of halogen on biological properties of molecules have had a marked impact on various fields such as pharmacology. It can improve metabolic stability, bioavailability and interactions with the biological target. However, it also increases the recalcitrance of the molecule to biotic and abiotic degradation. Ciprofloxacin (CPF) and Diclofenac (DCF) are two widely used halogenated pharmaceuticals, commonly found in the environment in concentrations that can range ng L−1 to mg L−1. CPF is a common human and veterinary broad-spectrum fluoroquinolone antibiotic. DCF is a non-steroidal anti-inflammatory drug (NSAID), also used as analgesic and antithermic treatment. In the present study, biodegradation of CPF and DCF was assessed by selective enrichements with actived sludge and with pure cultures of three different strains - Labrys portucalensis (F11) and two Rhodococcus spp. (FP1 and S2) – which had previously demonstrated capacity to degrade a range of halogenated compounds. For CPF selective enrichments, a degradation of 100% was achived after 206 days, although without fluoride release. These findings indicate that these selective enrichments are good candidates to find a bacterial strain able to biodegrade CPF. Regarding the pure cultures, F11 exhibited the highest degradation capacity (57%) after 62 days, but also without fluoride release. Concerning DCF selective enrichments, it was released 68% of the stoichiometrically expected cloride ion behind 131 days. In the experiments with pure cultures, F11 and S2, was released the totality of the stoichiometrically expected cloride, elapsed 131 days. These results indicate that these two strains are promising for DCF biodegradation.
- Occurrence of chiral bioactive compounds in the aquatic environment: a reviewPublication . Ribeiro, Cláudia; Ribeiro, Ana Rita; Maia, Alexandra S.; Tiritan, Maria ElizabethIn recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often neglected. However, enantioselective toxicity is well recognized, highlighting the need to include enantioselectivity in environmental risk assessment. Additionally, the information about enantiomeric fraction (EF) is crucial since it gives insights about: (i) environmental fate (i.e., occurrence, distribution, removal processes and (bio)degradation); (ii) illicit discharges; (iii) consumption pattern (e.g., illicit drugs, pharmaceuticals used as recreational drugs, illicit use of pesticides); and (iv) enantioselective toxicological effects. Thus, the purpose of this paper is to provide a comprehensive review about the enantioselective occurrence of chiral bioactive compounds in aquatic environmental matrices. These include pharmaceuticals, illicit drugs, pesticides, polychlorinated biphenyls (PCBs) and polycyclic musks (PCMs). Most frequently analytical methods used for separation of enantiomers were liquid chromatography and gas chromatography methodologies using both indirect (enantiomerically pure derivatizing reagents) and direct methods (chiral stationary phases). The occurrence of these chiral micropollutants in the environment is reviewed and future challenges are outlined.
- Chiral analysis of pesticides and drugs of environmental concern: biodegradation and enantiomeric fractionPublication . Maia, Alexandra S.; Ribeiro, Ana R.; Castro, Paula M. L.; Tiritan, Maria ElizabethThe importance of stereochemistry for medicinal chemistry and pharmacology is well recognized and the dissimilar behavior of enantiomers is fully documented. Regarding the environment, the significance is equivalent since enantiomers of chiral organic pollutants can also differ in biodegradation processes and fate, as well as in ecotoxicity. This review comprises designed biodegradation studies of several chiral drugs and pesticides followed by enantioselective analytical methodologies to accurately measure the enantiomeric fraction (EF). The enantioselective monitoring of microcosms and laboratory-scale experiments with different environmental matrices is herein reported. Thus, this review focuses on the importance of evaluating the EF variation during biodegradation studies of chiral pharmaceuticals, drugs of abuse, and agrochemicals and has implications for the understanding of the environmental fate of chiral pollutants.
- Enantioselective Determination of Fluoxetine and Norfluoxetine in WastewaterPublication . Ribeiro, Ana R.; Maia, Alexandra S.; Moreira, Irina S.; Afonso, Carlos; Castro, Paula M.L.; Tiritan, Maria E.Microbial degradation of chiral compounds during wastewater treatment processes can be enantioselective and needs chiral analytical methodology to discriminate the biodegradation of both enantiomers. An enantioselective HPLC-FD method was developed and validated to monitor the degradation of fluoxetine (FLX) enantiomers by wastewater and the possible formation of its metabolite norfluoxetine (NFLX). The Solid Phase Extraction (SPE) of 50 mL of wastewater samples on 500 mg Oasis MCX cartridges was followed by the HPLC analysis using a Chirobiotic V chiral stationary phase under reversed mode. The developed method wasvalidated within the wastewater effluent used in microcosms laboratory assays. The chiral SPE-HPLC-FD method demonstrated to be selective, linear, sensitive, accurate and precise to quantify the enantiomers of FLX and of its metabolites NFLX in wastewaters. The limits of detection (0.8-2.0 ng mL -1 ) and quantification (2.0 – 4.0 ng mL -1 ) were adequate to monitoring the degradation assays at environmental level. The method proved to be robust to follow the biodegradation assays using real wastewater samplesspiked with FLX, during 46 days. To the best of our knowledge, this is the first reportof simultaneous separation of FLX and NFLX enantiomers using a Chirobiotic V and the application of the validated method to the enantioselective degradation by wastewater