Oxidation of diclofenac in water by sodium hypochlorite: Identification of new degradation by-products and their ecotoxicological evaluation

Giovanni Luongo; Marco Guida; Antonietta Siciliano; Giovanni Libralato; Lorenzo Saviano; Angela Amoresano; Lucio Previtera; Giovanni Di Fabio; Armando Zarrelli

doi:10.1016/j.jpba.2020.113762

Oxidation of diclofenac in water by sodium hypochlorite: Identification of new degradation by-products and their ecotoxicological evaluation

J Pharm Biomed Anal. 2021 Feb 5:194:113762. doi: 10.1016/j.jpba.2020.113762. Epub 2020 Nov 12.

Authors

Giovanni Luongo¹, Marco Guida², Antonietta Siciliano³, Giovanni Libralato⁴, Lorenzo Saviano⁵, Angela Amoresano⁶, Lucio Previtera⁷, Giovanni Di Fabio⁸, Armando Zarrelli⁹

Affiliations

¹ Department of Chemical Sciences, University of Naples Federico II, Naples, Italy. Electronic address: giovanni.luongo@unina.it.
² Department of Biology, University of Naples Federico II, Naples, Italy. Electronic address: marco.guida@unina.it.
³ Department of Biology, University of Naples Federico II, Naples, Italy. Electronic address: antonietta.siciliano@unina.it.
⁴ Department of Biology, University of Naples Federico II, Naples, Italy. Electronic address: giovanni.libralato@unina.it.
⁵ Department of Biology, University of Naples Federico II, Naples, Italy. Electronic address: lorenzosaviano@libero.it.
⁶ Department of Chemical Sciences, University of Naples Federico II, Naples, Italy. Electronic address: angela.amoresano@unina.it.
⁷ Associazione Italiana per la Promozione delle Ricerche su Ambiente e Salute umana, Dugenta, BN, Italy. Electronic address: previter@unina.it.
⁸ Department of Chemical Sciences, University of Naples Federico II, Naples, Italy. Electronic address: difabio@unina.it.
⁹ Department of Chemical Sciences, University of Naples Federico II, Naples, Italy. Electronic address: zarrelli@unina.it.

PMID: 33248860
DOI: 10.1016/j.jpba.2020.113762

Abstract

Diclofenac (DCF) is the most widely prescribed non-steroidal anti-inflammatory drug in the world and it has been detected in drinking and surface waters. In this paper, the effect of chlorination process on DCF in aqueous solutions was investigated and the structures of 14 isolated degradation by-products (DPs), of which nine are new, have been determined from combining mass spectrometry and nuclear magnetic resonance data and justified by a proposed mechanism of formation beginning from the parent drug. Some degradation by-products show only one phenyl, others are dimers or trimers of the parental compound, which has undergone oxidative decarboxylation of the side chain and/or chlorination of this or one or both aromatic rings. Ecotoxicological bioassays evidenced the following sensitivities D. magna < R. subcapitata < A. fischeri. The isolated DPs (DP1-8, except for DP9) exhibited effects ≥ 50 % in the exposed microalgae and crustaceans showing toxicities mainly ranked from slight to acute.

Keywords: Chlorination; Degradation by-products; Diclofenac; Genotoxicity; Hypochlorite; Water treatment.

MeSH terms

Anti-Inflammatory Agents, Non-Steroidal / toxicity
Diclofenac* / toxicity
Oxidation-Reduction
Sodium Hypochlorite / toxicity
Water
Water Pollutants, Chemical* / analysis
Water Pollutants, Chemical* / toxicity

Substances

Anti-Inflammatory Agents, Non-Steroidal
Water Pollutants, Chemical
Water
Diclofenac
Sodium Hypochlorite