title: Hydrolysis of amphenicol and macrolide antibiotics: Chloramphenicol, florfenicol, spiramycin, and tylosin.
abstract: Antibiotics that enter the environment can present human and ecological health risks. An understanding of antibiotic hydrolysis rates is important for predicting their environmental persistence as biologically active contaminants. In this study, hydrolysis rates and Arrhenius constants were determined as a function of pH and temperature for two amphenicol (chloramphenicol and florfenicol) and two macrolide (spiramycin and tylosin) antibiotics. Antibiotic hydrolysis rates in pH 4-9 buffer solutions at 25°C, 50°C, and 60°C were quantified, and degradation products were characterized. All of the antibiotics tested remained stable and exhibited no observable hydrolysis under ambient conditions typical of aquatic ecosystems. Acid- and base-catalyzed hydrolysis occurred at elevated temperatures (50-60°C), and hydrolysis rates increased considerably below pH 5 and above pH 8. Hydrolysis rates also increased approximately 1.5- to 2.9-fold for each 10°C increase in temperature. Based on the degradation product masses found, the functional groups that underwent hydrolysis were alkyl fluoride, amide, and cyclic ester (lactone) moieties; some of the resultant degradation products may remain bioactive, but to a lesser extent than the parent compounds. The results of this research demonstrate that amphenicol and macrolide antibiotics persist in aquatic systems under ambient temperature and pH conditions typical of natural waters. Thus, these antibiotics may present a risk in aquatic ecosystems depending on the concentration present.
authors.affiliation: Department of Civil and Environmental Engineering, Washington State University, 405 Spokane Street, Pullman, WA 99164, USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Mitchell
authors.affiliation: Department of Agricultural and Biological Engineering, University of Florida, PO Box 110570, 1741 Museum Road, Gainesville, FL 32611, USA. Electronic address: jullman@ufl.edu.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Ullman
authors.affiliation: Department of Civil and Environmental Engineering, Washington State University, 405 Spokane Street, Pullman, WA 99164, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Teel
authors.affiliation: Department of Civil and Environmental Engineering, Washington State University, 405 Spokane Street, Pullman, WA 99164, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Watts
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis*; D002384:Catalysis; D002701:Chloramphenicol / Q000032:analysis*; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D018942:Macrolides / Q000032:analysis*; D011500:Protein Synthesis Inhibitors / Q000032:analysis; D015572:Spiramycin / Q000032:analysis*; D013696:Temperature; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000032:analysis; D015645:Tylosin / Q000032:analysis*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D011500:Protein Synthesis Inhibitors; D014874:Water Pollutants, Chemical; D014867:Water; D002701:Chloramphenicol; D015572:Spiramycin; C035534:florfenicol; D013839:Thiamphenicol; D015645:Tylosin
keywords: Amphenicol; Antibiotic; Degradation; Hydrolysis; Macrolide