Stability of tylosin in honey at elevated temperatures
Honey containing tylosin has been studied to determine the stability of this antibiotic over time at various temperatures. Tylosin and desmycosin, the latter a hydrolysis product of tylosin, were isolated from diluted honey samples by solid-phase extraction followed by high performance liquid chromatography. Tylosin converted to desmycosin exponentially with half-lives of about 102 days at 34°C, 9 days at 50°, 9 hours at 80°, and 48 minutes at 110°. The desmycosin then decayed to unknown products. The sum of tylosin and desmycosin also decayed exponentially, with half-lives of 3–5 times the tylosin half life at that temperature. The honey used in this study itself deteriorated at these temperatures and times, darkening in color and eventually acquiring insoluble material which required filtration to enable the analysis. Therefore, storage of honey containing tylosin at elevated temperatures is not a feasible method of reducing levels of any tylosin that might be present.