Consistency evaluation between matrix components ratio and microbiological potency of tylosin major components

BACKGROUND: The aim of our research work was to investigate the relative potencies of matrix components of tylosin, a multi-component antibiotic, and establishing a quantitative relationship between content and potency of each component. METHODS: The potencies of tylosin matrix components were determined by using three bioassay methods. The content of tylosin components (tylosin A, B, C, and D) in different tylosin samples were determined by using high pressure liquid chromatography (HPLC) technique and their theoretical potencies were calculated. Equivalency of theoretical and microbiological potencies for each sample was evaluated using statistical analysis. RESULTS: The highest amount of tylosin B content was found in tylosin phosphate and tartrate (up to 19%). Tylosin D content in all tylosin samples varied in the range of 0.03 to 18.73%. Tylosin A, B, and C showed similar sensitivity to the Kocuria rhizophila, the test organism in agar-diffusion method, while the potency of tylosin D was 39% of A. In the turbidimetric methods by Staphylococcus aureus, tylosin D and B responses to A component were ranged from 22.5 to 22.8% and 77.3 to 79.3%, respectively, while potencies of tylosin C and A were almost equal. The biopotency conversion factors were not resulted to a single factor, due to the different antibacterial activity of tylosin components. CONCLUSION: Our findings indicated that defining individual limit for the low active matrix components and for the total of other components with similar high activity could improve the accuracy of potency results. [Figure: see text]