title: Determination of equilibrium constant of amino carbamate adduct formation in sisomicin by a high pH based high performance liquid chromatography.
abstract: Amino carbamate adduct formation from the amino group of an aminoglycoside and carbon dioxide has been postulated as a mechanism for reducing nephrotoxicity in the aminoglycoside class compounds. In this study, sisomicin was used as a model compound for amino carbamate analysis. A high pH based reversed-phase high performance liquid chromatography (RP-HPLC) method is used to separate the amino carbamate from sisomicin. The carbamate is stable as the breakdown is inhibited at high pH and any reactive carbon dioxide is removed as the carbonate. The amino carbamate was quantified and the molar fraction of amine as the carbamate of sisomicin was obtained from the HPLC peak areas. The equilibrium constant of carbamate formation, Kc, was determined to be 3.3 × 10(-6) and it was used to predict the fraction of carbamate over the pH range in a typical biological systems. Based on these results, the fraction of amino carbamate at physiological pH values is less than 13%, and the postulated mechanism for nephrotoxicity protection is not valid. The same methodology is applicable for other aminoglycosides.
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA.
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Wlasichuk
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA. Electronic address: ltan@impaxlabs.com.
authors.forename: Li
authors.initials: L
authors.lastname: Tan
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA.
authors.forename: Yushen
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA.
authors.forename: Darin J
authors.initials: DJ
authors.lastname: Hildebrandt
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Achaogen, Inc., 7000 Shoreline Court, Suite 371, South San Francisco, CA 94080, USA.
authors.forename: Dane E
authors.initials: DE
authors.lastname: Karr
authors.affiliation: DiCE Molecules, 1455 Adams Court, Menlo Park, CA 94025, USA.
authors.forename: Donald E
authors.initials: DE
authors.lastname: Schmidt
mesh_terms: D000617:Aminoglycosides / Q000737:chemistry; D002219:Carbamates / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D056148:Chromatography, Reverse-Phase / Q000379:methods; D006863:Hydrogen-Ion Concentration; D012853:Sisomicin / Q000737:chemistry*
chemical_list: D000617:Aminoglycosides; D002219:Carbamates; D002245:Carbon Dioxide; D012853:Sisomicin
keywords: Carbamate; Equilibrium constant; High performance liquid chromatography; Nephrotoxicity; Sisomicin