- Synthesis and in vitro characterization of drug conjugates of l-carnitine as potential prodrugs that target human Octn2
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The objective was to evaluate the potential of drug conjugates with l-carnitine as prodrugs that target organic cation/carnitine transporter (OCTN2). Twenty-two l-carnitine analogues were evaluated for human organic cation/carnitine transporter (hOCTN2) inhibition; the 3'-hydroxyl group was found to be the only functional group not contributing to l-carnitine interaction with hOCTN2 among the three functional groups on l-carnitine (i.e., 3'-hydroxyl, amine, and carboxylate). The 3'-hydroxyl group on l-carnitine was therefore chosen as the conjugate site. Three drug-l-carnitine conjugates (i.e., valproyl-l-carnitine, naproxen-l-carnitine, and ketoprofen-l-carnitine) were synthesized along with two ketoprofen analogues that incorporated a linker group (glycolic acid or glycine) between ketoprofen and l-carnitine (i.e., ketoprofen-glycolic acid-l-carnitine and ketoprofen-glycine-l-carnitine). These potential prodrugs were evaluated for their in vitro inhibition, transport, and metabolism properties. All three drug-l-carnitine conjugates and ketoprofen-glycine-l-carnitine were OCTN2 inhibitors, as well as substrates. For valproyl-l-carnitine, Ki = 155± 19μM, Km = 132± 23μM, and normalized Jmax = 0.467± 0.028; for naproxen-l-carnitine, Ki = 5.97± 0.81μM, Km = 257± 57μM, and normalized Jmax = 0.141± 0.012; for ketoprofen-l-carnitine, Ki = 82.2± 5.3μM, Km = 77.0± 4.0μM, and normalized Jmax = 0.412± 0.015; for ketoprofen-glycine-l-carnitine, Ki = 14.4± 1.4μM, Km = 58.5± 8.7μM, and normalized Jmax = 0.0789± 0.0037. Ketoprofen-glycolic acid-l-carnitine was unstable in metabolic buffers and chemical buffers. On the contrary, naproxen-l-carnitine, ketoprofen-l-carnitine, and ketoprofen-glycine-l-carnitine were stable in chemical and metabolic buffers. The results demonstrate the potential of drug-l-carnitine conjugates to serve as prodrugs that target OCTN2.
- Diao, Lei,Polli, James E.
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p. 3802 - 3816
(2012/06/30)
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- Differentiation of Isomeric Acylcarnitines Using Tandem Mass Spectrometry
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Tandem mass spectrometry, using a four-sector instrument, has been used to distinguish isomeric acylcarnitines.Collisional activation of MH+ ions (or of acylcarnitine methyl ester cations) induces fragmentations of the acyl moieties, yielding daughter ions with relative abundances characteristic of individual isomers.Direct analyses of crude urine samples from children with metabolic disorders enable unequivocal identification of individual acylcarnitines, thus contributing to the characterization of the disorder.
- Gaskell, Simon, J.,Guenat, Christian,Millington, David S.,Maltby, David A.,Roe, Charles R.
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p. 2801 - 2805
(2007/10/02)
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