Investigation of Enantioselective Membrane Permeability of α-Lipoic Acid in Caco-2 and MDCKII Cell |
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| Authors: | Ryota Uchida Hinako Okamoto Naoko Ikuta Keiji Terao Takashi Hirota |
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| Affiliation: | 1.Department of Biopharmaceutics, Faculty of Pharmaceutical Science, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan; ;2.CycloChem Bio Co., Ltd., KIBC654R 5-5-2 Minatojima-minamimachi Chuo-ku, Kobe 650-0047, Japan; (H.O.); (K.T.);3.Graduate School of Medicine, Kobe University, 7-5-2 Kusunoki-cho Chuo-ku, Kobe 650-0017, Japan; |
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| Abstract: | α-Lipoic acid (LA) contains a chiral carbon and exists as two enantiomers (R-α-lipoic acid (RLA) and S-α-lipoic acid (SLA)). We previously demonstrated that oral bioavailability of RLA is better than that of SLA. This difference arose from the fraction absorbed multiplied by gastrointestinal availability (Fa × Fg) and hepatic availability (Fh) in the absorption phase. However, it remains unclear whether Fa and/or Fg are involved in enantioselectivity. In this study, Caco-2 cells and Madin–Darby canine kidney strain II cells were used to assess the enantioselectivity of membrane permeability. LA was actively transported from the apical side to basal side, regardless of the differences in its steric structure. Permeability rates were proportionally increased in the range of 10–250 µg LA/mL, and the permeability coefficient did not differ significantly between enantiomers. Hence, we conclude that enantioselective pharmacokinetics arose from the metabolism (Fh or Fg × Fh), and definitely not from the membrane permeation (Fa) in the absorption phase. |
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| Keywords: | α -lipoic acid pharmacokinetics enantioselective membrane permeability gastrointestinal availability hepatic availability Caco-2 MDCKII |
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