Non-Steroidal Anti-Inflammatory Drugs Are Inhibitors of the Intestinal Proton-Coupled Amino Acid Transporter (PAT1): Ibuprofen and Diclofenac Are Non-Translocated Inhibitors
<b>Background/Objectives</b>: The proton-coupled amino acid transporter (PAT1) is an intestinal absorptive solute carrier responsible for the oral bioavailability of some GABA-mimetic drug substances such as vigabatrin and gaboxadol. In the present work, we investigate if non-steroidal a...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Pharmaceutics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1999-4923/17/1/49 |
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| Summary: | <b>Background/Objectives</b>: The proton-coupled amino acid transporter (PAT1) is an intestinal absorptive solute carrier responsible for the oral bioavailability of some GABA-mimetic drug substances such as vigabatrin and gaboxadol. In the present work, we investigate if non-steroidal anti-inflammatory drug substances (NSAIDs) interact with substrate transport via human (h)PAT1. <b>Methods</b>: The transport of substrates via hPAT1 was investigated in Caco-2 cells using radiolabeled substrate uptake and in <i>X. laevis</i> oocytes injected with <i>hPAT1 cRNA</i>, measuring induced currents using the two-electrode voltage clamp technique. The molecular interaction between NSAIDs and hPAT1 was investigated using an AlphaFold2 model and molecular docking. <b>Results:</b> NSAIDs such as ibuprofen, diclofenac, and flurbiprofen inhibited proline uptake via hPAT1, with IC<sub>50</sub> values of 954 (logIC<sub>50</sub> 2.98 ± 0.1) µM, 272 (logIC<sub>50</sub> 2.43 ± 0.1) µM, and 280 (logIC<sub>50</sub> 2.45 ± 0.1) µM, respectively. Ibuprofen acted as a non-competitive inhibitor of hPAT1-mediated proline transport. In hPAT1-expressing oocytes, ibuprofen and diclofenac did not induce inward currents, and inhibited inward currents caused by proline. Molecular modeling pointed to a binding mode involving an allosteric site. <b>Conclusions:</b> NSAIDs interact with hPAT1 as non-translocated non-competitive inhibitors, and molecular modeling points to a binding mode involving an allosteric site distinct from the substrate binding site. The present findings could be used as a starting point for developing specific hPAT1 inhibitors. |
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| ISSN: | 1999-4923 |