Mechanistic Insights into PEPT1-Mediated Transport of a Novel Antiepileptic, NP-647

作者：Khomane Kailas S; Nandekar Prajwal P; Wahlang Banrida; Bagul Pravin; Shaikh Naeem; Pawar Yogesh B; Meena Chhuttan Lal; Sangamwar Abhay T; Jain Rahul; Tikoo K; Bansal Arvind K^*

来源：Molecular Pharmaceutics, 2012, 9(9): 2458-2468.

DOI：10.1021/mp200672d

• TRH analogues
• Caco-2 cells
• peptide transporters
• PEPT1 (SLC15A1)
• intestinal oligopeptide transporter
• homology modeling
• docking studies
• molecular dynamics simulation

The present study, in general, is aimed to uncover the properties of the transport mechanism or mechanisms responsible for the uptake of NP-647 into Caco-2 cells and, in particular, to understand whether it is a substrate for the intestinal oligopeptide transporter, PEPT1 (SLC15A1). NP-647 showed a carrier-mediated, saturable transport with Michaelis-Menten parameters K-m = 1.2 mM and V-max = 2.2 mu M/min. The effect of pH, sodium ion (Na+), glycylsarcosine and amoxicillin (substrates of PEPT1), and sodium azide (Na+/K+-ATPase inhibitor) on the flux rate of NP-647 was determined. Molecular docking and molecular dynamics simulation studies were carried out to investigate molecular interactions of NP-647 with transporter using homology model of human PEPT1. The permeability coefficient (PappCaco-2) of NP-647 (32.5 x 10(-6) cm/s) was found to be four times higher than that of TRH. Results indicate that NP-647 is transported into Caco-2 cells by means of a carrier -mediated, proton dependent mechanism that is inhibited by Gly-Sar and amoxicillin. In turn, NP-647 also inhibits the uptake of Gly-Sar into Caco-2 cells and, together, this evidence suggests that PEPT1 is involved in the process. Docking and molecular dynamics simulation studies indicate high affinity of NP-647 toward PEPT1 binding site as compared to TRH. High permeability of NP-647 over TRH is attributed to its increased hydrophobicity which increases its affinity toward PEPT1 by interacting with the hydrophobic pocket of the transporter through hydrophobic forces.

• 出版日期2012-9