Ethylene Glycol-Linked Amino Acid Diester Prodrugs of Oleanolic Acid for PepT1-Mediated Transport: Synthesis, Intestinal Permeability and Pharmacokinetics

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• 作者：Feng Cao ; Jinghao Jia ; Zhi Yin ; Yahan Gao ; Lei Sha ; Yisheng Lai ; Qineng Ping ; Yihua Zhang
• 刊名：Molecular Pharmaceutics
• 出版年：2012
• 出版时间：August 6, 2012
• 年：2012
• 卷：9
• 期：8
• 页码：2127-2135
• 全文大小：343K
• 年卷期：v.9,no.8(August 6, 2012)
• ISSN：1543-8392

文摘

The purposes of this study were to expand the structure of parent drugs selected for peptide transporter 1 (PepT1)-targeted ester prodrug design and to improve oral bioavailability of oleanolic acid (OA), a Biopharmaceutics Classification System (BCS) class IV drug. Through an ethoxy linker the carboxylic acid group of OA was conjugated with the carboxylic acid group of different amino acid promoieties to form six diester prodrugs. The effective permeability (P_eff) of prodrugs was screened by in situ rat single-pass intestinal perfusion (SPIP) model in two buffers with different pH (6.0 and 7.4) as PepT1 employs a proton-gradient as the driving force. Compared to OA, 2.5-fold, 2.3-fold, 2.2-fold, 2.1-fold, and 1.9-fold enhancement of P_eff in buffer with pH 6.0 was observed for l-Phe ester (5c), l-Val ester (5a), l-Lys ester (5e), d-Phe ester (5d), and d-Val ester (5b), respectively. Furthermore, P_eff of 5a, 5c, 5d and 5e in pH 6.0 was significantly higher than that in pH 7.4 (p < 0.01), respectively. These results showed that the H⁺ concentration of perfusion solution had great effect on the transport of the prodrugs across intestinal membrane. For the further evaluation of affinity to PepT1, inhibition studies were performed by coperfusing 0.1 mM prodrug with 50 mM glycyl-sarcosine (Gly-Sar, a typical substrate of PepT1). It turned out that the P_eff of 5a, 5b, 5c and l-Tyr ester (6f) significantly reduced in the presence of Gly-Sar (1.7-fold, 2.2-fold, 1.9-fold, and 1.4-fold, respectively). We supposed that it may be attributed to PepT1 mediated transport of these prodrugs. 5a and 6f were selected as the optimal target prodrugs for oral absorption in vivo. Following intragastric administration of 300 mg/kg (calculated as OA) 5a, 6f and OA in three groups of rats, compared with group OA, C_max for the group of 5a and 6f was enhanced by 1.56-fold and 1.54-fold, respectively. F_app of group 5a and 6f was 2.21- and 2.04-fold increased, respectively, indicating that 5a and 6f had better oral absorption than OA. The combined results also suggest that diester prodrugs which conjugated two carboxylic acid groups of proper amino acid promoieties and parent drug through a linker can be used for PepT1-targeted prodrug design. With this strategy, oral bioavailability of OA in rats could be improved significantly.

Keywords:

oleanolic acid; peptide transporter 1; ester prodrug; in situ single-pass intestinal perfusion; pharmacokinetics; bioavailability