Peptide transporters are integral plasma membrane proteins that mediate the cellular uptake of dipeptides and tripeptides in addition to a variety of peptidomimetics. The carriers, which occur predominantly in the brush-border membranes of epithelial cells of the small intestine, lung, choroid plexus and kidney, contribute to absorption, distribution and elimination of their substrates. The cellular uptake of peptides and peptidomimetics involves the cotransport of protons down an inwardly directed, electrochemical proton gradient that provides the driving force and causes the electrogenicity of the translocation step. Peptide transporters represent excellent targets for the delivery of pharmacologically active compounds because their substrate-binding site can accommodate a wide range of molecules of differing size, hydrophobicity and charge.

Mammalian peptide transporters as targets for drug delivery

Apical sodium-dependent bile acid transporter, drug target for bile acid related diseases and delivery target for prodrugs: Current and future challenges.

Natural products and their derivatives are important sources for drug discovery; however, they usually have poor solubility and low activity and require structural modification. Amino acids are highly soluble in water and have a wide range of activities. The introduction of amino acids into natural products is expected to improve the performance of these products and minimize their adverse effects. Therefore, this review summarizes the application of amino acids in the structural modification of natural products and provides a theoretical basis for the structural modification of natural products in the future. The articles were divided into six types based on the backbone structures of the natural products, and the related applications of amino acids in the structural modification of natural products were discussed in detail.

/pdf/application-of-amino-acids-in-the-structural-modification-of-2np2ig0b9s.pdf

Application of Amino Acids in the Structural Modification of Natural Products: A Review

Design, synthesis and evaluation of novel scutellarin and scutellarein-N,N-bis-substituted carbamate-l-amino acid derivatives as potential multifunctional therapeutics for Alzheimer's disease.

A valine carbamate prodrug of daidzein was synthesized to improve its bioavailability because of the poor solubility and low permeability of daidzein. To evaluate the pharmacokinetic behavior of the prodrug, a sensitive and high-throughput method was developed and validated for the simultaneous determination of daidzein and its prodrug in rat plasma. The samples were extracted by ethyl acetate and then analyzed by a supercritical fluid chromatography with electrospray ionization tandem mass spectrometry method. The separation was achieved by an ACQUITY UPC2 ™ BEH 2-EP column maintained at 40°C using carbon dioxide (≥99.99%) and methanol within 3.0 min by gradient elution. The mass transition ion pairs were m/z 254.8→136.7, 398.0→254.9, and 271.0→91.07 for daidzein, the prodrug, and genistein, respectively. The calibration curves were linear over the concentration ranges of 2-500 (r > 0.997) and 10.0-5000.0 ng/mL (r > 0.996) with lower limits of quantification of 2 and 10 ng/mL for daidzein and the prodrug, respectively. The intra- and interday accuracy and precision were within ±15% for all quality control samples. This developed method enabled high specificity, low cost, low solvent consumption, and a brief analysis time and was successfully applied to a bioavailability evaluation of daidzein and its carbamate prodrug.

A sensitive, high-throughput, and eco-friendly analysis of daidzein and its valine carbamate prodrug in rat plasma by supercritical fluid chromatography with tandem mass spectrometry

A series of 4′-l-amino acid carbamate derivatives of scutellarin methyl ester were synthesized Physiochemical properties evaluation results showed that designed target compounds have higher chemical and enzymatic stability, and aqueous solubility The permeability (P
 app
 AP to BL) of 4c, 4f, and 4g in Caco-2 cell was 8, 7, and 13 times higher than that of scutellarin, respectively, especially 4g had highest P
 app AP to BL value (185 ± 029 × 10−6 cm/s) and lowest ER (P
 app BL to AP/P
 app
 AP to BL) value 056 In vitro anti-oxidative evaluation results revealed that 4g can protect against H2O2-induced PC12 cells oxidative damage by attenuating the MMP loss and decreasing H2O2-induced ROS production

l-Amino acid carbamate prodrugs of scutellarin: synthesis, physiochemical property, Caco-2 cell permeability, and in vitro anti-oxidative activity

A series of 4′-N-substituted (aminomethyl) benzoate-7-substituted nicotinic acid ester derivatives of scutellarein was designed and synthesized. Evaluation of physiochemical properties showed that the newly designed compounds had greater chemical stability and aqueous solubility than scutellarin or scutellarein. The permeabilities (P
 app AP to BL) of compounds 7b and 7e in Caco-2 cells were 5.9-fold and 3.7-fold higher than that of scutellarin, and 3.7-fold and 2.4-fold higher than that of scutellarein. The permeabilities (P
 app AP to BL) of compounds 7b and 7e in an in vitro model of the blood–brain barrier were 9.7-fold and 5.9-fold higher than that of scutellarin, and 9.2-fold and 5.6-fold higher than that of scutellarein.

Permeability of novel 4′- N -substituted (aminomethyl) benzoate-7-substituted nicotinic acid ester derivatives of scutellarein in Caco-2 cells and in an in vitro model of the blood-brain barrier

A series of adefovir mono L-amino acid ester, mono bile acid ester derivatives was designed and synthesized. The newly designed compounds have potent anti-anti-hepatitis B activity, especially compound 6c, which has more potent antiviral activity and a higher selectivity index (EC50 0.65 μmol/L, SI 582.24) than adefovir dipivoxil. Uptake of compounds 6a–f into rat primary hepatocytes was 71.56, 63.92, 142.88, 104.25, 67.84, and 39.95-fold, respectively, higher than that of adefovir dipivoxil. In the presence of Na+, uptake of compounds 6a–c by Na+/taurocholate co-transporting polypeptide-Human embryonic kidney 293 cells was 128.5, 137.2 and 121.7-fold higher than that of adefovir dipivoxil. Potential binding modes of compounds 6a and 6c to human apical Na+-dependent bile acid transporter were also investigated.

Novel adefovir mono L-amino acid ester, mono bile acid ester derivatives: Design, synthesis, biological evaluation, and molecular docking study

The invention discloses a compound with a chemical structure as described in the specification, and pharmaceutically acceptable salts, salt crystalline hydrates and salt crystalline solvents thereof. In the chemical structure, R1 is H or OH; R2 is H or OH; and R3 is an alkyl group with 1 to 4 carbon atoms. Antiviral activity and primary hepatocyte uptaking experiment results show that the compound has better antiviral activity and liver cell transfer specificity than adefovir dipivoxil, and can be used for preparation of drugs treating hepatitis B virus infection.

Adefovir thio L-amino acid ester and mono bile acid ester derivatives and preparation method thereof

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l-Amino acid carbamate prodrugs of scutellarin: synthesis, physiochemical property, Caco-2 cell permeability, and in vitro anti-oxidative activity

Permeability of novel 4′- N -substituted (aminomethyl) benzoate-7-substituted nicotinic acid ester derivatives of scutellarein in Caco-2 cells and in an in vitro model of the blood-brain barrier

Novel adefovir mono L-amino acid ester, mono bile acid ester derivatives: Design, synthesis, biological evaluation, and molecular docking study

Adefovir thio L-amino acid ester and mono bile acid ester derivatives and preparation method thereof