1. Improved Micellar Formulation for Enhanced Delivery for Paclitaxel
Jieni Xu, Xiaolan Zhang, Yichao Chen, Yixian Huang, Pengcheng Wang, Yuan Wei, Xiaochao Ma, Song Li Mol Pharm. 2017 Jan 3;14(1):31-41. doi: 10.1021/acs.molpharmaceut.6b00581. Epub 2016 Nov 30.
We have previously improved the bioactivity of PEG5k-FTS2 system by incorporating disulfide bond (PEG5k-S-S-FTS2) to facilitate the release of farnesyl thiosalicylic acid (FTS).1 Later, fluorenylmethyloxycarbonyl (Fmoc) moiety has been introduced to PEG5k-FTS2 system (PEG5k-Fmoc-FTS2) in order to enhance drug loading capacity (DLC) and formulation stability.2 In this study, we have brought in both disulfide linkage and Fmoc group to PEG5k-FTS2 to form a simple PEG5k-Fmoc-S-S-FTS2 micellar system. PEG5k-Fmoc-S-S-FTS2 conjugate formed filamentous micelles with a ~10-fold decrease in critical micellar concentration (CMC). Compared with PEG5k-Fmoc-FTS2, our novel system exhibited further strengthened DLC and colloidal stability. More FTS was freed from PEG5k-Fmoc-S-S-FTS2 in treated tumor cells compared to PEG5k-Fmoc-FTS2, which was correlated to an increased cytotoxicity of our new carrier in these cancer cells. After loading Paclitaxel (PTX) into PEG5k-Fmoc-S-S-FTS2 micelles, it showed more potent efficiency in inhibition of tumor cell proliferation than Taxol and PTX-loaded PEG5k-Fmoc-FTS2. PTX release kinetics of PTX/PEG5k-Fmoc-S-S-FTS2 was much slower than that of Taxol and PTX/PEG5k-Fmoc-FTS2 in normal release medium. In contrast, in glutathione (GSH)-containing medium, PTX in PEG5k-Fmoc-S-S-FTS2 micelles revealed faster and more complete release. Pharmacokinetics and tissue distribution study showed that our PEG5k-Fmoc-S-S-FTS2 system maintained PTX in circulation for a longer time and delivered more PTX to tumor sites with less accumulation in major organs. Finally, PTX-loaded PEG5k-Fmoc-S-S-FTS2 micelles resulted in a superior therapeutic effect in vivo compared to Taxol and PTX formulated in PEG5k-Fmoc-FTS2 micelles.
2. Large-Scale Asymmetric Synthesis of Fmoc-( S)-2-Amino-6,6,6-Trifluorohexanoic Acid
Zizhen Yin, Hiroki Moriwaki, Hidenori Abe, Toshio Miwa, Jianlin Han, Vadim A Soloshonok ChemistryOpen. 2019 Jun 7;8(6):701-704. doi: 10.1002/open.201900131. eCollection 2019 Jun.
Here we report the first large-scale synthesis of Fmoc-(S)-2-amino-6,6,6-trifluorohexanoic acid via asymmetric alkylation of chiral Ni(II)-complex of glycine Schiff base with CF3(CH2)3I. The synthesis was performed on over 100 g scale and can be recommended as the most advanced procedure for reliable preparation of large amounts of enantiomerically pure Fmoc-(S)-2-amino-6,6,6-trifluorohexanoic acid for protein engineering and drug design. Chiral auxiliary used in this protocol can be >90 % recovered and reused.
3. Evolving nanomaterials using enzyme-driven dynamic peptide libraries (eDPL)
Apurba K Das, Andrew R Hirsth, Rein V Ulijn Faraday Discuss. 2009;143:293-303; discussion 359-72. doi: 10.1039/b902065a.
This paper describes the application of dynamic combinatorial libraries (DCL) towards the discovery of self-assembling nanostructures based on aromatic peptide derivatives and the continuous enzymatic exchange of amino acid sequences. Ultimately, the most thermodynamically stable self-assembling structures will dominate the system. In this respect, a library of precursor components, based on N-fluorenyl-9-methoxycarbonyl (Fmoc)-amino acids (serine, S and threonine, T) and nucleophiles (leucine, L-; phenylalanine, F-; tyrosine, Y-; valine, V-; glycine, G-; alanine, A-OMe amino-acid esters) were investigated to produce Fmoc-dipeptide esters, denoted Fmoc-XY-OMe. Upon exposure to a protease (thermolysin), which catalyses peptide bond formation and hydrolysis under aqueous conditions at pH 8, dynamic libraries of self-assembling gelator species were generated. Depending on the molecular composition of the precursors present in the library different behaviours were observed. Single components, Fmoc-SF-OMe and Fmoc-TF-OMe, dominated over time in Fmoc-S/(L+F+Y+V+G+A)-OMe and Fmoc-T/ (L+F+Y+V+G+A)-OMe libraries. This represented > 80% of all peptide formed suggesting that a single component molecular structure dominates in these systems. In a competition experiment between Fmoc-(S+T)/F-OMe, conversions to each peptide corresponded directly with ratios of starting materials, implying that a bi-component nanostructure, where Fmoc-TF-OMe and Fmoc-SF-OMe are incorporated equally favourably, was formed. Several techniques including HPLC, LCMS and fluorescence spectroscopy were used to characterize library composition and molecular interactions within the self-selecting libraries. Fluorescence spectroscopy analysis suggests that the most stable peptide nanostructures show significant pi-pi intermolecular electronic communication. Overall, the paper demonstrates a novel evolution-based approach with self-selection and amplification of supramolecular peptide nanostructures from a complex mixture of amino acid precursors.
