Synthesis and Structural Characterization of Macrocyclic α-ABpeptoids and Their DNA-Encoded Library.

The first synthesis of macrocyclic α-ABpeptoids with varying lengths is described. X-ray crystal structures reveal that cyclic trimer displays a chair-like conformation with a cct amide sequence and cyclic tetramer has a saddle-like structure with an uncommon cccc amide arrangement. The creation of a DNA-encoded combinatorial library of macrocyclic α-ABpeptoids is described.

Cationic, amphipathic small molecules based on a triazine-piperazine-triazine scaffold as a new class of antimicrobial agents.

Poor proteolytic resistance, toxicity and salt/serum sensitivity of antimicrobial peptides (AMPs) limits their practical clinical application. Here, to overcome these drawbacks of AMPs and develop novel antimicrobial agents, a series of small molecules based on a triazine-piperazine-triazine scaffold that mimic the cationic amphipathic structure of AMPs were synthesized and evaluated their potential as a new class of antimicrobial agents. All designed compounds showed strong antimicrobial activity and negligible hemolytic activity. Particularly, five compounds (9, 11, 12, 15, and 16) presented excellent cell selectivity with proteolytic resistance, salt/serum stability and anti-inflammatory activity against lipopolysaccharide (LPS)-induced inflammation. These five compounds exhibited similar or 2-4 fold higher antimicrobial activity than melittin against six antibiotic-resistant bacteria tested. Similar to the intracellular-targeting AMP, buforin-2, these compounds displayed an intracellular mode of antimicrobial action. These compounds showed potent biofilm inhibitory and eradicating activities against multidrug-resistant Pseudomonas aeruginosa (MDRPA). Additionally, these compounds displayed synergistic or additive effects when combined with selected clinically used antibiotics. Furthermore, these compounds have been proven to inhibit pro-inflammatory cytokine release by directly binding to LPS and blocking the interaction between LPS and CD14/TLR4 receptor in LPS-stimulated RAW264.7 macrophage cells. Overall, our results demonstrate the potential of the designed compounds as a novel class of multifunctional antimicrobial agents to combat bacterial infection.

Evaluation of the cell permeability of bicyclic peptoids and bicyclic peptide-peptoid hybrids.

Bicyclization has proven to be an effective strategy for significantly restricting conformational flexibility in peptides and peptidomimetics such as peptoids. Such constrained bicyclic peptoids would have far higher conformational rigidity than monocyclic and linear ones, allowing them to have enhanced binding affinity and selectivity for their biological targets. Herein, we show that bicyclic peptoids have superior cellular uptake efficiency than their linear counterparts regardless of their side chains and ring sizes. As a representative example, an 8-mer bicyclic peptoid achieves a CP50 value of 1.2 µM, which is > 5-times superior to the corresponding linear peptoid. Additionally, we also demonstrate that bicyclic peptide-peptoid hybrids are much more cell-permeable than native peptides. Due to their favorable properties including improved cellular uptake, resistance to proteolytic degradation, relatively large sizes, and enormous structural diversity, constrained bicyclic peptoids and peptide-peptoid hybrids will play an important role as potential drug leads, especially in targeting intracellular protein-protein interactions, which are traditionally considered undruggable.

Design and synthesis of a DNA-encoded combinatorial library of bicyclic peptoids.

Here we describe the design and synthesis of a DNA-encoded library of bicyclic peptoids. We show that our solid-phase strategy is facile and DNA-compatible, yielding a structurally diverse combinatorial library of bicyclic peptoids of various ring sizes. We also demonstrate that affinity-based screening of a DNA-encoded library of bicyclic peptoids enables to efficiently identify high-affinity ligands for a target protein. Given their highly constraint structures, as well as increased cell permeability and proteolytic stability relative to native peptides, bicyclic peptoids could be an excellent source of protein capture agents. As such, our DNA-encoded library of bicyclic peptoids will serve as versatile tools that facilitate the generation of potent ligands against many challenging targets, such as intracellular protein-protein interactions.

Cell-penetrating, amphipathic cyclic peptoids as molecular transporters for cargo delivery.

Here we describe the design, synthesis, and biological evaluation of cell-penetrating, amphipathic cyclic peptoids as a novel class of molecular transporters. We demonstrated that macrocyclization, along with the introduction of hydrophobic residues, greatly enhanced cellular uptake of polyguanidine linear peptoids. The amphipathic cyclic peptoids showed an order of magnitude more efficient intracellular delivery ability, compared to a commonly used polyarginine cell-penetrating peptide, representing one of the best molecular transporters reported to date. Given the excellent cell-permeability, proteolytic stability, and ease of synthesis, the amphipathic cyclic peptoids would be broadly applicable to a wide range of clinical and biological applications.

Hydrophobic Tagging-Mediated Degradation of Transcription Coactivator SRC-1.

Steroid receptor coactivator-1 (SRC-1) is a transcription coactivator playing a pivotal role in mediating a wide range of signaling pathways by interacting with related transcription factors and nuclear receptors. Aberrantly elevated SRC-1 activity is associated with cancer metastasis and progression, and therefore, suppression of SRC-1 is emerging as a promising therapeutic strategy. In this study, we developed a novel SRC-1 degrader for targeted degradation of cellular SRC-1. This molecule consists of a selective ligand for SRC-1 and a bulky hydrophobic group. Since the hydrophobic moiety on the protein surface could mimic a partially denatured hydrophobic region of a protein, SRC-1 could be recognized as an unfolded protein and experience the chaperone-mediated degradation in the cells through the ubiquitin-proteasome system (UPS). Our results demonstrate that a hydrophobic-tagged chimeric molecule is shown to significantly reduce cellular levels of SRC-1 and suppress cancer cell migration and invasion. Together, these results highlight that our SRC-1 degrader represents a novel class of therapeutic candidates for targeting cancer metastasis. Moreover, we believe that the hydrophobic tagging strategy would be widely applicable to develop peptide-based protein degraders with enhanced cellular activity.

One-bead-one-compound screening approach to the identification of cyclic peptoid inhibitors of cyclophilin D as neuroprotective agents from mitochondrial dysfunction.

In an effort designed to discover superior inhibitors of cyclophilin D (CypD), we identified and screened members of a one-bead-one-compound (OBOC) library of cyclic peptoid analogues of cyclosporin A (CsA). The results show that the one member of this cyclic peptoid family, I11, inhibits mitochondrial membrane potential changes mediated by CypD.

Targeted Degradation of Transcription Coactivator SRC-1 through the N-Degron Pathway.

Aberrantly elevated steroid receptor coactivator-1 (SRC-1) expression and activity are strongly correlated with cancer progression and metastasis. Here we report, for the first time, the development of a proteolysis targeting chimera (PROTAC) that is composed of a selective SRC-1 binder linked to a specific ligand for UBR box, a unique class of E3 ligases recognizing N-degrons. We showed that the bifunctional molecule efficiently and selectively induced the degradation of SRC-1 in cells through the N-degron pathway. Importantly, given the ubiquitous expression of the UBR protein in most cells, PROTACs targeting the UBR box could degrade a protein of interest regardless of cell types. We also showed that the SRC-1 degrader significantly suppressed cancer cell invasion and migration in vitro and in vivo. Together, these results demonstrate that the SRC-1 degrader can be an invaluable chemical tool in the studies of SRC-1 functions. Moreover, our findings suggest PROTACs based on the N-degron pathway as a widely useful strategy to degrade disease-relevant proteins.

Bridged α-helix mimetic small molecules.

Herein, we report a strategy for generating conformationally restricted α-helix mimetic small molecules by introducing covalent bridges that limit rotation about the central axis of α-helix mimetics. We demonstrate that the bridged α-helix mimetics have enhanced binding affinity and specificity to the target protein due to the restricted conformation as well as extra interaction of the bridge with the protein surface.

DNA-Encoded Combinatorial Library of Macrocyclic Peptoids.

We report the design and synthesis of a DNA-encoded one-bead one-compound library of cyclic peptoids composed of more than 11 million molecules. We show that affinity-based screening of this large library can identify cyclic peptoid ligands for a target protein. In this work, we developed a simple method for amplifying the PCR product from DNA tags on a single bead, thereby enabling determination of the structures of hit cyclic peptoids with no need for high-throughput sequencing and complicated data analysis. We also developed a sublibrary screening strategy to minimize false positives caused by the interference of coding DNA tags before starting laborious and impractical hit confirmation. Given the simplicity and robustness of the synthesis and screening, along with the desirable features of macrocyclic peptoids including improved conformational rigidity, our method will be highly useful for discovering biologically active molecules modulating challenging targets such as protein-protein interactions that are not easily targeted by typical peptidomimetics and small-molecules.

A solid-phase method for synthesis of dimeric and trimeric ligands: Identification of potent bivalent ligands of 14-3-3σ.

Multivalent protein-protein interactions including bivalent and trivalent interactions play a critical role in mediating a wide range of biological processes. Hence, there is a significant interest in developing molecules that can modulate those signaling pathways mediated by multivalent interactions. For example, multimeric molecules capable of binding to a receptor protein through a multivalent interaction could serve as modulators of such interactions. However, it is challenging to efficiently generate such multimeric ligands. Here, we have developed a facile solid-phase method that allows for the rapid generation of (homo- and hetero-) dimeric and trimeric protein ligands. The feasibility of this strategy was demonstrated by efficiently synthesizing fluorescently-labeled dimeric peptide ligands, which led to dramatically increased binding affinities (~400-fold improvement) relative to a monomeric 14-3-3σ protein ligand.

Oligomers of α-ABpeptoid/ß3 -peptide hybrid.

Peptoids, oligomers of N-substituted glycines, have been attracting increasing interest due to their advantageous properties as peptidomimetics. However, due to the lack of chiral centers and amide hydrogen atoms, peptoids, in general, do not form folding structures except that they have α-chiral side chains. We have recently developed "peptoids with backbone chirality" as a new class of peptoid foldamers called α-ABpeptoids and demonstrated that they could have folding conformations owing to the methyl groups on chiral α-carbons in the backbone structure. Here we report α-ABpeptoid/ß3 -peptide oligomers as a unique peptidomimetic structure with a heterogeneous backbone. This hybrid structure contains a mixed α-ABpeptoid and ß3 -peptide residues arranged in an alternate manner. These α-ABpeptoid/ß3 -peptide oligomers could form intramolecular hydrogen bonding and have better cell permeability relative to pure peptide sequences. These oligomers were shown to adopt ordered folding structures based on circular dichroism studies. Overall, α-ABpeptoid/ß3 -peptide oligomers may represent a novel class of peptidomimetic foldamers and will find a wide range of applications in biomedical and material sciences.

Solid-Phase Synthesis and Circular Dichroism Study of ß-ABpeptoids.

The development of peptidomimetic foldamers that can form well-defined folded structures is highly desirable yet challenging. We previously reported on α-ABpeptoids, oligomers of N-alkylated ß²-homoalanines and found that due to the presence of chiral methyl groups at α-positions, α-ABpeptoids were shown to adopt folding conformations. Here, we report ß-ABpeptoids having chiral methyl group at ß-positions rather than α-positions as a different class of peptoids with backbone chirality. We developed a facile solid-phase synthetic route that enables the synthesis of ß-ABpeptoid oligomers ranging from 2-mer to 8-mer in excellent yields. These oligomers were shown to adopt ordered folding conformations based on circular dichroism (CD) and NMR studies. Overall, these results suggest that ß-ABpeptoids represent a novel class of peptidomimetic foldamers that will find a wide range of applications in biomedical and material sciences.

Clinical and Laboratory Findings of Middle East Respiratory Syndrome Coronavirus Infection.

There is a paucity of data regarding the differentiating characteristics of patients with laboratory-confirmed and those negative for Middle East respiratory syndrome coronavirus (MERS-CoV) in South Korea. This hospital-based retrospective study compared MERS-CoV-positive and MERS-CoV-negative patients. A total of seven positive patients and 55 negative patients with a median age of 43 years (P = 0.845) were included. No statistical differences were observed with respect to their sex and the presence of comorbidities. At the time of admission, headache (28.6% vs. 3.6%; odds ratio [OR], 10.60; 95% confidence interval [CI], 1.22-92.27), myalgia (57.1% vs. 9.1%; OR, 13.33; 95% CI, 2.30-77.24), and diarrhea (57.1% vs. 14.5%; OR, 7.83; 95% CI, 1.47-41.79) were common among MERS-CoV-positive patients. MERS-CoV-positive patients were more likely to have a low platelet count (164 ± 76.57 vs. 240 ± 79.87) and eosinophil (0.27 ± 0.43 vs. 2.13 ± 2.01; P = 0.003). Chest radiography with diffuse bronchopneumonia was more frequent in MERS-CoV-positive patients than in negative patients (100% vs. 62.5%; P = 0.491). The symptoms of headache, myalgia, and diarrhea, as well as laboratory characteristics, including low platelet counts and eosinophil, and chest X-ray showing diffuse bronchopneumonia might enhance the ability to detect patients in South Korea infected with MERS-CoV.

Aromatherapy for Managing Pain in Primary Dysmenorrhea: A Systematic Review of Randomized Placebo-Controlled Trials.

Aromatherapy, the therapeutic use of essential oils, is often used to reduce pain in primary dysmenorrhea. Eleven databases, including four English (PubMed, AMED, EMBASE, and the Cochrane Library) and seven Korean medical databases, were searched from inception through August 2018 without restrictions on publication language. Randomized controlled trials (RCTs) testing aromatherapy for pain reduction in primary dysmenorrhea were considered. Data extraction and risk-of-bias assessments were performed by two independent reviewers. All of the trials reported superior effects of aromatherapy for pain reduction compared to placebo (n = 1787, standard mean difference (SMD): -0.91, 95% CI: -1.17 to -0.64, p < 0.00001) with high heterogeneity (I² = 88%). A sub-analysis for inhalational aromatherapy for the alleviation of pain also showed superior effects compared to placebo (n = 704, SMD: -1.02, 95% CI: -1.59 to -0.44, p = 0.0001, I² = 95%). With regard to aromatherapy massage, the pooled results of 11 studies showed favorable effects of aromatherapy massage on pain reduction compared to placebo aromatherapy massage (n = 793, SMD: -0.87, 95% CI: -1.14 to -0.60, p < 0.00001, I² = 70%). Oral aromatherapy had superior effects compared to placebo (n = 290, SMD: -0.61, 95% CI: -0.91 to -0.30, p < 0.0001, I² = 0%). In conclusion, our systemic review provides a moderate level of evidence on the superiority of aromatherapy (inhalational, massage, or oral use) for pain reduction over placebo in primary dysmenorrhea.

Submonomer Strategy toward Divergent Solid-Phase Synthesis of α-ABpeptoids.

A novel submonomer solid-phase synthetic method for α-ABpeptoid oligomers is reported. Iterative submonomer coupling and Fukuyama-Mitsunobu alkylation enable facile, divergent synthesis of α-ABpeptoid oligomers substituted with chemically diverse side chains in excellent yields.

A Forkhead Box Protein†C2 Inhibitor: Targeting Epithelial-Mesenchymal Transition and Cancer Metastasis.

The epithelial-mesenchymal transition (EMT) has been suggested as a new target for therapeutic intervention of metastatic cancer. Forkhead box protein C2 (FOXC2) is known to be necessary for initiating and maintaining EMT, and therefore bestows on cancer cells metastatic and cancer stem cell (CSC)-like phenotypes, allowing cells to acquire higher motility, invasiveness, self-renewal, and therapy resistance. Here, we describe the first inhibitor of FOXC2, MC-1-F2. MC-1-F2 was able to induce cadherin switching and reverse EMT through the degradation of FOXC2 and blocking of its nuclear localization. In addition, MC-1-F2 was very effective in inhibiting cancer cell migration and invasion. As the first small-molecule inhibitor of FOXC2 and the first compound targeting EMT-associated transcription factor, MC-1-F2 will pave the way for a new anticancer therapeutic agent targeting metastatic cancer and help to elucidate the network of EMT signaling pathways.

Fennel (Foeniculum vulgare) on management of menopausal symptoms: A protocol for systematic review of randomized controlled trials.

BACKGROUND: Fennel (Foeniculum vulgare) is often used in women's health care to treat dysmenorrhea, increase the milk supply, and address symptoms of menopause. The object of this review is to evaluate the current evidence on the efficacy of fennel for the management menopausal symptoms. METHODS AND ANALYSES: Thirteen databases will be searched from their inception to the present. These include PubMed, AMED, EMBASE, the Cochrane Library, six Korean medical databases (Korean Studies Information Service System, DBPIA, the Korean Institute of Science and Technology Information, the Research Information Service System, KoreaMed, and the Korean National Assembly Library), and 3 Chinese databases (the China National Knowledge Infrastructure Database [CNKI], the Chongqing VIP Chinese Science and Technology Periodical Database [VIP], and Wanfang Database). Study selection, data extraction, and assessments will be performed independently by 2 researchers. The risk of bias will be assessed using the Cochrane risk of bias tool. ETHICS AND DISSEMINATION: Ethical approval is not required, given that this protocol is for a systematic review only. The review will be published in a peer-reviewed journal and disseminated both electronically and in print. The review will be updated to inform and guide healthcare practice and policy. TRIAL REGISTRATION NUMBER: PROSPERO 2018 CRD42018085698.

Comparison of Cell Permeability of Cyclic Peptoids and Linear Peptoids.

Cyclic peptoids are emerging as an attractive class of peptidomimetics. Compared to their linear counterparts, cyclic peptoids should have increased conformational rigidity and preorganized structures, enabling them to bind more tightly to target proteins without major entropy penalty. Because cyclic peptoids lack the amide protons in their backbones like linear peptoids, it is perceived that cyclic peptoids are seemingly cell permeable as much as linear peptoids. However, no systematic investigation for cell permeability of cyclic peptoids has been reported yet. Here, we, for the first time, demonstrate that cyclic peptoids are far more cell permeable than linear counterparts irrespective of their size and side chains. This study highlights that cyclic peptoids, along with combinatorial library and high-throughput screening technologies, will serve as a rich source of protein binding molecules, particularly targeting intracellular proteins, given their excellent cell permeability in addition to their conformational rigidity and proteolytic stability.

Targeted Inhibition of the NCOA1/STAT6 Protein-Protein Interaction.

The complex formation between transcription factors (TFs) and coactivator proteins is required for transcriptional activity, and thus disruption of aberrantly activated TF/coactivator interactions could be an attractive therapeutic strategy. However, modulation of such protein-protein interactions (PPIs) has proven challenging. Here we report a cell-permeable, proteolytically stable, stapled helical peptide directly targeting nuclear receptor coactivator 1 (NCOA1), a coactivator required for the transcriptional activity of signal transducer and activator of transcription 6 (STAT6). We demonstrate that this stapled peptide disrupts the NCOA1/STAT6 complex, thereby repressing STAT6-mediated transcription. Furthermore, we solved the first crystal structure of a stapled peptide in complex with NCOA1. The stapled peptide therefore represents an invaluable chemical probe for understanding the precise role of the NCOA1/STAT6 interaction and an excellent starting point for the development of a novel class of therapeutic agents.