Eun Ji Park

Exendin-4 Inhibits HMGB1-Induced Inflammatory Responses in HUVECs and in Murine Polymicrobial Sepsis

High mobility group box-1 (HMGB1) protein acts as a late mediator of severe vascular inflammatory conditions. Orientin has been known to have anxiolytic and antioxidative activities. However, the effect of orientin on HMGB1-induced inflammatory response has not been studied. We assessed this question by monitoring the effects of post-treatment orientin and its derivatives on lipopolysaccharide (LPS) and cecal ligation and puncture (CLP)-mediated release of HMGB1 and HMGB1-mediated regulation of pro-inflammatory responses in human umbilical vein endothelial cells (HUVECs) and septic mice. Post-treatment orientin was found to suppress LPS-mediated release of HMGB1 and HMGB1-mediated cytoskeletal rearrangements. Orientin inhibited HMGB1-mediated hyperpermeability and leukocyte migration in septic mice. Orientin also induced down-regulation of CLP-induced release of HMGB1 and mortality. Collectively, these results suggest that orientin may be regarded as a candidate therapeutic agent for treatment of vascular inflammatory diseases via inhibition of the HMGB1 signaling pathway.

Long-acting injectable formulations of antipsychotic drugs for the treatment of schizophrenia

Antipsychotic drugs have been used to treat patients with schizophrenia and other psychotic disorders. Long-acting injectable antipsychotic drugs are useful for improving medication compliance with a better therapeutic option to treat patients who lack insight or adhere poorly to oral medication. Several long-acting injectable antipsychotic drugs are clinically available. Haloperidol decanoate and fluphenazine decanoate are first-generation depot drugs, but the use of these medicines has declined since the advent of second-generation depot agents, such as long-acting risperidone, paliperidone palmitate, and olanzapine pamoate. The second-generation depot drugs are better tolerated and have fewer adverse neurological side effects. Long-acting injectable risperidone, the first depot formulation of an atypical antipsychotic drug, was prepared by encapsulating risperidone into biodegradable microspheres. Paliperidone palmitate is an aqueous suspension of nanocrystal molecules, and olanzapine pamoate is a microcrystalline salt of olanzapine and pamoic acid suspended in aqueous solution. This review summarizes the characteristics and recent research of formulations of each long-acting injectable antipsychotic drug.

Caffeic acid phenethyl ester activation of Nrf2 pathway is enhanced under oxidative state: Structural analysis and potential as a pathologically targeted therapeutic agent in treatment of colonic inflammation

Caffeic acid phenethyl ester (CAPE) is a polyphenolic natural product that possesses numerous biological activities including anti-inflammatory effects. CAPE-mediated nuclear factor-erythroid 2 p45 (NF-E2)-related factor 2 (Nrf2) activation is likely responsible for some of its biological effects. CAPE was chemically modified to yield CAPE analogues that were subjected to experiments examining cellular Nrf2 activity. CAPE and the CAPE analogue with a catechol moiety, but not the other analogues, activated the Nrf2 pathway. In addition, only biotin-labeled CAPE analogues with the catechol moiety precipitated Kelch-like ECH associated protein 1 (Keap1) when incubated with cell lysates and streptavidin agarose beads. Sodium hypochlorite (NaOCl) oxidation of the catechol moiety in CAPE produced an oxidized, electrophilic form of CAPE (Oxi-CAPE) and greatly enhanced the ability of CAPE to activate Nrf2 and to bind to Keap1. Rectal administration of CAPE ameliorated 2,4,6-trinitrobenzene sulfonic acid-induced rat colitis and activated the Nrf2 pathway in the inflamed colon, and incubation of CAPE in the lumen of the inflamed distal colon generated Oxi-CAPE. However, these biological effects and chemical change of CAPE were not observed in the normal colon. Our data suggest that CAPE requires the catechol moiety for the oxidation-enhanced activation of the Nrf2 pathway and has potential as a pathologically targeted Nrf2-activating agent that is exclusively activated in pathological states with oxidative stress such as colonic inflammation.

A Double‐Chambered Protein Nanocage Loaded with Thrombin Receptor Agonist Peptide (TRAP) and γ‐Carboxyglutamic Acid of Protein C (PC‐Gla) for Sepsis Treatment

New protein nanocages are designed bearing two functional proteins, γ-carboxyglutamic acid of protein C (PC-Gla) and thrombin receptor agonist peptide (TRAP), and have an anti-septic response. These nanoparticles reduce sepsis-induced organ injury and septic mortality in vivo. Noting that there are currently no medications for severe sepsis, these results show that novel nanoparticles can be used to treat sepsis.

Chromatographic methods for characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers

The objective of this study was to develop chromatographic methods for the determination of the modification degree and the characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers (PEG-PAMAMs). The PEG-PAMAMs were prepared by reacting PAMAM generation 4 with monomethoxy PEG-nitrophenyl carbonate (mPEG-NPC). The modification degrees of PEG-PAMAMs were determined by quantifying 4-nitrophenol released from mPEG-NPC after PEGylation reaction using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The PEG-PAMAMs, which have poor UV absorbances, were characterized by HPLC with charged aerosol detection. This study demonstrates that the combination of these two detectors is a powerful tool for the preparation and characterization of PEG-PAMAMs.

Drug release testing methods of polymeric particulate drug formulations

The long-term controlled delivery of drugs has been successfully achieved by biodegradable polymeric particulate systems. The drug release testing method is important for the characterization of dosage form performance under in vitro standardized conditions and can provide insight into the in vivo performance of the drug product. In vitro drug release testing methods for polymeric particulate systems are classified into sample and separate (SS), dialysis, and continuous flow (CF) methods. In the SS method, the drug-loaded microparticles are suspended in a vessel and the samples for the analysis are obtained by separating the particles using filtration or centrifugation. The dialysis method physically separates microparticles from the release media by a membrane, which eliminates the undesired loss of particles during sample preparation and handling. The CF method uses apparatus consisted of flow-through cell that holds the sample, pump and water bath in closed or open ends system. In this method, the release media is continuously circulated through a cell containing drug-loaded microparticles. This review summarizes the principles of the drug release testing methods and discusses their characteristics with the recent research results.

Exendins and exendin analogs for diabetic therapy: a patent review (2012-2015)

ABSTRACT Introduction: Since exendin-4 (exenatide) was approved for diabetes therapy in 2005, several exendin analogs have been developed for the treatment of type 2 diabetes mellitus. As exenatide is a relatively short-acting injectable agent, major approaches have focused on developing long-acting exendin analogs to improve patient compliance and convenience. Areas covered: In this review, the authors report on patents related to exendins and exendin analogs from 2012 to 2015. The patents have been divided into three categories based on the technologies used to develop the new chemical entities: 1) chemical bioconjugate analogs; 2) recombinant fusion protein analogs; and 3) multifunctional peptide analogs. Expert opinion: Recently, research on exendins and their analogs has grown significantly, leading to the development of long-acting analogs and multifunctional peptides. While long-acting injectable agents are still the major products in the pharmaceutical industry, a significant growth is expected in the development of orally available exendins.

Mono-lithocholated exendin-4-loaded glycol chitosan nanoparticles with prolonged antidiabetic effects

Hydrophobically modified glycol chitosan (HGC) nanoparticles loaded with mono-lithocholic acid-conjugated exendin-4 at the Lys(27) residue (LAM1-Ex4) were prepared and characterized by particle size measurement, proteolytic stability, in vitro drug-release profile, and in vivo antidiabetic effects in a db/db diabetic mouse model. Compared with Ex-4-loaded HGC nanoparticles (Ex4/HGC NPs) prepared as a control, LAM1-Ex4-loaded HGC nanoparticles (LAM1-Ex4/HGC NPs) showed improved drug-loading efficiency, small particle size, enhanced resistance against proteolytic digestion, and an extended in vitro drug release profile. These findings may be attributable to the strong hydrophobic interaction between LAM1-Ex4 and the inner core of HGC. Furthermore, LAM1-Ex4/HGC NPs showed prolonged hypoglycemic efficacy in db/db mice, lasting 1 week after a single subcutaneous administration. The present study demonstrated that LAM1-Ex4/HGC NPs have considerable potential as a long-acting sustained-release antidiabetic system for type 2 diabetes.

Palmitoylation of octreotide for incorporation into poly(amidoamine) dendrimers

Poly(amidoamine) (PAMAM) dendrimers are nano-sized carrier molecules with tremendous promise in polymeric drug delivery systems. The purpose of this study was to prepare and characterize palmitoyl-octreotide-incorporated PAMAM dendrimers. As octreotide is hydrophilic, it was difficult to be incorporated into PAMAM dendrimers. This study demonstrated that the conjugation of palmitic acid (palmitoylation) was effective for the incorporation of octreotide into PAMAM dendrimers. The site-specific palmitoylation at the N-terminal amine of octreotide was successfully performed by a reversible protection approach using maleic anhydride, and the conditions for the production of the final product were optimized. The incorporation yield of palmitoyl-octreotide into PAMAM dendrimers was significantly higher than that of octreotide. The palmitoyl-octreotide-incorporated PAMAM dendrimer has a potential as a new drug delivery system for somatostatin therapeutics.

Antibody–drug conjugates for targeted anticancer drug delivery

Antibody–drug conjugates (ADCs) are tumor-targeted therapeutic agents that combine the specificity of monoclonal antibodies (mAbs) with the potent anti-tumor effects of cytotoxic drugs. Over the past few years, ADCs have become a powerful tool in the field of cancer chemotherapy. Recently, two ADC products, brentuximab vedotin (Adcetris®) and trastuzumab emtansine (Kadcyla®), have received FDA approval and there are more than 40 ADC candidates in clinical trials for the treatment of various cancers. Despite the success of some products, considerable interests for the next generation of ADCs have focused on the development of homogeneous conjugates because most of the current ADCs are highly heterogeneous with different drug-to-antibody ratios and drug conjugation sites. Recent studies have demonstrated that the site-specific conjugation of drugs to mAbs could produce homogeneous ADC with better pharmacokinetic properties and improved therapeutic index. A number of approaches, including the use of engineered cysteines, the insertion of unnatural amino acids, and enzymatic ligation, have addressed the challenging issues for the synthesis of homogeneous ADC. This review discusses the limitations of current ADC technologies and describes recent site-specific conjugation methods that can be used to prepare homogeneous ADCs for targeted anticancer drug delivery.