Molecular Weight Dependent Glucose Lowering Effect of Low Molecular Weight Chitosan Oligosaccharide (GO2KA1) on Postprandial Blood Glucose Level in SD Rats Model

Jo, Sung-Hoon,Ha, Kyoung-Soo,Moon, Kyoung-Sik,Kim, Jong-Gwan,Oh, Chen-Gum,Kim, Young-Cheul,Apostolidis, Emmanouil,Kwon, Young-In Molecular Diversity Preservation International (MD 2013 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.14 No.7

<P>This research investigated the effect of enzymatically digested low molecular weight (MW) chitosan oligosaccharide on type 2 diabetes prevention. Three different chitosan oligosaccharide samples with varying MW were evaluated <I>in vitro</I> for inhibition of rat small intestinal α-glucosidase and porcine pancreatic α-amylase (GO2KA1; <1000 Da, GO2KA2; 1000–10,000 Da, GO2KA3; MW > 10,000 Da). The <I>in vitro</I> results showed that all tested samples had similar rat α-glucosidase inhibitory and porcine α-amylase inhibitory activity. Based on these observations, we decided to further investigate the effect of all three samples at a dose of 0.1 g/kg, on reducing postprandial blood glucose levels in Sprague-Dawley (SD) rat model after sucrose loading test. In the animal trial, all tested samples had postprandial blood glucose reduction effect, when compared to control, however GO2KA1 supplementation had the strongest effect. The glucose peak (C<I><SUB>max</SUB></I>) for GO2KA1 and control was 152 mg/dL and 193 mg/dL, respectively. The area under the blood glucose-time curve (AUC) for GO2KA1 and control was 262 h mg/dL and 305 h mg/dL, respectively. Furthermore, the time of peak plasma concentration of blood glucose (T<I><SUB>max</SUB></I>) for GO2KA1 was significantly delayed (0.9 h) compared to control (0.5 h). These results suggest that GO2KA1 could have a beneficial effect for blood glucose management relevant to diabetes prevention in normal and pre-diabetic individuals. The suggested mechanism of action is via inhibition of the carbohydrate hydrolysis enzyme α-glucosidase and since GO2KA1 (MW < 1000 Da) had higher <I>in vivo</I> effect, we hypothesize that it is more readily absorbed and might exert further biological effect once it is absorbed in the blood stream, relevant to blood glucose management.</P>

Chaperoning Roles of Macromolecules Interacting with Proteins <i>in Vivo</i>

Choi, Seong Il,Lim, Keo-Heun,Seong, Baik L. Molecular Diversity Preservation International (MD 2011 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.12 No.3

<P>The principles obtained from studies on molecular chaperones have provided explanations for the assisted protein folding <I>in vivo</I>. However, the majority of proteins can fold without the assistance of the known molecular chaperones, and little attention has been paid to the potential chaperoning roles of other macromolecules. During protein biogenesis and folding, newly synthesized polypeptide chains interact with a variety of macromolecules, including ribosomes, RNAs, cytoskeleton, lipid bilayer, proteolytic system, <I>etc</I>. In general, the hydrophobic interactions between molecular chaperones and their substrates have been widely believed to be mainly responsible for the substrate stabilization against aggregation. Emerging evidence now indicates that other features of macromolecules such as their surface charges, probably resulting in electrostatic repulsions, and steric hindrance, could play a key role in the stabilization of their linked proteins against aggregation. Such stabilizing mechanisms are expected to give new insights into our understanding of the chaperoning functions for <I>de novo</I> protein folding. In this review, we will discuss the possible chaperoning roles of these macromolecules in <I>de novo</I> folding, based on their charge and steric features.</P>

Experimental and Computational Characterization of Biological Liquid Crystals: A Review of Single-Molecule Bioassays

Eom, Kilho,Yang, Jaemoon,Park, Jinsung,Yoon, Gwonchan,Soo Sohn, Young,Park, Shinsuk,Yoon, Dae Sung,Na, Sungsoo,Kwon, Taeyun Molecular Diversity Preservation International (MD 2009 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.10 No.9

<P>Quantitative understanding of the mechanical behavior of biological liquid crystals such as proteins is essential for gaining insight into their biological functions, since some proteins perform notable mechanical functions. Recently, single-molecule experiments have allowed not only the quantitative characterization of the mechanical behavior of proteins such as protein unfolding mechanics, but also the exploration of the free energy landscape for protein folding. In this work, we have reviewed the current state-of-art in single-molecule bioassays that enable quantitative studies on protein unfolding mechanics and/or various molecular interactions. Specifically, single-molecule pulling experiments based on atomic force microscopy (AFM) have been overviewed. In addition, the computational simulations on single-molecule pulling experiments have been reviewed. We have also reviewed the AFM cantilever-based bioassay that provides insight into various molecular interactions. Our review highlights the AFM-based single-molecule bioassay for quantitative characterization of biological liquid crystals such as proteins.</P>

3D QSAR Pharmacophore Modeling, <i>in Silico</i> Screening, and Density Functional Theory (DFT) Approaches for Identification of Human Chymase Inhibitors

Arooj, Mahreen,Thangapandian, Sundarapandian,John, Shalini,Hwang, Swan,Park, Jong Keun,Lee, Keun Woo Molecular Diversity Preservation International (MD 2011 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.12 No.12

<P>Human chymase is a very important target for the treatment of cardiovascular diseases. Using a series of theoretical methods like pharmacophore modeling, database screening, molecular docking and Density Functional Theory (DFT) calculations, an investigation for identification of novel chymase inhibitors, and to specify the key factors crucial for the binding and interaction between chymase and inhibitors is performed. A highly correlating (<I>r</I> = 0.942) pharmacophore model (Hypo1) with two hydrogen bond acceptors, and three hydrophobic aromatic features is generated. After successfully validating “Hypo1”, it is further applied in database screening. Hit compounds are subjected to various drug-like filtrations and molecular docking studies. Finally, three structurally diverse compounds with high <I>GOLD</I> fitness scores and interactions with key active site amino acids are identified as potent chymase hits. Moreover, DFT study is performed which confirms very clear trends between electronic properties and inhibitory activity (IC<SUB>50</SUB>) data thus successfully validating “Hypo1” by DFT method. Therefore, this research exertion can be helpful in the development of new potent hits for chymase. In addition, the combinational use of docking, orbital energies and molecular electrostatic potential analysis is also demonstrated as a good endeavor to gain an insight into the interaction between chymase and inhibitors.</P>

Dynamic Structure-Based Pharmacophore Model Development: A New and Effective Addition in the Histone Deacetylase 8 (HDAC8) Inhibitor Discovery

Thangapandian, Sundarapandian,John, Shalini,Lee, Yuno,Kim, Songmi,Lee, Keun Woo Molecular Diversity Preservation International (MD 2011 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.12 No.12

<P>Histone deacetylase 8 (HDAC8) is an enzyme involved in deacetylating the amino groups of terminal lysine residues, thereby repressing the transcription of various genes including tumor suppressor gene. The over expression of HDAC8 was observed in many cancers and thus inhibition of this enzyme has emerged as an efficient cancer therapeutic strategy. In an effort to facilitate the future discovery of HDAC8 inhibitors, we developed two pharmacophore models containing six and five pharmacophoric features, respectively, using the representative structures from two molecular dynamic (MD) simulations performed in Gromacs 4.0.5 package. Various analyses of trajectories obtained from MD simulations have displayed the changes upon inhibitor binding. Thus utilization of the dynamically-responded protein structures in pharmacophore development has the added advantage of considering the conformational flexibility of protein. The MD trajectories were clustered based on single-linkage method and representative structures were taken to be used in the pharmacophore model development. Active site complimenting structure-based pharmacophore models were developed using Discovery Studio 2.5 program and validated using a dataset of known HDAC8 inhibitors. Virtual screening of chemical database coupled with drug-like filter has identified drug-like hit compounds that match the pharmacophore models. Molecular docking of these hits reduced the false positives and identified two potential compounds to be used in future HDAC8 inhibitor design.</P>

Effects of the Molecular Weight and the Degree of Deacetylation of Chitosan Oligosaccharides on Antitumor Activity

Park, Jae Kweon,Chung, Mi Ja,Choi, Ha Na,Park, Yong Il Molecular Diversity Preservation International (MD 2011 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.12 No.1

<P>Effects of the degree of deacetylation (DDA) and the molecular mass of chitosan oligosaccharides (CTS-OS), obtained from the enzymatic hydrolysis of high molecular weight chitosan (HMWC), on antitumor activity was explored. The DDA and molecular weights of CTS-OS were determined by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-TOF MS) analysis. The CTS-OS were found to be a mixture of mainly dimers (18.8%), trimers (24.8%), tetramers (24.9%), pentamers (17.7%), hexamers (7.1%), heptamers (3.3%), and octamers (3.4%). The CTS-OS were further fractionated by gel-filtration chromatography into two major fractions: (1) COS, consisting of glucosamine (GlcN)<SUB>n</SUB>, n = 3–5 with DDA 100%; and (2) HOS, consisting of (GlcN)<SUB>5</SUB> as the minimum residues and varying number of <I>N</I>-acetylglucosamine (GlcNAc)<SUB>n</SUB>, n = 1–2 with DDA about 87.5% in random order. The cytotoxicities, expressed as the concentration needed for 50% cell death (CC<SUB>50</SUB>), of CTS-OS, COS, and HOS against PC3 (prostate cancer cell), A549 (lung cancer cell), and HepG2 (hepatoma cell), were determined to be 25 μg·mL<SUP>−1</SUP>, 25 μg·mL<SUP>−1</SUP>, and 50 μg·mL<SUP>−1</SUP>, respectively. The HMWC was approximately 50% less effective than both CTS-OS and COS. These results demonstrate that the molecular weight and DDA of chitosan oligosaccharides are important factors for suppressing cancer cell growth.</P>

Application of Novel Polymorphic Microsatellite Loci Identified in the Korean Pacific Abalone ( <i>Haliotis diversicolor supertexta</i> (Haliotidae)) in the Genetic Characterization of Wild and Released Populations

An, Hye Suck,Lee, Jang Wook,Hong, Seong Wan Molecular Diversity Preservation International (MD 2012 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.13 No.9

<P>The small abalone, <I>Haliotis diversicolor supertexta</I>, of the family Haliotidae, is one of the most important species of marine shellfish in eastern Asia. Over the past few decades, this species has drastically declined in Korea. Thus, hatchery-bred seeds have been released into natural coastal areas to compensate for the reduced fishery resources. However, information on the genetic background of the small abalone is scarce. In this study, 20 polymorphic microsatellite DNA markers were identified using next-generation sequencing techniques and used to compare allelic variation between wild and released abalone populations in Korea. Using high-throughput genomic sequencing, a total of 1516 (2.26%; average length of 385 bp) reads containing simple sequence repeats were obtained from 86,011 raw reads. Among the 99 loci screened, 28 amplified successfully, and 20 were polymorphic. When comparing allelic variation between wild and released abalone populations, a total of 243 different alleles were observed, with 18.7 alleles per locus. High genetic diversity (mean heterozygosity = 0.81; mean allelic number = 15.5) was observed in both populations. A statistical analysis of the fixation index (<I>F</I><SUB>ST</SUB>) and analysis of molecular variance (AMOVA) indicated limited genetic differences between the two populations (<I>F</I><SUB>ST</SUB> = 0.002, <I>p</I> > 0.05). Although no significant reductions in the genetic diversity were found in the released population compared with the wild population (<I>p</I> > 0.05), the genetic diversity parameters revealed that the seeds released for stock abundance had a different genetic composition. These differences are likely a result of hatchery selection and inbreeding. Additionally, all the primer pair sets were effectively amplified in another congeneric species, <I>H. diversicolor diversicolor</I>, indicating that these primers are useful for both abalone species. These microsatellite loci may be valuable for future aquaculture and population genetic studies aimed at developing conservation and management plans for these two abalone species.</P>

Astaxanthin Improves Stem Cell Potency via an Increase in the Proliferation of Neural Progenitor Cells

Kim, Jeong-Hwan,Nam, Soo-Wan,Kim, Byung-Woo,Choi, Woobong,Lee, Jong-Hwan,Kim, Wun-Jae,Choi, Yung-Hyun Molecular Diversity Preservation International (MD 2010 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.11 No.12

<P>The present study was designed to investigate the question of whether or not astaxanthin improves stem cell potency via an increase in proliferation of neural progenitor cells (NPCs). Treatment with astaxanthin significantly increased proliferation and colony formation of NPCs. For identification of possible activated signaling molecules involved in active cell proliferation occurring after astaxanthin treatment, total protein levels of several proliferation-related proteins, and expression levels of proliferation-related transcription factors, were assessed in NPCs. In Western blot analysis, astaxanthin induced significant activation of phosphatidylinositol 3-kinase (PI3K) and its downstream mediators in a time-dependent manner. Results of RT-PCR analysis showed upregulation of proliferation-related transcription factors and stemness genes. To estimate the relevance of PI3K and mitogen-activated protein, or extracellular signal-regulated kinase kinase (MEK) signaling pathways in cell growth of astaxanthin-treated NPCs, inhibition assays were performed with LY294002, a specific inhibitor of PI3K, and PD98059, a specific inhibitor of MEK, respectively. These results clearly showed that astaxanthin induces proliferation of NPCs via activation of the PI3K and MEK signaling pathways and improves stem cell potency via stemness acting signals.</P>

Reactive Oxygen Species Enhance TLR10 Expression in the Human Monocytic Cell Line THP-1

Kim, Donghee,Kim, Yeon Ju,Koh, Hyun Sook,Jang, Tae Yang,Park, Hyo Eun,Kim, Jae Young Molecular Diversity Preservation International (MD 2010 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.11 No.10

<P>We investigated TLR10 expression in human monocytes, THP-1 cells, cultured in hypoxia (3% O<SUB>2</SUB>). Levels of both TLR10 mRNA and protein in THP-1 cells cultured in hypoxia were significantly higher than those cultured in normoxia (20% O<SUB>2</SUB>). We examined intracellular reactive oxygen species (ROS) content in hypoxic cells, and TLR10 expression in cells treated with hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>), to determine whether the increase in TLR10 expression observed with hypoxia was due to an increase in intracellular ROS levels. We found that the level of intracellular ROS in cells subject to hypoxia was significantly higher than in normoxia. Experiments with ROS synthesis inhibitors revealed that hypoxia induced ROS production is mainly due to NADPH oxidase activity. TLR10 mRNA expression was increased by treatment with H<SUB>2</SUB>O<SUB>2</SUB> at concentrations ranging from 50 to 250 μM. We screened the TLR10 promoter and found putative binding sites for transcription factors (TFs), such as NF-κB, NF-AT and AP-1. Next, we examined TF activities using a luciferase reporter assay. Activities of NF-κB, NF-AT and AP-1 in the cells treated with H<SUB>2</SUB>O<SUB>2</SUB> were significantly higher than in untreated cells. The experiment with TF inhibitors revealed that ROS-induced upregulation of TLR10 expression is mainly due to NF-κB activation. Overall, our results suggest that hypoxia or ROS increase TLR10 expression in human monocytes and the transcriptional activities of NF-κB are involved in this process. Therefore, it is suggested that ROS produced by various exogenous stimuli may play a crucial role in the regulation of expression and function of TLR10 as second messengers.</P>

The Reversal of Drug-Resistance in Tumors Using a Drug-Carrying Nanoparticular System

Oh, Kyung Taek,Baik, Hye Jung,Lee, A Hyeong,Oh, Young Taik,Youn, Yu Seok,Lee, Eun Seong Molecular Diversity Preservation International (MD 2009 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.10 No.9

<P>Medical applications of nanoparticular systems have attracted considerable attention because of their potential use in therapeutic targeting of disease tissues and their lower level of toxicity against healthy tissue, relative to traditional pharmaceutical drugs. The use of nanoparticular systems has been shown to overcome the limitations of most anticancer drugs in clinical applications. In particular, the improved performance of smarted nanoparticular system for solving the drug resistance problems that typically interrupt tumor treatment has provided a promising strategy for successful tumor chemotherapy. This review highlights recent studies that have examined the therapeutic effect of nanoparticular systems on drug-resistant tumors and presents insight on how they work.</P>