Chemical Synthesis and Characterization of α-N-Octanoyl and Other α-N-Acyl Colistin Nonapeptide Derivatives

Eight α-N-acyl colistin nonapeptide derivatives including three aliphatic, four aromatic and one alicyclic derivatives were synthesized by the reaction of colistin nonapeptide with corresponding acid chlorides. This acylation reaction was carried out under the condition kept restrictedly at pH 5,0 in order to introduce an acyl group only to α-amino group but not to γ-amino group existing in a colistin nonapeptide molecule. Synthetic method and several physico-chemical natures of these acyl colistin nonapeptide derivatives are given in this paper.

All of the acylated derivatives thus synthesized exhibited characteristic antimicrobial activities. Antimicrobial spectra were substantially based upon a gram-negative type and not so much altered by chemical structures of acyl groups which were considerably differentiated from each other such as cyclic or chain form. Thus, more possible response of carbon size than its structure to the antimicrobial effectiveness was inferred. In spite of almost no toxicity and feeble antimicrobial activity of colistin nonapeptide itself, these acylated colistin nonapeptide derivatives showed a toxicity against mice at a dose of 16.9~70 mg/kg in LD₅₀, which, however, was inferior to the toxicity of colistin sulfate, possibly correspondent to their much weaker antimicrobial activities, as a whole. Hence, it seems likely that acyl part of these acylated colistin nonapeptide derivatives including that of colistin is seriously responsible for the biological activities.     

Molecular phylogeny of Punctaria mageshimensis reveals evidence for its transfer to Spatoglossum as S. mageshimense (Dictyotales,Phaeophyceae)

Taxonomy of the little‐studied brown algal species Punctaria mageshimensis (Ectocarpales s.l.) was reexamined by molecular phylogeny and morphology. In the genetic analyses of newly collected specimens using plastid rbcL and psaA gene sequences, the specimens morphologically referable to P. mageshimensis were phylogenetically distant from Ectocarpales s.l. and were included in the clade of Spatoglossum (Dictyotales). Morphological reexamination of the type specimen and newly collected specimens confirmed its systematic position in Dictyotales: Branched thallus; cushion‐shaped rhizoidal holdfast occasionally forming secondary holdfast at the bottom of the thallus; many discoidal plastids without pyrenoid per cell; tetrasporangium‐like reproductive structures with dark, homogeneous cell content; occurrence of hair tufts. Genetically P. mageshimensis was most related to a reported sequence of Spatoglossum asperum, but P. mageshimensis was considerably different from S. asperum as well as other known Spatoglossum species in the deep habitat and in having scarcely‐branched lanceolate and considerably thickened thallus. In conclusion, we propose the transfer of P. mageshimensis to Spatoglossum as S. mageshimense comb. nov.     

Chemical forms of selenium for cancer prevention.

Cancer is becoming an increasingly significant disease worldwide. Currently, more than 7 million people die each year from cancer. With the existing knowledge, at least one-third of worldwide cancer cases could be prevented. Searching for naturally occurring agents in routinely consumed foods that may inhibit cancer development, although challenging, constitutes a valuable and plausible approach to the control and prevention of cancer. To date, the use of the micronutrient selenium (Se) in human clinical trials is limited, but the outcome indicates that Se is among the most promising agents. Although it is convenient to describe the effects of Se in terms of the element, it must always be kept in mind that the chemical form of Se and the dose are determinants of its biological activities. Hyphenated techniques based on coupling chromatographic separation with inductively coupled plasma mass spectrometric (ICP-MS) detection are now established as the most realistic and potent analytical tools available for real-life speciation analysis. These speciation investigations provide evidence that the Se compounds, which can generate monomethylated Se (e.g., Se-methylselenocysteine and methylseleninic acid), are more efficacious than other Se compounds because of their chemoprevention activity.     

Central and peripheral administration of amylin induces energy expenditure in anesthetized rats

Amylin is a peptide hormone that is co-released with insulin from pancreatic β-cells following a meal. Intracerebroventricular (icv) administration of amylin (1–100 pmol), or an amylin agonist, salmon calcitonin, elicited dose-dependent thermogenic, tachycardic, and hyperthermic responses in urethane-anesthetized rats. Intravenous (iv) administration of higher doses of amylin (100 pmol–20 nmol) also induced similar responses, although the amplitudes of these responses were significantly smaller than those elicited by icv administration, suggesting the primary action of amylin to be in the brain. However, the iv administration of amylin induced the responses slightly faster than the icv injection, the former responses occurring <4 min and the latter, at 8–10 min, after the administration. The iv but not the icv injection of amylin increased the respiratory exchange ratio transiently (<20 min), though the thermogenic response lasted for a longer period after both injections, indicating a shift from mixed fuel to predominantly carbohydrate utilization in the initial phase of thermogenesis induced by the iv injection of amylin. The differences in substrate utilization and latency of the responses suggest that the actions of amylin include partly different targets when administered centrally and peripherally. Moreover, pretreatment with a β-adrenergic blocker, propranolol (5 mg kg⁻¹, iv), blocked all responses elicited by either icv or iv administration of amylin, whereas ablation of the area postrema in the hindbrain did not influence the effects of icv-administered amylin. These results suggest the involvement of amylin in postprandial energy expenditure, mediated by peripheral β-adrenoceptors.     

Synthetic construction of sugar-amino acid hybrid polymers involving globotriaose or lactose and evaluation of their biological activities against Shiga toxins produced by Escherichia coli O157:H7

Synthetic assembly of sugar moieties and amino acids in order to create “sugar-amino acid hybrid polymers” was accomplished by means of simple radical polymerization of carbohydrate monomers having an amino acid-modified polymerizable aglycon. Amines derived from globotriaoside and lactoside as glycoepitopes were condensed with known carbobenzyloxy derivatives, including Z-Gly, Z-l-Ala and Z-β-Ala, which had appropriate spacer ability and a chiral center to afford fully protected sugar-amino acid hybrid compounds in good yields. After deprotection followed by acryloylation, the water-soluble glycomonomers were polymerized with or without acrylamide in the presence of a radical initiator in water to give corresponding copolymers and homopolymers, which were shown by SEC analysis to have high molecular weights. Evaluation of the biological activities of the glycopolymers against Shiga toxins (Stxs) was carried out, and the results suggested that glycopolymers having highly clustered globotriaosyl residues had high affinity against Stx2 (K_D?=?2.7～4.0?µM) even though other glycopolymers did not show any affinity or showed very weak binding affinity. When Stx1 was used for the same assay, all of the glycopolymers having globotriaosyl residues showed high affinity (K_D?=?0.30～1.74?µM). Interestingly, couple of glycopolymers having lactosyl moieties had weaker binding affinity against Stx1. In addition, when cytotoxicity assays were carried out for both Stxs, glycopolymers having highly clustered globotriaosyl residues showed higher affinity than that of the copolymers, and only highly clustered-type glycopolymers displayed neutralization potency against Stx2.     

Interaction between Sendai virus and KB cell lines with altered cell fusion ability: a study employing electron spin resonance.

The nature of the interaction between Sendai virus and Sil mutant cells was examined by measuring a change in ESR spectrum of spin-labeled phosphatidylcholine molecules on the viral envelope. When spin-labeled virus was incubated with the Sil cells that had a reduced ability to respond to virus-induced cell fusion, interchange of the phospholipid molecules between viral envelope and cell surface membrane occurred to a smaller extent than that observed with parental cells. Moreover, the degree of the interchanging correlated with the degree of the fusion capacity of the mutant lines. The results show that the mutant cells carry such a lesion(s) on their surface membranes that the viral envelopes can hardly fuse into them.     

Establishment and characterization of a cell line from the American opossum (Didelphys virginiana)

A permanent tissue-cultured cell line (designated OK) has been established from kidney tissue of an adult American opossum. The OK line has been characterized with respect to morphology, chromosome constitution, tissue-culture requirements, and attainable mitotic arrest. The cells are epithelial-like with a stable nondiploid chromosomal modal number of 23. Cells grown in Eagle's minimal essential medium with 10% fetal bovine serum have a mean doubling time of 18 hr. The cell line OK is potentially useful for the isolation and purification of the mammalian X chromosome because of the size differential between the smaller X's and the larger autosomes.     

The levels of mature glycosylated nicastrin are regulated and correlate with gamma-secretase processing of amyloid beta-precursor protein

Nicastrin, a type-I transmembrane glycoprotein, is a necessary component of the high molecular weight presenilin (PS) complexes that mediate intramembranous cleavage of beta-amyloid precursor protein (betaAPP) and Notch. Nicastrin undergoes trafficking-dependent glycosylation maturation, and PS1 interacts preferentially with these maturely glycosylated forms of nicastrin. We investigated the effects of differing levels of the immature and mature endoglycosidase-H-resistant forms of nicastrin on Abeta40- and Abeta42-peptide secretion in several cell lines stably expressing a mutant nicastrin (D336A/Y337A) that increases Abeta secretion. There was no correlation between Abeta secretion and the level of over-expression of the immature forms of nicastrin. The total level of mature nicastrin remained constant, but mutant nicastrin replaced endogenous mature nicastrin in varying degrees. Differences in the levels of mature mutant nicastrin positively correlated with Abeta secretion, but did not influence either betaAPP trafficking or processing by alpha- and beta-secretases. Proper trafficking and terminal maturation of nicastrin is therefore a necessary event for the regulated intramembranous proteolysis of betaAPP.     

Marine Hydroquinone Zonarol Prevents Inflammation and Apoptosis in Dextran Sulfate Sodium-Induced Mice Ulcerative Colitis

Background and Aim

We previously identified an anti-inflammatory compound, zonarol, a hydroquinone isolated from the brown algae Dictyopteris undulata as a marine natural product. To ascertain the in vivo functions of zonarol, we examined the pharmacological effects of zonarol administration on dextran sulfate sodium (DSS)-induced inflammation in a mouse model of ulcerative colitis (UC). Our goal is to establish a safe and effective cure for inflammatory bowel disease (IBD) using zonarol.

Methods and Results

We subjected Slc:ICR mice to the administration of 2% DSS in drinking water for 14 days. At the same time, 5-aminosalicylic acid (5-ASA) at a dose of 50 mg/kg (positive control) and zonarol at doses of 10 and 20 mg/kg, were given orally once a day. DSS-treated animals developed symptoms similar to those of human UC, such as severe bloody diarrhea, which were evaluated by the disease activity index (DAI). Treatment with 20 mg/kg of zonarol, as well as 5-ASA, significantly suppressed the DAI score, and also led to a reduced colonic ulcer length and/or mucosal inflammatory infiltration by various immune cells, especially macrophages. Zonarol treatment significantly reduced the expression of pro-inflammatory signaling molecules, and prevented the apoptosis of intestinal epithelial cells. Finally, zonarol protected against in vitro lipopolysaccharide (LPS)-induced activation in the RAW264.7 mouse macrophage cell line.

Conclusions

This is the first report that a marine bioproduct protects against experimental UC via the inhibition of both inflammation and apoptosis, very similar to the standard-of-care sulfasalazine, a well-known prodrug that releases 5-ASA. We believe that the oral administration of zonarol might offer a better treatment for human IBDs than 5-ASA, or may be useful as an alternative/additive therapeutic strategy against UC, without any evidence of side effects.