Theobromine enhances absorption of cacao polyphenol in rats

Several concentrations of theobromine (TB) and (?)-epicatechin (EC) were coadministered to rats, and plasma EC and its metabolites were determined using ultra-high-performance liquid chromatography–tandem mass spectrometry. It has been demonstrated that TB increases the absorption of EC in a dose-dependent manner. Cocoa powder had a similar effect, and the mechanism involved is not thought to depend on tight junctions.     

Phenol Ethers and Terpenes of Six Heterotropa Species Distributed in the Ryukyu Islands and Formosa

A new intracellular peptidase, which we call “d-peptidase S,” was purified from Nocardia orientalis IFO 12806 (ISP 5040). The purified enzyme was homogeneous on disc gel electrophoresis. The molecular weight and the isoelectric point were estimated to be 52,000 and 4.9, respectively. The optimum pH for the hydrolysis of d-leucyl-d-leucine was 8.0 to 8.1, and the optimum temperature was 36°C. The purified enzyme usually hydrolyzed the peptide bonds preceding the hydrophobic D-amino acids of dipeptides. Tri- and tetra-peptides extending to the amino terminus of such peptides were also hydrolyzed. Therefore, the enzyme is a carboxylpeptidase-like peptidase specific to d-amino acid peptides. The Km values for d-leucyl-d-leucine and l-leucyl-d-leucine were 0.21 × 10^-3 and 0.44 × 10^-3 m respectively. The activity was inhibited by several sulfhydryl reagents and two chelators, 8-hydroxyquinoline and o-phenanthroline.     

Gene cloning and biochemical characterization of eryngase,a serine aminopeptidase of Pleurotus eryngii belonging to the family S9 peptidases

Pleurotus eryngii serine aminopeptidase that has peptide bond formation activity, redesignated as eryngase, was cloned and expressed. Eryngase has a family S9 peptidase unit in the C-terminal region having a catalytic triad of Ser, Asp, and His. In the phylogenetic relations among the subfamilies of family S9 peptidase (S9A, prolyl oligopeptidase; S9B, dipeptidyl peptidase; S9C, acylaminoacyl peptidase; S9D, glutamyl endopeptidase), eryngase existed alone in the neighbor of S9C subfamily. Mutation of the active site Ser524 of the eryngase with Ala eliminated its catalytic activity. In contrast, S524C mutant maintained low catalytic activity. Investigation of aminolysis activity using l-Phe-NH₂ as a substrate showed that S524C mutant exhibited no hydrolysis reaction but synthesized a small amount of l-Phe-l-Phe-NH₂ by the catalysis of aminolysis. In contrast, wild-type eryngase hydrolyzed the product of aminolysis l-Phe-l-Phe-NH₂. Results show that the S524C mutant preferentially catalyzed aminolysis when on an l-Phe-NH₂ substrate.     

A taxonomic review of the genus Astrocharis Koehler (Echinodermata: Ophiuroidea: Asteroschematidae), with a description of a new species

A revision of the genus Astrocharis Koehler (Echinodermata: Ophiuroidea: Asteroschematidae) is based on 41 specimens, including three syntypes of Astrocharis virgo Koehler, one syntype of Astrocharis ijimai Matsumoto and the holotype of Astrocharis gracilis Mortensen. Astrocharis gracilis is a junior subjective synonym of A. ijimai. A. virgo and A. ijimai are redescribed. A new species, Astrocharis monospinosa is described from southwestern Japan. A tabular key to the three species of the genus Astrocharis is provided.     

Origin and evolution of genes related to ABA metabolism and its signaling pathways

Since plants cannot move to avoid stress, they have sophisticated acclimation mechanisms against a variety of abiotic stresses. The phytohormone abscisic acid (ABA) plays essential roles in abiotic stress tolerances in land plants. Therefore, it is interesting to address the evolutionary origins of ABA metabolism and its signaling pathways in land plants. Here, we focused on 48 ABA-related Arabidopsis thaliana genes with 11 protein functions, and generated 11 orthologous clusters of ABA-related genes from A. thaliana, Arabidopsis lyrata, Populus trichocarpa, Oryza sativa, Selaginella moellendorffii, and Physcomitrella patens. Phylogenetic analyses suggested that the common ancestor of these six species possessed most of the key protein functions of ABA-related genes. In two species (A. thaliana and O. sativa), duplicate genes related to ABA signaling pathways contribute to the expression variation in different organs or stress responses. In particular, there is significant expansion of gene families related to ABA in evolutionary periods associated with morphological divergence. Taken together, these results suggest that expansion of the gene families related to ABA signaling pathways may have contributed to the sophisticated stress tolerance mechanisms of higher land plants.     

Structure-based selection of small molecules to alter allele-specific MHC class II antigen presentation

Class II major histocompatibility molecules are the primary susceptibility locus for many autoimmune disorders, including type 1 diabetes. Human DQ8 and I-A(g7), in the NOD mouse model of spontaneous autoimmune diabetes, confers diabetes risk by modulating presentation of specific islet peptides in the thymus and periphery. We used an in silico molecular docking program to screen a large "druglike" chemical library to define small molecules capable of occupying specific structural pockets along the I-A(g7) binding groove, with the objective of influencing presentation to T cells of the autoantigen insulin B chain peptide consisting of amino acids 9-23. In this study we show, using both murine and human cells, that small molecules can enhance or inhibit specific TCR signaling in the presence of cognate target peptides, based upon the structural pocket targeted. The influence of compounds on the TCR response was pocket dependent, with pocket 1 and 6 compounds inhibiting responses and molecules directed at pocket 9 enhancing responses to peptide. At nanomolar concentrations, the inhibitory molecules block the insulin B chain peptide consisting of amino acids 9-23, endogenous insulin, and islet-stimulated T cell responses. Glyphosine, a pocket 9 compound, enhances insulin peptide presentation to T cells at concentrations as low as 10 nM, upregulates IL-10 secretion, and prevents diabetes in NOD mice. These studies present a novel method for identifying small molecules capable of both stimulating and inhibiting T cell responses, with potentially therapeutic applications.     

Discovery of atrop fixed alkoxy-aminobenzhydrol derivatives: novel, highly potent and orally efficacious squalene synthase inhibitors

We have recently reported the discovery of the new benzhydrol template, which has a highly potent inhibitory activity for squalene synthase, as typified by compound 1 (SSI IC(50)=0.85 nM). However, it was composed of a pair of easy rotatable atropisomers. In the effort to fix the isomerization, a highly potent alkoxy-aminobenzhydrol scaffold was developed. Some of these acquired compounds demonstrating strong cholesterol synthesis inhibitory activities in a rat hepatic cell. Moreover, two of the series compounds exhibited specific plasma lipid-lowering effects in in vivo animal models.     

Ascorbic acid and N-acetyl cysteine prevent uncoupling of nitric oxide synthase and increase tolerance to ischemia/reperfusion injury in diabetic rat heart

Oxidative stress may cause a loss of tetrahydrobiopterin (BH4), a co-factor of nitric oxide synthase (NOS), decrease the bioavailability of NO and aggravate ischemia/reperfusion (I/R) injury in diabetic heart. We hypothesized that ascorbic acid (AA) and N-acetyl cysteine (NAC) protect the diabetic heart from I/R injury by increasing BH4/dihydrobiopterin (BH2) ratio and inhibiting uncoupling of NOS. Diabetes mellitus was induced in rats by streptozotocin treatment, and the hearts were isolated and perfused. BH4 and BH4/BH2 ratio decreased in the diabetic heart associated with increased production of superoxide and nitrotyrosine (NT). Treatment with AA or NAC significantly increased BH4/BH2 ratio in the diabetic heart associated with decreased production of superoxide and NT and increased generation of nitrate plus nitrite (NOx). Pre-treatment with AA or NAC before 30 min ischemia followed by 120 min reperfusion improved left ventricular (LV) function and reduced infarct size in the diabetic but not non-diabetic hearts. The NOS inhibitor, L-NAME, inhibited the increase in the generation of superoxide, NT and NOx, but aggravated LV function and increased infarct size in the diabetic heart. L-NAME also abrogated the increase in NOx and improvement of LV function and the infarct size-limiting effect induced by AA or NAC in the diabetic heart. These results suggest that AA and NAC increase BH4/BH2 ratio and prevent NOS uncoupling in the diabetic heart. Resultant increase in the bioavailability of NO renders the diabetic heart toleratant to I/R injury.