Targeted disruption of the mouse protein phosphatase ppm1l gene leads to structural abnormalities in the brain.

PPM1L, a member of the metal-dependent protein phosphatase (PPM) family, is involved in regulating the stress-activated protein kinase pathway and ceramide trafficking. However, the physiological function of PPM1L in the brain is unclear. In this study, we generated and analyzed ppm1l-deficient mice in order to investigate PPM1L functions in the brain. Our results indicate that ppm1l is highly expressed in the central nervous system during mouse development and that ppm1lΔ/Δ mice display impaired motor performance and morphological abnormalities in the forebrain. Electron microscopic and immunohistochemical analyses suggest that these abnormalities are due to impaired axonal tract formation. Our novel findings suggest an important role for PPM1L in brain development.

Characterization of the α-Amylase Inhibitory Activity of Oligomeric Proanthocyanidins from Acacia mearnsii Bark Extract.

Acacia mearnsii (Fabaceae) contains acacia polyphenols, which are a complex mixture of proanthocyanidins that are mainly composed of 5-deoxycatechin units. In this study, an aqueous extract of A. mearnsii bark was fractionated and the α-amylase inhibitory activity of each fraction was evaluated. The (13)C NMR and MS data and the pyrolysis products obtained from the active and inactive fractions were compared. The spectroscopic results clearly indicated that fractions with strong inhibitory activity contained proanthocyanidin oligomers with catechol-type B-rings rather than pyrogallol-type B-rings HPLC analysis of the pyrolysis products showed peaks for pyrocatechol were only observed in the mixtures obtained from the fractions with high inhibitory activities. In addition,(+)-pinitol was isolated as a major polyol of the extract at a level comparable with that of sucrose.

α-Amylase and lipase inhibitory activity and structural characterization of acacia bark proanthocyanidins.

The bark extract of Acacia mearnsii showed strong lipase and α-amylase inhibition activities. Fractionation of the extract by column chromatography and subsequent (13)C NMR and MALDI-TOF-MS analysis revealed that the active substances are proanthocyanidin oligomers mainly composed of 5-deoxyflavan-3-ol units. In addition, 4'-O-methylrobinetinidol 3'-O-ß-D-glucopyranoside, fisetinidol-(4α,6)-gallocatechin, and epirobinetinidol-(4ß,8)-catechin were isolated as new compounds, and their structures were determined from spectroscopic data. Furthermore, a modified thiol degradation method using strongly acidic conditions was applied to the extract to yield three thiol degradation products derived from robinetinidol units. This method is useful for characterizing acacia proanthocyanidins (wattle tannins).

Increase of theaflavin gallates and thearubigins by acceleration of catechin oxidation in a new fermented tea product obtained by the tea-rolling processing of loquat ( Eriobotrya japonica ) and green tea leaves.

In a project to produce a new fermented tea product from non-used tea leaves harvested in the summer, we found that kneading tea leaves ( Camellia sinensis ) with fresh loquat leaves ( Eriobotrya japonica ) accelerated the enzymatic oxidation of tea catechins. The fermented tea obtained by tea-rolling processing of tea and loquat leaves had a strong, distinctive flavor and a plain aftertaste, which differed from usual black, green, and oolong teas. The phenolic constituents were similar to those of black tea. However, the concentrations of theaflavin 3-O-gallate, theaflavin 3,3'-di-O-gallate, and thearubigins were higher in the tea leaves kneaded with loquat leaves than in tea leaves kneaded without loquat leaves. The results from in vitro experiments suggested that acceleration of catechin oxidation was caused by the strong oxidation activity of loquat leaf enzymes and a coupled oxidation mechanism with caffeoyl quinic acids, which are the major phenolic constituents of loquat leaves.

Polymer-like polyphenols of black tea and their lipase and amylase inhibitory activities.

Lipase and amylase inhibitory activities of black tea were examined. After solvent partitioning of a black tea extract with the ethyl acetate and n-butanol, the two soluble fractions showed comparable inhibitory activities. Activity in the ethyl acetate fraction was mainly attributable to polyphenols with low-molecular weights, such as theaflavin gallates. On the other hand, the active substance in the n-butanol layer was ascertained to be a polymer-like substance. 1H- and 13C-NMR spectra showed signals arising from the flavan A-ring and galloyl groups, although signals due to flavan B-rings were not detected, suggesting that the polymer-like substances were generated by oxidative condensation of flavan B-rings, a result which was previously deduced from our results of in vitro catechin oxidation experiments. Enzymatic oxidation of epicatechin 3-O-gallate produced a similar polymer-like substance and suggested that condensation between a B-ring and galloyl groups was involved in the polymerization reaction.

Structures of epicatechin gallate trimer and tetramer produced by enzymatic oxidation.

During black tea production, catechins and their galloyl esters are enzymatically oxidized to generate a complex mixture of black tea polyphenols. The role of galloyl ester groups in this process has yet to be determined. Enzymatic oxidation of epicatechin 3-O-gallate (1) yielded two new oxidation products, theaflavate C and bistheaflavate A, along with theaflavate A (2), a known dimer of 1 generated by coupling of the B-ring with the galloyl group. Theaflavate C is a trimer of 1 and possesses two benzotropolone moieties generated by the oxidative coupling of the galloyl groups with the catechol B-rings. Bistheaflavate A was found to be a tetramer produced by intermolecular coupling of two benzotropolone moieties of 2. From the structures of the products, it was deduced that oxidative coupling of galloyl groups resulted in extension of the molecular size of the products in catechin oxidation.

Association of tannins and related polyphenols with the cyclic peptide gramicidin S.

The association of 10 different tannins and related polyphenols with gramicidin S, a cyclic peptide having a rigid beta-turn structure, has been examined using 1H-NMR spectroscopy. In the presence of pentagalloylglucose and epigallocatechin-3-O-gallate, the proton signals due to proline and the adjacent phenylalanine moieties selectively shifted to up field, suggesting a regioselective association with the beta-turn structure. The association was also supported by the observation of intermolecular nuclear Overhauser effects between epigallocatechin-3-O-gallate and the peptide. In contrast, ellagitannins, biogenetically derived from pentagalloylglucose, showed small and non-selective chemical shift changes, suggesting that interaction with these tannins is relatively weak. The hydrophobicity of the tannin molecules and the steric hindrance of the interaction site are thought to be important in the association.