Characterization and Identification of Bioactive Polyphenols in the Trapabispinosa Roxb. Pericarp Extract.

In this study, we present the isolation and characterization of the structure of six gallotannins (1-6), three ellagitannins (7-9), a neolignan glucoside (10), and three related polyphenolic compounds (gallic acid, 11 and 12) from Trapa bispinosa Roxb. pericarp extract (TBE). Among the isolates, the structure of compound 10 possessing a previously unclear absolute configuration was unambiguously determined through nuclear magnetic resonance and circular dichroism analyses. The α-glucosidase activity and glycation inhibitory effects of the isolates were evaluated. Decarboxylated rugosin A (8) showed an α-glucosidase inhibitory activity, while hydrolyzable tannins revealed stronger antiglycation activity than that of the positive control. Furthermore, the identification and quantification of the TBE polyphenols were investigated by high-performance liquid chromatography coupled to ultraviolet detection and electrospray ionization mass spectrometry analysis, indicating the predominance of gallic acid, ellagic acid, and galloyl glucoses showing marked antiglycation properties. These findings suggest that there is a potential food industry application of polyphenols in TBE as a functional food with antidiabetic and antiglycation activities.

Expression and functional characterization of sugar beet phosphoethanolamine/phosphocholine phosphatase under salt stress.

Choline is a vital metabolite in plant and synthesized from phosphocholine by phosphocholine phosphatase. The Arabidopsis At1g17710 was identified as the first plant gene encoding the phosphatase for both phosphoethanolamine and phosphocholine (PECP) with much higher catalytic efficiency (>10-fold) for former. In betaine accumulating plants, choline is further required for betaine synthesis. In this report, we found three putative PECP genes in sugar beet, betaine accumulating plants. Two genes encode the proteins of 274 amino acid residues and designated as BvPECP1S and BvPECP2S. Another gene encodes the 331 amino acid protein (BvPECP2L) consisted of BvPECP2S with extra C-terminal amino acid. Enzymatic assays of BvPECP1S revealed that BvPECP1S exhibited the phosphatase activity for both phosphoethanolamine and phosphocholine with higher affinity (>1.8-fold) and catalytic efficiency (>2.64-fold) for phosphocholine. BvPECP2L exhibited low activity. RT-PCR experiments for BvPECP1S showed the increased expression in young leaf and root tip under salt-stress whereas the increased expression in all organs under phosphate deficiency. The expression level of BvPECP2L in salt stressed young leaf and root tip was induced by phosphate deficient. Physiological roles of BvPECP1S and BvPECP2L for the betaine synthesis were discussed.

Proanthocyanidin and anthocyanins from the hulls and beards of red-kerneled rice and their antiglycation properties.

In the current study, we isolated a proanthocyanidin oligomer from the hulls of red-kerneled rice. The structure of the oligomer was characterized based on spectral data and chemical reaction. Furthermore, two anthocyanins were isolated from the beards of the same source. The proanthocyanidins and beard extract showed more potent inhibitory and cleaving activities than those of positive controls, respectively.

Polyphenols from flowers of Magnolia coco and their anti-glycation effects.

We investigated the inhibitory effects of several plant extracts on advanced glycation end-products (AGEs) formation. Among tested samples, the flower extract of Magnolia coco showed significant inhibition of AGE formation. We isolated and characterized procyanidin oligomer and four other compounds from the flowers, and evaluated their inhibitory effects on AGE formation and the AGE-derived crosslink-cleaving activity of the isolated compounds.

Isolation and functional characterization of 3-phosphoglycerate dehydrogenase involved in salt responses in sugar beet.

The present study investigated the significance of serine biosynthetic genes for salt stress in sugar beet (Beta vulgaris). We isolated a total of four genes, two each encoding D-3-phosphoglycerate dehydrogenase (BvPGDHa and BvPGDHb) and serine hydroxymethyl transferase (BvSHMTa and BvSHMTb). mRNA transcriptional expression for BvPGDHa was significantly enhanced under salt stress conditions in both leaves and roots of sugar beet, whereas it was reduced for BvPGDHb. On the other hand, BvSHMTa was expressed transiently in leaves and roots under salt stress, whereas expression level of BvSHMTb was not altered. PGDH activity was high in storage root. After salt stress, PGDH activity was increased in leaf, petiole, and root. Recombinant proteins were expressed in Escherichia coli. The K m values for 3-phosphoglycerate in PGDHa and PGDHb were 1.38 and 2.92 mM, respectively. The findings suggest that BvPGDHa and BvSHMTa play an important role during salt stress in sugar beet.