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.

Red-kerneled rice proanthocyanidin inhibits arachidonate 5-lipoxygenase and decreases psoriasis-like skin inflammation.

5-lipoxygenase is a key enzyme in the synthesis of leukotrienes from arachidonic acid. The produced leukotrienes are involved in inflammatory diseases including psoriasis, asthma, and atherosclerosis. A suitable 5-lipoxygenase inhibitor might be useful for preventing and improving the symptoms of leukotriene-related inflammatory diseases. Here, we investigate the mechanism underlying the anti-inflammatory effect of a proanthocyanidin found in red-kerneled rice. Red-kerneled rice proanthocyanidin exhibited potent mixed noncompetitive inhibition of human and rat 5-lipoxygenases, with an IC50 values of 15.1 µM against human enzyme, and 7.0 µM against rat enzyme, respectively. This compound decreased leukotriene B4 production in rat basophilic leukemia-2H3 cells. In imiquimod-induced psoriasis-like mouse skin, topical application of the proanthocyanidin suppressed hyperplasia, decreased inflammatory cell infiltration, and down-regulated expression of the psoriasis-associated genes Il17a, Il22, S100a9, and Krt1. Lipid metabolome analysis by electrospray ionization mass spectrometry showed that red-kerneled rice proanthocyanidin treatment of psoriasis-like mouse skin dose-dependently decreased the production of leukotriene B4 but no other arachidonate metabolites. Red-kerneled rice proanthocyanidin inhibits 5-lipoxygenase, resulting in a decrease in leukotriene B4 production and psoriasis-like mouse skin inflammation. These results suggest that this proanthocyanidin may be therapeutically effective for treating leukotriene-related diseases.

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.

Simultaneous Quantification of Ellagitannins and Related Polyphenols in Geranium thunbergii Using Quantitative NMR.

Compared to commonly employed liquid chromatography-based methods, quantitative nuclear magnetic resonance (qNMR) is a recently developed method for accurate quantification of natural compounds in extracts. The simultaneous quantification of ellagitannins and the related polyphenols of Geranium thunbergii were studied using qNMR after a short-term and long-term decoction. The qNMR fingerprint for quantifying ellagitannin was presented in this work. Geraniin was observed in the short-term decoction as a major component while corilagin was the major component of the long-term decoction. An aqueous acetone extract of G. thunbergii after long-term decoction was extracted with diethyl ether, ethyl acetate, and n-butanol. Corilagin was found as a major constituent in the ethyl acetate and n-butanol extracts. Furthermore, the contents of these polyphenols in G. thunbergii from six locations in Japan and three locations in China were quantified. The contents of geraniin and corilagin in G. thunbergii from Japan were higher than those from China. Our finding raised the possibility that qNMR can be effectively employed as a simple, accurate, and efficient method for quantification of ellagitannins in medicinal plants.

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.

Proanthocyanidins in an astringent persimmon inhibit Salmonella pathogenicity island 1 (SPI1) secretion.

BACKGROUND: Astringent compounds contained in persimmon fruits have been widely used in Japan as food preservatives and thus as anti-bacterial and anti-fungi reagents. However, the molecular mechanism of the anti-microbial activity has been unclear. One of the virulence secretion systems in Salmonella enterica was used to test the anti-microbial activity of extracts from a persimmon (Diospyros kaki Thunb 'Saijo'). RESULTS: We found that the extract could inhibit the secretion of virulence proteins but did not affect cell growth and determined the critical concentrations of the extract to show the effect. Then, the effective fraction on the suppression of secretion of virulence proteins was purified from the crude extracts using solvent partition, absorption chromatography and gel filtration chromatography. The anti-bacterial fraction was analysed by HCl-butanol treatment and gel permeation chromatography followed by nuclear magnetic resonance and identified as the octamers of epigallocatechin and its gallate as major components. CONCLUSION: Proanthocyanidins suppress the secretion of Salmonella pathogenicity island 1 virulence proteins.