Trapping mechanism by di-d-psicose anhydride with methylglyoxal for prevention of diabetic nephropathy.

Di-d-psicose anhydride (DPA), derived from functional rare saccharide as d-psicose, is investigated for its strong chelating ability. Methylglyoxal (MGO), an important precursor of advanced glycation end-products (AGEs), promotes obesity, and causes complications such as diabetic nephropathy. On mesangial cells, DPA can substantially reduce the negative effects of MGO. DPA effectively trapping MGO in mesangial cells. The bonding properties of the DPA-MGO adduct were discussed by mass spectrometry and nuclear magnetic resonance (NMR). The NMR spectra of the DPA-MGO adduct provide evidence for chelation bonding. The inhibition of AGE formation and the mass spectrometry results of the DPA-MGO adduct indicate that DPA can scavenge MGO at a molar ratio of 1:1. DPA suppressed 330 % of the up-regulated receptor for an AGEs protein expression to a normal level and restored the suppressed glyoxalase 1 level to 86 % of the normal group. This research provides important evidence and theoretical basis for the development of AGE inhibitors derived from rare saccharide.

Phenylalkyl Glycosides from the Flowers of Brugmansia arborea L. and Their Radical Scavenging Effect and Protective Effect on Pancreatic Islets Damaged by Alloxan in Zebrafish (Danio rerio) Larvae.

The study aimed to investigate the antioxidant and antidiabetic activity of Brugmansia arborea L. flower extracts, solvent fractions, and isolated compounds. B. arborea L flowers were extracted with aqueous methanol, and concentrated extract was successively partitioned into EtOAc, n-BuOH, and H2O fractions. Repeated silica gel and octadecyl silica gel column chromatographies for EtOAc and n-BuOH fractions led to the isolation of a new phenylalkyl glycoside (6), along with five known ones. Several spectroscopic data led to the structure determination of one new phenylalky glycoside as brugmansioside C (named) (6) and five known ones as benzyl-O-ß-D-glucopyranoside (1), benzyl-O-ß-D-glucosyl-(1→6)-ß-D-glucopyranoside (2), 2-phenylethyl-O-ß-D-glucopyranoside (3), 2-phenylethyl-O-ß-D-glucosyl-(1→6)-ß-D-glucopyranoside (4), and 3-phenylpropyl-O-ß-D-glucopyranoside (5). The five known ones (1-5) were isolated from B. arborea flowers for the first time in this study. The extract, solvent fractions, and all isolated compounds showed radical scavenging activities using ABTS radical, and EtOAc fraction showed the highest scavenging capacity, whereas compounds 2, 4, and 6 did not display the capacity to use the DPPH radical. The extract, solvent fractions, and all isolated compounds showed a protective effect on pancreatic islets damaged by alloxan treatment in zebrafish larvae. The pancreatic islet size treated with EtOAc, n-BuOH fractions, and all compounds significantly increased by 64.0%, 69.4%, 82.0%, 89.8%, 80.0%, 97.8%, 103.1%, and 99.6%, respectively, compared to the alloxan-induced group. These results indicate that B. arborea flowers and their isolated compounds are useful as potential antioxidant and antidiabetic agents.