New prenyl flavanone and diarylbutanol from Uvaria siamensis stem bark and their α-glucosidase inhibitory activity.

One new prenyl flavanone (1), (2S)-8-prenyl-5,6-dihydroxy-7-methoxyflavanone, and one new diarylbutanol (2), (7'S)-3'-hydroxy-linderagatin-A, were isolated from the stem bark of Uvaria siamensis (Annonaceae), along with five known compounds, eriodictyol (3), quercetin (4), paprazine (5), N-trans-caffeoyltyramine (6), and N-trans-feruloyltyramine (7). Their structures were determined through extensive spectroscopic analyses and comparison with the literature. The α-glucosidase inhibitory potential of 1-7 was evaluated. Compound 6 showed the highest inhibitory activity against α-glucosidase and exhibited superior potency compared to the positive control, with an IC50 value of 0.12 µM.

Crystal structure of the apurinic/apyrimidinic endonuclease XthA (HP1526 protein) from Helicobacter pylori.

Helicobacter pylori is a bacterium that causes gastritis, peptic ulcer disease and adenocarcinoma while infecting human stomach. In the stomach H. pylori is under stresses caused by reactive oxygen and nitrogen species from host immune response, which causes oxidative DNA damage. The DNA damage in single base is repaired by base excision repair (BER) and/or nucleotide incision repair (NIR) pathways. H. pylori retains a minimal set of enzymes involved in the BER and NIR pathways. The HP1526 protein is a single apurinic/apyrimidinic (AP) endonuclease homologous to E. coli Xth protein but little is known for its structure up to now. In this study, the structure of the recombinant HP1526 protein from H. pylori (HpXthA) has been determined at a high resolution of 1.84 Å. From the structural analysis the HpXthA was found to belong to the Xth-like AP endonuclease family carrying the common fold of a central bilayer ß-sheet flanked by α-helices with a divalent metal ion bound. A Mn2+ ion and a 1,3-butanediol were unusually found and modeled around the active site. Structural and sequence comparisons among the AP endonucleases show well-conserved residues for metal and DNA binding and for catalysis. Interestingly, the presence of a small polar residue Ser201 of the HpXthA commonly found in NIR-proficient AP endonucleases instead of an aspartate residue in NIR-deficient enzymes suggests that the HpXthA retain a nucleotide incision repair activity.

Two new dimethylpyranoflavanones from the roots of Melodorum fruticosum.

Two previously unreported dimethylpyranoflavanones, pyronomelodorones A and B (1 and 2), along with five known compounds, 7-O-methyldihydrowogonin (3), 5,6,7-trimethoxyflavanone (4), 5,6-dihydroxy-7-methoxy-dihydroflavone (5), 5,7,8-trimethoxydihydroflavone (6), and pinostrobin (7), were isolated from the roots of Melodorum fruticosum. The structures of all isolates were fully characterized using spectroscopic data and comparison with the previous literature. All isolates were evaluated for their in vitro α-glucosidase inhibition and their cytotoxicity against KB, HepG2, and MCF7 cell lines. Among the isolates, compound 1 exhibited the most inhibitory activity against α-glucosidase and was superior to the positive control with an IC50 value of 1.32 µM. Compounds 1 and 2 showed weak cytotoxicity against the three human cancer cell lines, with IC50 values in the range of 53.3-79.0 µM.

A new triterpenoid saponin from Glinus oppositifolius.

From the ethanol extract of Glinus oppositifolius, collected at Phu Yen province, Viet Nam, one new triterpenoid saponin (1) and four known compounds (2-5) were isolated. By means of NMR and HR-ESI-MS analyses, their structure was elucidated as 3-O-(ß-D-xylopyranosyl-(1→3)-ß-D-xylopyranosyl)spergulagenin A or glinusopposide V (1), glinusopposide L (2), spergulin B (3), vitexin (4) and astralagin (5). Two compounds (1-2) showed weak inhibitory activity against α-glucosidase.

Regioselective Radical Amino-Functionalizations of Allyl Alcohols via Dual Catalytic Cross-Coupling.

The regioselective amination and cross-coupling of a range of nucleophiles with allyl alcohols has been enabled by a dual catalytic strategy. This approach entails the combined action of an Ir photocatalyst that enables mild access to N-radicals via an energy transfer mechanism, as well as a Cu complex that intercepts the ensuing alkyl radical upon cyclization. Merger of this Cu-catalyzed cross-coupling enables a broad range of nucleophiles (e.g. CN, SCN, N3, vinyl, allyl) to engage in radical amino-functionalizations of olefins. Notably, stereo, regio, and kinetic probes provide insights into the nature of this Cu-based radical interception.

Tracking Objects Based on Multiple Particle Filters for Multipart Combined Moving Directions Information.

Object tracking is an important procedure in the computer vision field as it estimates the position, size, and state of an object along the video's timeline. Although many algorithms were proposed with high accuracy, object tracking in diverse contexts is still a challenging problem. The paper presents some methods to track the movement of two types of objects: arbitrary objects and humans. Both problems estimate the state density function of an object using particle filters. For the videos of a static or relatively static camera, we adjusted the state transition model by integrating the movement direction of the object. Also, we propose that partitioning the object needs tracking. To track the human, we partitioned the human into N parts and, then, tracked each part. During tracking, if a part deviated from the object, it was corrected by centering rotation, and the part was, then, combined with other parts.