Hydroxymethylation hydroxylation of 1,3-diarylpropene through a catalytic diastereoselective Prins reaction: cyclization logic and access to brazilin core.

A catalytic diastereoselective Prins reaction for hydroxymethylation and hydroxylation of 1,3-diarylpropene was successfully utilized to prepare various 1,3-dioxanes 7 in 14-88% yields. Take advantage of the synthetic intermediate 7h, the key B/C rings in brazilin core could be constructed by the sequential of Friedel-Crafts/Ullmann-Ma rather than Ullmann-Ma/Friedel-Crafts reactions.

Dually crosslinked self-healing hydrogels originating from cell-enhanced effect.

A new cell-loading strategy is proposed to improve the self-healing properties of hydrogels prepared by free-radical polymerization. The introduction of normal human dermal fibroblast (NHDF) cells enables the formation of dually crosslinked hydrogels through hydrogen interactions between cell secretions (mainly the secretory proteins) and polymer chains. This allows an enhancement of the self-healing efficiency from 73% to 92% and an acceleration of the self-healing rate (12 times). Based on the excellent biocompatibility, antibacterial property and low toxicity, we extended the use of dually crosslinked hydrogels as wound dressings to expedite wound healing. This cell-loading concept for constructing dually crosslinked hydrogels offers an available pathway to design smart materials useful for biomedical applications.

Quercetin protects gastric epithelial cell from oxidative damage in vitro and in vivo.

Epithelial injury caused by reactive oxygen species (ROS) including H2O2 plays a critical role in the pathogenesis of gastric disorders. Therefore, pharmacological intervention targeting reactive oxygen species elimination has highly clinical values in therapy of gastric diseases. Although quercetin has been found to possess gastroprotective activity, whether it has a protective activity againress related injury to gastric epithelial cells remains unknown. The aim of the study is herein to investigate a possible protective effect of quercetin against oxidative stress in vitro and vivo. Human gastric epithelial GES-1 cells were pretreated with quercetin and then challenged with H2O2. In vivo reactive oxygen species production in acute gastric mocosa injury was assessed using a chemiluminescent probe L-012 (8-amino-5-chloro-7-phenylpyrido [3,4-d]pyridazine-1,4-(2H,3H)dione) after quercetin was administered to mice. In GES-1 cells, pretreatment of quercetin can significantly diminish H2O2-induced cell viability loss; decrease intracellular reactive oxygen species and Ca(2+) influx; restore H2O2-induced ΔΨm dissipation. It also upregulates peroxisome proliferator-activated receptor-γ coactivator (PGC-1α) expression under the state of oxidative stress, and the downstream cell apoptosis significantly decreased. In vivo, chemiluminescence imaging shows that quercetin attenuates reactive oxygen species production and gastric damages in acute gastric mucosal injury. We first reported the evidence that quercetin can protect gastric epithelial GES-1 cells from oxidative damage and ameliorate reactive oxygen species production during acute gastric mucosal injury in mice. This might be ascribed to its inhibition of oxidative stress, regulation of mitochondrial dysfunction, initiation of antioxidant defense and inhibition of apoptosis.