Physicochemical-property guided design of a highly sensitive probe to image nitrosative stress in the pathology of stroke.

In vivo real-time imaging of nitrosative stress in the pathology of stroke has long been a formidable challenge due to both the presence of the blood-brain barrier (BBB) and the elusive nature of reactive nitrogen species, while this task is also informative to gain a molecular level understanding of neurovascular injury caused by nitrosative stress during the stroke episode. Herein, using a physicochemical property-guided probe design strategy in combination with the reaction-based probe design rationale, we have developed an ultrasensitive probe for imaging nitrosative stress evolved in the pathology of stroke. This probe demonstrates an almost zero background fluorescence signal but a maximum 1000-fold fluorescence enhancement in response to peroxynitrite, the nitrosative stress marker. Due to its good physicochemical properties, the probe readily penetrates the BBB after intravenous administration, and quickly accumulates in mice brain to sense local vascular injuries. After accomplishing its imaging mission, the probe is easily metabolized and therefore won't cause safety concerns. These desirable features make the probe competent for the straightforward visualization of nitrosative stress progression in stroke pathology.

Characterization of the ligand binding of PGRP-L in half-smooth tongue sole (Cynoglossus semilaevis) by molecular dynamics and free energy calculation

Background: Peptidoglycan (PGN) recognition proteins (PGRPs) are important pattern recognition receptors of the host innate immune system that are involved in the immune defense against bacterial pathogens. PGRPs have been characterized in several fish species. The PGN-binding ability is important for the function of PGRPs. However, the PGRP-PGN interaction mechanism in fish remains unclear. In the present study, the 3-D model of a long PGRP of half-smooth tongue sole (Cynoglossus semilaevis) (csPGRP-L), a marine teleost with great economic value, was constructed through the comparative modeling method, and the key amino acids involved in the interaction with Lys-type PGNs and Dap-type PGNs were analyzed by molecular dynamics and molecular docking methods. Results: csPGRP-L possessed a typical PGRP structure, consisting of five ß-sheets and four α-helices. Molecular docking showed that the van der Waals forces had a slightly larger contribution than Coulombic interaction in the csPGRP-L-PGN complex. Moreover, the binding energies of csPGRP-L-PGNs computed by MM-PBSA method revealed that csPGRP-L might selectively bind both types of MTP-PGNs and MPP-PGNs. In addition, the binding energy of each residue of csPGRP-L was also calculated, revealing that the residues involved in the interaction with Lys-type PGNs were different from that with Dap-type PGNs. Conclusions: The 3-D structure of csPGRP-L possessed typical PGRP structure and might selectively bind both types of MTP- and MPP-PGNs, which provided useful insights to understanding the functions of fish PGRPs.

Two new cassane-type diterpenes from the seeds of Caesalpinia crista.

Two new cassane-type diterpenes, phangininoxys D and E (1 and 2), together with five known compounds were isolated from the seeds of Caesalpinia crista Linn. The structures of these compounds were elucidated by means of various spectroscopic analyses. All the isolated compounds were evaluated for cytotoxicity activities against HeLa, HT-29 and KB cell lines, and compound 7 showed moderate selective activities against KB cell line with an IC50 value of 17.1 µM.

N-butanol fraction of Entada phaseoloides ethanol extract inhibits hepatocellular carcinoma HepG2 cell proliferation by inducing apoptosis.

PURPOSE: To screen for substances with inhibitory effects on the proliferation of hepatocellular carcinoma (HCC) HepG2 cell line from extracts of traditional Chinese medicinal plants including Heliciopsis lobata (Merr.) Sleum, Bidens pilosa, Entada phaseoloides, Plantago major, and Smilax, and unveil their mechanism of action. METHODS: 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to assess the inhibition of HepG2 cell proliferation by plant extracts. Cell apoptosis was evaluated by Hoechst 33342 staining and mitochondrial transmembrane potential (ΔCgr;m) dissipation was measured using JC-1 probe by fluorescence microscopy. RESULTS: Heliciopsis lobata, Bidens, Plantago, and Smilax extracts showed reduced inhibitory effects on HepG2 cell proliferation compared with Entada phaseoloides (all p<0.05). The n-butanol fraction of Entada phaseoloides ethanol extract exhibited the highest inhibition rate. Treatment of HepG2 cells with 500, 250, and 100 µg/ml n-butanol extract resulted in 89.92±0.58%, IC50 81.66±0.42%, 68.85±0.57% decrease in cell viability, respectively, indicating an IC50 of 9.27 µg/ml. In the presence of 100 µg/ml entada phaseoloides n-butanol extract for 24h, apoptotic nuclei and hyperchromatic, dense fluorescent massive granules were observed in the cytoplasm, effects that increased with extract concentrations in HepG2 cells. Finally, we showed that Entada phaseoloides n-butanol extract induced depolarization of mitochondrial membrane potential. CONCLUSIONS: Entada phaseoloides n-butanol extract inhibits HepG2 cell proliferation by inducing cell apoptosis likely through mitochondrial apoptotic pathway. This extract is therefore a potential natural source towards the discovery for a new drug-candidate for the treatment of HCC.