Effect of Ultrasonic Irradiation on the Physicochemical and Structural Properties of Laminaria japonica Polysaccharides and Their Performance in Biological Activities

Due to the large molecular weight and complex structure of Laminaria japonica polysaccharides (LJP), which limit their absorption and utilization by the body, methods to effectively degrade polysaccharides had received more and more attention. In the present research, hot water extraction coupled with three-phase partitioning (TPP) was developed to extract and isolate LJP. Ultrasonic L. japonica polysaccharides (ULJP) were obtained by ultrasonic degradation. In addition, their physicochemical characteristics and in vitro biological activities were investigated. Results indicated that ULJP had lower weight-average molecular weight (153 kDa) and looser surface morphology than the LJP. The primary structures of LJP and ULJP were basically unchanged, both contained α-hexo-pyranoses and were mainly connected by 1,4-glycosidic bonds. Compared with LJP, ULJP had stronger antioxidant activity, α-amylase inhibitory effect and anti-inflammatory effect on RAW264.7 macrophages. The scavenging rate of DPPH free radicals by ULJP is 35.85%. Therefore, ultrasonic degradation could effectively degrade LJP and significantly improve the biological activity of LJP, which provided a theoretical basis for the in-depth utilization and research and development of L. japonica in the fields of medicine and food.     

Neolignans from the Fruits of Magnolia obovata Inhibit NO Production and Have Neuroprotective Effects

One new sesquineolignan, obovatalignan A ( 1 ), and one new neolignan, obovatalignan B ( 2 ), were isolated from the Magnolia obovata fruits. Their chemical structure, including absolute configuration, was determined based on various spectroscopic methods, such as HR‐EI‐MS, 1D‐NMR (¹H, ¹³C, DEPT), 2D‐NMR (gCOSY, gHSQC, gHMBC, NOESY), and CD spectroscopy. The compounds were evaluated for protective effects against glutamate‐induced oxidative stress in HT22‐immortalized hippocampal cells and inhibitory activity against NO production in LPS‐induced RAW 264.7 cells. Compounds 1 and 2 exhibited protective effects against glutamate‐induced oxidative stress with EC₅₀ values of 18.1 ± 1.23 and 7.10 ± 0.78 μm , respectively, as well as inhibitory effects on NO production with IC₅₀ values of > 30.0 and 8.22 ± 2.01 μm , respectively.     

Disruption of lipid rafts impairs the production of nitric oxide in lipopolysaccharide-stimulated murine RAW264.7 macrophages

Upon stimulation with lipopolysaccharide, murine RAW264.7 macrophages generated a high amount of nitric oxide. Pretreatment of macrophages with methyl-β-cyclodextrin, which disrupted the lipid raft microdomains of the plasma membrane, inhibited the generation of nitric oxide by down-regulating the expression of inducible nitric oxide synthase. Methyl-β-cyclodextrin exposure significantly inhibited the degradation of IκB-α, blocked the translocation of p65/RelA into the nuclei and prevented the activation of the NF-κB signaling pathway. The results suggest that the expression of inducible nitric oxide synthase and the consequent production of nitric oxide depend on the integrity of the lipid rafts.     

Polyphenols from the Peels of Punica granatum L. and Their Bioactivity of Suppressing Lipopolysaccharide-Stimulated Inflammatory Cytokines and Mediators in RAW 264.7 Cells via Activating p38 MAPK and NF-κB Signaling Pathways

Punica granatum L. (Punicaceae) is a popular fruit all over the world. Owning to its enriched polyphenols, P. granatum has been widely used in treating inflammation-related diseases, such as cardiovascular diseases and cancer. Twenty polyphenols, containing nine unreported ones, named punicagranins A–I (1–9), along with eleven known isolates (10–20), were obtained from the peels. Their detailed structures were elucidated based on UV, IR, NMR, MS, optical rotation, ECD analyses and chemical evidence. The potential anti-inflammatory activities of all polyphenols were examined on a lipopolysaccharide (LPS)-induced inflammatory macrophages model, which indicated that enhancing nitric oxide (NO) production in response to inflammation stimulated in RAW 264.7 cells was controlled by compounds 1, 3, 5–8, 10, 11, 14 and 16–20 in a concentration-dependent manner. The investigation of structure–activity relationships for tannins 6–8 and 12–20 suggested that HHDP, flavogallonyl and/or gallagyl were key groups for NO production inhibitory activity. Western blotting indicated that compounds 6–8 could down-regulate the phosphorylation levels of proteins p38 MAPK, IKKα/β, IκBα and NF-κB p65 as well as inhibit the levels of inflammation-related cytokines and mediators, such as IL-6, TNF-α, iNOS and COX-2, at the concentration of 30 μM. In conclusion, polyphenols are proposed to be the potential anti-inflammatory active ingredients in P. granatum peels, and their molecular mechanism is likely related to the regulation of the p38 MAPK and NF-κB signaling pathways.     

A renewal theory based performance and configuration framework of the IEEE 802.11ah RAW mechanism

IEEE 802.11ah is a new Wi-Fi standard for sub-1Ghz communications, aiming to address the challenges of the Internet of Things (IoT). Significant changes in the legacy 802.11 standards have been proposed to improve the network performance in high contention scenarios, the most important of which is the Restricted Access Window (RAW) mechanism. This mechanism promises to increase the throughput and energy efficiency by dividing stations into different groups. Under this scheme, only the stations belonging to the same group may access the channel, which reduces the collision probability in dense scenarios. However, the standard does not define the RAW grouping strategy. In this paper, we develop a new mathematical model based on the renewal theory, which allows for tracking the number of transmissions within the limited RAW slot contention period defined by the standard. We then analyze and evaluate the performance of RAW mechanism. We also introduce a grouping scheme to organize the stations and channel access time into different groups within the RAW. Furthermore, we propose an algorithm to derive the RAW configuration parameters of a throughput maximizing grouping scheme. We additionally explore the impact of channel errors on the contention within the time-limited RAW slot and the overall RAW optimal configuration. The presented analytical framework can be applied to many other Wi-Fi standards that integrate periodic channel reservations. Extensive simulations using the MATLAB software validate the analytical model and prove the effectiveness of the proposed RAW configuration scheme.     

An Enzyme‐Responsive Prodrug with Inflammation‐Triggered Therapeutic Drug Release Characteristics

Long‐term use of nonsteroidal anti‐inflammatory drugs (NSAIDs) for relieving inflammatory reactions can lead to severe side effects. It is of great importance to configure new dosing strategies for alleviating the side effects of NSAIDs. In this work, an enzyme‐responsive anti‐inflammatory prodrug capable of generating indomethacin upon the trigger of inflammation is developed. A monomer is first prepared after the esterification of carboxyl groups of indomethacin by hydroxyl groups of N‐(2‐hydroxyethyl) acrylamide. Then, a polymer prodrug, with indomethacin linked through ester bonds on the side chain, is synthesized by free radical polymerization of the monomer. The therapeutic drug component can be triggered to release from the prodrug under the stimulation of cholesterol esterase, mimicking the inflammation environment. On the contrary, there is only a small amount of drug released in the absence of the enzyme. Therefore, the drug can be triggered to release under the stimulation of an environment mimicking inflammation. Furthermore, the in vitro studies at the cellular level indicate that the enzyme‐responsive prodrug can efficiently relieve inflammatory responses induced by lipopolysaccharide in RAW264.7 macrophage cells while indicating no cytotoxicity.