Synthesis of a Novel Nitronyl Nitroxide Radical and Determination of its Protective Effects Against Infrasound-Induced Injury

Nitronyl Nitroxide Ameliorates Hypobaric Hypoxia-Induced Cognitive Impairment in Mice by Suppressing the Oxidative Stress, Inflammatory Response and Apoptosis

Abundant investigations have shown that hypobaric hypoxia (HH) causes cognitive impairment, mostly attributed to oxidative stress, inflammation, and apoptosis. HPN (4'-hydroxyl-2-subsitiuted phenylnitronyl nitroxide) is an excellent free radical scavenger with anti-inflammatory and anti-apoptotic activities. Our previous study has found that HPN exhibited neuroprotective effect on HH induced brain injury. In the present study, we examined the protective effect and potential mechanism of HPN on HH-induced cognitive impairment. Male mice were exposed to HH at 8000 m for 3 days with and without HPN treatment. Cognitive performance was assessed by the eight-arm radical maze. The histological changes were assayed by Nissle staining. The hippocampus cell apoptosis was detected by Tunnel staining. The levels of inflammatory cytokines and oxidative stress markers were detected. The expression of oxidative stress, inflammation-related and apoptosis-related proteins was determined by western blot. HPN administration significantly and mitigated HH induced histological damages and spatial memory loss with the evidence of decreased working memory error (WME), reference memory error (RME), total errors (TE) and total time (TT). In addition, HPN treatment significantly decreased the content of H2O2 and MDA, increased the levels of SOD, CAT, GSH-Px and GSH, and inhibited the synthesis of TNF-α, IL-1β and IL-6. Moreover, HPN administration could down-regulate the expression of NF-κB, TNF-α, Bax, and cleaved caspase-3 and up-regulate the expression of Nrf2, HO-1 and Bcl-2. The number of apoptotic cells was also significantly decreased in the hippocampus of mice in the HPN group. There results indicate that HPN improve HH-induced cognitive impairment by alleviating oxidative stress damage, suppressing inflammatory response and apoptosis and may be a powerful candidate compound for alleviating memory loss induced by HH.

Pre-Exposure to Environmental Enrichment Protects against Learning and Memory Deficits Caused by Infrasound Exposure

With the development of industrialization in recent years, infrasound has become an important component of public noise. To date, diverse studies have revealed the negative effects of infrasound on the central nervous system (CNS), especially the learning and memory ability. It is widely reported that environmental enrichment (EE) ameliorates the learning and memory deficits in different models of brain injury. Therefore, the present study was designed to determine the possible benefits of pre-exposure to EE in preventing functional deficits following infrasound exposure and their related mechanism. Adult male rats were given enriched or standard housing for 30 days. Following enrichment, the rats were exposed to 16 Hz, 130 dB infrasound for 14 days, and then their learning and memory ability was assessed. Changes to neuroinflammation, apoptosis, and oxidative stress in the hippocampus were also detected. Our results showed that the infrasound-induced deficit in learning and memory was attenuated significantly in EE pre-exposed rats. Pre-exposure to EE could induce a decrease in proinflammatory cytokines and increased anti-inflammatory cytokines and antioxidant properties in the hippocampus. Moreover, pre-exposure to EE also exerted antiapoptosis functions by upregulating the B-cell lymphoma/leukemia-2 (Bcl-2) level and downregulating the P53 level in the hippocampus. In conclusion, the results of the present study suggested that EE is neuroprotective when applied before infrasound exposure, resulting in an improved learning and memory ability by enhancing antioxidant, anti-inflammatory, and antiapoptosis capacities.

The potent radioprotective agents: Novel nitronyl nitroxide radical spin-labeled resveratrol derivatives

It is commonly known that radiotherapy is still a key modality for treatment of cancer. Though this effect is desirable during radiotherapy, it leads to radiotoxicity on normal healthy cells. In the present research, we designed, synthesized and analyzed a series of nitronyl nitroxide radical (NITR) spin-labeled resveratrol (RES) derivatives. The cytotoxicity of the newly synthesized substances was tested on Jurkat T cells. The derivatives were studied as reactive oxygen species (ROS) scavenger to protect ionizing radiation of Jurkat T cells upon 6 Gy X-irradiation. The experimental results revealed that compound 2 and 3 could significantly alleviate the damage of Jurkat T cells, as evidenced by decreasing ROS production and restoring the cell apoptosis. Further mechanism investigations indicated that the radioprotective effects of the novel derivatives were largely associated with modulating the expression of apoptotic proteins including cIAP-1, cIAP-2, cytochrome c, caspase-3 and caspase-9. Based on the experimental result, we disclosed that the novel NITR spin-labeled RES derivatives exhibit the potential to be used as the novel radioprotective candidates to ameliorate the injury induced by ionizing radiation.

Tetrahydroxystilbene Glucoside Ameliorates Infrasound-Induced Central Nervous System (CNS) Injury by Improving Antioxidant and Anti-Inflammatory Capacity

Background

Infrasound is a major threat to global health by causing injuries of the central nervous system (CNS). However, there remains no effective therapeutic agent for preventing infrasound-caused CNS injury. 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glycoside (THSG) exerts protective function against CNS injuries and may have beneficial effects on infrasound-induced CNS impairment.

Methods

A mouse model with CNS (oxidative stress-induced inflammation and neuronal apoptosis) injuries was established when the mouse was exposed to the infrasound of 16 Hz at 130 dB for 2 h each day and the duration of treatment was 8 d. The mice were divided into the control (CG, healthy mice), the model (MG, model mice), and the THSG (EG, experimental group, model mice treated with THSG) groups. The learning and memory impairments caused by infrasound were examined using a Morris water maze test. Lipid profiles, antioxidant biomarkers, and inflammatory cytokines in hippocampus tissue were measured by using corresponding ELISA kits. Meanwhile, BCL-2/BAX/caspase-3 signaling pathway was measured in the hippocampi and prefrontal cortex of the mouse brain using real-time qPCR and Western blot. Nissl's stain was used to measure neuronal necrosis in the hippocampi and prefrontal cortex of the mouse brain.

Results

THSG significantly ameliorated the learning and memory impairments caused by infrasound. On the other hand, THSG improved lipid profiles, increased antioxidant properties by affecting the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA), and displayed anti-inflammatory action via the downregulation of IL- (interleukin-) 6, IL-8, IL-10, TNF- (tumor necrosis factor-) α, and hs-CRP (high-sensitivity C-reactive protein) in the hippocampal tissues of the mouse model (P < 0.05). Additionally, Nissl's stain showed that THSG inhibited infrasound-induced neuronal necrosis in the hippocampi and prefrontal cortex. Besides, THSG exerted antiapoptosis function by upregulating the level of Bcl-2 and downregulating the levels of BAX and caspase-3 in the hippocampi.

Conclusion

THSG may be an effective anti-infrasound drug against CNS injury by improving antioxidant, anti-inflammatory, antiapoptosis, and antinecrosis capacities. Further research is still needed to confirm the exact molecular mechanism.

The crystal structure of 2-[4-hydroxy-3-methoxyphenyl]-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl, C14H19N2O4

C14H19N2O4, orthorhombic, P212121 (no. 19), a = 9.263(10) Å, b = 9.874(11) Å, c = 15.431(16) Å, V = 1407(3) Å3, Z = 4, R gt(F) = 0.0542, wR ref(F 2) = 0.1323, T = 296(2) K.