Mitochondria-Targeted Nitronyl Nitroxide Radical Nanoparticles for Protection against Radiation-Induced Damage with Antioxidant Effects.

Radiotherapy is a non-invasive method that is widely applied to treat and alleviate cancers. However, radiation-induced effects in the immune system are associated with several side effects via an increase in oxidative stress and the inflammatory response. Therefore, it is imperative to develop effective clinical radiological protection strategies for the radiological protection of the normal organs and immune system in these patients. To explore more effective radioprotective agents with minimal toxicity, a mitochondria-targeted nitronyl nitroxide radical with a triphenylphosphine ion (TPP-NIT) was synthesized and its nanoparticles (NPs-TPP-NIT) were prepared and characterized. The TPP-NIT nanoparticles (NPs-TPP-NIT) were narrow in their size distribution and uniformly distributed; they showed good drug encapsulation efficiency and a low hemolysis rate (<3%). The protective effect of NPs-TPP-NIT against X-ray irradiation-induced oxidative damage was measured in vitro and in vivo. The results show that NPs-TPP-NIT were associated with no obvious cytotoxicity to L-02 cells when the concentration was below 1.5 × 10-2 mmol. NPs-TPP-NIT enhanced the survival rate of L-02 cells significantly under 2, 4, 6, and 8 Gy X-ray radiation exposure; the survival rate of mice was highest after 6 Gy X-ray irradiation. The results also show that NPs-TPP-NIT could increase superoxide dismutase (SOD) activity and decrease malondialdehyde (MDA) levels after the L-02 cells were exposed to 6.0 Gy of X-ray radiation. Moreover, NPs-TPP-NIT could significantly inhibit cell apoptosis. NPs-TPP-NIT significantly increased the mouse survival rate after irradiation. NPs-TPP-NIT displayed a marked ability to reduce the irradiation-induced depletion of red blood cells (RBCs), white blood cells (WBCs), and platelets (PLTs). These results demonstrate the feasibility of using NPs-TPP-NIT to provide protection from radiation-induced damage. In conclusion, this study revealed that NPs-TPP-NIT may be promising radioprotectors and could therefore be applied to protect healthy tissues and organs from radiation during the treatment of cancer with radiotherapy.

Moslosooflavone protects against brain injury induced by hypobaric hypoxic via suppressing oxidative stress, neuroinflammation, energy metabolism disorder, and apoptosis.

OBJECTIVES: To investigate the protect effect of moslosooflavone against brain injury induced by hypobaric hypoxia (HH) in mice. METHODS: Protective effects of moslosooflavone in oxidative stress, neuroinflammation, energy metabolism disorder, and apoptosis were studied in HH-induced brain damage mice. The pathological morphology in the cortex of mice was determined by hematoxylin and eosin staining. The related protein expressions were detected by western blot. KEY FINDINGS: Moslosooflavone improved HH-induced brain histopathological changes, reduced the contents of ROS and MDA, and elevated the levels of antioxidant enzymes and GSH in HH-exposed brains of mice. Moslosooflavone also markedly enhanced the ATPase activities and PK, ATP contents, while reducing LDH activity and the LD, TNF-α, IL-1ß, and IL-6 contents HH-exposed brains of mice. In addition, moslosooflavone notably decreased the expression of HIF-1α, VEGF, Bax, and cleaved caspase-3 dramatically increasing the expression of Bcl-2, Nrf2, and HO­1 in HH-exposed brains of mice. CONCLUSIONS: Our current studies indicate that moslosooflavone protects HH-induced brain injury possibly through alleviating oxidative stress and neuroinflammation, maintaining the balance of energy metabolism, and inhibiting cell apoptosis.

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-1ß 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.

Protective effect of 5,6,7,8-Tetrahydroxyflavone on high altitude cerebral edema in rats.

High altitude cerebral edema (HACE) is a potentially life-threatening disease encountered at high altitudes. However, effective methods for HACE prophylaxis are limited. Convincing evidence confirms that oxidative stress induced by hypobaric hypoxia (HH) is one of the main factors that account for the development of HACE. 5,6,7,8-Tetrahydroxyflavone (THF), a flavone with four consecutive OH groups in ring A, exhibited excellent antioxidant activity in vitro and could attenuate HH induced injury in vivo. The aim of this study was to investigate the protective effect of THF against HACE and its underlying mechanisms. THF administration significantly suppressed HH induced oxidative stress by reducing the formation of hydrogen peroxide and malondialdehyde, by increasing the levels of glutathione and superoxide dismutase in brain tissue. Simultaneously, THF administration inhibited inflammatory responses by decreasing the levels of tumor necrosis factor-α, interleukin-1ß, and interleukin-6 in serum and brain tissue. In addition, THF administration mitigated the energy metabolism disorder induced by HACE as evidenced by decreased levels of lactic acid, lactate dehydrogenase and pyruvate kinase as well as increased ATP levels and ATPase activities. Furthermore, THF administration decreased the expression of matrix metalloproteinase-9, aquaporin 4, hypoxia-inducible factor-1α and vascular endothelial growth factor, which attenuated blood-brain barrier (BBB) disruption and brain edema. Additionally, THF administration improved HACE induced cognitive dysfunction. These results show that THF is a promising agent in the prevention and treatment of HACE.

Design, synthesis and anti-hypoxia activity of HPN derivatives containing lipophilic long chains.

OBJECTIVE: To design and synthesize long-chain substituted 2-[(4'-hydroxyethoxy) phenyl]-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide (HPN) derivatives with enhanced anti-hypoxic activity. METHODS: HPN derivatives 1, 3, 5 containing lipophilic long chains were synthesized via the alkylation of HPN with 6-bromohexan-1-ol, ethyl 6-bromohexanoate or 6-bromohexane, respectively using acetonitrile as the solvent and K 2CO 3 as the acid-binding agent at 60 ℃. Derivative 2 was synthesized via hydrolysis reactions of derivative 1 in the NaOH/CH 3OH/H 2O system. Using dichloromethane as the solvent and N, N'-diisopropylcarbodiimide as the dehydrating agent, HPN underwent esterification with hexanoic acid to obtain derivative 4. The structures of derivatives 1-5 were characterized by infrared spectroscopy, electron paramagnetic resonance and high resolution mass spectrometry. The purities of derivatives were detected by high performance liquid chromatography, and the lipid solubilities of derivatives were evaluated by calculating the oil-water partition coefficients (log P). Anti-hypoxia activities of HPN and its long-chain lipophilic derivatives 1-5 were evaluated using normobaric hypoxia test and acute decompression hypoxia test. RESULTS: The structures of the derivatives were confirmed by infrared spectroscopy, electron paramagnetic resonance and high resolution mass spectroscopy. The yields of target derivatives were all above 92%, and the purities were all above 96%. The log P values of derivatives 1-5 were 2.78, 2.00, 2.04, 2.88 and 3.10, which were higher than that of HPN (0.97). Derivatives 1-5 significantly prolonged the survival time of mice at the dose of 0.3 mmol/kg in normobaric hypoxic test and reduced the mortality rate of acute decompression hypoxic mice to 60%, 70%, 60%, 70% and 40%, respectively. CONCLUSIONS: The synthesis of derivatives 1-5 is convenient, and the yield is high. The synthesized derivatives especially derivative 5 show anti-hypoxic activity similar to or better than HPN at lower doses.