Lipid Peroxidation: A Signaling Mechanism in Diagnosis of Diseases

Quantification of reactive oxygen species, is perplexing either in vivo or in vitro due to their short half-lives. Consequently, to define the magnitude of oxidative stress, the more stable oxidation products can be measured in biological samples. The oxidative stress leads to the lipid peroxidation that involves the initiation, termination and propagation of lipid radicals, wherein, the process involves the oxygen uptake, rearrangement of the double bonds in unsaturated lipids, that leads to polyunsaturated fatty acid deterioration. Subsequently, the toxic signaling end products are considered as biomarkers of free radicals that act both as signaling molecules and as cytotoxic products cause covalent alteration of lipid peroxidation products. The use of validated signaling mechanism (s) of Lipid peroxidation and products derived thereof exhibits its use clinical practice and basic clinical research as well as in clinical practice has become common place, and their presence as endpoints in clinical trials is now broadly accepted. This knowledge can be used to diagnose disease earlier, or to prevent it before it starts. The signaling markers can be used to excel the effectiveness of the prevailing medicines and to improve the new medicines.

Tumor-killing nanoreactors fueled by tumor debris can enhance radiofrequency ablation therapy and boost antitumor immune responses

Radiofrequency ablation (RFA) is clinically adopted to destruct solid tumors, but is often incapable of completely ablating large tumors and those with multiple metastatic sites. Here we develop a CaCO3-assisted double emulsion method to encapsulate lipoxidase and hemin with poly(lactic-co-glycolic acid) (PLGA) to enhance RFA. We show the HLCaP nanoreactors (NRs) with pH-dependent catalytic capacity can continuously produce cytotoxic lipid radicals via the lipid peroxidation chain reaction using cancer cell debris as the fuel. Upon being fixed inside the residual tumors post RFA, HLCaP NRs exhibit a suppression effect on residual tumors in mice and rabbits by triggering ferroptosis. Moreover, treatment with HLCaP NRs post RFA can prime antitumor immunity to effectively suppress the growth of both residual and metastatic tumors, also in combination with immune checkpoint blockade. This work highlights that tumor-debris-fueled nanoreactors can benefit RFA by inhibiting tumor recurrence and preventing tumor metastasis.

Acute radiofrequency electromagnetic radiation exposures cause neuronal DNA damage and impair neurogenesis in the young adolescent rat brain

Mobile phone is now a commonly used communication device in all age groups. Young adolescents use it for longer duration and effect of its radiofrequency electromagnetic radiation (RF-EMR) on their brain structure and function need detailed investigation. In the present study, we investigated the effect of RF-EMR emitted from mobile phones, on young adolescent rat brain. Wistar rats (5 weeks, male) were exposed to RF-EMR signal (2,115 MHz) from a mobile phone at a whole body averaged specific absorption rate (SAR) of 1.15 W/kg continuously for 8 h. Higher level of lipid peroxidation, carbon centered lipid radicals and DNA damage were observed in the brain of rat exposed to RF-EMR. Number of neural progenitor cells (NPCs) in dentate gyrus (DG) were found to be relatively low in RF-EMR exposed rats that may be due to reduced neurogenesis. Acute exposure to RF-EMR induced neuronal degeneration in DG region with insignificant variation in CA3, CA1 and cerebral cortex sub regions of hippocampus. Findings of this study, indicate that acute exposure of high frequency RF-EMR at relatively higher SAR may adversely impact the neurogenesis and function of adolescent rat brain. Generation of carbon centered lipid radicals, and nuclear DNA damage might be playing critical role in reduced neurogenesis and higher neuronal degeneration in the cortex and hippocampus of brain. Detailed understanding of RF-EMR induced alteration in brain function will be useful to develop appropriate interventions for reducing the impact caused by RF-EMR damage.

The Study of the Neuroprotective Effect of the Extract from Chelidonium Majus L. in Vitro

The protection of neurons from damage and death is an important challenge in the development of treatment of brain ischemia and neurodegenerative diseases. This study aims to investigate protective effect of the extract prepared from Chelidonium majus, which contains total alkaloids. In the present study, we examined antioxidant activity of total alkaloids from Chelidonium majus in vitro. Hydroxyl radical and lipid radicals were detected using spin trapping agents with ESR spectrometer. Chelidonium majus extract exhibited dose-dependent scavenging effects on lipid radicals. Halfmaximal inhibitory concentration (IC50) of the extract was 2.96 mg/ml, whereas for hydroxyl radicals it was 55.13 mg/ ml. These results showed that extract of Chelidonium majus is partly inhibited free radicals. Antioxidant effects of this extract were further demonstrated by protecting enzyme activity of the mitochondrial respiratory electron transport chain (complex I) in isolated brain mitochondrial dysfunction induced by MDA. However, it did not change the decreased level of complex II, and malate dehydrogenase (MDH) in a concentration of 12 and 25 mg/ml. Here, we examined the neuroprotective effect of the extract from Chelidonium majus against oxidative stress in cultured cortical neurons, using MTT. We found that pretreatment with the extract of Chelidonium majus (0.05 and 0.5 mg/ml) significantly inhibited H2O2-induced cell death in cortical neurons.Furthermore, the use of a luciferase reporter (ARE-luc) assay showed that extract from Chelidonium majus activates protective signaling pathway in primary cortical neurons through ARE/Nrf2 pathway.Together, this suggests that total alkaloids from Chelidonium majus may be neuroprotective by increasing anti-oxidant gene expression.

Investigation into the potential chemical mechanism of the pro-oxidant activity of carotenoids with liposomes under UV-irradiation

This study focuses on the behavior of ?-carotene and lutein inside multilamellar liposomes under continuous UV-irradiation. The liposomes were obtained by the thin film method and carotenoids (Crts) were incorporated by mixing at various concentrations (0.005, 0.0075, 0.02, 0.07 and 0.5 mol %). Liposomes formation and the presence of Crts inside them were confirmed by SEM microscopy and FT-IR spectroscopy, respectively. The antioxidant/pro- -oxidant activity of Crts inside liposomes was determined by the thiobarbituric acid?malondialdehyde (TBA?MDA) test. The investigated Crts acted more or less unexpected (as pro-oxidants) inside the lipid bilayers, interacting with the UV-produced lipid radicals and simultaneously suffering under the UV-irradiation. Their pro-oxidant activity with liposomes and under UV-irradiation could be explained by the formation of unstable adducts in the reaction with peroxyl radicals, or by Crts-cation radicals formation via the electron transfer mechanism. Such tentatively unexpected behavior of carotenoids should be taken into consideration in further carotenoids-based UV-filters projections in cosmetic formulations for skin protection.

Lipid radicals cause light-induced retinal degeneration

We have succeeded in detecting and scavenging lipid radicals in the retina of light induced AMD mice model.