Cisplatin-induced hydroxyl radicals mediate pro-survival autophagy in human lung cancer H460 cells

BACKGROUND: Accumulated evidence demonstrates cisplatin, a recommended chemotherapy, modulating pro-survival autophagic response that contributes to treatment failure in lung cancer patients. However, distinct mechanisms involved in cisplatin-induced autophagy in human lung cancer cells are still unclear. RESULTS: Herein, role of autophagy in cisplatin resistance was indicated by a decreased cell viability and increased apoptosis in lung cancer H460 cells pre-incubated with wortmannin, an autophagy inhibitor, prior to treatment with 50 µM cisplatin for 24 h. The elevated level of hydroxyl radicals detected via flow-cytometry corresponded to autophagic response, as evidenced by the formation of autophagosomes and autolysosomes in cisplatin-treated cells. Interestingly, apoptosis resistance, autophagosome formation, and the alteration of the autophagic markers, LC3-II/LC3-I and p62, as well as autophagy-regulating proteins Atg7 and Atg3, induced by cisplatin was abrogated by pretreatment of H460 cells with deferoxamine, a specific hydroxyl radical scavenger. The modulations in autophagic response were also indicated in the cells treated with hydroxyl radicals generated via Fenton reaction, and likewise inhibited by pretreatment with deferoxamine. CONCLUSIONS: In summary, the possible role of hydroxyl radicals as a key mediator in the autophagic response to cisplatin treatment, which was firstly revealed in this study would benefit for the further development of novel therapies for lung cancer.

Effects of Shengxue Pills on formaldehyde-induced cell damage in mice / 中草药

Objective: To explore the prophylactic and curative effects of Shengxue Pills on formaldehyde-induced cell damage of lung, liver, spleen, bone marrow, and peripheral blood lymphocytes in mice and the mechanisms. Methods: The mice were randomly divided into five groups: control, Shengxue Pill prophylaxis, Shengxue Pill therapy, and two model groups. ELISA was used to detect hydroxyl radicals, superoxide anion radical, and ornithine decarboxylase (ODC) activities in the lung, liver, and spleen cells. Bone marrow cells and peripheral blood lymphocyte micronucleus rate were observed with high power lens. Results: Hydroxyl radicals, superoxide anion radicals, and ODS activities in the cells of the organs in mice were investigated, and the number of bone marrow cells and peripheral blood lymphocyte micronucleus rate in mice in the prophylacitc and therapeutic groups were significantly greater than those in the model groups, respectively as well as in the normal group. Conclusion: Shengxue Pills could prevent and cure the formaldehyde-induced cell damages of the lung, liver, spleen, bone marrow, and peripheral blood lymphocytes of mice.

Emergence of oxyl radicals as selective oxidants.

Hydroxyl radicals (HO·) are derived in Fenton reaction with ferrous salt and H2O2 in acid medium, and at neutral pH, metal-oxyl radicals (M-O·) predominate. Evidence is accumulating that M-O· radicals are also active in oxidation reactions, in addition to metal-oxo (M=O) now shown in many publications. Reactivity of these radicals gives selective oxidized products useful in cellular activities, in contrast to purported indiscriminate cell damage by hydroxyl radicals. Reactions with vanadium compounds, such as diperoxovanadate, peroxo-bridged mixed valency divanadate, vanadium-oxyl radical, tetravalent vanadyl and decavanadate illustrates selective gain in oxidative capacity of oxo- and oxyl- species. Occurrence of ESR signals typical of hydroxyl radicals is demonstrated in cell homogenates and tissue perfusates treated with spin trap agents. It is known for a long time lipid peroxides are formed in tissue microsomal systems exclusively in presence of salts of iron, among many metals tested. Oxygen and a reducing agent, ascorbate (non-enzymic) or NADPH (enzymic) are required to produce 'ferryl', the chelated Fe=O active form (possibly Fe-O· and Fe-O-O-Fe ?) for the crucial step of H-atom abstraction. Yet literature is replete with unsupported affirmations that hydroxyl radicals initiate lipid peroxidation, an unexplained fixation of mindset. The best-known ·OH generator, a mixture of ferrous salt and H2O2, does not promote lipid peroxidation, nor do the many hydroxyl radical quenching agents stop it. The availability of oxo and oxyl-radical forms with transition metals, and also with non metals, P, S, N and V, calls for expansion of vision beyond superoxide and hydroxyl radicals and explore functions of multiple oxygen radicals for their biological relevance.

Efecto protector de los polifenoles de Rhizophora mangle L sobre el daño oxidativo a proteínas y ADN / Protective effect of polyphenols from Rhizophora mangle L on oxidative damage to proteins and DNA

Al extracto acuoso de la corteza de Rhizophora mangle L se le ha demostrado un amplio espectro de usos medicinales: en el tratamiento de la mastitis bovina, la curación de heridas,las infecciones uterinas y las úlceras gastroduodenales; debido a sus propiedades antiséptica, cicatrizante, antiinflamatoria y antioxidante. Sin embargo, no se han completado los estudios de la actividad antioxidante a todos los niveles de complejidad para dilucidar los mecanismos de acción involucrados en este efecto farmacológico. Objetivo: determinar si el extracto acuoso de R. mangle y su fracción polifenólica protegen a las principales biomoléculas del daño oxidativo. La evaluación de la actividad antioxidante del extracto de R mangle y su fracción polifenólica sobre las principales biomoléculas se determinó mediante ensayo de daño oxidativo a la albúmina de suero bovino expuesta a los radicales hidroxilo generados en el sistema Fenton y ensayo de degradación oxidativa del ADN inducido por el sistema bleomicina-Fe3+.El extracto de R. mangle y su fracción polifenólica, a la máxima concentración ensayada, disminuyeron la oxidación de los grupos sulfidrilos en 87,3 y 89,1 por ciento; e inhibieron la degradación del ADN en 98,4 y 91,9 por ciento, respectivamente. El análisis de regresión mostró que ambos efectos fueron dependientes de la concentración de taninos en el extracto y su fracción. La comparación de las líneas de regresión reveló que el extracto y su fracción resultaron igualmente eficaces en proteger a la albúmina de suero bovino de la oxidación por los radicales hidroxilos, sin embargo, el extracto fue más eficaz en proteger al ADN de la degradación oxidativa que su fracción. El extracto acuoso de R. mangle mostró un efecto protector a las principales biomoléculas del daño oxidativo, evidenciado por la inhibición de la pérdida de grupos sulfidrilos en la albúmina de suero bovino y la disminución de la degradación del ADN...

The aqueous extract from Rhizophora mangle (L) bark has demonstrated a broad spectrum of medicinal uses; for example, in treating bovine mastitis, wound healing, uterine infections and gastroduodenal ulcers, due to its antiseptic, healing, anti-inflammatory and antioxidant properties. However, the antioxidant activity in its whole complexity has not been fully studied in order to elucidate the mechanisms of action involved in this pharmacological effect. Objective: to determine if R. mangle bark aqueous extract and its polyphenolic fraction protect the main biomolecules from oxidative damage. The antioxidant activity of R. mangle extract and its polyphenolic fraction on the main biomolecules was determined by the following methods: oxidative damage trial on bovine serum albumin exposed to hydroxyl radicals generated in the Fenton system and the bleomycin-Fe3+ system-induced DNA oxidative degradation trial. Results: the R. mangle bark extract and its polyphenolic fraction, at the highest tested concentration, reduced the sulfhydryl group oxidation by 87,3 percent and 89,1 percent and they also inhibited the DNA degradation by 98.4 percent and 91.9 percent respectively. The regression analysis demonstrated that both effects depended on tannin concentration in the extract and its fraction. The comparison of regression lines revealed that the extract and its fraction were equally effective in protecting bovine serum albumin from oxidation by hydroxyl radicals; however, the extract was more effective when protecting DNA from oxidative degradation than its fraction. The R mangle aqueous extract showed a protective effect on the main biomolecules from the oxidative damage, evidenced by inhibiting loss of sulfhydryl group in bovine serum albumin and decreasing the DNA degradation. At the same time, it was shown that polyphenolic compounds present in the extract were the main responsible for the antioxidant effects observed in this study

Hydroxyl Radical Production after Intrastriatal Injection of Dopamine and the Effect of Growth Hormone on the Apoptosis of Striatal Neurons Injured by Hypoxia-ischemia in Newborn Rat Brain / 대한소아내분비학회지

PURPOSE:We investigated the production of oxygen hydroxyl radicals in the striatum of neonatal rat brain after intrastriatal injection of dopamine (DA) and the effect of growth hormone (GH) on the apoptosis of striatal neurons injured by hypoxia-ischemia. METHODS:The extracellular striatal levels of 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA as indicators of hydroxyl radical(OH-) production were measured by in vivo microdialysis in the striatums of 7 day-old newborn rats (n=10) after direct intrastriatal infusion of dopamine hydrochloride (1.0 micromol/microL). The samples of perfused artificial cerebrospinal fluid (CSF) were collected every 10 minutes interval. The levels of DA, 2,3-DHBA and 2,5-DHBA of CSF were analysed by HPLC (high performance liquid chromatography). Also, the brains were removed at 24 hour after hypoxic-ischemic injury by Rice-Vannucci method. The coronal sections (12 micrometer) of paraffin-fixed brains were stained by TUNEL (terminal transferase-mediated dUTP nick-end-labelling) technique, and the neuronal cells undergoing apoptosis in the striatum were observed by fluorescent microscopy and compared between GH-treated (50 mg/kg, Dong-Ah Pharmacy Co.) and saline-treated rats. RESULTS:The extracellualr striatal levels of 2,3-DHBA and 2,5-DHBA increased abruptly in the first 10 minutes samples after intrastriatal injection of DA. After then, the levels declined slowely. The levels of striatal extracelluar 2.3-DHBA increased up to 621.8+/-508.7% of basal levels (P<0.05), and the levels of 2.5-DHBA increased up to 262.8+/-198.1% of basal levels (P<0.05). GH reduced markedly the number of apoptotic neuronal cells in the striatum after hypoxic-ischemic brain injury. CONCLUSION: The level of hydroxyl radicals increased abruptly after intrastriatal injection of DA and GH reduced markedly the number of apoptotic neuronal cells in the striatum after hypoxic-ischemic brain injury.

Membrane lipid peroxidation by ultrasound: Mechanism and implications.

Ultrasonic radiation produced a dose-dependent linear increase in lipid peroxidation in the liposomes membrane as reflected in the measurement of conjugated dienes, lipid hydroperoxides and malondialdehydes. Ultrasound induced malondialdehyde production could not be inhibited by any significant degree by superoxide dismutase or histidine or dimethyl furan but was very significantly inhibited by butylated hydroxytoluene, cholesterol, sodium benzoate, dimethyl sulphoxide, sodium formate and EDTA. The scavenger studies indicated the functional role of hydroxyl radicals in the initiation of ultrasound induced lipid peroxidation.