Inhibitory effect of bifemelane on superoxide generation by activated neutrophils measured using a simple chemiluminescence method

Antioxidant properties of carvedilol: Inhibition of lipid peroxidation, protein oxidation and superoxide generation

Oxidative stress has been suggested to be an etiological factor in cerebro- and cardiovascular disorders. We examined antioxidant activities of carvedilol, a beta- and alpha-adrenoreceptor blocker. Carvedilol suppressed lipid auto-oxidation and protein carbonyl formation in brain homogenate in a dose-dependent manner. Carvedilol also suppressed superoxide generation of human neutrophils. These properties of carvedilol should be suitable for treating hypertension resulting in cerebro- and cardiovascular diseases.

Antioxidant properties and protective effects of a standardized extract of Hypericum perforatum on hydrogen peroxide-induced oxidative damage in PC12 cells

Free radical scavenging and antioxidant activities of a standardized extract of Hypericum perforatum (SHP) were examined for inhibition of lipid peroxidation, for hydroxyl radical scavenging activity and interaction with 1,1-diphenyl-2-picrylhydrazyl stable free radical (DPPH). Concentrations between 1 and 50 microg/ml of SHP effectively inhibited lipid peroxidation of rat brain cortex mitochondria induced by Fe2+/ascorbate or NADPH system. The results showed that SHP scavenged DPPH radical in a dose-dependent manner and also presented inhibitory effects on the activity of xanthine oxidase. In contrast, hydroxyl radical scavenging occurs at high doses. The protective effect of the standardized extract against H2O2-induced oxidative damage on the pheochromocytoma cell line PC 12 was investigated by measuring cell viability via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) assays, caspase-3-enzyme activity and accumulation of reactive oxygen species [2',7'-dichlorofluorescin (DCF) assay]. Following 8-h cell exposure to H2O2 (300 microM), a marked reduction in cell survival was observed, which was significantly prevented by SHP (pre-incubated for 24 h) at 1-100 microg/ml. In a separate experiment, different concentrations of the standardized extract (0.1-100 microg/ml) also attenuated the increase in caspase-3 activity and suppressed the H2O2 -induced reactive oxygen species generation. Taken together, these results suggest that SHP shows relevant antioxidant activity both in vitro and in a cell system, by means of inhibiting free radical generation and lipid peroxidation.

Antioxidant properties of nicergoline; inhibition of brain auto-oxidation and superoxide production of neutrophils in rats

Oxidative stress has been suggested to adversely influence cerebrovascular disorders and some neurodegenerative disorders. We examined whether nicergoline, an agent widely used for treating cerebrovascular disorders and senile mental impairment, possesses antioxidant activities and some beneficial effect on neutrophils generating free radicals. Although nicergoline did not scavenge superoxide produced from a superoxide-generating system, it significantly inhibited superoxide secretion from stimulated neutrophils. Auto-oxidation of brain homogenate of rats, monitored by formation of thiobarbituric acid-reactive substances, was suppressed by nicergoline in a dose-dependent manner. The oxidation of the homogenate was accelerated by activated neutrophils and was significantly suppressed by nicergoline. These observations suggest that nicergoine is an antioxidant that inhibits not only lipid peroxidation but also free radical generation from neutrophils. These properties of nicergoline should be beneficial in some pathological conditions including cerebrovascular and neurodegenerative disorders in which oxidative stress may have a pathoetiological role.

Bifemelane protects cultured cortical neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity

This study was performed to examine the neuroprotective action of bifemelane against glutamate cytotoxicity in cultured cortical neurons obtained from fetal rats. Cell viability was markedly reduced by a brief exposure to glutamate. Glutamate cytotoxicity was reduced by exposing cultures to bifemelane at concentrations of 1-10 microM for 24 hr prior to glutamate exposure. In contrast, glutamate cytotoxicity was not affected by adding bifemelane to the glutamate-containing-medium without pretreatment. Bifemelane did not affect N-methyl-D-aspartate (NMDA)-induced currents, although the higher concentration (100 microM) of the drug reduced them. These findings suggest that bifemelane protects against glutamate neurotoxicity without affecting NMDA receptors.

Serum of Behçet's disease enhances superoxide production of normal neutrophils

Using an MCLA-dependent chemiluminescence technique, we evaluated superoxide production by neutrophils isolated from 7 patients with Behçet's disease. After stimulation by phorbol myristate acetate, N-formyl-methionyl-leucyl-phenylalanine or opsonized zymosan, neutrophils from the patients produced significantly more superoxide than those from 20 controls. Pretreatment of control neutrophils with serum prominently enhanced superoxide production, and serum from Behçet's disease patients had a significantly greater effect than that from controls. These findings suggest that serum from patients with Behçet disease contains the priming factor(s) that can enhance enhanced superoxide production by neutrophils in response to stimulation.

Are the reactive oxygen-derived species (ROS) interactive properties of the many therapeutic drugs from various categories pertinent to their beneficial effects?

Many pathologic states are known to involve the generation of reactive oxygen species, (ROS). It is not known at present to what extent these phenomena are due to ROS formation, or if their formation is a result of the disease. Many therapeutic drugs either scavenge ROS or inhibit their formation. The purpose of this review is to match the drugs used for certain diseases with their anti-ROS actions. This attempted correlation is made to try to give an answer to the title question.

Activated microglia cause superoxide-mediated release of iron from ferritin

Ferritin contains the greatest part of the iron found in the brain, and the release of iron stores from ferritin has an essential role in iron-dependent lipid peroxidation. We examined the effect of cultured microglia on iron mobilization from ferritin. Microglia stimulated by phorbol myristate acetate caused the release of iron from ferritin, which was detected by monitoring iron-ferrozine complex formation. This iron mobilization was mediated by microglial superoxide production, as evidenced by the significant inhibitory effect of superoxide dismutase. The role of superoxide was also supported by the close correspondence of cumulative microglial superoxide production, as demonstrated by the MCLA (Cypridina luciferin analogue)-dependent chemiluminescence assay, to the time course of iron release from ferritin. Iron release induced by activated microglia may be partly responsible for the oxidative damage that is thought to occur in Parkinson's disease and other neurodegenerative disorders.

Inhibitory effects of bromocriptine on phospholipid peroxidation induced by dopa and iron

Membrane lipid peroxidation has been suggested to participate in the nigral degeneration of Parkinson's disease. In the present study, we demonstrate that bromocriptine inhibits lipid peroxidation in phospholipid liposomes induced by dopa and iron complexes. Because this lipid peroxidation is not mediated by active oxygen species, antioxidant properties of bromocriptine do not seem to be derived from radical scavenging effects in our experimental conditions. Bromocriptine had no scavenging effect on superoxide produced by hypoxanthine-xanthine oxidase when determined by the chemiluminescence assay using MCLA, a Cypridina luciferin analog, as a probe.