Protective Effect of Antioxidants in Nitric Oxide/COX-2 Interaction during Inflammatory Pain: The Role of Nitration.

In clinical practice, inflammatory pain is an important, unresolved health problem, despite the utilization of non-steroidal anti-inflammatory drugs (NSAIDs). In the last decade, different studies have proven that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved in the development and maintenance of inflammatory pain and hyperalgesia via the post-translation modification of key proteins, such as manganese superoxide dismutase (MnSOD). It is well-known that inducible cyclooxygenase 2 (COX-2) plays a crucial role at the beginning of the inflammatory response by converting arachidonic acid into proinflammatory prostaglandin PGE2 and then producing other proinflammatory chemokines and cytokines. Here, we investigated the impact of oxidative stress on COX-2 and prostaglandin (PG) pathways in paw exudates, and we studied how this mechanism can be reversed by using antioxidants during hyperalgesia in a well-characterized model of inflammatory pain in rats. Our results reveal that during the inflammatory state, induced by intraplantar administration of carrageenan, the increase of PGE2 levels released in the paw exudates were associated with COX-2 nitration. Moreover, we showed that the inhibition of ROS with Mn (III) tetrakis (4-benzoic acid) porphyrin(MnTBAP) antioxidant prevented COX-2 nitration, restored the PGE2 levels, and blocked the development of thermal hyperalgesia.

Antioxidant activity of oleuropein and semisynthetic acetyl-derivatives determined by measuring malondialdehyde in rat brain.

OBJECTIVES: The purpose of this study was the evaluation of the antioxidant activity of natural and semisynthetic polyphenol derivatives from Olea europea L., by assessing malondialdehyde (MDA), an important marker of oxidative stress. METHODS: Polyphenol as hydroxytyrosol, oleuropein, oleuropein aglycone as mix of four tautomeric forms and their respective acetyl-derivatives were obtained from olive leaves using semisynthetic protocols. These compounds were administered intraperitoneally to Wistar rats treated with paraquat, an herbicide which is able to cause oxidative stress after central administration. Malondialdehyde was derivatized with 2,4-dinitrophenylhydrazine to produce hydrazone that was purified by solid-phase extraction. Using high-performance liquid chromatography coupled with a diode array, free and total MDA was measured on homogenate rat brain as marker of lipid peroxidation. The analytical method was fully validated and showed linearity in the tested concentration range, with detection limit of 5 ng/ml. Recovery ranged from 94.1 to 105.8%. KEY FINDINGS: Both natural and semisynthetic polyphenol derivatives from a natural source as olive leaves were able to reduce MDA detection. The more lipophilic acetyl-derivatives showed an antioxidant activity greater than parent compounds. This potency seems to put in evidence a strict correlation between lipophilicity and bioavailability.

Phthalates: European regulation, chemistry, pharmacokinetic and related toxicity.

Phthalates are chemicals widely used in industry and the consequences for human health caused by exposure to these agents are of significant current interest. Phthalate toxicity targets the reproductive and respiratory systems primarily, but they also may be involved in the processes of carcinogenesis and even in autism spectrum disorders. This article discusses the molecular and cellular mechanisms involved in organ toxicity of phthalates; furthermore, pharmacokinetic, chemistry and the European regulation are summarized.

The antidote effect of quinone oxidoreductase 2 inhibitor against paraquat-induced toxicity in vitro and in vivo.

BACKGROUND AND PURPOSE The mechanisms of paraquat (PQ)-induced toxicity are poorly understood and PQ poisoning is often fatal due to a lack of effective antidotes. In this study we report the effects of N-[2-(2-methoxy-6H-dipyrido{2,3-a:3,2-e}pyrrolizin-11-yl)ethyl]-2-furamide (NMDPEF), a melatonin-related inhibitor of quinone oxidoreductase2 (QR2) on the toxicity of PQ in vitro & in vivo. EXPERIMENTAL APPROACH Prevention of PQ-induced toxicity was tested in different cells, including primary pneumocytes and astroglial U373 cells. Cell death and reactive oxygen species (ROS) were analysed by flow cytometry and fluorescent probes. QR2 silencing was achieved by lentiviral shRNAs. PQ (30 mg·kg(-1)) and NMDPEF were administered i.p. to Wistar rats and animals were monitored for 28 days. PQ toxicity in the substantia nigra (SN) was tested by a localized microinfusion and electrocorticography. QR2 activity was measured by fluorimetry of N-benzyldihydronicotinamide oxidation. KEY RESULTS NMDPEF potently antagonized non-apoptotic PQ-induced cell death, ROS generation and inhibited cellular QR2 activity. In contrast, the cytoprotective effect of melatonin and apocynin was limited and transient compared with NMDPEF. Silencing of QR2 attenuated PQ-induced cell death and reduced the efficacy of NMDPEF. Significantly, NMDPEF (4.5 mg·kg(-1)) potently antagonized PQ-induced systemic toxicity and animal mortality. Microinfusion of NMDPEF into SN prevented severe behavioural and electrocortical effects of PQ which correlated with inhibition of malondialdehyde accumulation in cells and tissues. CONCLUSIONS AND IMPLICATIONS NMDPEF protected against PQ-induced toxicity in vitro and in vivo, suggesting a key role for QR2 in the regulation of oxidative stress.

Hypolipemic and hypoglycaemic activity of bergamot polyphenols: from animal models to human studies.

Bergamot juice produces hypolipemic activity in rats though the mechanism remains unclear. Here we investigated on the effect of bergamot extract (BPF) in diet-induced hyperlipemia in Wistar rats and in 237 patients suffering from hyperlipemia either associated or not with hyperglycaemia. BPF, given orally for 30 days to both rats and patients, reduces total and LDL cholesterol levels (an effect accompanied by elevation of cHDL), triglyceride levels and by a significant decrease in blood glucose. Moreover, BPF inhibited HMG-CoA reductase activity and enhanced reactive vasodilation thus representing an efficient phytotherapeutic approach in combating hyperlipemic and hyperglycaemic disorders.