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a-Lipoic acid (ALA) has been termed the 'ideal' antioxidant, a readily absorbed and bioavailable compound capable of scavenging a number of free radicals, and it has been used for treating diseases in which oxidative stress plays a major role. The present study was designed to gain a better understanding for the positive effects of ALA on the models of acute and chronic inflammation in rats, and also determine its anti-oxidative potency. In an acute model, three doses of ALA (50, 100 and 200 mg/kg) and one dose of indomethacin (25 mg/kg) or diclofenac (25 mg/kg) were administered to rats by oral administration. The paw volumes of the animals were calculated plethysmometrically, and 0·1 ml of 1 % carrageenan (CAR) was injected into the hind paw of each animal 1 h after oral drug administration. The change in paw volume was detected as five replicates every 60 min by plethysmometry. In particular, we investigated the activities of catalase, superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR), inducible NO synthase (iNOS) and myeloperoxidase (MPx), and the amounts of lipid peroxidation (LPO) or total GSH in the paw tissues of CAR-injected rats. We showed that ALA exhibited anti-inflammatory effects on both acute and chronic inflammations, and a strongly anti-oxidative potency on linoleic acid oxidation. Moreover, the administration of CAR induced oedema in the paws. ALA significantly inhibited the ability of CAR to induce: (1) the degree of acute inflammation, (2) the rise in MPx activity, (3) the increases of GST and iNOS activities and the amount of LPO and (4) the decreases of GPx, GR and SOD activities and the amount of GSH. In conclusion, these results suggest that the anti-inflammatory properties of ALA, which has a strong anti-oxidative potency, could be related to its positive effects on the antioxidant system in a variety of tissues in rats.

The anti-inflammatory effects of the methanol extract of the lichen species Peltigera rufescens (Weis.) Humb (MEPR) (Peltigeraceae) on acute (carrageenan-induced) and chronic (cotton pellet granule) phases of inflammation were investigated. The MEPR was capable of reducing carrageenan-induced inflammation and showed a potent antiproliferative effect (63.5%) in the chronic inflammation model. Inflammation is related to neutrophil infiltration and the production of neutrophil-derived mediators and free radicals. The MEPR reduced the myeloperoxidase and inducible nitric oxide synthase (NOS) activities, which were increased by carrageenan injection. Carrageenan injection also increased the lipid peroxidation (LPO) as compared with untreated paw tissues. The administration of MEPR, diclofenac, and indomethacin reduced the LPO in paw tissues through amelioration of the antioxidant defense systems. Neutrophil infiltration and neutrophil-derived free radicals in tissues therefore appeared to play an important role in the inflammation process induced by carrageenan. The anti-inflammatory effect of MEPR could be attributed to its reducing effect on the neutrophil-derived free radicals and its ameliorating effect on the antioxidant defense systems.

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