Antioxidant eugenosedin-A protects against lipopolysaccharide-induced hypotension, hyperglycaemia and cytokine immunoreactivity in rats and mice

Eugenosedin‐A has been demonstrated to possess α/β‐adrenoceptor and serotonergic receptor blocking activities. We have investigated by what mechanisms eugenosedin‐A prevents lipopolysaccharide (LPS)‐induced hypotension, vascular hyporeactivity, hyperglycaemia, oxidative injury or inflammatory cytokines formation in rats. Intravenous administration of eugenosedin‐A, trazodone, yohimbine (1 mg kg−1), aminoguanidine or ascorbic acid (15 mg kg−1) normalized LPS (10 mg kg−1)‐induced hypotension. Pretreatment with eugenosedin‐A or the other agents 30 min before LPS injection reduced aortic hyporeactivity. LPS‐induced increases in plasma interleukin‐1β (IL‐β), IL‐6, interferon‐γ (IFN‐γ), tumour necrosis factor‐α (TNF‐α) and blood glucose levels were significantly inhibited by eugenosedin‐A (1 mg kg−1, i.v.). The same dose of trazodone, a chloropiperazinylbenzene‐type antidepressant, and yohimbine, an α2‐adrenoceptor antagonist, reduced IL‐1β and TNF‐α, but it could not inhibit hyperglycaemia. Aminoguanidine, an inducible nitric oxide synthase (iNOS) inhibitor, and ascorbic acid, an antioxidant, decreased IL‐1β, TNF‐α contents and hyperglycaemia. Eugenosedin‐A and the other agents inhibited Fe2+‐ascorbic acid‐induced peroxidation in rat cortex, indicating that those agents had antioxidant effects, with the exception of aminoguanidine. In free radical scavenged experiments, eugenosedin‐A and ascorbic acid eliminated peroxyl radicals. All test agents inhibited the LPS‐induced increase of malondialdehyde (MDA) content in rat brain homogenates. When mice were administered an intraperitoneal injection of LPS alone, mortality occurred from 4 to 16 h, after which time all were dead. However, eugenosedin‐A significantly prolonged the survival time after LPS injection, suggesting that eugenosedin‐A protected against LPS‐induced cardiovascular dysfunction, hyperglycaemia, tissue injury and inflammatory cytokine production. This was attributable mainly to the antioxidant and peroxyl radical scavenged effects of eugenosedin‐A, and which may be, at least in part, due to its blockade on α/β‐adrenergic and serotonergic receptors.